WO2008120955A1

WO2008120955A1 - Composition for protecting plant diseases comprising 1,4-dithiane-2,5-diol as a biocontrol agent and method for controlling plant disease using the same

Info

Publication number: WO2008120955A1
Application number: PCT/KR2008/001872
Authority: WO
Inventors: Young Soon Kim; Jin-Cheol Kim; Hyo Hyun Seo; Gyung Ja Choi; Ae Ran Park
Original assignee: Industry Foundation Of Chonnam National University; Korea Research Institute Of Chemical Technology
Priority date: 2007-04-03
Filing date: 2008-04-03
Publication date: 2008-10-09
Also published as: KR100831065B1

Abstract

The present invention relates to a composition for preventing plant diseases comprising 1, 4 - di thiane- 2, 5 - diol, and a method for preventing plant diseases by using the same. The compound, 1, 4 -di thiane - 2, 5 -diol plays dual roles: (i) antimicrobial action to inhibit development of fungi, and (ii) induction of defense action of plant cells. Thus, the compound, 1, 4 - di thiane - 2, 5 -diol, which shows high activity of preventing various plant diseases, can be applied as a means to inhibit pathogen infection (as a antimicrobial) and to activate defense mechanism of plant.

Description

COMPOSITION FOR PROTECTING PLANT DISEASES COMPRISING 1,4-

DITHIANE-2, 5-DIOL AS A BIOCONTROL AGENT AND METHOD FOR

CONTROLLING PLANT DISEASE USING THE SAME

[Technical Field]

The present invention relates to a composition for preventing plant diseases comprising 1 , 4 - dithiane - 2 , 5 - diol as a biocontrol agent and a method for controlling plant diseases using the same. More specifically, the present invention relates to a biocontrol agent which can induce defense reaction in plant cells, and its role as a biocontrol agent which can block invasion of fungi into plant cells .

[Background Art]

Since plants possess cell mechanism to protect themselves from invasion of pathogenic organisms, their complicated protective reactions are activated upon recognition of pathogens. These involve acute protection occurring at the site of infection, followed by activation of immune function in the whole body of the plant, thereby appearing as expression and accumulation of pathogen- related (PR) proteins. Several enzymes, like glucanase, chitinase and lysozyme, have been well characterized as the pathogen- related proteins in plants. In general, it is known that some plant hormones such as salycilic acid, jasmonic acid and ethylene can elicit the expression of defense - related PR proteins in plants. However, the treatment of these hormones has usually accompanied serious growth retardation effect on the plants .

Harvest loss is severe in intensive agriculture due to damages by plant pathogens and pests . It caused increasing demand for the use of synthetic pesticide that creates environmental pollution, residual toxicity, etc. Thus, it is necessary to develop environmentally friendly biocontrol agent .

Food additives mean substances that are intentionally used for the purpose of improving the quality of food to enhance nutritive and substantial value of food, as well as to improve the preservation or preference. Compound named as 1 , 4 -dithiane - 2 , 5 -diol is a food additive, which has been used for chickens, clams, coffee, eggs, mustard, oysters, pork, prawns, tomatoes, tunas, and the like to provide the flavor of meat, sulfur or egg yolk. It is also found in the nature.

According to the present invention, application of 1 , 4 - dithiane - 2 , 5 -diol can provide a method to reduce the harvest loss of crops by specifically preventing pathogenic infection without harmful side - effects . Thus, a novel antimicrobioal formulation has been developed according to the present invention.

Primary object for the application of this substance is to activate defense system of a plant by eliciting plant defense reaction, such as expression of PR genes.

Secondarily, a formulation for 1 , 4 -dithiane- 2 , 5 - diol was developed to inhibit mycelial growth, spore germination and appressorium formation of fungal pathogens. When the initial growth of fungi is properly blocked at the infection site on the plant, secondary infection by proliferated spores can be prevented on the infected plants. In this way, it would be resulted in effective protection from widespreading of pepper anthracnose, rice blast, tomato late blight, or the like, which is hardly prevented by conventional agrochemical s .

[ Disclosure] [Technical Problem]

The present inventors have searched for a substance with antimicrobial activity, employing a food additive of which the safety had been mostly confirmed already, and they found that 1 , 4 -dithiane - 2 , 5 -diol exhibits high antimicrobial activity against various plant pathogens, and high inductive resistance against pepper anthracnose. Thus, an object of the present invention is to provide a biocontrol agent which can induce defense reaction in plant cells by employing 1 , 4 - dithiane -2 , 5 - diol, and an environmentally friendly composition for preventing plant diseases, which exhibits excellent protection activity against various plant diseases.

Another object of the present invention is to provide a method for preventing plant diseases. Thus, the present invention is to provide antimicrobial composition comprising 1 , 4 - dithiane- 2 , 5 - diol as an active ingredient.

[Technical Solution]

The present invention relates to a composition for preventing plant diseases comprising 1 , 4 - dithiane- 2 , 5 - diol and a method for preventing plant diseases by using the same, wherein the composition is characterized to have 100-500 μg/ml of effective amount of the dithianediol . More specifically, the present invention relates to a composition for preventing plant diseases comprising 1 , 4 - dithiane- 2 , 5 -diol (C₄H₈O₂S₂) compound represented by Chemical Formula (1) as an active ingredient, and a method for preventing plant diseases by through topical application of the composition to plants.

Further, the present invention relates to an antimicrobial agent comprising 1 , 4 -dithiane - 2 , 5 -diol compound as an active ingredient. [Chemical Formula 1]

The compound, 1 , 4 - dithiane - 2 , 5 -diol , represented by Chemical Formula (1) has a function to protect plants by- controlling proliferation of pathogenic organisms in a plant by inducing direct antimicrobial action and defense reaction of plant cells. The compound, 1 , 4 -dithiane- 2 , 5 - diol, represented by Chemical Formula (1) exhibits plant protection effect by i) inhibiting germination and growth of fungal spores; and ii) activating defense mechanism in plant cells, depending on the concentration.

The microorganisms include fungi selected from the group consisting of Colletotrichum gloeosporioides , C. coccodes , Magnaporthe grisea, Phytophthora infestans, Alternaria brassicicola , Rhi zoctonia solani , and bacteria selected from the group consisting of Acidovorax konj aci , Agrobacterium tumefaciens and Pectobacterium carotovora subsp. carotovora . The composition for preventing plant diseases comprising 1 , 4 -dithiane - 2 , 5 - diol represented by Chemical Formula (1) according to the present invention exhibits strong antagonism against the plant diseases such as anthracnose, rice blast, late blight or rust of plants selected from the group consisting of hot pepper, rice, tomato and wheat .

In order to demonstrate the antimicrobial action of 1 , 4 - dithiane - 2 , 5 -diol represented by Chemical Formula (1) against phytopathogens , spores of Colletotrichum gloeosporioides were directly treated with 1 , 4 - dithiane- 2,5-diol. As a result, the normal development of fungal spore was significantly inhibited (Fig. 1) . Germinated spores form appressorium which are essential for the penetration of plant epidermal cells, as the germ tube grows. However, the spores treated with low concentration of 1 , 4 -dithiane- 2 , 5 -diol showed the tendency of reduced elongation of germ tube and reduced formation of appressorium. When the strain was treated with 500 μg/ml of 1 , 4 -dithiane - 2 , 5 -diol , spore germination was completely inhibited.

In order to observe the effect of 1 , 4 - dithiane- 2 , 5 - diol during the infection of anthracnose fungus on pepper plants, the fruits or seedlings was pretreated with 1 , 4 -dithiane- 2 , 5 -diol , and anthracnose fungus was inoculated on the near site. As the result, formation of lesion on the pepper fruit was inhibited from the stage of initial infection (Fig. 2) . Depending on the concentration of 1 , 4 -dithiane - 2 , 5 -diol , treatment with 100 μg/ml resulted in 25% decrease of lesion formation, while decreased 98% with 500 μg/ml (Fig. 3) . In order to confirm the effect of 1 , 4 -dithiane- 2 , 5 -diol on activation of defense system in the plant, expression of pathogen related (PR) proteins was observed in the pepper fruits (Fig. 4) . As the result, it was found that expression of primary PR genes increased remarkably in pepper fruits treated with 1 , 4 -dithiane- 2 , 5 -diol .

Further, in order to observe the effect of 1,4- dithiane - 2 , 5 -diol on total protein accumulation in pepper fruits, the protein profile of the fruits was comparatively analyzed by means of 2 -dimensional electrophoresis (Fig. 5) . As the result, it was found that a few protein profiles were altered due to the treatment with 1 , 4 -dithiane- 2 , 5 -diol . These results suggest that 1 , 4 -dithiane- 2 , 5 -diol affects gene transcription and protein accumulation in the pepper fruit, and, particularly, the compound has a function to activate the defense mechanism against the pathogen.

Consequently, 1 , 4 -dithiane- 2 , 5 -diol induces expression of defense- related gene, thereby protecting the pepper fruit which is sensitive to fungal infection. When the fungal spores were inoculated on the pepper fruits treated with 1 , 4 -dithiane - 2 , 5 -diol , lesion formation was effectively controlled to maintain the fruit healthy (Fig. 6) . The result suggests the usability of 1 , 4 - dithiane- 2 , 5 -diol as an effective biocoritrol agent for preventing plant diseases. Use of 1 , 4 - dithiane - 2 , 5 -diol can also contribute to environmental conservation by the reduction of the amount of agrochemicals used for raising crops, as well as reduction of the harvest cost.

[Description of Drawings]

Fig. 1 is a photograph showing inhibition of growth and development of anthracnose fungus treated with 1,4- dithiane- 2 , 5 -diol according to Example 1 (the numbers represent the amount of 1 , 4 - dithiane - 2 , 5 -diol (μg/ml) .

Fig. 2 is a photograph showing inhibition of pathogenic symptoms of anthracnose on the green pepper fruits which had been treated with various concentrations of 1 , 4 - dithiane - 2 , 5 - diol according to Example 3.

Fig. 3 shows the results of inhibition of pathogenic symptoms of anthracnose depending on the concentration of 1 , 4 - dithiane - 2 , 5 -diol applied to green pepper fruit in Example 3 [(A) lesion diameter; (B) number of spores formed from one lesion,- (C) lesion formation (%) and size, after 9 days from the inoculation. * range of the lesion diameter] .

Fig. 4 is the results showing induction of expression of PR gene in the pepper fruits treated with various concentrations of 1 , 4 -di thiane - 2 , 5 -diol according to Example 4 [ (A) induction of expression of PR gene depending on the concentration of 1 , 4 -dithiane - 2 , 5 -diol , after 24 hours from the treatment; (B) expression of PR gene depending on the time after inoculation of anthracnose fungus (0, 24, 48, 72 hr from inoculation) in the pepper fruits pretreated with 1 , 4 -dithiane- 2 , 5 -diol (500 μg/ml). DD: 1 , 4 -dithiane - 2 , 5 -diol ; FI: fungal infection of anthracnose fungus,- DD+FI: fungal infection of anthracnose fungus after pretreatment with 1,4- dithiane-2 , 5-diol (500 μg/ml) for 30 minutes; 1% DMSO: treatment with 1% DMSO employed as solvent for 1,4- dithiane-2 , 5-diol] .

Fig. 5 is a photograph comparing the profile of protein accumulation altered by the treatment of 1,4- dithiane- 2 , 5 -diol and fungal inoculation in green pepper fruits according to Example 4 [(A) protein profile of green pepper of control group; (B) protein profile exhibited after 48 hours from fungal infection; (C) protein profile exhibited after 48 hours from treatment with 1 , 4-dithiane-2 , 5-diol (500 μg/ml); (D) protein profile exhibited after 48 hours from pretreatment with 1 , 4 - dithiane - 2 , 5 -diol (500 μg/ml) for 30 minutes and then inoculation of anthracnose fungus. White squares show the protein increased by treatment with dithianediol . ] Fig. 6 is a photograph showing the effect of 1,4- dithiane - 2 , 5 -diol for preventing fungal disease in pepper seedlings according to Example 6 ( 1 , 4 - dithiane -2 , 5 - diol was treated in the concentration of 0, 125, 250, 500 and 1000 μg/ml, respectively, and then spores of anthracnose fungus were sprayed) .

[Best Mode]

Now the present invention is described in detail by referring to Examples. It should be noted that Examples are described to illustrate the present invention, but not intended to restrict the scope of the invention.

[Example 1] Effect of treating with 1 , 4 -dithiane- 2 , 5 -diol on inhibiting development of pepper anthracnose

Monoclone isolate KG13 ( Kumho Life Environmental Science Research Institute) of anthracnose fungus (C. gloeosporioides) was cultured at 28 ^°C on potato dextrose agar medium (PDA, Difco) in dark for 7 days. The spores were harvested and suspended in sterile distilled water. In order to examine the effect of 1 , 4 -dithiane - 2 , 5 -diol on the development of C. gloeosporioides , dose - response test was carried out. A solution of 1 , 4 - dithiane- 2 , 5 - diol was dissolved in 1% dimethylsulfoxide (DMSO) . Dithianediol (10 μl) and the same amount of spore suspension (5 x 10⁵ spores/ml) were mixed and the mixture was cultured on a cover glass for 24 hours. The cover glass was incubated in a plastic box (25 x 16 x 6 cm) containing wet paper towel therein to maintain 100% of relative humidity at 28 ^°C under dark condition. Normally, the spores of C. gloeosporioides began the germination on cover glass to form germ tubes after about one hour of culture, and formed appressorium at the end of the tube. However, normal development of the fungi was severely- inhibited by treatment with 1 , 4 - dithiane - 2 , 5 -diol .

Fig. 1 shows abnormal growth of anthracnose fungus treated with 1 , 4 -dithiane - 2 , 5 -diol . Treatment with a low concentration (100 μg/ml) of 1 , 4 -dithiane- 2 , 5 -diol gave the tendency of reduced elongation of the germ tube, and often generated spores without the formation of appressorium. Growth of anthracnose fungus was completely blocked upon treatment with 1 , 4 - dithiane- 2 , 5 - diol in a concentration of 500 μg/ml.

[Example 2] Effect of 1 , 4 -dithiane- 2 , 5 -diol on the growth of various pathogens

The effect of 1 , 4 -dithiane - 2 , 5 - diol on germination and growth of various phyto-pathogenic fungi and bacteria was examined. Solutions of 1 , 4 - dithiane- 2 , 5 -diol dissolved in 1% dimethyl sulfoxide (DMSO) at concentrations of 10, 3.3, 1.1, 0.37 and 0.123 mg/ral were employed for the test .

Three (3) kinds of bacteria, Acidovorax konjaci (from National Institute of Agricultural Science and

Technology, NIAST), Agrobacterium tumefaciens (from

NIAST) and Pectobacterium carotovora subsp. carotovora

(from NIAST) were cultured in nutrient broth for 1 to 2 days and diluted with 9% sterile NaCl solution to make 10⁴ cell/ml to be employed as an inoculation source.

For three (3) kinds of fungi, Alternaria bassicicola (from Korea Research Institute of Chemical Technology, KRICT), Manaporthe grisea (from KRICT) and Col letotrichum coccodes (from Korea University) , the spores generated in solid culture medium were harvested with sterile water, and the concentration was adjusted to 10⁵ spores/ml to be employed as an inoculation source. Since Rhizoctonia solani (from KRICT) did not form spores in vitro, it was cultured in potato dextrose broth (PDB) for 7 days to provide culture fluid, which was then pulverized for 10 seconds to be employed as an inoculation source.

One hundred microliter of nutrient broth and potato dextrose broth for bacteria and fungi, respectively, were divided into 96-well plate, and the inoculum and 1,4- dithiane - 2 , 5 -diol solution (1 μl each) were inoculated, respectively. After culturing at 30 ^°C for bacteria or 25 ^°C for fungi for 1-4 days, the minimum inhibitory concentrations for growth were determined.

As a result, 1 , 4 - dithiane- 2 , 5 - diol exhibited the minimum inhibitory concentration at 33.3 μg/ml for the two pathogens, Rhizoctonia solani and Pectobacterium carotovora subsp. carotovora, while exhibiting 100 μg/ml for other organisms. It was found that the compound inhibited germination and growth of all strains tested.

[Table 1]

[Example 3] Protection of pepper fruits from infection with anthracnose fungus

Pepper fruits were treated with various concentrations of 1 , 4 -dithiane - 2 , 5 - diol , and lesion formation by anthracnose fungus was observed. Before infection, 10 μl of 1 , 4 -dithiane - 2 , 5 -diol was treated on the surface of the fruits for 30 minutes. Then, 10 μl (5 x 10⁵ spores/ml) of anthracnose spore suspension was inoculated on the near site. The inoculated fruit was placed in a plastic box (25 x 16 x 6 cm) containing wet paper towel therein, in order to maintain 100% of relative humidity under dark condition at 28 °C .

Fig. 2 is a photograph exhibiting the difference of lesion formation after 9 days, depending on the concentration of 1 , 4 - dithiane- 2 , 5 -diol . For a control group, distilled water or 1% dimethylsul foxide (DMSO) used as a vehicle were treated, respectively.

As the result, as compared to the control group, mean diameter of the lesion decreased by about 37% when treated with 100 μg/ml of 1 , 4 -dithiane - 2 , 5 -diol solution; 87% and 96% with 500 and 1000 μg/ml, respectively (Fig. 3A) . Mean number of spores formed in a lesion was inhibited by 47%, 97% and 100% for the groups treated with 100, 500 and 1000 μg/ml of the compound, respectively (Fig. 3B) .

As the rate of the lesion formation (%), lesion was formed in about 63% of the pepper fruits in the control group, while 47%, 2.7% and 1% of lesion formation occurred with 100, 500 and 1000 μg/ml of 1 , 4 -dithiane -

2,5-diol treatment, respectively (Fig. 3C) .

From those results, it is found that 1 , 4 -dithiane - 2,5-diol has antimicrobial activity against anthracnose fungus, and thus the compound can protect the plant cells from infection of the pathogen.

[Example 4] Expression of plant defense- related gene and alteration of plant protein profile

In order to test whether 1 , 4 -dithiane- 2 , 5 -diol induce the expression of pathogen- related protein gene to activate defense mechanism in plant cells, Northern blot analysis was carried out on the pepper fruits treated with 1 , 4 - dithiane - 2 , 5 -diol and then infected with anthracnose fungus .

Probes of defense - related genes such as PR3

(chitinase class II (CAChi2)), PR5 (Thaumat in- 1 ike protein (TLP) ) , PRlO and PepThi were used to determine the gene expression in the pepper fruits by means of Northern hybridization.

The primer pairs used for synthesis of probes via PCR process were PR3-5' (ATG GAG TTC TCT GTA TCA CCA GTG G) (Sequence No. 1); PR3-3'(TCC GAA TGT CTA AAG TGG TAC AAG) (Sequence No. 2); PR5-5' (ATG GGC TAT TTG AGA TCA TCT) (Sequence No. 3); PR5-3'(TCA CCT CTC TGC AAT CAA TAT) (Sequence No. 4); PR10-5' (CTG ACA AGT CCA CAG CCT CAG) (Sequence No. 5); PR10-3'(GTT CTT TCC ATG ACA ACC AAT TG) (Sequence No. 6); Pepthi - 5 ' (GGG GGA TCC AAA ATG GCT CGT TCC) (Sequence No. 7); and Pepthi - 3 '( CTC GGT ACC CTT TAT TTA ATT TTG TGT GAC ACT) (Sequence No. 8) .

As the result, PR genes such as PR3 , PR5 , PRlO and PepThi were induced in the pepper fruits treated with 1 , 4 -dithiane-2 , 5-diol (Fig. 4) . PR3 and PR5 were strongly induced at the initial stage of induction and then gradually decreased, while PepThi transcript was largely increased with the lapse of time. This demonstrates that 1 , 4 - dithiane - 2 , 5 -diol induces activation of defense mechanism in plant cells. Further, when spores of anthracnose fungus were inoculated successively with 1 , 4 -dithiane - 2 , 5 - diol treatment, PR genes were expressed in an excessive amount. These results show that 1 , 4 - dithiane- 2 , 5 -diol activates defense - related mechanism in plant cells. For proteome analysis, soluble protein was extracted from the pepper fruits. About 500 μg of the extracted protein was subjected to isoelectric focusing by using a

13 cm immobile dry strip (pH 4-7, Amersham Pharmacia) .

The proteins separated depending on the pH were subjected to SDS-PAGE electrophoresis for secondary dimension.

Then the proteins were stained via silver staining to show the protein profile (Fig. 5) .

It was found that, in response to the treatment with

1 , 4 - dithiane - 2 , 5 -diol , the protein profiles was slightly altered, in addition to the quantitative change. This result showed that cell metabolism was slightly changed by treatment of 1 , 4 -dithiane- 2 , 5 -diol .

These results suggest that 1 , 4 -dithiane- 2 , 5 -diol affects gene transcription and protein accumulation in pepper fruits, and particularly, the compound has a function to activate the defense reaction mechanism, as can be recognized from the result of gene expression.

Thus, 1 , 4 -dithiane - 2 , 5 -diol protects the pepper fruit from anthracnose fungus by expression of defense- related genes to enhance the productivity.

[Example 6] Activity of dithianediol on preventing plant diseases

In order to examine the activity of 1 , 4 -dithiane- 2,5-diol on preventing plant diseases, the protection against rice blight, tomato late blight and wheat leaf rust and pepper anthracnose were examined as followed.

First, 1 , 4 -dithiane-2 , 5-diol was dissolved in DMSO, and the solution was diluted with Tween 20 solution (250 μg/ml) with final concentration of 1,000, 500, 250 and 125 μg/ml. The concentration of DMSO was finally adjusted to the level of 1%. 30 ml of distilled water containing 0.3 ml of DMSO (final concentration 1%) and 7.5 mg of Tween 20 (final concentration 250 μg/ml) was used as a negative control. The solution of 1,4- dithiane- 2 , 5 -diol and the control were sprayed, respectively, on the surface of the leaves of the pepper seedlings on the day before inoculation of the pathogen, and dried at ambient temperature for 24 hours. The rice, tomato and wheat used for the test were sown in soil (about 70%) in a plastic pot (4.5 cm in diameter) , and cultivated in a greenhouse at 25±5^°C for 1 to 4 weeks .

A spore suspension (5 x 10⁵ spores/ml) of Magnaporthe grisea (KRICT) as a causative organism of rice blast was inoculated by spraying to young seedlings at 3^rd or 4^th leaf stage, and the plant seedlings were maintained in a moist chamber at 25 °C for a day, followed by cultivating in an incubator at 25 ^°C for 5 days, to induce the infection. A suspension of zoospores (10⁵ zoosporansium/ml ) released from zoosporangium of Phytophthora infestans (from Kangnung National University), as the causative organism of late blight, was inoculated by spraying to young seedlings of tomato at 3^rd or 4^th leaf stage, and the plant seedlings were maintained in a moist chamber at 25 "C for 2 days, followed by cultivating in an incubator at 25 ^°C with constant humidity for 2 days.

In the case of wheat leaf rust, a suspension of spores of Puccinia recondita (University of Incheon) , causing rust, was diluted in Tween 20 solution (250 μg/ml) in an amount of 0.67 g spores/ liter . The solution was sprayed to young seedlings at 1^st leaf stage. The plant seedlings were maintained in a moist chamber at 20 °C for one day. Then, they were transferred to an incubator at 20 °C and cultivated for 6 days to induce wheat leaf rust .

For the test for preventing anthracnose symptoms in pepper plants, a spore suspension (1 x 10⁶ spores/ml) of Colletotrichum coccodes (Korea University) was inoculated by spraying to hot pepper plants at 5^th or 6^th leaf stage. The plants were maintained in a moist chamber for 2 days and stood for 1 day at 25 °C .

Lesion areas were observed after 7 days of inoculation for rice blast and wheat leaf rust, after 4 days of inoculation for tomato late blight, and after 3 days of inoculation for pepper anthracnose .

By using the rate of lesion formation examined as above, disease control values were calculated according to Equation (1) , and inhibitory activities of 1,4- dithiane- 2 , 5 -diol against four plant diseases were shown in Table 2.

[Equation 1]

Control value (%) = [1 - { (lesion area rate of treated group) /( lesion area rate of untreated group)}] xlOO

[Table 2]

As shown in Table 2, 1 , 4 -dithiane - 2 , 5 - diol exhibited strong antifungal activity against pepper anthracnose and moderate antifunal activity against rice blast, tomato late blight and wheat leaf rust.

[industrial Applicability]

The present invention provides a composition for preventing plant diseases comprising 1 , 4 - dithiane- 2 , 5 - diol as an active biocontrol agent, a method for preventing plant diseases using the same, and antimicrobial agent comprising 1 , 4 - dithiane - 2 , 5 -diol as an active ingredient. Being a food additive, 1,3- dithiane - 2 , 5 -diol is harmless to human body, but exhibits high activity for preventing various plant diseases such as pepper anthracnose and rice blight. Accordingly dithianediol can be used for development of environmentally friendly biocontrol agent as naturally occurring compound and production of higher value-added organic products.

[Sequence List Text]

Sequence No. 1 is PR3 - 5 ' (ATG GAG TTC TCT GTA TCA CCA GTG G) . Sequence No. 2 is PR3-3' (TCC GAA TGT CTA AAG TGG TAC AAG) .

Sequence No. 3 is PR5-5' (ATG GGC TAT TTG AGA TCA TCT) .

Sequence No. 4 is PR5-3' (TCA CCT CTC TGC AAT CAA TAT) . Sequence No. 5 is PR10-5' (CTG ACA AGT CCA CAG CCT CAG) .

Sequence No. 6 is PR10-3' (GTT CTT TCC ATG ACA ACC AAT TG) . Sequence No. 7 is Pepthi - 5 ' (GGG GGA TCC AAA ATG GCT CGT TCC) .

Sequence No. 8 is Pepthi-3' (CTC GGT ACC CTT TAT TTA ATT TTG TGT GAC ACT) .

Claims

[CLAIMS]

[Claim l]

A composition for preventing plant diseases comprising 1 , 4 -dithiane- 2 , 5 -diol represented by Chemical Formula (1) as an active ingredient. [Chemical Formula 1]

[Claim 2] A composition for preventing plant diseases according to claim 1, wherein the plant disease is selected from the group consisting of anthracnose, rice blast, late blight and rust.

[Claim 3]

A composition for preventing plant diseases according to claim 2, wherein the plant is selected from the group consisting of pepper, rice, tomato and wheat.

[Claim 4]

An antimicrobial agent comprising 1 , 4 - dithiane - 2 , 5 - diol represented by Chemical Formula 1 as an active ingredient .

[Chemical Formula 1]

[Claim 5]

An antimicrobial agent according to claim 4, wherein the microorganism belongs to the group consisting of

Colletotrichum genus, Magnaporthe genus, Phytophthora genus, Alternaria genus, Rhizoctonia genus, Acidovorax genus, Agrobacterium genus and Pectobacterium genus.

[Claim β]

A method for preventing plant diseases by treating plants with the composition according to any one of claims 1 to 3.