Identification and fine mapping of qSW2 for leaf slow wilting in soybean

Drought is one of the abiotic stresses limiting the production of soybean(Glycine max).Elucidation of the genetic and molecular basis of the slow-wilting(SW)trait of this crop offers the prospect of its genetic improvement.A panel of 188 accessions and a set of recombinant inbred lines produced from a cross between cultivars Liaodou 14 and Liaodou 21 were used to identify quantitative-trait loci(QTL)associated with SW.Plants were genotyped by Specific-locus amplified fragment sequencing and seedling leaf wilting was assessed under three water-stress treatments.A genome-wide association study identified 26 SW-associated single-nucleotide polymorphisms(SNPs),including three located in a 248-kb linkage-disequilibrium(LD)block on chromosome 2.Linkage mapping revealed a major-effect QTL,qSW2,associated with all three treatments and adjacent to the LD block.Fine mapping in a BC_(2)F_(3) population derived from a backcross between Liaodou 21 and R26 confined qSW2 to a 60-kb interval.Gene expression and sequence variation analysis identified the gene Glyma.02 g218100,encoding an auxin transcription factor,as a candidate gene for qSW2.Our results will contribute significantly to improving drought-resistant soybean cultivars by providing genetic information and resources.

Reactions of Oil Palm (Elaeis guineensis Jacq) Progenies to Fusarium Wilt Disease Caused by Fusarium oxysporum f.sp. Elaeidis under Natural Infection

The oil palm (Elaeisguineensis Jacq) is used worldwide in commercial agriculture for the production of palm oil, palm kernel oil and palm wine. It produces more oil per plant than any other oil-producing crop in the world. Production is constrained by several factors among which pests/diseases are of utmost importance. Vascular wilt (VW) caused by Fusarium oxysporum is the most devastating disease infecting this crop. Its soil-borne ecology has made the use of fungicides to manage this disease too expensive and inpragmatic. There is need for concerted research in the breeding and selection of wilt-tolerant progenies as an essential step in the management of Fusarium wilt disease. The study aims to assess the incidence and severity of vascular wilt among tested oil palm progenies, to evaluate the reduction in yield caused by the disease in the susceptible progenies and to identify the wilt-tolerant, high-yielding progenies. The study was carried out at Pamol Plantations Limited (PPL) in Ndian Estate (Ndian Division), in the Southwest Region of Cameroon. Three field trials were evaluated for tolerance/susceptibility to Fusarium wilt. Each trial consisted of 15 oil palm progenies replicated 4 times. Each progeny had 25 oil palm stands in each replicate. Hence, a total of 1500 oil palm stands were assessed. The experimental design was a randomized complete block (RCB) with trial codes: Trial 2001/1, planted in 2001;Trial 2001/2, planted in 2002;Trial 2001/3, planted in 2003. Each trail had an area of 12 ha, with a plant density of 143 palms·ha−1. Wilt incidence, severity, index, and yield were evaluated on 45 progenies from the 3 trails after identifying Fusarium oxysporum from oil palm plant part. Data was subjected to analysis of variance, Fischer’s least significant difference test (LSD) for mean separation. Identification of Fusarium was based on descriptive analysis. Incidence of VW in the 3 trials ranged from 1% - 39%. Also, 45% of infected plants were from progeny 676 while 1% was from progenies 689, 693, 694 and 710. Disease severity was from 0.9 in progeny 686 to 4.55 in 676. Wilt index ranged from 131 for progeny 694 and 710 to 495 for progenies 705. Out of the 45 progenies evaluated, 27 were tolerant (1 < 100) and 18 susceptible (1 ≥ 100). Within the tolerant progenies, 4 were significant (1 < 20) while 5 out of 18 were significantly susceptible (1 ≥ 185). Mean yield reduction of the susceptible progenies was 34.8% while in the tolerant progenies, it increased by 9.5% when compared to their controls. Progenies 702, 703 and 709 are recommended for planting based on the level of tolerance to Fusarium wilt disease and yield.

Expression analysis of the R2R3-MYB gene family in upland cotton and functional study of GhMYB3D5 in regulating Verticillium wilt resistance

Improving plant resistance to Verticillium wilt(VW),which causes massive losses in Gossypium hirsutum,is a global challenge.Crop plants need to efficiently allocate their limited energy resources to maintain a balance between growth and defense.However,few transcriptional regulators specifically respond to Verticillium dahliae and the underlying mechanism has not been identified in cotton.In this study,we found that the that expression of most R2R3-MYB members in cotton is significantly changed by V.dahliae infection relative to the other MYB types.One novel R2R3-MYB transcription factor(TF)that specifically responds to V.dahliae,GhMYB3D5,was identified.GhMYB3D5 was not expressed in 15 cotton tissues under normal conditions,but it was dramatically induced by V.dahliae stress.We functionally characterized its positive role and underlying mechanism in VW resistance.Upon V.dahliae infection,the up-regulated GhMYB3D5 bound to the GhADH1 promoter and activated GhADH1expression.In addition,GhMYB3D5 physically interacted with GhADH1 and further enhanced the transcriptional activation of GhADH1.Consequently,the transcriptional regulatory module GhMYB3D5-GhADH1 then promoted lignin accumulation by improving the transcriptional levels of genes related to lignin biosynthesis(GhPAL,GhC4H,Gh4CL,and GhPOD/GhLAC)in cotton,thereby enhancing cotton VW resistance.Our results demonstrated that the GhMYB3D5 promotes defense-induced lignin accumulation,which can be regarded as an effective way to orchestrate plant immunity and growth.

5-Aminolevulinic acid against strawberry Fusarium wilt:Bidirectional regulation of biocontrol agents and pathogens

Strawberry Fusarium wilt (SFW) is a systematic soil-borne disease caused by Fusarium oxysporum f.sp.fragaria (Fof),which infects the vascular bundles,blocking water and nutrient transport from roots to the aboveground.It is a severe pathogen which spreads rapidly and destroys strawberry production.Finding a way to control this disease is of great scientific value and practical importance.In this study,three fungi were isolated from the vascular tissues of sick strawberries in the field.After DNA sequencing,they were identified as Fof,Aspergillus fumigatus and Trichoderma harzianum,respectively,among which the first two are pathogens and the third is a probiotic.All fungi were controlled by thiophanate-methyl (TM),a commercial fungicide.On PDA medium,20 mg·L^(-1)5-aminolevulinic acid (ALA),a natural non-protein amino acid,promoted T.harzianum proliferation,but inhibited Fof and A.fumigatus.In confrontation test,the growth of Fof or A.fumigatus was inhibited by T.harzianum and exogenous ALA promoted T.harzianum growth but significantly inhibited the pathogen growth.When three species of fungi were separately or combinedly inoculated on healthy strawberry plants,T.harzianum promoted plant growth and development while Fof or A.fumigatus caused growth retardation,where Fof directly caused leaf yellowing and plant wilting.When the plants inoculated with different fungus were treated with ALA,the results turned out that ALA alleviated SFW symptoms by bidirectionally promoting T.harzianum proliferation and inhibiting Fof and A.fumigatus.Thus,ALA might be used in comprehensively controlling SFW in strawberry industry.

Screening of Soil Antagonistic Bacteria for Watermelon Fusarium Wilt

[Objective] The aim of this study was to screen bacteria strains with stable antagonistic effect against watermelon fusarium wilt from soil and investigate the biological control of watermelon fusarium wilt by applying the antagonistic bacteria strains into soil.[Method] Actinomycete strains,fluorescent bacteria strains and bacillus strains were isolated from soil samples by the dilution-plate method,then its resistance was screened respectively by the improved confront culture method after colonies were purified.Finally,bacteria strains with better antagonistic effect were identified.[Result] 29 bacteria strains with stable antagonistic effect against watermelon fusarium wilt were screened from 39 soil samples,which contained 15 fluorescent bacteria strains,5 bacillus strains and 9 actinomycete strains.Furthermore,three antagonistic bacteria strains of FM2,FM3 and FM4 with the strongest antagonism were identified primarily.[Conclusion] According to cultural characteristics,morphological observation,biochemical and physiological tests,FM2 belongs to bacillus subtilis,while FM3 and FM4 belong to micrococcus.

Comparative Assessment of Genetic Diversity of Peanut (Arachis hypogaea L.)Genotypes with Various Levels of Resistance to Bacterial Wilt Through SSR and AFLP Analyses

Bacterial wilt （BW） caused by Ralstonia solanacearum is an important constraint to peanut （Arachis hypogaea L.） production in several Asian and African countries, and planting BW-resistant cultivars is the most feasible method for controlling the disease. Although several BW-resistant peanut germplasm accessions have been identified, the genetic diversity among these has not been properly investigated, which has impeded efficient utilization. In this study, the genetic relationships of 31 peanut genotypes with various levels of resistance to BW were assessed based on SSR and AFLP analyses. Twenty-nine of 78 SSR primers and 32 of 126 AFLP primer combinations employed in this study were polymorphic amongst the peanut genotypes tested. The SSR primers amplified 91 polymorphic loci in total with an average of 3.14 alleles per primer, and the AFLP primers amplified 72 polymorphic loci in total with an average of 2.25 alleles per primer. Four SSR primers （14H06, 7G02, 3A8, 16C6） and one AFLP primer （P1M62） were found to be most efficient in detecting diversity. The genetic distance between pairs of genotypes ranged from 0.12 to 0.94 with an average of 0.53 in the SSR data and from 0.06 to 0.57 with an average of 0.25 in the AFLP data. The SSR-based estimates of the genetic distance were generally larger than that based on the AFLP data. The genotypes belonging to subsp, fastigiata possessed wider diversity than that of subsp, hypogaea. The clustering of genotypes based on the SSR and AFLP data were similar but the SSR clustering was more consistent with morphological classification ofA. hypogaea. Optimum diverse genotypes of both subsp, hypogaea and subsp.fastigiata can be recommended based on this analysis for developing mapping populations and breeding for high yielding and resistant cultivars.

Resistance Evaluation of Eggplant Resources to Verticillium wilt in Sichuan Province

[Objective] Aimed to lay a scientific foundation for eggplant resistant breeding, the resistant field identification of eggplant resources to Verticillium wilt was carried out. [Method] Test materials were 35 eggplant resources, which were collected from various places in Sichuan province since 2001. These eggplant resources were made resistance evaluation to Verticillium wilt by watering injured roots with Verticillium dahliae spore suspension. [Result] The eggplant resources had good resistance to Verticillium wilt. Among 35 evaluated resources, 10 resources like 242-9OP, 41-1,35-R5, etc. were resistant, while 23 resources like 68 ×47, Zizaoqie, 32-1, etc. were tolerant. Some resistant resources like 41-1,35-R5, 47-R1, etc. had been transferred into new resistant varieties like EF9910, etc. by breeding institutes. [Conclusion] The resistant level and future resistance breeding direction of eggplant resources in Sichuan were clarified by the resistance evaluation of eggplant resources so as to provide a technical guidance for eggplant resistance breeding.

Isolation and Identification of Antifungal Bacterial Strain KL-1 against Plant Wilt Disease

[Objective] The antifungal bacteria of plant wilt disease was screened and identified to provide foundation for the study on bio-control preparation of plant wilt disease.[Method] Confrontation culture method was adopted to screen the bio-control bacteria with good antifungal effect against plant wilt disease,Biolog bacteria automatic identification system and 16S rDNA sequence analysis method were selected to identify its taxonomic status,the biological safety of the strain towards cotton and mice was also determined.[Result] 12 bacterial strains were isolated from rhizosphere of cotton.Among those strains,5 isolates showed antifungal activity against F.decemcellulare Brick,F.oxysporum f.sp.Diathi,F.oxysporum f.sp.vasinfectum.The antifungal effect of KL-1 strain against three target strains of pathogen reached 69.09%,80.78% and 78.89% respectively.Identification results of Biolog bacteria automatic identification system and 16S rDNA sequence analysis method showed that KL-1strain was Bacillus amyloliquefaciens;primary determination results of biological safety also showed that the strain KL-1 was safe and non-toxic towards cotton and mice.[Conclusion] KL-1strain of B.amyloliquefaciens had antifungal effect against several pathogens of plant wilt diseases,which was safe and non-toxic towards cotton and mice,being the bio-control strain with research and development potential.

Preliminary Study on Garlic Root Exudates Influences to the Growth of Pomegranate Wilt Pathogen(Ceratocystis fimbriata)and Bacillus subtilis

[Objectives] This paper aims to explore the possibility to intercrop garlic with pomegranate tree to control pomegranate wilt.[Methods] Root exudates of garlic is cultivated in 1/5 concentration of MS solution and distilled water is examined in lab to test their effect to growth of mycelia of pomegranate wilt pathogen（Ceratocystis fimbriata）and multiplication of Bacillus subtilis.[Results] The result shows that garlic root exudates whatever cultivated in MS solution or distilled water could not inhibit or promote mycelia growth of C.fimbriata.However,garlic root exudates cultivated in both methods effectively promote multiplication of B.subtilis.[Conclusions] It is suggested that intercropping garlic with pomegranate tree by combining application B.subtilis could be a promising way to prevent pomegranate wilt spread in practice.

0.1%噁霉灵颗粒剂防治番茄枯萎病效果初探

通过比较不同用量、不同噁霉灵药剂产品对防治番茄枯萎病的效果,探索噁霉灵防治番茄枯萎病的田间药效。结果发现,施用基肥时,0.1%噁霉灵颗粒剂防治效果因施用量的增大而提高,且施用简便、省时,每667 m^(2)节省成本375元左右。植株发病初期,采用70%噁霉灵可湿性粉剂喷雾能控制病害的发生,但盛果期发病时田间操作难度大。综合考虑,0.1%噁霉灵颗粒剂可有效防治番茄枯萎病,同时降低单位面积生产成本,提高种植效益。

16%噁霉灵·咯菌腈悬浮剂防治黄瓜枯萎病田间防效试验

本试验以常用枯萎病防治药剂25g/L咯菌腈悬浮剂和15%噁霉灵水剂为对照,研究了16%噁霉灵·咯菌腈悬浮剂防治黄瓜枯萎病的田间防病效果。结果表明,16%噁霉灵·咯菌腈悬浮剂32mg/kg、40mg/kg和53.3mg/kg3个处理两次药后的防效分别为73.60%、79.33%和82.92%;16%噁霉灵·咯菌腈悬浮剂40mg/kg处理的防效与对照药剂25g/L咯菌腈悬浮剂35.7mg/kg和15%噁霉灵水剂42.86mg/kg处理防效相当,表明16%噁霉灵·咯菌腈悬浮剂具有较好的防治效果,对作物安全,可在生产中推广使用。

3%中生菌素可湿性粉剂防治番茄青枯病的效果初探

通过3%中生菌素可湿性粉剂(WP)防治番茄青枯病的室内抑菌和田间药效试验发现,该药剂对番茄青枯病具有良好效果,EC50为0.22mg·L-1,第3次施药后30d,3%中生菌素WP600倍液的防效为83.27%,与对照药剂72%硫酸链霉素可溶性粉剂(SP)1000倍液、77%可杀得WP600倍液差异达极显著水平。产量调查结果显示,3%中生菌素WP600倍液产量比清水对照增加1505.0kg·(667m2)-1,保产率达89.85%。

30.2%芽敌水剂对烟草青枯病抑制效果的研究

[目的]寻找有效的防治烟草青枯病的药剂，为降低青枯病的损失奠定基础。[方法]选择烟草青枯病发生较重的田块作为试验田，采取灌根的方法进行药效试验，比较4种药剂对烟草青枯病抑制效果。[结果]经过连续2年的小区药效试验表明：施用芽敌水剂后，随着时间推移，青枯病的发病速度和危害程度明显降低。在烟草青枯病易发田块，当烟株打顶后喷施30．2％的芽敌水剂2次，对烟株抑芽效果达到82．27％-91．43％，对青枯病防治效果达53．13％。硼肥加石硫合剂处理对青枯病抑制有一定作用。[结论]30．2％芽敌水剂对烟草青枯病的发生有明显的抑制作用，既抑芽又防病，是防治烟草青枯病的理想药剂。

Inhibitory Effects of Extracts from Marigold(Tagetes patula) against Tomato Fusarium Wilt

[ Objective ] The study aimed to explore a new way for the control of Tomato Fusarium Wilt. [ Method ] Different solvents were used to prepare the ex-tracts of marigold, and the inhibitory effects of different extraction solvents and different extraction parts of marigold against Tomato Fusar/um Wilt were compared. [ Result ] Among different solvent extracts of marigold, chloroform extracts had the strongest inhibitory effects against the growth of the pathogen; among the chloro- form extracts from different parts of marigold, root extract had the most obvious inhibitory effect against the disease, followed by flower and leaf extracts, and the in- hibitory effect of stem extract was the weakest. [ Conclusion ] The active components of marigold have inhibitory effect against Tomato Fusarium Wilt, and the plant has good development prospects and application value.

Bioinformatics Analysis of Antifungal Peptide 25a2 of Cotton Verticillium Wilt

Protein 25a2 is the antifungal peptide of cotton Verticillium wilt which was isolated from Bacillus amyloliquefaciens. The amino acid sequence of antifungal peptide 25a2 was analyzed using bioinformatics tools, and the characters of signal peptides, transmembrane topological structura, physicochemical signatures, protein domain, secondary and tertiary structure of protein were predicted. The results showed that 25a2 was a secreted protein, the sequence of which included a signal peptide in N end and a transmembrane domain in C end. The predicted secondary structure showed that the antibacterial peptide was mainly free random coils, belonging to mixed protein, three-dimensional model of 25a2 was a compact ball. These results showed that the most possible action mechanism of antifungal peptide 25a2 might be ＂carpet＂ model.

Effects of Seedling-cake Integrated with Arbuscular Mycorrhizal Fungi on Resistance of Bacterial Wilt in Pepper (Capsicum annuum L.)

[Objective] The aim was to investigated the effects of seedling-cake with AMF on resistance of pepper （Capsicum annuum L.） to bacterial wilt. [Methods] A pot experiment was conducted to evaluate the dynamics of mycorrhizal colonization, disease index, morbidity rate, control effect and several agronomic traits of mycorrhizal seedlings after inoculation with RS in two kinds of seeding-cakes with AMF. [Results] Two kinds of seedling-cakes formed steadily mycorrhizal colonization after inoculation, which enhanced disease-resistance and decreased morbidity rate and disease index in different degrees. What’s more, the performance of self-made seedling-cakes was obviously better than that of commercial seedling-cakes. [Conclusions] Self-made seedling-cakes with AMF have superior performance on bacterial wilt resistance of pepper, which should be made use of in other crops extensively.

Molecular Marker Assisted Selection for Fusarium Wilt Resistance Breeding in Watermelon(Citrullus lanatus)

Molecular identification on diploid and tetraploid watermelon breeding lines which were resistant to Fusarium wilt was carried out with the published dCAPS marker ＂4451_fon＂ which was closely linked with resistance gene of Fusarium wilt race 1. The results showed that all the diploid and tetraploid lines expressed as re- sistant genotype, which were defined as Fusarium wilt-resistant materials. The re- sults were consistent with that of artificial inoculation identification. Molecular identifi- cation results also indicated that the resistant lines were homozygote, and the Fusarium wilt-resistant gene would not separate or lose during the future self- crossed purification. Therefore, resistance selection would not be necessary in their progeny populations. The study results thought that dCAPS marker ＂4451_fon＂ could be applied on molecular marker assisted selection for Fusarium wilt resistance breeding in watermelon to increase breeding selection efficiency and accelerate breeding progress.

5%依维菌素微乳剂注干预防松材线虫病效果评价

在室内开展依维菌素对松材线虫的生物活性测定,并在松材线虫病疫区进行不同剂量的5%依维菌素微乳剂林间注干预防松材线虫病试验。结果表明:依维菌素对松材线虫的LC_(50)为0.640 9 mg·L^(-1),林间注干施用时,5%依维菌素微乳剂用量为2.0 mL·cm^(-1)胸径时对松材线虫病预防效果为100.00%,与制剂用量为1.0 mL·cm^(-1)胸径的预防效果(92.11%)存在显著差异,而与制剂用量为1.5 mL·cm^(-1)胸径的预防效果(97.37%)差异不显著。建议在使用5%依维菌素微乳剂预防松材线虫病时,制剂用量为1.5~2.0 mL·cm^(-1)胸径为宜,选择在松材线虫病预防期和侵染初期使用。研究结果为松材线虫病新型注干药剂的筛选、推广应用奠定了基础。

Purification of Antifungal Protein from Biocontrol Strain XG-1 against Fusarium Wilt of Watermelon

[Objective] This study aimed to isolate and purify the antifungal protein against Fusarium oxysporum f. sp niveum （FON） from Bacillus subtilis XG-I. [Method] The crude protein was obtained by using fractional precipitation with am- monium sulfate, then chromatography using both DEAE-Sepharose FF anion ex- change and Sephacryl S-100 gel filtration columns was adopted for further purifica- tion of the protein, followed by MALDI-TOF-MS analysis of the structure of the at- tained protein which was antagonistic to FON. [Result] The result from MALDI-TOF- MS analysis suggested that the antifungal protein extracted from strain XG-1 was highly homologous to the flagellin （gi114278900） deriving from B. subtilis, with a pro- tein score of 248 and a coverage rate of 63%. It was thus speculated that this an- tagonistic protein was a kind of flagellin with a molecular mass of 30.6 kD. [Conclusion] The results from this study provide theoretical basis for clarifying the mechanisms of the action of strain XG-1 as well as important references for the preven- tion and control of watermelon Fusarium wilt.

42%威百亩水剂对松材线虫疫木熏杀处理试验

为了评价42%威百亩水剂对松材线虫疫木的熏蒸效果,采用室内试验和林间试验相结合的方法,研究不同浓度施药量、不同温度和不同处理时间对威百亩熏蒸防治松材线虫病的作用效果。室内熏蒸试验结果表明:42%威百亩水剂对松褐天牛幼虫的致死率随着药剂浓度的增加和熏蒸时间延长而增加,在0.25 L·m^(-3)时7 d的死亡率达93.3%,在1.0 L·m^(-3)时5 d的死亡率达100%;相同药剂浓度下,温度越高对松褐天牛幼虫的致死率越高,在5℃时10 d的死亡率为96.0%;在10℃时10 d的死亡率高达100%。林间熏蒸试验结果表明:42%威百亩水剂对松材线虫疫木里的天牛幼虫和松材线虫都表现出良好的熏杀作用,在0.5 L·m^(-3)剂量30 d和0.75 L·m^(-3)剂量15 d天牛幼虫死亡率达100%,且30 d疫木内松材线虫死亡率为100%;熏杀效果显著优于常用磷化铝。