CN110699279A

CN110699279A - Achromobacter and application thereof in improving peanut iron nutrition

Info

Publication number: CN110699279A
Application number: CN201910974062.5A
Authority: CN
Inventors: 左元梅; 王天琪; 李士芹; 王男麒
Original assignee: China Agricultural University
Current assignee: China Agricultural University
Priority date: 2019-04-15
Filing date: 2019-10-14
Publication date: 2020-01-17
Anticipated expiration: 2039-10-14
Also published as: CN110699279B

Abstract

The invention discloses an achromobacter and application thereof in improving peanut iron nutrition, wherein the achromobacter is named 1604IPR-02, and the preservation number is CGMCC NO. 169955. The achromobacter 1604IPR-02 is gram-negative bacteria, has no spores, has strong siderophore production capacity, can convert indissolvable iron in soil into effective iron, can increase soil nutrients, promotes plants to absorb the soil iron, can be particularly successfully colonized in peanut rhizosphere soil, promotes peanut growth and improves yield, and has great application potential.

Description

Achromobacter and application thereof in improving peanut iron nutrition

Technical Field

The invention belongs to the fields of microbiology and plant growth-promoting bacteria, and particularly relates to a colorless bacillus with high siderophore production capability and plant iron nutrition improvement capability and application thereof.

Background

Peanuts are not only one of the main edible oil crops in China, but also an important raw material in the food and grease processing industry and a high-quality substitute for margarine and olive oil. China is a big country for peanut production and has an important effect on the development of national economy. Iron is one of various biologically essential elements, which is involved in important metabolic activities in the organism. The plant needs the participation of elemental iron in the physiological metabolic processes such as photosynthesis, respiration, DNA synthesis and the like. However, most of the iron in the soil exists in a indissoluble state of ferric oxide, the bioavailability is low, particularly on the calcareous soil, the pH value of the soil is high, so that the soluble iron content is extremely low, and therefore, the plants growing on the calcareous soil are easy to have iron deficiency yellowing symptoms. In calcareous soil in north China, etiolation caused by iron deficiency of peanuts is an important factor for limiting the yield and quality of the peanuts. At present, the method is mainly used for breeding a variety with high-efficiency utilization of iron and spraying an iron fertilizer to improve the iron-deficiency yellowing of peanuts in production, but the breeding period is long, and the effect of spraying the iron fertilizer such as ferrous sulfate is not good. In recent years, the utilization of rhizosphere beneficial bacteria to promote the efficient absorption and utilization of plant nutrients becomes a hot point, and one of the hot points comprises the utilization of rhizosphere growth-promoting bacteria to improve the plant iron nutrition.

In agricultural production, the use of chemical fertilizers increases crop yield, but also releases a large amount of harmful substances to the environment, pollutes soil, water sources and food, and poses great threats to human health and living environment. Therefore, it is urgent to develop and utilize a new fertilizer source that can replace chemical fertilizers in response to the needs of green agriculture and sustainable development of agriculture.

Microorganisms in iron-deficient environments are often in an iron-stressed state, and form a set of special mechanisms for activating, absorbing and transporting indissoluble iron in the long-term evolution process of microorganisms, so that effective absorption of soluble iron is guaranteed, and an iron carrier is generated. The application of the siderophore bacteria can not only reduce the negative influence of the plants caused by iron deficiency, but also promote the growth of the plants through direct or indirect action. The development and application of the bacterial strain resource for producing the siderophore are to improve the peanut yield and the iron nutrition of the peanut. In the prior art, most of the common siderophore bacteria are pseudomonas and bacillus, and the species and the growth promotion effect of the siderophore bacteria are relatively single. Therefore, the search for a new siderophore bacterial strain with a potent growth-promoting function is an urgent need for those skilled in the art.

Disclosure of Invention

The invention aims to provide a achromobacter with high yield of siderophores, which can improve the plant iron nutrition, promote the plant growth and improve the plant yield, and an application thereof.

To achieve the object of the present invention, Achromobacter sp of the present invention is isolated from the rhizosphere soil of peanuts in the middle of the peanut-corn intercropping system and named 1604IPR-02, hereinafter abbreviated as 1604 IPR-02. The strain 1604IPR-02 was Achromobacter sp (Achromobacter sp.) after 16S rRNA gene sequence analysis. The strain is preserved in China general microbiological culture Collection center (CGMCC for short, the address: No. 3 of West Lu No.1 of Beijing university, Chaozhou, Ind. region of Tokyo, China academy of sciences, postal code 100101) at 18 days 12.2018, is classified and named as Achromobacter (Achromobacter sp.), and has the preservation number of CGMCC No. 16955.

1604IPR-02 bacterial colony and thallus characteristics are as follows: the colony is round, the center is convex, the color is light yellow, the edge is smooth and neat, and the thallus is moist and semitransparent. The morphological characteristics of the observed body by a microscope are rod-shaped, single cell, gram stain is negative and no spore exists.

The physiological and biochemical characteristics of the strain are as follows: the gelatin can be liquefied, the starch is hydrolyzed, nitrate is not reduced, acid is not produced after glucose is hydrolyzed, catalase is positive, and citrate can be utilized.

The Achromobacter (Achromobacter sp.)1604IPR-02 is fermented, and the obtained fermentation product also belongs to the protection scope of the invention.

In the examples of the present invention, the medium used for the fermentation was LB medium. The composition is as follows: 5g of yeast extract; 10g of peptone; 10g of sodium oxide; adding distilled water to a constant volume of 1000 mL; 15-20g of agar; sterilizing at 121 deg.C for 20min with pH of 7.0; the fermentation conditions were: the temperature is 30 ℃, and the rotation speed is 150-.

The invention provides a microbial inoculum containing the Achromobacter sp 1604IPR-02 or a fermentation product thereof.

Preferably, the microbial inoculum is a plant growth promoting microbial inoculum, a plant lateral root growth promoter or a plant iron nutrition improving agent.

Preferably, the microbial inoculum contains Achromobacter sp 1604IPR-02 with effective viable count not less than 1 × 10⁹CFU/mL。

Experiments show that the Achromobacter (Achromobacter sp.)1604IPR-02 has the effects of producing iron carriers with high yield, promoting the improvement of the iron nutrition of the peanuts and increasing the yield of the peanuts. The growth-promoting bacterium preparation can promote and improve the iron nutrition of peanut plants, promote the growth of lateral roots, improve the nutrient absorption capacity and improve the dry weight and yield of the plants.

The invention provides a biological fertilizer containing the Achromobacter sp 1604IPR-02 or a fermentation product thereof.

The invention provides an application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the microbial inoculum thereof in promoting the conversion of insoluble iron in soil into soluble iron which can be effectively absorbed by plants.

The invention provides an application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the same in promoting iron absorption of plants in soil.

The invention provides application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the same to generating auxin in promoting plant root development, promoting lateral root growth, increasing the absorption area of a plant root system and promoting nutrient absorption capacity.

The invention provides application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the same in improving dry weight and yield of plants.

The invention provides an application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the same in a high-yield siderophore.

The invention provides an application of Achromobacter sp 1604IPR-02 or a fermentation product thereof or a microbial inoculum or a biological fertilizer containing the same in improving relative expression quantity of genes related to iron absorption and transport of plants.

Preferably, the genes are AhFIT, AhFRO1(ferri reduction oxidase), AhNRAMP1 and AhFRDL, and all of the genes are related to iron absorption and transport.

Preferably, in the above application, the plant is peanut. It will be appreciated by those skilled in the art that the 1604IPR-02 of the present invention can be applied to the growth of other crops, and also has similar growth promoting effects as described above.

The invention has the beneficial effects that the Achromobacter (Achromobacter sp.)1604IPR-02 is obtained by separating the rhizosphere soil of the intercropping peanuts in a peanut and corn intercropping system, has a high-yield iron carrier, converts insoluble iron in the soil into soluble effective iron, increases soil nutrients, and has multiple growth promoting functions of promoting the absorption of the peanuts to the soil iron in a seedling stage and a full fruit stage, improving the iron nutrition of the peanuts, improving the relative expression of iron absorption and transportation related genes, improving the dry weight and yield of the peanuts and the like. In the application process, the strain is pollution-free, residue-free and biologically environment-friendly, and is a growth-promoting strain with good application prospect in the field of plant growth promotion.

Drawings

FIG. 1 is a graph showing the growth of Achromobacter 1604 IPR-02.

FIG. 2 is a picture of the formation of a yellow halo on a blue CAS plate by Achromobacter 1604 IPR-02.

FIG. 3 is a graph of siderophore production by Achromobacter 1604 IPR-02.

FIG. 4 is a graph showing the iron hydroxide dissolution curve of Achromobacter 1604 IPR-02.

FIG. 5 shows the effect of Achromobacter 1604IPR-02 on the concentration of active iron in peanut leaves at seedling stage.

FIG. 6 shows the effect of Achromobacter 1604IPR-02 on AhFIT, AhFRO1, AhNRAMP, and AhFRDL gene expression in peanuts at seedling stage.

FIG. 7 shows the effect of Achromobacter 1604IPR-02 on total root length, total root area, root mean diameter, and root volume of peanuts in seedling stage.

FIG. 8 is a graph of the effect of Achromobacter 1604IPR-02 on dry weight of peanuts at seedling stage.

FIG. 9 is a graph of the effect of Achromobacter 1604IPR-02 on growth of peanuts at seedling stage.

FIG. 10 shows the effect of Achromobacter 1604IPR-02 on the fresh weight of aerial parts and roots of peanuts in seedling stage.

FIG. 11 shows the effect of Achromobacter 1604IPR-02 on SPAD values of new and old leaves in seedling stage.

FIG. 12 shows the effect of Achromobacter 1604IPR-02 on the height of saturated peanut plants.

FIG. 13 shows the effect of Achromobacter 1604IPR-02 on the concentration of active iron in the foliage of saturated peanuts.

FIG. 14 shows the effect of Achromobacter 1604IPR-02 on SPAD values of new, functional and old leaves of saturated peanuts.

FIG. 15 is a graph showing the effect of Achromobacter 1604IPR-02 on net photosynthetic rate, stomatal conductance, intercellular carbon dioxide content and transpiration rate of peanuts in full-bearing period.

FIG. 16 is a graph showing the effect of Achromobacter 1604IPR-02 on the dry weight of new leaves, old leaves, stems, roots and fruits of peanuts in the full-bearing stage.

FIG. 17 is a graph showing the effect of Achromobacter 1604IPR-02 on growth of saturated peanuts.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The following media used in the following examples were formulated as follows without specific reference: LB culture medium: 10g of tryptone, 5g of yeast extract, 10g of sodium chloride and 15-20g of agar, wherein the volume is adjusted to 1L by using distilled water, and the pH is adjusted to 7.0.

CAS assay plate: CAS dye liquor contains 0.02515g/100ml of Chrome Azurol S (CAS) and FeCl₃0.0027g/100ml, 0.1456g/100ml of cetyltrimethylammonium bromide (HDTMA) and 0.1mol/L of phosphate buffer pH 6.8 containing Na per 100ml of phosphate buffer₂HPO₄·2H₂O 2.2427g，NaH₂PO₄·2H₂O 0.5905g，KH₂PO₄0.075g，NH₄0.250g of Cl and 0.125g of NaCl, and the mixture was diluted 10 times when used. Each 100ml of the solution contains 1ml of 20% sucrose solution, 3ml of 10% hydrolyzed casein amino acid and 1mmol/L CaCl₂100μL，1mmol/L MgSO₄2ml of agar and 1.8g of agar are slowly added with 5ml of each of the salt solution and the CAS stain at about 60 ℃ to obtain a blue detection plate. Sterilizing at 121 deg.C for 15 min.

Sucrose-aspartate Medium (MSA): sucrose, 20 g/L; aspartic acid, 2 g/l; k₂HPO₄,1g/L；MgSO₄·7H₂O,0.5g/L。

Preparation of CAS blue detection solution:

solution A0.079 CAS is dissolved in 50mL deionized water, 10mL1mmol/l FeCl is added₃Solution (containing 10mmol/L HCI);

solution B0.069 hexadecyltrimethylammonium bromide (HDTMA) was dissolved in 40mL deionized water;

and C, slowly adding the solution A into the solution B along the wall of the beaker, and slightly shaking to uniformly mix the solution A and the solution B to obtain a solution C, namely a CAS blue detection solution.

Example 1 Achromobacter (Achromobacter sp.) screening, isolation and identification

1. Screening and separating strains:

achromobacter 1604IPR-02 is separated from intercropping peanut rhizosphere soil in a peanut and corn intercropping system, a soil sample is re-suspended in sterile water and then cultured on a CAS solid culture medium, and strains with strong siderophore production capacity are selected. The colorless bacillus is obtained through further screening and breeding, and the purified bacillus is named 1604 IPR-02.

2. Determination of morphological and physiological and biochemical characteristics of strain 1604IPR-02

(1) The colony characteristics and thallus morphology of strain 1604IPR-02 are as follows: the colony is round, the center is convex, the color is light yellow, the edge is smooth and neat, and the thallus is moist and semitransparent. The morphological characteristics of the observed body by a microscope are rod-shaped, single cell, gram stain is negative and no spore exists.

(2) Physiological and biochemical characteristics of strain 1604IPR-02 the physiological and biochemical characteristics of this strain are: the gelatin can be liquefied, the starch is hydrolyzed, nitrate is not reduced, acid is not produced after glucose is hydrolyzed, catalase is positive, and citrate can be utilized.

3. Strain 1604 IPR-0216S rDNA sequence determination and analysis

The 1604IPR-02 strain 16S rDNA sequence is subjected to PCR amplification to obtain a 4297bp PCR product. BLAST comparison of the 16SrDNA sequence (shown in SEQ ID NO. 11) shows that 1604IPR-02 has a similarity of 98% or more to a plurality of different strains of Achromobacter, and the strain 1604IPR-02 is identified as Achromobacter (Achromobacter sp.) by combining the morphology, culture characteristics and physiological and biochemical analysis results of the strain.

The strain is preserved in China general microbiological culture Collection center (CGMCC for short, the address: No. 3 of West Lu No.1 of Beijing university facing Yang district, microbial research institute of China academy of sciences, zip code 100101) in 2018, 12 months and 18 days, and is classified and named as Achromobacter sp, and the preservation number is CGMCC No. 16955.

Example 2 Achromobacter 1604IPR-02 growth Curve and siderophore Curve determination

(1) Growth Curve determination

12 Erlenmeyer flasks containing 50ml of sterile LB medium were numbered 0, 3, 6, 12, 24, 30, 36, 48, 60, 72, 96, 120, respectively. Achromobacter 1604IPR-02 was inoculated into 12 numbered Erlenmeyer flasks at an inoculum size of 1%, and cultured at 30 ℃ with shaking at a rate of 180 r/min. Then, the flasks were taken out at corresponding times to determine the OD values. Pouring the uninoculated LB culture solution into a cuvette, selecting a 600nm wavelength spectrophotometer to adjust a zero point as a blank control, sequentially measuring the culture solution from 0h at different time, properly diluting the bacterial suspension with high concentration by using an uninoculated LB liquid culture medium, measuring to enable the OD value to be within 0.10-0.65, and multiplying the OD value measured after dilution by the dilution multiple to obtain the final OD value. The measured time was plotted on the abscissa and the OD600 value was plotted on the ordinate to plot the growth curve of the bacteria. (FIG. 1)

From the growth curve, the Achromobacter 1604IPR-02 enters a slow phase after inoculation, enters a logarithmic phase after 9h of culture, enters a stationary phase after 60h, and enters a decay phase after 96h of culture.

(2) Siderophore assay

The Achromobacter 1604IPR-02 is inoculated on an LB solid culture medium, dark culture is carried out for 2d at the temperature of 30 ℃, a bacterial block with the diameter of 6mm is taken along the edge of a bacterial colony, and the bacterial block is inoculated on a CAS detection plate and cultured for 72 h. As can be seen in FIG. 2, a yellow circle appears around the colony of Achromobacter 1604IPR-02, indicating the ability of the bacterium to produce siderophores.

Taking 12 conical flasks containing 50ml of sterile MSA liquid culture medium, which are numbered 0, 3, 6, 12, 24, 30, 36, 48, 60, 72, 96 and 120 respectively. Achromobacter 1604IPR-02 was inoculated to the numbered MSA medium at an inoculum size of 1%, and cultured with shaking at 30 ℃ at a rate of 180 r/min. Then, the flasks were taken out at corresponding times to determine the OD values. Pouring the uninoculated MSA culture solution into a cuvette, adjusting the zero point on a 630nm wavelength spectrophotometer, mixing the uninoculated MSA culture medium with an isometric CAS detection solution as a control, sampling the culture solution at different times from 0h in sequence, adding the isometric CAS detection solution, properly diluting the mixed solution with high concentration with the uninoculated MSA culture medium to ensure that the OD630 value is within 0.10-0.65, and multiplying the OD value measured after dilution by the dilution multiple to obtain the final OD value.

The calculation formula for the siderophore productivity is:

siderophore productivity ═ [ (control OD value-culture OD value)/control OD value ] × 100%

The siderophore curve of the bacteria was plotted with the measured time as the abscissa and siderophore productivity as the ordinate. (FIG. 3)

The curve of the bacterial strain producing siderophore is more consistent with the curve of the bacterial growth, the secretion of siderophore reaches the maximum after 96h of culture, and the maximum siderophore unit (siderophore units) reaches 33.69 percent.

(3) Determination of iron hydroxide dissolving Capacity

Achromobacter 1604IPR-02 was inoculated into 20ml of liquid MSA medium and cultured. After 24 hours, 100. mu.l of each of the precultured bacterial suspensions was inoculated to iron-deficient, + FeCl₃(10. mu.M) and + Fe (OH)₃(200mg/l) in 100ml of liquid MSA medium, shaking-culturing at 120RPM at 30 ℃. And (4) sucking a certain amount of culture medium for 12h, 24h, 48h, 72h and 96h respectively, measuring the OD value at 600nm, and making a growth-time response curve.

Fe(OH)₃Was prepared by slowly adding 1M NaoH to 5m MFeCl₃In solution until the pH of the solution reaches 6.5-7. And centrifuging the precipitate, washing with deionized water for many times, and drying in an oven at 100 ℃ for later use.

As can be seen from FIG. 4, the seed was seeded on a FeCl-containing material₃Or Fe (OH)₃The growth curves of the Achromobacter 1604IPR-02 are almost consistent and are obviously better than those of the Achromobacter 1604IPR-02 cultured in an iron-deficiency culture medium. Indicating Achromobacter 1604IPR-02 having a certain Fe (OH)₃The dissolving capacity can convert the indissolvable iron in the culture medium into soluble iron.

Example 3 Effect of Achromobacter 1604IPR-02 on peanut growth and iron Nutrition

1. The strain 1604IPR-02 of the invention is cultured in LB liquid medium at 30 ℃ to 10 DEG C⁹cfu/ml, centrifuging at 5000rpm in a high speed centrifuge for 10min, pouring off the supernatant, and adding 10g/l NaCl distilled water solution sterilized in equal amount to prepare bacterial suspension for later use.

And 5, 16 days in 2018, the peanuts are transplanted in a greenhouse of resource and environment college of Chinese agriculture university in Beijing, and the variety of the peanuts adopts Luhua 14. And adding bacterial liquid according to 20 ml/strain every week from the first week after thinning, wherein the concentration of the bacterial liquid in the bacterial adding treatment is as follows: 1X 10⁹CFU/ml, control group was added with equal concentration of sterile saline solution. Two sets of treatments treated 4 pots each, with 2 biological replicates per pot. The samples are collected twice in one month (seedling stage) and three months (full fruit stage) after the peanut transplantation. Full fruit periodMeasuring the net photosynthetic rate, the stomatal conductance and the transpiration rate of the peanuts by using a photosynthetic instrument one week before sample collection, measuring the total root length, the average root diameter, the root area and the root volume of the peanuts by using a root system root-sweeping instrument after the samples are collected in the seedling stage, and measuring the dry weight and the yield of the peanuts after the samples are collected twice and dried.

2. Blade active iron assay: about 1g of fresh leaves were taken and cut into pieces, placed into a centrifuge tube containing 10mL of HCl, the lid was tightened, and shaken with a shaker for 5 hours. Then filtered through qualitative filter paper, and the supernatant was collected and stored in a refrigerator at-20 ℃. And measuring the iron content of the leaching solution by ICP.

3. Plant gene expression assay

Total RNA extraction: trizol method for extracting plant RNA

Ii, reverse transcription of mRNA: reverse transcription of extracted RNA by RR047A kit

Iii real-time quantitative PCR

1) Releasing reverse transcription cDNA by 3 times as a template;

2) preparing mixed solution according to the number of samples according to the following reaction system, respectively sucking 23 mu L of the mixed solution, adding 2 mu L of template, and uniformly mixing;

ddH2O 9.5.5 μ L; power SYBER Green PCR Master Mix 12.5. mu.L; 5. mu.M Primer F1. mu.L; 5 μ M Primer R1 μ L (FIT, FRO, NRAMP, and FRDL gene primers); template (inverted cDNA) 2. mu.L. A total of 25. mu.L. The peanut iron absorption related gene relative quantitative Real time PCR primer selected by the invention comprises AhUbiquitin internal reference primer and specific primer pairs aiming at the 4 genes, and the nucleotide sequences of the primers are respectively shown in SEQ ID NO. 1-10.

3) The measurement is carried out by using a BIO-RAD iQ5 fluorescent quantitative PCR instrument, and the reaction program is as follows:

a.95℃10min；b.(95℃15sec 60℃1min)×40；c.95℃15sec60℃1min 98℃30sec。

4) and after the detection is finished, carrying out gel electrophoresis detection on the PCR product, and collecting data for calculation and analysis.

4. Results

FIGS. 5-6 show that the concentration of active iron in peanut leaves after the application of Achromobacter 1604IPR-02 at seedling stage is 21.93mg kg^-1FW increased by 13.92% over the control with an equivalent amount of saline solution. And the relative expression quantities of several genes related to the iron absorption and transportation in the plant body are respectively 2.11, 2.74, 4.82 and 1.98, which are respectively improved to 1.8 times, 9 times and 2.1 times.

As can be seen from FIG. 7, the total root length, the average root diameter, the root area and the root volume of the peanuts in the seedling stage after the treatment of the Achromobacter 1604IPR-02 are respectively 2.34 m/plant and 805.83 cm/plant²Strain, 1.10 mm/strain, 17.49cm³The strains are respectively increased by 221.13%, 726.68%, 105.86% and 1244% compared with the control.

As can be seen from FIG. 8, the application of Achromobacter 1604IPR-02 increased the dry weight of the aerial parts and roots of the seedlings of peanuts by 2.53 g/strain and 0.23 g/strain by 74.55% and 82.99% respectively as compared with the control. In conclusion, after the colorless bacillus 1604IPR-02 is inoculated, the nutrition of peanut iron is obviously improved in the seedling stage, the expression of genes related to iron absorption and transport is increased, and the growth and development of peanuts and root configuration are obviously promoted, as shown in figure 9.

After the achromobacter 1604IPR-02 is applied, the fresh weight of the overground part and the fresh weight of the root of the peanut at the seedling stage are respectively 12.84 g/plant and 2.86 g/plant, which are increased by 59.10 percent and 74.39 percent compared with the control group. The results show that the growth of the peanut can be remarkably promoted after the treatment of the achromobacter 1604 IPR-02. See fig. 10.

As can be seen in FIG. 11, after Achromobacter treatment, the SPAD of the new and old leaves in the seedling stage was 45.83 and 52.67, which are increased by 7.16% and 2.93% compared with the control. The result shows that the achromobacter 1604IPR-02 can effectively relieve the chlorosis symptom of new leaves and old leaves of peanuts in the seedling stage.

As can be seen from FIG. 12, after the peanuts are grown to the full period after the Achromobacter 1604IPR-02 is applied, the plant height of the peanuts is increased to 39.7cm, which is 31.89% higher than that of the control. The achromobacter 1604IPR-02 can obviously promote the growth and development of peanuts.

As can be seen in FIG. 13, the concentration of active iron in the new leaves of peanuts after the application of the Achromobacter 1604IPR-02 in the full fruit stage was 17.16mg "kg^-1FW, 116.1% increase over control.

As can be seen from FIG. 14, after the peanuts in the full-bearing period are treated by the Achromobacter 1604IPR-02, the SPAD values of the functional leaves and the old leaves are 45.96 and 44.17, which are respectively increased by 14.84% and 26.93% compared with the control. The result shows that the achromobacter 1604IPR-02 can obviously improve the chlorosis symptom of functional leaves and old leaves of peanuts in the full fruit period.

As can be seen from FIG. 15, the photosynthetic rate of the clean peanut leaves, the stomatal conductance, the intercellular carbon dioxide content and the transpiration rate after the treatment with the Achromobacter 1604IPR-02 are 8.59. mu. molCO₂〃m^-2〃s^-1、0.143μmol〃H₂O〃m^-2〃s^-1、304μmol〃CO₂〃mol^-1And 3.13mmol "H₂O〃m^-2〃s^-1Compared with the control group, the increase of 127.14%, 107.08%, 8.46% and 48.69%, the three indexes of the new leaf are respectively 6.60 mu mol "CO₂〃m^-2〃s^-1、0.15μmol〃H₂O〃m^-2〃s^-1、312.7μmol〃CO₂〃mol^-1And 3.25mmol "H₂O〃m^-2〃s^-1The increases were 112.31%, 60.66%, 4.58% and 104.4% over the control.

From FIG. 16, it is concluded that the dry weights of the new leaves, old leaves, stems and roots of the peanuts after inoculation of the Achromobacter 1604IPR-02 are respectively increased by 62.96%, 94.34%, 27.27% and 6.25% compared with the control, and the dry weight of the fruits reaches 4.22 g/strain and is increased by 24.31% compared with the control, wherein the dry weights of the new leaves, old leaves, stems and roots of the peanuts after inoculation of the Achromobacter 1604IPR-02 are respectively increased by 2.44 g/strain, 2.06 g/strain, 1.96 g/strain and 0. In conclusion, after the achromobacter 1604IPR-02 is inoculated, the iron nutrition of the peanuts is also obviously improved in the full-fruit period, the photosynthetic related indexes are obviously improved, and the growth and development of the peanuts and the fruit yield are obviously promoted (figure 17).

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

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actaatgaca agggttgcgc tcgttgcggg acttaaccca acatctcacg acacgagctg 420

acgacagcca tgcagcacct gtgttccggt tctcttgcga gcactgccaa atctcttcgg 480

cattccagac atgtcaaggg taggtaaggt ttttcgcgtt gcatcgaatt aatccacatc 540

atccaccgct tgtgcgggtc cccgtcaatt cctttgagtt ttaatcttgc gaccgtactc 600

cccaggcggt caacttcacg cgttagctgc gctaccaagg cccgaaggcc ccaacagcta 660

gttgacatcg tttagggcgt ggactaccag ggtatctaat cctgtttgct ccccacgctt 720

tcgtgcatga gcgtcagtgt tatcccagga ggctgccttc gccatcggtg ttcctccgca 780

tatctacgca tttcactgct acacgcggaa ttccacctcc ctctgacaca ctctagcccg 840

gtagttaaaa atgcagttcc aaagttaagc tctgggattt cacatctttc tttccgaacc 900

gcctgcgcac gctttacgcc cagtaattcc gattaacgct tgcaccctac gtattaccgc 960

ggctgctggc acgtagttag ccggtgctta ttctgcaggt accgtcagtt tcgcgaggta 1020

ttaacccgcg acgtttcttt cctgccaaaa gtgctttaca acccgaaggc cttcatcgca 1080

cacgcgggat ggctggatca gggtttcccc cattgtccaa aattccccac tgctgcctcc 1140

cgtaggagtc tgggccgtgt ctcagtccca gtgtggctgg tcgtcctctc aaaccagcta 1200

cggatcgtcg ccttggtgag ccgttacccc accaactagc taatccgata tcggccgctc 1260

caatagtgca aggtcttgcg atcccctgct ttcccccgta gggcgtatgc ggtattagct 1320

acgctttcgc gtagttatcc cccgctactg ggcacgttcc gatacattac tcacccgttc 1380

gccactcgcc accagaccga agtccgtgct gccgttcgac tgcatgtgta aagcatcccc 1440

cc 1442

Claims

1. Achromobacter (Achromobacter sp.)1604IPR-02 with the preservation number of CGMCC NO. 169955.

2. The Achromobacter (Achromobacter sp.)1604IPR-02 fermentation product of claim 1.

3. A microbial inoculum containing Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1.

4. The microbial agent according to claim 3, which is a plant growth promoting microbial agent, a plant lateral root growth promoter or a plant iron nutrition improver.

5. The microbial preparation according to claim 3 or 4, wherein the number of viable bacteria of Achromobacter sp 1604IPR-02 is not less than 1X 10⁹CFU/mL。

6. A biofertilizer comprising the Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1.

7. Use of Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1, or the microbial agent according to any one of claims 3 to 4 or the biological fertilizer according to claim 5 for promoting the conversion of poorly soluble iron in soil into soluble iron that can be efficiently absorbed by plants.

8. Use of Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1, or a microbial agent according to any one of claims 3 to 4 or a biological fertilizer according to claim 5 for promoting iron absorption in soil by plants.

9. Use of Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1, or a microbial agent according to any one of claims 3 to 4 or a biological fertilizer according to claim 5 for promoting plant root development, promoting nutrient absorption capacity, or increasing plant dry weight and yield.

10. Use of Achromobacter (Achromobacter sp.)1604IPR-02 or a fermentation product thereof according to claim 1, or a microbial agent according to any one of claims 3 to 4 or a biological fertilizer according to claim 5 for increasing relative expression level of genes involved in iron absorption and transport in plants.