WO2023206318A1 - miR528在禾本科牧草生产和育种中的应用 - Google Patents

miR528在禾本科牧草生产和育种中的应用 Download PDF

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WO2023206318A1
WO2023206318A1 PCT/CN2022/090135 CN2022090135W WO2023206318A1 WO 2023206318 A1 WO2023206318 A1 WO 2023206318A1 CN 2022090135 W CN2022090135 W CN 2022090135W WO 2023206318 A1 WO2023206318 A1 WO 2023206318A1
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mir528
grass
seq
gene
expression
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French (fr)
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曹晓风
杨荣新
宋显伟
唐善杰
赵庆华
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中国科学院遗传与发育生物学研究所
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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H5/00—Angiosperms, i.e. flowering plants, characterised by their plant parts; Angiosperms characterised otherwise than by their botanic taxonomy
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H6/00—Angiosperms, i.e. flowering plants, characterised by their botanic taxonomy
    • A01H6/46—Gramineae or Poaceae, e.g. ryegrass, rice, wheat or maize
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09—Recombinant DNA-technology
    • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
    • C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
    • C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)

Definitions

  • This application relates to the application of miR528 in grass forage production and breeding. Specifically, this application relates to the application of down-regulation of miR528 expression/function in improving grass yield, tillering ability and regeneration ability.
  • Grassland is an important part of ecological agriculture and is crucial to the sustainable development of modern agriculture and animal husbandry and the ecological environment for human survival.
  • the area of "three modernizations" (degradation, desertification, and salinization) of grassland has been increasing day by day, resulting in increasingly acute conflicts between grassland and livestock, serious water and soil erosion, and the deterioration of the ecological environment year by year, which has seriously affected the economy. , ecology and the development of various social undertakings. For this reason, grassland ecological protection and restoration work is imperative.
  • Comprehensive improvement and selection of high-yielding, high-quality forage species are one of the most effective ways to protect and restore grassland ecology.
  • Graminous grasses are a major group of pastures and usually have the advantages of tender grass quality, good palatability, and rich nutrition. In addition to serving as high-quality forage, some grass species can also be used to produce bioenergy.
  • Switchgrass Pieranicum virgatum
  • Switchgrass is native to North America and has the characteristics of fast growth, high yield, and strong environmental adaptability. In particular, its lignocellulose content is extremely high, and its ethanol conversion rate can reach 57%. Therefore, the application of switchgrass in bioenergy has received widespread attention in the United States.
  • Leymus chinensis is widely distributed in Eurasia and is one of the important grasses in natural pastures. Leymus chinensis is also known as the "King of Grasses" because of its excellent quality, cold resistance, drought resistance, and alkali resistance. In addition to being used as forage, Leymus chinensis rhizomes have extremely strong penetration and expansion capabilities, and can form a developed underground rhizome network, which has a strong role in entangling and holding soil. It is a good plant for grassland restoration and soil and water conservation.
  • Tillering is a special branching characteristic independent of the main stem produced on the basal node of the stem during the growth and development of grasses. It is one of the important agronomic traits of grasses and directly affects the grass yield and seed yield of grasses.
  • the regeneration ability is the main characteristic of grass grass, which is directly related to the yield and mowing resistance of the grass. Cattle and sheep gnawing or manual mowing during grazing can remove the meristem at the top of the plant, promote the germination or elongation of recessive tillers and buds at the base, thereby stimulating pasture regeneration. Cultivating grasses with strong tillering and regeneration capabilities is one of the important ways to fundamentally solve the current contradiction between grass and livestock, repair and protect grassland resources, and protect the green ecological environment.
  • miR528 has an important regulatory function on the tillering and regeneration ability of grasses such as switchgrass and Leymus chinensis. That is, down-regulation of the expression and/or function of miR528 in grasses can significantly increase the tiller number and/or regeneration ability of grasses.
  • the present invention provides a method for improving the tillering ability and/or regeneration ability of grass grass, which includes down-regulating the expression and/or function of miR528 in grass grass.
  • the grasses include, but are not limited to, Panicum virgatum, Leymus chinensis, Brachypodium distachyon, Miscanthus, and Elytrigia intermedia. , Uraria crinita, Setaria viridis, Anastatica, Elymus sibiricus, Panicum miliaceum, and Bromus inermis. In some embodiments, the grasses are switchgrass and Leymus chinensis.
  • the down-regulation of the expression of miR528 is achieved by gene knockout or gene editing of the gene encoding miR528, MIR528. In some embodiments, the down-regulation of the expression of miR528 is achieved by gene editing of the transcribed region of the encoding gene MIR528, and/or its upstream regulatory region, and/or its downstream regulatory region. In some embodiments, the CRISPR/Cas9 system is used to perform gene editing on the transcribed region encoding the gene MIR528, and/or its upstream regulatory region, and/or its downstream regulatory region.
  • an sgRNA that is reverse complementary to the encoding gene MIR528 is used in the CRISPR/Cas9 system: CAGTGGAAGGGGCATGCAG (SEQ ID NO: 4), and the Cas9 protein is targeted to the encoding gene MIR528 by using the CRISPR/Cas9 system, Changes in the sequence of the coding gene result in down-regulation of miR528 expression.
  • the function of miR528 is down-regulated by STTM. In some embodiments, the functional downregulation of miR528 is performed by expressing in grass grass a sequence that is recognized by and interacts with miR528. In some embodiments, the functional downregulation of miR528 is performed by expressing in grass grass an artificial mimic target sequence or a short tandem mimic target sequence that is recognized by, interacts with, and interacts with miR528 without being cleaved by miR528. In some embodiments, the function of miR528 is down-regulated by introducing into grass grass a vector expressing an artificial mimic target sequence and/or a short tandem mimic target, wherein the vector constitutively expresses the artificial mimic target sequence or a short tandem mimic target.
  • the synthetic analog target sequence includes or consists of the nucleotide sequence shown in SEQ ID NO: 1.
  • the short tandem analog target is a sequence obtained by connecting two artificially synthesized analog target sequences (SEQ ID NO:1) through a 48nt spacer sequence (SEQ ID NO:2) (SEQ ID NO: 3), which functions to downregulate the function of miR528.
  • the present invention also provides the application of expression and/or functional down-regulation of miR528 in improving the tillering ability and regeneration ability of grasses.
  • the present invention also provides an artificial simulated target sequence and a short tandem simulated target (STTM) that can realize the functional down-regulation of miR528 in grasses.
  • the synthetic analog target sequence includes or consists of the nucleotide sequence shown in SEQ ID NO: 1.
  • the short tandem analog target comprises or consists of the nucleotide sequence set forth in SEQ ID NO:3.
  • the present invention also provides a CRISPR-Cas9 vector and its sgRNA capable of knocking out or gene editing the miR528 encoding gene MIR528 in grasses.
  • the inventors of the present invention have found that down-regulating the expression and/or function of miR528 has no adverse effect on the plant height of grasses. Therefore, on the basis of significantly enhancing the tillering ability of grasses, the biomass of grasses can be greatly increased. accumulation.
  • downregulation of the expression and/or function of miR528 will enhance the regeneration ability of grasses and contribute to the increase in the total amount of forage. For grasses that can be used as both forage and bioenergy plants, the increase in total supply is beneficial to the development of the livestock industry and the ethanol fuel industry.
  • the present invention also provides a method for cultivating a new line of grass forage with enhanced tillering ability and/or regeneration ability, which method includes down-regulating the expression and/or function of miR528 in the new line of grass forage.
  • Figure 1 shows the alignment results of miR528 precursor sequences in several sequenced grasses.
  • Figure 2 shows that the mature sequence of miR528 is present in a variety of grasses.
  • Figure 3 shows the STTM sequence used to inhibit the function of miR528 in Example 3. This sequence contains two miR528 binding sites, and each site contains a "bulge" of 3 bases (CTA) in the middle, so it cannot be cleaved by miR528.
  • CTA 3 bases
  • Figure 4 shows the STTM expression vector constructed in Example 4, in which the STTM sequence that specifically binds to miR528 is driven by the constitutive promoter ubiquitin promoter.
  • Figure 5 shows the STTM expression level in switchgrass introduced with the STTM expression vector in Example 5.
  • Figure 6 shows the phenotype of switchgrass introduced with the STTM expression vector in Example 6, wherein the switchgrass introduced with the STTM expression vector has increased tiller number and biomass compared to switchgrass introduced with the empty vector.
  • Figure 7 shows the regeneration phenotype of the switchgrass introduced with the STTM expression vector 10 days after mowing in Example 7, wherein compared with the switchgrass introduced with the empty vector, the regeneration ability of the switchgrass introduced with the STTM expression vector is enhanced after mowing.
  • Figure 8 shows the results of sequence editing and identification of switchgrass miR528 after introducing the miR528 CRISPR/Cas9 vector in Example 9.
  • Figure 9 shows the results of sequence editing and identification of Leymus chinensis miR528 after the introduction of the miR528 CRISPR/Cas9 vector in Example 9.
  • Figure 10 shows that the transgenic switchgrass with knockout of miR528 in Example 10 exhibits a phenotype of enhanced regeneration ability.
  • Figure 11 shows that the miR528 knockout transgenic Leymus chinensis in Example 10 exhibits a phenotype of enhanced regeneration ability.
  • miRNA refers to a class of endogenous small RNAs with a length of 21-24nt. They do not encode proteins, but negatively regulate the expression of target genes at the post-transcriptional level in the form of complementary base pairing, thereby regulating the expression of target genes at the post-transcriptional level. Participate in processes such as biological growth and development and environmental response. In plants, miRNAs mainly negatively regulate the expression of target genes by degrading target mRNAs, and then exert regulatory functions in a variety of biological processes.
  • STTM Short Tandem Target Mimic
  • STTM is composed of two artificially synthesized miRNA target sequences connected in series. There is a 3-base bulge structure at the miRNA cleavage site of the two simulated targets. This structure enables the miRNA to interact with the simulated target. The target binds but cannot cleave it, so simulated target binding can adsorb the miRNA and inhibit its regulation of the real endogenous target gene.
  • CRISPR-Cas9 Clustered Regularly Interspaced Short Palindromic repeats/CRISPR associated 9) system
  • CRISPR-Cas9 Clustered Regularly Interspaced Short Palindromic repeats/CRISPR associated 9) system
  • ZFN Zinc Finger Nuclease
  • TALEN Transcription Activator-like Effector Nucleases
  • Genome editing technology is widely used in the fields of gene therapy and crop improvement. The principle is that the endonuclease Cas9 cuts the double-stranded DNA at the target site under the targeting effect of guide RNA (sgRNA). The broken DNA introduces mutations during the repair process to achieve sequence changes in the target gene.
  • sgRNA guide RNA
  • miR528 is one of the earliest reported miRNA family members in rice and is conserved in monocots.
  • Chinese patent application CN201410423077.X records the role of miR528 in rice heading period and anti-virus. Specifically, overexpression of miR528 advances the heading time of rice, while downregulation of expression enhances rice's resistance to RSV virus and delays the heading time.
  • miR528 has an important regulatory function on the tillering and regeneration ability of grasses such as switchgrass and Leymus chinensis. That is, down-regulation of the expression and/or function of miR528 in grasses can significantly increase the tiller number and/or regeneration ability of grasses. Therefore, the present invention provides the application of miR528 in grass production and breeding.
  • a first aspect of the present invention provides a method for improving the tillering ability and/or regeneration ability of grasses, thereby improving the biomass accumulation of grasses and contributing to an increase in the total amount of grasses.
  • the increase in total supply is beneficial to the development of the livestock industry and the ethanol fuel industry.
  • the method includes down-regulating the expression and/or function of miR528 in grasses.
  • the grasses may include, but are not limited to, Panicum virgatum, Leymus chinensis, Brachypodium distachyon, Miscanthus, Elytrigia intermedia ), Uraria crinita, Setaria viridis, Anastatica, Elymus sibiricus, Panicum miliaceum, and Bromus inermis.
  • the grasses are switchgrass and Leymus chinensis.
  • the down-regulation of the expression of miR528 can be achieved by gene knockout or gene editing of the gene encoding miR528, MIR528.
  • the down-regulation of the expression of miR528 can be achieved by gene editing of the transcribed region of the encoding gene MIR528, and/or its upstream regulatory region, and/or its downstream regulatory region.
  • the CRISPR/Cas9 system can be used to perform gene editing on the transcribed region encoding the gene MIR528, and/or its upstream regulatory region, and/or its downstream regulatory region.
  • an sgRNA that is reverse complementary to the encoding gene MIR528 is used in the CRISPR/Cas9 system: CAGTGGAAGGGGCATGCAG (SEQ ID NO: 4), and the Cas9 protein is targeted to the encoding gene MIR528 by using the CRISPR/Cas9 system, Changes in the sequence of the coding gene (which may include base deletions, substitutions or insertions) result in downregulation of the expression of miR528.
  • the function of miR528 can be down-regulated through STTM.
  • the STTM method may include expressing in grass grass a sequence that is recognized by and interacts with miR528.
  • the STTM method may include expressing in grass grass an artificial mimic target sequence or a short tandem mimic target that is recognized by, interacts with, and interacts with, but not cleaved by, miR528.
  • the STTM method may include introducing a vector expressing an artificial mimic target sequence and/or a short tandem mimic target into the grass grass to downregulate the function of miR528, wherein the vector constitutively expresses the artificial mimic target sequence or Short tandem analog targets.
  • the synthetic analog target sequence may include or consist of a nucleotide sequence as shown below: CTCCTCTGCATCTAGCCCCTTCCA (SEQ ID NO: 1).
  • two tandem synthetic analog target sequences are separated by a 48nt spacer sequence, resulting in a short tandem analog target that can also function to downregulate miR528, where the spacer sequence is as follows: gttgttgttgttatggtctaatttaaatatggtctaaagaagaagaat (SEQ ID NO :2).
  • the final functional short tandem analog target contains or consists of the nucleotide sequence shown below:
  • a second aspect of the present invention also provides a method for cultivating a new line of grass forage with enhanced tillering ability and/or regeneration ability, which includes down-regulating the expression and/or function of miR528 in the new line of grass forage, such as Relative to the parent grass, or wild type grass.
  • the method for down-regulating the expression and/or function of miR528 in the new grass line may be as described in part (1) above.
  • the third aspect of the present invention also provides a CRISPR-Cas9 vector and its sgRNA capable of knocking out or gene editing the miR528 encoding gene MIR528 in grasses.
  • the sgRNA comprises or consists of the nucleotide sequence shown below: CAGTGGAAGGGGCATGCAG (SEQ ID NO: 4).
  • the fourth aspect of the present invention also provides an artificial simulated target sequence and a short tandem simulated target (STTM) capable of realizing the functional down-regulation of miR528 in grass forage. Both of them can be used in the STTM method to realize the functional down-regulation of miR528 in grass. .
  • STTM short tandem simulated target
  • the synthetic analog target sequence includes or consists of the nucleotide sequence shown in SEQ ID NO: 1.
  • the short tandem analog target includes or consists of the nucleotide sequence set forth in SEQ ID NO:3.
  • a DNA sequence CTCCTCTGCATGCCCCTTCCA (SEQ ID NO: 6), which is complementary to the mature sequence of miR528, and a DNA sequence TGTATCGTTCCAATTTTATCGGATGT (SEQ ID NO: 7), which is complementary to the U6 snRNA sequence, were artificially synthesized and used as internal controls for loading amounts between different materials.
  • Polynucleotide kinase T4PNK (NEB, M0201S) was used to label the terminal ⁇ - 32P isotope of the above two DNA sequences respectively (the labeling probe system is shown below), and the labeled DNA sequences were used as hybridization probes.
  • T4PNK labeled probe system 1 ⁇ l of DNA probe at 10 ⁇ M, 5 ⁇ l of 10 ⁇ T4kinase Buffer, 5 ⁇ l of ⁇ - 32 P isotope-labeled ATP, 1 ⁇ l of T4PNK (10 U/ ⁇ l), and 38 ⁇ l of ultrapure water. React on a heating block at 37°C for 1 hour.
  • RNA from different forage materials was extracted using TRNzol (TIANGEN), electrophoresed through a 15% polyacrylamide gel containing 7M urea at 200V for 2 hours, and then transferred to a membrane for hybridization.
  • the hybridization reaction was carried out overnight at 42°C, and the membrane was washed twice with membrane washing buffer (2XSSC, 0.2% SDS). Then the membrane was wrapped with plastic wrap.
  • the isotope signal was collected using the Typhoon FLA9500 laser scanning imager, and the isotope signal was collected based on the signal strength. Weakly characterized miR528 accumulation.
  • the STTM sequence specific for mature miR528 was designed as shown in Figure 3 . Specifically, a miR528 binding site was designed at both ends of a sequence with a total length of 96 bases, and an additional 3 bases were added between the 10th and 11th bases of the miR528 binding region.
  • SEQ ID NO:3 The specific sequence is shown in SEQ ID NO:3. This sequence can bind to miR528 but will not be cleaved by post-transcriptional regulation mediated by miR528.
  • DNA sequence CF3380 (SEQ ID NO:8) and its reverse complement sequence CF3381 (SEQ ID NO:9) were synthesized.
  • the STTM transgenic vector constructed in Example 4 was transferred into switchgrass callus, and a part of the callus was transferred into the empty vector as a control. After differentiation and emergence, the seedlings were transferred to vermiculite nutrient soil for culture. After 4 months, TRNzol (TIANGEN) was used to extract the total RNA of transgenic switchgrass. 2 ⁇ g of total RNA was taken from each sample, reverse transcribed to generate cDNA through HiScript II 1st Strand cDNA synthesis kit (Vazyme, R211), and then quantitative PCR was used to detect the expression level of STTM RNA in each transgenic line.
  • TRNzol TIANGEN
  • the primers used to detect STTM expression are CF6738 (SEQ ID NO:10) and CF6739 (SEQ ID NO:11), and the primers used to amplify the internal reference gene ACTIN are CF6095 (SEQ ID NO:12) and CF6096 (SEQ ID NO:13 ).
  • the STTM expression levels in each transgenic line are shown in Figure 5. In multiple independent transgenic lines, high levels of STTM RNA expression were detected; however, in the transgenic lines transformed into the empty vector, no STTM RNA expression was detected.
  • the CRISPR/Cas9 knockout vector pCXUN-Cas9 was a kind gift from Professor Wang Rongchen.
  • OsU3-sgRNA plasmid (see Chinese patent application CN201810059520.8) as a template and forward primer U3-F (SEQ ID NO:14)
  • Use the reverse primer HX8366 (SEQ ID NO:15) to amplify the first half of the guide RNA expression cassette; use the forward primer HX8365 (SEQ ID NO:16) and the reverse primer U3-R (SEQ ID NO:17) to amplify The second half of the guide RNA expression cassette.
  • the two fragments were connected to the KpnI restriction site of pCXUN-Cas9 through homologous recombination to construct a CRISPR/Cas9 vector for targeted editing of the miR528 coding sequence
  • the PCR system during the vector transformation process is: 10ng plasmid template, 2 ⁇ l forward primer (10 ⁇ M), 2 ⁇ l reverse primer (10 ⁇ M), 25 ⁇ l 2 ⁇ Phanta Max Buffer, 1 ⁇ l dNTP Mix (10mM each), Phanta Max Super-Fidelity DNA Polymerase (1U/ ⁇ l) (Nanjing Novezan Biotechnology Co., Ltd., P505-d1) 1 ⁇ l, add ddH 2 O to make up to 50 ⁇ l.
  • the PCR reaction program was: 94°C for 2 min; (94°C for 30 s, 58°C for 30 s, 72°C for 30 s) ⁇ 32 cycles; 72°C for 10 min, and maintained at 16°C.
  • the enzyme digestion system is: 5 ⁇ l of 10 ⁇ CutSmart Buffer, 1 ⁇ l of restriction endonuclease (KpnI, 4U/ ⁇ l), 1 ⁇ g of pCXUN-Cas9 plasmid, ddH 2 O, complete to 50 ⁇ l, and digest at 37°C for at least 8 hours.
  • the miR528 CRISPR/Cas9 vector constructed in Example 8 was transformed into switchgrass and Leymus chinensis calli.
  • the obtained transgenic regenerated plants were genotyped, and forward primer CP1102 (SEQ ID NO:18) and reverse primer CP1103 (SEQ ID NO:19) were used to identify switchgrass miR528 copy 1 (chr01N in Figure 8: 33956382-33956402) ;
  • the PCR system is: 50ng genomic DNA, 0.8 ⁇ l forward primer (10 ⁇ M), 0.8 ⁇ l reverse primer (10 ⁇ M), 10 ⁇ l 2 ⁇ Phanta Max Buffer, 0.4 ⁇ l dNTP Mix (10mM each), Phanta Max Super-Fidelity DNA Polymerase ( 1U ⁇ l) (Nanjing Novezan Biotechnology Co., Ltd., P505-d1) 0.4 ⁇ l, ddH 2 O was added to 20 ⁇ l.
  • the PCR reaction program was: 94°C for 2 min; (94°C for 30 s, 58°C for 30 s, 72°C for 30 s) ⁇ 35 cycles; 72°C for 10 min, and maintained at 16°C.
  • the sequencing results were compared with the reference genome sequence.
  • the miR528 sequence editing detection results of switchgrass and Leymus chinensis are shown in Figure 8 and Figure 9 respectively.
  • Crispr-49, crispr-50, crispr-51 and crispr-54 in Figure 8 Respectively indicate different switchgrass transgenic regenerated plants.
  • Leymus chinensis miR528 CR-1, Leymus chinensis miR528 CR-2, Leymus chinensis miR528 CR-6 and Leymus chinensis miR528 CR-7 in Figure 9 respectively indicate different Leymus chinensis transgenic regenerated plants. It can be seen that we used CRISPR/Cas9 technology to obtain transgenic regenerated plants of switchgrass and Leymus chinensis with changes in the miR528 sequence.
  • Example 10 Identification of regeneration ability of miR528 CRISPR/Cas9 gene editing in switchgrass and Leymus chinensis
  • the top parts of the 4-month-old transgenic switchgrass seedlings with knockout of miR528 cultured in vermiculite nutrient soil were cut uniformly, so that only 15cm long stems remained in the above-ground part of the plants. Each plant was divided into equal sizes from the roots and replanted. Return to the vermiculite nutrient soil and culture, and observe the phenotype of new tillers after one week and two weeks respectively.
  • the transgenic switchgrass with knockout of miR528 showed a faster budding rate, indicating that the transgenic switchgrass with knockout of miR528 has stronger regeneration ability after mowing.
  • miR528 knockout transgenic Leymus chinensis has stronger regeneration ability and higher number of tillers, indicating that miR528 knockout can improve the regeneration ability and tillering ability of Leymus chinensis.
  • the present invention provides the application of miR528 in the production and breeding of grasses.
  • By down-regulating the expression and/or function of miR528 in grasses the tiller number and regeneration ability of grasses can be significantly improved, thereby contributing to Production and breeding of grasses suitable for industrial applications.

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Abstract

本发明公开miR528在禾本科牧草生产和育种中的应用，通过下调miR528的表达和/或功能，能够显著增强禾本科牧草的分蘖能力和/或再生能力，有助于禾本科牧草生物量累积，并有助于培育具有增强的分蘖能力和/或再生能力的禾本科牧草新品系。

Description

miR528在禾本科牧草生产和育种中的应用 技术领域
本申请涉及miR528在禾本科牧草生产和育种中的应用。具体而言，本申请涉及miR528表达/功能下调在提高禾本科牧草产量、分蘖能力和再生能力中的应用。
背景技术
草原是生态农业重要组成部分，对现代农牧业可持续发展和人类生存的生态环境至关重要。但由于长期的过度开发和掠夺式利用，草原“三化”(退化、沙化、盐碱化)面积日益增加，导致草畜矛盾日益尖锐，水土流失严重，生态环境逐年恶化，已严重影响了经济、生态和各项社会事业的发展。为此，草原生态保护修复工作势在必行。而综合改良和筛选高产、优质的牧草品种是草原生态保护修复最有效的途径之一。
禾本科牧草是牧草的一个主要类群，通常具有草质柔嫩、适口性好、营养丰富等优点。除了作为优质饲草外，一些禾本科草种还可用于生产生物能源。柳枝稷(Panicum virgatum)原产于北美，具有速生、高产、环境适应能力强等特性，特别是其木质纤维素含量极高，乙醇转化率可达到57％。因此柳枝稷在生物能源方面的应用在美国已被广泛关注。
羊草(Leymus chinensis)广泛分布于欧亚大陆，是天然草场上的重要牧草之一。因其具有品质优良，耐寒、耐旱、耐碱等优点，羊草也被誉为“禾草之王”。除作为饲草外，羊草根茎穿透和扩展能力极强，且能形成发达的地下根茎网络，盘结固持土壤作用强大，是很好的草原修复和水土保持植物。
分蘖是禾本科牧草生长发育过程中在茎秆基部节上产生的独立于主干的一种特殊分枝特性，为禾本科牧草的重要农艺性状之一，直接影响牧草的产草量和种子产量。而再生能力是禾本科牧草的主要特性，直接关乎牧草的产量及耐刈割性。放牧过程中的牛羊啃食或人工刈割能移去植物顶端分生组织，促进基部隐性蘖、芽的萌发或和伸长，从而刺激牧草再生。培育分蘖及再生能力强的禾本科牧草，是从根本上解决目前草畜矛盾，修复和保护草原资源，保护绿色生态环境的重要途径之一。
发明内容
本申请的发明人通过大量研究，发现miR528对柳枝稷和羊草等禾本科牧草的分蘖及再生能力上具有重要的调控功能。即，禾本科牧草中的miR528的表达和/或功能的下 调，能够显著提高禾本科牧草的分蘖数和/或再生能力。
因此，本发明提供一种提高禾本科牧草的分蘖能力和/或再生能力的方法，其包括使禾本科牧草中的miR528的表达和/或功能下调。
在一些实施方式中，所述禾本科牧草包括但不限于柳枝稷(Panicum virgatum)、羊草(Leymus chinensis)、二穗短柄草(Brachypodium distachyon)、芒草(Miscanthus)、中间偃麦草(Elytrigia intermedia)、猫尾草(Uraria crinita)、狗尾草(Setaria viridis)、复活草(Anastatica)、老芒麦(Elymus sibiricus)、黍(Panicum miliaceum)、和无芒雀麦(Bromus inermis)。在一些实施方式中，所述禾本科牧草为柳枝稷和羊草。
在一些实施方式中，所述miR528的表达下调通过miR528编码基因MIR528的基因敲除或基因编辑等实现。在一些实施方式中，所述miR528的表达下调通过对编码基因MIR528的转录区、和/或其上游调控区、和/或其下游调控区进行基因编辑实现。在一些实施方式中，采用CRISPR/Cas9系统对编码基因MIR528的转录区、和/或其上游调控区、和/或其下游调控区进行基因编辑。在一些实施方式中，在所述CRISPR/Cas9系统中采用与编码基因MIR528反向互补的sgRNA：CAGTGGAAGGGGCATGCAG(SEQ ID NO:4)，通过使用该CRISPR/Cas9系统将Cas9蛋白靶向编码基因MIR528，对该编码基因的序列造成改变，从而造成miR528的表达下调。
在一些实施方式中，通过STTM的方法使miR528的功能下调。在一些实施方式中，miR528的功能下调为通过在禾本科牧草中表达能够被miR528识别且与miR528相互作用的序列而进行。在一些实施方式中，miR528的功能下调为通过在禾本科牧草中表达能够被miR528识别、且与miR528相互作用而不被miR528切割的人工模拟靶序列或短串联模拟靶标而进行。在一些实施方式中，通过向禾本科牧草导入表达人工模拟靶序列和/或短串联模拟靶标的载体而使miR528的功能下调，其中该载体组成型地表达人工模拟靶序列或短串联模拟靶标。在一些实施方式中，人工合成模拟靶序列包含如SEQ ID NO:1所示的核苷酸序列或由其组成。在一些实施方式中，短串联模拟靶标为由两条人工合成模拟靶序列(SEQ ID NO:1)通过一条具有48nt的间隔序列(SEQ ID NO:2)连接而获得的序列(SEQ ID NO:3)，其发挥使miR528的功能下调的功能。
本发明还提供了miR528的表达和/或功能下调在改善禾本科牧草的分蘖能力和再生能力中的应用。
本发明还提供一种能够实现禾本科牧草中miR528的功能下调的人工模拟靶序列和短串联模拟靶标(STTM)。在一些实施方式中，人工合成模拟靶序列包含如SEQ ID NO:1所示的核苷酸序列或由其组成。在一些实施方式中，短串联模拟靶标包含如SEQ ID  NO:3所示的核苷酸序列或由其组成。
本发明还提供一种能够实现miR528编码基因MIR528在在禾本科牧草中敲除或对其进行基因编辑的CRISPR-Cas9载体及其sgRNA。
本发明的发明人发现，下调miR528的表达和/或功能，对禾本科牧草的株高没有不良影响，因而在显著增强禾本科牧草的分蘖能力的基础上，可以大大增加禾本科牧草的生物量累积。此外，miR528表达和/或功能的下调，会增强禾本科牧草的再生能力，有助于牧草总量的增加。对于既可作为饲草又可作为生物能源植物的禾本科牧草而言，总供应量的增加，利于畜牧业和乙醇燃料产业的发展。
本领域技术人员可以利用上述发现，改良和培育出miR528的表达和/或功能下调的牧草新品系，以方便该技术的推广。因此，本发明还提供一种培育具有增强的分蘖能力和/或再生能力的禾本科牧草新品系的方法，该方法包括使所述禾本科牧草新品系中miR528的表达和/或功能下调。
附图说明
本申请的内容将在以下结合附图进一步阐述，其中附图仅为示例说明，并不限制本发明的范围。
图1示出几种已测序禾本科牧草中miR528前体序列的比对结果。
图2示出多种禾本科牧草中均存在miR528成熟序列。
图3示出实施例3中用于抑制miR528功能的STTM序列，该序列含有两个miR528结合位点，各位点中间含有3个碱基(CTA)的“凸起”，因此不能被miR528切割。
图4示出实施例4中所构建的STTM表达载体，其中特异结合miR528的STTM序列在组成型启动子泛素启动子的驱动下。
图5示出实施例5中导入STTM表达载体的柳枝稷中的STTM表达水平。
图6示出实施例6中导入STTM表达载体的柳枝稷的表型，其中与导入空载体的柳枝稷相比，导入STTM表达载体的柳枝稷具有增加的分蘖数目和生物量。
图7示出实施例7中导入STTM表达载体的柳枝稷在刈割10天后的再生表型，其中与导入空载体的柳枝稷相比，导入STTM表达载体的柳枝稷刈割后再生能力增强。
图8示出实施例9中导入miR528 CRISPR/Cas9载体后，柳枝稷miR528序列编辑鉴定结果。
图9示出实施例9中导入miR528 CRISPR/Cas9载体后，羊草miR528序列编辑鉴定结果。
图10示出实施例10中miR528敲除的转基因柳枝稷表现出再生能力增强的表型。
图11示出实施例10中miR528敲除的转基因羊草表现出再生能力增强的表型。
具体实施方式
本申请的内容将在以下结合具体实施方式的描述进一步阐述，其中具体实施方式仅为示例说明，并不限制本发明的范围。本申请实施方式中的各元素可以做出变更、取代、省略等，而不脱离本发明的本质。本申请的保护范围由权利要求及其等同方式决定。
在本文中，术语“miRNA”是指一类长度为21-24nt的内源小分子RNA，它们不编码蛋白质，而是以碱基互补配对的形式在转录后水平负调控靶基因的表达，进而参与到生物的生长发育及环境响应等过程中。在植物中，miRNA主要通过降解靶mRNA而负调控靶基因的表达，进而在多种生物学过程中行使调控功能。
在本文中，术语“短串联模拟靶标(Short Tandem Target Mimic,STTM)”或“STTM”是指一种抑制miRNA功能的方法。具体而言，STTM由两个人工合成的miRNA模拟靶标序列串联构成，在这两个模拟靶标的miRNA切割位点处都具有一个3个碱基的凸起结构，这一结构使miRNA能与模拟靶标结合但无法对其进行切割，因此模拟靶标结合可以吸附miRNA从而抑制其对真正内源靶基因的调控。
在本文中，术语“CRISPR-Cas9(Clustered Regularly Interspaced Short Palindromic repeats/CRISPR associated 9)系统”是指一种基因编辑系统。由于CRISPR-Cas9系统的精确性和易用性，其逐渐取代了传统的锌指核酸酶(Zinc Finger Nuclease，ZFN)、类转录激活因子效应物核酸酶(Transcription Activator-like Effector Nucleases，TALEN)等基因组编辑技术，被广泛用于基因治疗、作物改良领域。其原理是核酸内切酶Cas9在向导RNA(sgRNA)的靶向作用下，对靶位点的双链DNA进行切割，断裂的DNA在修复过程中引入突变，实现对靶基因的序列改变。已有研究表明利用CRISPR/Cas9技术可以对miRNA编码区进行靶向编辑从而抑制miRNA的功能。
在本文中，术语“miR528”是水稻中最早被报道的miRNA家族成员之一，且在单子叶植物中保守存在。中国专利申请CN201410423077.X记载了miR528在水稻抽穗期和抗病毒方面的作用。具体而言，miR528的过量表达使水稻抽穗时间提前，而表达下调则使得水稻的抗RSV病毒能力增强、且抽穗时间延迟。
本申请的发明人通过大量研究，发现miR528对柳枝稷和羊草等禾本科牧草的分蘖及再生能力上具有重要的调控功能。即，禾本科牧草中的miR528的表达和/或功能的下 调，能够显著提高禾本科牧草的分蘖数和/或再生能力。因此，本发明提供了miR528在禾本科牧草生产和育种中的应用。
(1)miR528在禾本科牧草生产中的应用
本发明的第一方面提供一种提高禾本科牧草的分蘖能力和/或再生能力的方法，由此可以提高禾本科牧草的生物量累积，有助于牧草总量的增加。对于既可作为饲草又可作为生物能源植物的禾本科牧草而言，总供应量的增加，利于畜牧业和乙醇燃料产业的发展。所述方法包括使禾本科牧草中的miR528的表达和/或功能下调。
在一些实施方式中，所述禾本科牧草可包括但不限于柳枝稷(Panicum virgatum)、羊草(Leymus chinensis)、二穗短柄草(Brachypodium distachyon)、芒草(Miscanthus)、中间偃麦草(Elytrigia intermedia)、猫尾草(Uraria crinita)、狗尾草(Setaria viridis)、复活草(Anastatica)、老芒麦(Elymus sibiricus)、黍(Panicum miliaceum)、和无芒雀麦(Bromus inermis)。在一些实施方式中，所述禾本科牧草为柳枝稷和羊草。
在一些实施方式中，所述miR528的表达下调可通过miR528编码基因MIR528的基因敲除或基因编辑等实现。
在一些实施方式中，所述miR528的表达下调可通过对编码基因MIR528的转录区、和/或其上游调控区、和/或其下游调控区进行基因编辑实现。
在一些实施方式中，可采用CRISPR/Cas9系统对编码基因MIR528的转录区、和/或其上游调控区、和/或其下游调控区进行基因编辑。在一些实施方式中，在所述CRISPR/Cas9系统中采用与编码基因MIR528反向互补的sgRNA：CAGTGGAAGGGGCATGCAG(SEQ ID NO:4)，通过使用该CRISPR/Cas9系统将Cas9蛋白靶向编码基因MIR528，对该编码基因的序列造成改变(可包括碱基的缺失、置换或插入)，从而造成miR528的表达下调。
在一些实施方式中，可通过STTM的方法使miR528的功能下调。在一些实施方式中，该STTM的方法可包括在禾本科牧草中表达能够被miR528识别且与miR528相互作用的序列。在一些实施方式中，该STTM的方法可包括在禾本科牧草中表达能够被miR528识别、且与miR528相互作用而不被miR528切割的人工模拟靶序列或短串联模拟靶标。在一些实施方式中，该STTM的方法可包括向禾本科牧草导入表达人工模拟靶序列和/或短串联模拟靶标的载体以使miR528的功能下调，其中该载体组成型地表达人工模拟靶序列或短串联模拟靶标。
在一些实施方式中，人工合成模拟靶序列可包含如以下所示的核苷酸序列或由其组成：CTCCTCTGCATCTAGCCCCTTCCA(SEQ ID NO:1)。
在一些实施方式中，两个串联的人工合成模拟靶序列由48nt的间隔序列隔开，得到也可以发挥下调miR528的功能的短串联模拟靶标，其中间隔序列如以下所示：gttgttgttgttatggtctaatttaaatatggtctaaagaagaagaat(SEQ ID NO:2)。最终发挥功能的短串联模拟靶标包含如下所示的核苷酸序列或由其组成：
CTCCTCTGCATCTAGCCCCTTCCAgttgttgttgttatggtctaatttaaatatggtctaaagaagaagaatCTCCTCTGCATCTAGCCCCTTCCA(SEQ ID NO:3)。
(2)miR528在禾本科牧草的育种中的应用
本发明第二方面还提供一种培育具有增强的分蘖能力和/或再生能力的禾本科牧草新品系的方法，其包括使所述禾本科牧草新品系中miR528的表达和/或功能下调，例如相对于母本禾本科牧草，或者野生型禾本科牧草。
在一些实施方式中，使所述禾本科牧草新品系中miR528的表达和/或功能下调的方法可采用如上第(1)部分中描述的方法。
(3)实现miR528编码基因MIR528在禾本科牧草中敲除或对其进行基因编辑的CRISPR-Cas9载体及其sgRNA
本发明第三方面还提供一种能够实现miR528编码基因MIR528在禾本科牧草中敲除或对其进行基因编辑的CRISPR-Cas9载体及其sgRNA。在一些实施方式中，该sgRNA包含如下所示的核苷酸序列或由其组成：CAGTGGAAGGGGCATGCAG(SEQ ID NO:4)。通过使用该CRISPR-Cas9载体，可以将其Cas9蛋白靶向miR528编码基因MIR528，并对该编码基因进行编辑，例如产生碱基的缺失、插入或突变等，从而产生miR528丰度下降表达。
(4)人工模拟靶序列和短串联模拟靶标(STTM)
本发明第四方面还提供一种能够实现禾本科牧草中miR528的功能下调的人工模拟靶序列和短串联模拟靶标(STTM)，两者可用于STTM的方法中实现禾本科牧草中miR528的功能下调。
在一些实施方式中，人工合成模拟靶序列包含如SEQ ID NO:1所示的核苷酸序列或由其组成。在一些实施方式中，短串联模拟靶标包含如SEQ ID NO:3所示的核苷酸序列或由其组成。
以下通过具体实施例详细描述本发明的内容。
实施例1、miR528前体blast及序列比对
利用水稻miR528的成熟区编码序列：TGGAAGGGGCATGCAGAGGAG(SEQ ID NO:5)，在Phytozome V13(https://phytozome-next.jgi.doe.gov/)已测序基因组的植物 物种中进行blast，将完全匹配的序列及其旁侧序列(前后各200bp)进行二级序列的折叠分析，将能折叠stem-loop的序列调出，存成fasta格式。利用Clustal X2和Genedoc进行序列比对及编辑。
比对结果见图1。结果显示，在多种禾本科草基因组中均存在miR528前体。
实施例2、成熟miR528在多种牧草中的检测
人工合成一段与miR528成熟序列互补的DNA序列CTCCTCTGCATGCCCCTTCCA(SEQ ID NO:6)，以及一段和U6snRNA序列互补的DNA序列TGTATCGTTCCAATTTTATCGGATGT(SEQ ID NO:7)用作不同材料间上样量的内参。利用多聚核苷酸激酶T4PNK(NEB,M0201S)对以上两条DNA序列分别进行末端γ- 32P同位素标记(标记探针体系如下所示)，将标记好的DNA序列用作杂交探针。
T4PNK标记探针体系：(10μM)DNA探针1μl，10×T4kinase Buffer 5μl，γ- 32P同位素标记的ATP 5μl，T4PNK(10U/μl)1μl，超纯水38μl。在加热块上37℃反应1小时。
利用TRNzol(TIANGEN)提取不同牧草材料的总RNA，并通过含有7M尿素的15％聚丙烯酰胺胶200V电泳2小时，转膜后用于杂交。杂交在42℃条件下反应过夜，利用洗膜缓冲液(2XSSC，0.2％SDS)洗膜两次，然后用保鲜膜将膜包好，利用Typhoon FLA9500激光扫描成像仪采集同位素信号，并依据信号强弱表征miR528累积量。
杂交结果见图2，表明在所检测的各种牧草中均能检测到成熟的miR528。
实施例3、成熟miR528特异的STTM序列设计
如图3所示设计对成熟miR528特异的STTM序列。具体而言，在一段总长96个碱基序列的两端，各设计一个miR528结合位点，并在miR528结合区的第10-11碱基间额外加3个碱基。
具体序列如SEQ ID NO:3所示，该序列能够结合miR528，但不会被miR528介导的转录后调控所切割。
实施例4、miR528 STTM转基因载体构建
首先合成DNA序列CF3380(SEQ ID NO:8)及其反向互补序列CF3381(SEQ ID NO:9)。
将CF3380和CF3381等摩尔混匀，95℃变性10分钟后自然冷却至室温，退火形成双链DNA双链，利用pENTR TM/TEV/D-TOPO TM克隆试剂盒(ThermoFisher，K253520)将双链DNA重组到中间载体，得到目的DNA片段；然后利用Gateway TM LR Clonase TM试剂盒(ThermoFisher，11791020)将该目的DNA片段连入双元表达载体pNIAC6B，并使其 位于玉米Ubquintin强启动子下游，具体实验流程完全按照试剂盒说明书操作，所得最终双元表达载体图谱见图4。
实施例5、miR528 STTM转基因株系鉴定
利用农杆菌介导的愈伤侵染体系，将实施例4中构建好的STTM转基因载体转入柳枝稷愈伤，同时一部分愈伤转入空载体做对照。分化出苗后转移到蛭石营养土培养，4个月后利用TRNzol(TIANGEN)提取转基因柳枝稷的总RNA。每个样品取2μg总RNA，通过HiScript II 1st Strand cDNA合成试剂盒(Vazyme，R211)逆转录生成cDNA，然后利用定量PCR检测各个转基因株系中STTM RNA的表达水平。用于检测STTM表达的引物为CF6738(SEQ ID NO:10)和CF6739(SEQ ID NO:11)，扩增内参基因ACTIN的引物为CF6095(SEQ ID NO:12)和CF6096(SEQ ID NO:13)。
各转基因株系中的STTM表达量如图5所示。在多个独立的转基因株系中，均检测到了较高水平的STTM RNA表达；而在转入空载体的转基因株系中，未检测到STTM RNA表达。
实施例6、miR528 STTM转基因柳枝稷分蘖数鉴定
观察蛭石营养土中培养的4个月大的转基因柳枝稷的表型。如图6所示，与转入空载体的对照株系相比，miR528被抑制的转基因株系具有更多的分枝数，且生长高度不受影响，总生物量增多。换言之，miR528被抑制的转基因株系表现出更强的分蘖能力和更大的生物量积累。
实施例7、miR528 STTM转基因柳枝稷刈割后再生能力鉴定
将蛭石营养土中培养的4个月大的转基因柳枝稷苗顶端部分进行统一刈割，使植株地上部只保留15cm长茎秆，并将各个植株从根部分成同等大小，重新种回到蛭石营养土中培养，10天后观察新生分蘖表型。
结果如图7所示，与转入空载体的对照株系相比，miR528被抑制的转基因株系具有更多新萌发的芽，分枝数较多。表明miR528被抑制的转基因株系表现出更强的再生能力。
实施例8、miR528 CRISPR/Cas9转基因载体构建
CRISPR/Cas9敲除载体pCXUN-Cas9(可参见中国专利申请CN201610639854.3)为王荣臣老师惠赠。对于特异性靶向miR528编码序列的向导RNA表达盒的扩增，我们以OsU3-sgRNA质粒(可参见中国专利申请CN201810059520.8)为模板，使用正向引物U3-F(SEQ ID NO:14)与反向引物HX8366(SEQ ID NO:15)扩增向导RNA表达盒前半部分片段；使用正向引物HX8365(SEQ ID NO:16)与反向引物U3-R(SEQ ID NO:17)扩增 向导RNA表达盒后半部分片段。通过同源重组的方法将两个片段连接至pCXUN-Cas9 KpnI酶切位点处，构建成为靶向编辑miR528编码序列的CRISPR/Cas9载体。
载体改造过程中PCR体系为：质粒模板10ng，正向引物(10μM)2μl，反向引物(10μM)2μl，2×Phanta Max Buffer 25μl，dNTP Mix(10mM each)1μl，Phanta Max Super-Fidelity DNA Polymerase(1U/μl)(南京诺唯赞生物科技股份有限公司，P505-d1)1μl，ddH 2O补齐至50μl。
PCR反应程序为：94℃2min；(94℃30s，58℃30s，72℃30s)×32个循环；72℃10min，16℃保持。
酶切体系为：10×CutSmart Buffer 5μl，限制性内切酶1μl(KpnI，4U/μl)，pCXUN-Cas9质粒1μg，ddH 2O补齐至50μl，37℃消化至少8小时。
实施例9、miR528 CRISPR/Cas9基因编辑柳枝稷和羊草基因的鉴定
利用农杆菌介导的愈伤侵染体系，将实施例8中构建好的miR528 CRISPR/Cas9载体转化柳枝稷和羊草愈伤。对获得的转基因再生植株进行基因型鉴定，使用正向引物CP1102(SEQ ID NO:18)和反向引物CP1103(SEQ ID NO:19)鉴定柳枝稷miR528拷贝1(图8中chr01N：33956382-33956402)；使用正向引物CF8647(SEQ ID NO:20)和反向引物CF8648(SEQ ID NO:21)鉴定柳枝稷miR528拷贝2(图8中chr01N：44585338-44585358)；使用正向引物CF8639(SEQ ID NO:22)和反向引物CF8640(SEQ ID NO:23)鉴定柳枝稷miR528拷贝3(图8中chr09K：69181090-69181070)；使用正向引物CF8641(SEQ ID NO:24)和反向引物CF8642(SEQ ID NO:25)鉴定柳枝稷miR528拷贝4(图8中chr09N：80434960-80434940)。使用正向引物CP4085(SEQ ID NO:26)和反向引物CF4086(SEQ ID NO:27)鉴定羊草miR528拷贝1；使用正向引物CP4089(SEQ ID NO:28)和反向引物CF4090(SEQ ID NO:29)鉴定羊草miR528拷贝2。对PCR产物进行测序，鉴定每棵再生植株的编辑类型。
PCR体系为：基因组DNA 50ng，正向引物(10μM)0.8μl，反向引物(10μM)0.8μl，2×Phanta Max Buffer 10μl，dNTP Mix(10mM each)0.4μl，Phanta Max Super-Fidelity DNA Polymerase(1Uμl)(南京诺唯赞生物科技股份有限公司，P505-d1)0.4μl，ddH 2O补齐至20μl。
PCR反应程序为：94℃2min；(94℃30s，58℃30s，72℃30s)×35个循环；72℃10min，16℃保持。
将测序结果与参考基因组序列进行比对，柳枝稷和羊草的miR528序列编辑检测结果分别如图8和图9所示，图8中的crispr-49、crispr-50、crispr-51和crispr-54分别指示不 同的柳枝稷转基因再生植株，图9中的羊草miR528 CR-1、羊草miR528 CR-2、羊草miR528 CR-6和羊草miR528 CR-7分别指示不同的羊草转基因再生植株。可见，我们利用CRISPR/Cas9技术获得了miR528序列产生变化的柳枝稷和羊草转基因再生植株。
实施例10、miR528 CRISPR/Cas9基因编辑柳枝稷和羊草再生能力鉴定
将蛭石营养土中培养的4个月大的miR528敲除的转基因柳枝稷苗顶端部分进行统一刈割，使植株地上部只保留15cm长茎秆，并将各个植株从根部分成同等大小，重新种回到蛭石营养土中培养，分别在一周和两周后观察新生分蘖表型。
如图10所示，miR528敲除的转基因柳枝稷表现出更快的出芽速率，表明miR528敲除的转基因柳枝稷具有更强的刈割后再生能力。
将营养土中生长6个月大的miR528敲除的转基因羊草保留单个分蘖，种到新的蛭石营养土中，分别在一个月和两个月后观察新生分蘖表型。
如图11所示，miR528敲除的转基因羊草具有更强的再生能力和更多的分蘖数目，表明miR528敲除可以提高羊草的再生能力和分蘖能力。
此处描述的实施例只用于说明(作为例证)，技术人员所做的各种修改或变更也应包括在专利申请的实质范围内。
工业应用性
本发明提供了miR528在禾本科牧草的生产和育种中的应用，通过使禾本科牧草中的miR528的表达和/或功能下调，能够显著提高禾本科牧草的分蘖数及再生能力，进而有助于禾本科牧草的生产和育种，适于工业应用。

Claims (12)

  1. 一种增强禾本科牧草的分蘖能力和/或再生能力的方法，其包括使禾本科牧草中miR528的表达和/或功能下调。
  2. 根据权利要求1所述的方法，其中所述miR528的表达下调为通过miR528编码基因MIR528的基因敲除或基因编辑而进行。
  3. 根据权利要求2所述的方法，其中所述基因编辑为对所述编码基因MIR528的转录区、和/或其上游调控区、和/或其下游调控区的基因进行编辑。
  4. 根据权利要求2或3所述的方法，其中所述基因编辑为通过CRISPR/Cas9系统进行。
  5. 根据权利要求1所述的方法，其中所述miR528的功能下调为通过在禾本科牧草中表达能够被miR528识别、且与miR528相互作用而不被miR528切割的人工模拟靶序列和/或短串联模拟靶标而进行。
  6. 根据权利要求5所述的方法，其中向所述禾本科牧草导入表达所述人工模拟靶序列和/或短串联模拟靶标的载体，其中所述载体组成型地表达所述人工模拟靶序列和/或短串联模拟靶标。
  7. 根据权利要求5或6所述的方法，其中所述人工模拟靶序列包含如SEQ ID NO:1所示的核苷酸序列或由其组成。
  8. 根据权利要求5或6所述的方法，其中所述短串联模拟靶标包含如SEQ ID NO:3所示的核苷酸序列或由其组成。
  9. 根据权利要求1-8中任一项所述的方法，其中所述禾本科牧草包括柳枝稷(Panicum virgatum)、羊草(Leymus chinensis)、二穗短柄草(Brachypodium distachyon)、芒草(Miscanthus)、中间偃麦草(Elytrigia intermedia)、猫尾草(Uraria crinita)、狗尾草(Setaria viridis)、复活草(Anastatica)、老芒麦(Elymus sibiricus)、黍(Panicum miliaceum)、和无芒雀麦(Bromus inermis)。
  10. 一种培育具有增强的分蘖能力和/或再生能力的禾本科牧草新品系的方法，其包括使所述禾本科牧草新品系中miR528的表达和/或功能下调。
  11. 一种人工模拟靶序列，其包含如SEQ ID NO:1所示的核苷酸序列或由其组成。
  12. 一种短串联模拟靶标，其包含如SEQ ID NO:3所示的核苷酸序列或由其组成。
PCT/CN2022/090135 2022-04-29 2022-04-29 miR528在禾本科牧草生产和育种中的应用 WO2023206318A1 (zh)

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CN102134571A (zh) * 2010-01-26 2011-07-27 中国科学院遗传与发育生物学研究所 OsmiR528的调控位点及其应用
CN105219799A (zh) * 2015-10-22 2016-01-06 天津吉诺沃生物科技有限公司 一种基于CRISPR/Cas系统的多年生黑麦草的育种方法
CN105441445A (zh) * 2014-08-26 2016-03-30 中国科学院遗传与发育生物学研究所 miR528的调控位点及其应用
CN106434658A (zh) * 2016-09-22 2017-02-22 浙江农林大学 水稻mir528基因启动子及其应用
CN114525297A (zh) * 2020-11-04 2022-05-24 中国科学院遗传与发育生物学研究所 miR528在禾本科牧草生产和育种中的应用

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102134571A (zh) * 2010-01-26 2011-07-27 中国科学院遗传与发育生物学研究所 OsmiR528的调控位点及其应用
CN105441445A (zh) * 2014-08-26 2016-03-30 中国科学院遗传与发育生物学研究所 miR528的调控位点及其应用
CN105219799A (zh) * 2015-10-22 2016-01-06 天津吉诺沃生物科技有限公司 一种基于CRISPR/Cas系统的多年生黑麦草的育种方法
CN106434658A (zh) * 2016-09-22 2017-02-22 浙江农林大学 水稻mir528基因启动子及其应用
CN114525297A (zh) * 2020-11-04 2022-05-24 中国科学院遗传与发育生物学研究所 miR528在禾本科牧草生产和育种中的应用

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