Resistance Evaluation of Soybean Germplasm from Huanghuai Region to Phytophthora Root Rot

The aim of the study was to establish a set of differential strains and to identify soybean resistant genes to Phytophthora root rot and then to apply those strains for analysis of the resistant genes Rps1a,Rps1c,and Rps1k that soybean cultivars or lines may carry.Virulence formula of 125 Phytophthora sojae isolates were determined using the hypocotyls inoculation technique,the strains,which includ 6 isolates with different virulence formulas,were applied to identify the resistance of 55 soybean cultivars or lines and resistant genes were analyzed using the gene postulating procedure.Eighteen reaction types occurred in 55 cultivars or lines and results of gene postulation indicated that 2 cultivars or lines probably carried gene Rps1c and no cultivar may carry genes Rps1a or Rps1k.A few of soybean cultivars or lines from Huanghuai Region carry Rps genes Rps1a,Rps1c and Rps1k and tend to infect by P.sojae,so resistant cultivars or lines need to be bred and popularized actively.

Impact of long-term chemical fertilizer and organic amendment to Fusarium root rot of soybean

Soil suppressiveness to Fusarium root rot of soybean had been observed in a black soil field after a long-term fertilization with nitrogen(N)and phosphorus(P)fertilizer combined with pig manure as organic amendment(NPM),rather than that with only nitrogen and phosphorus fertilizer(NP)or no fertilizer(NF).To determine the microbial role on this suppressiveness,fungal and bacterial community characteristics in NPM,NP and NF treatments were investigated by q PCR and DGGE.Compared with the similar bacterial community characteristics among 3 treatments,fungal community,especially Fusarium population size and community composition in NPM treatment were different with those of NP and NF groups.Based on the isolation and pathogenicity test,pathogenic F.oxysporum,F.graminearum,F.verticillioide and F.lateritium absolutely dominated Fusarium community in NF and NP groups.Nonpathogenic F.avenaceum,F.equiseti,F.culmorum,F.redolens,F.solani and F.tricinctum dominated Fusarium community in NPM group.Isolation rate of pathogenic Fusarium in NPM reduced from 100%to 38%in NF.These results suggested that the dominance of soil non-pathogenic Fusarium population induced by organic amendment might play an important role on suppressing Fusarium root rot in the tested field.

Evaluation of phytophthora root rot-resistant <i>Capsicum annuum</i>accessions for resistance to phytophthora foliar blight and phytophthora stem blight

A mixture of six Georgia isolates of Phytophthora capsici (Leon.), the causal agent of phytophthora blight, were used for greenhouse mass screening of over 700 accessions of Capsicum annuum for both stem blight and foliar blight. From this screening, it was determined that resistance to both forms of the disease were relatively common in the germplasm, but resistance to one form of the disease was not strongly correlated to resistance to the other form. Ten accessions previously shown to possess root rot resistance were tested for resistance to stem rot and leaf blight, and were found to also be highly resistant to these forms of the disease. It appears that single accessions have resistance to foliar, stem and root rot caused by P. capsici, which may simplify breeding for resistance to all three forms of the disease.

Resistance identification of bivalent fungi-resistant genes transformed soybean to Phytophthora sojae

Soybean is one of the most important sources of edible oil and proteins in the world. However, it suffers from many kinds of fungal diseases which is a major limiting factor in soybean production. The fungal disease can be effectively controlled by breeding plant cultivars with genetic transformation. In this study, the resistance to Phytophthora sojae of five bivalent transgenic soybean lines was identified using the hypocotyls inoculation technique. The lines were the T2 of the transgenic soybean which were transformed with kidney bean chitinase gene and barley ribosome inactivating protein gene, and were positive by Southern Blot analysis. The resistance difference was studied through comparing the death percentage of transgenic soybean with the control. The results showed that four lines were more resistant to P sojae, whereas other one had no significant difference in comparison with the control. These transgenic soybean lines with enhanced resistance to P sojae will be useful in soybean resistance breeding.

Colonization by Klebsiella variicola FH-1 stimulates soybean growth and alleviates the stress of Sclerotinia sclerotiorum

Sclerotinia stem rot,caused by Sclerotinia sclerotiorum,is a destructive soil-borne disease leading to huge yield loss.We previously reported that Klebsiella variicola FH-1 could degrade atrazine herbicides,and the vegetative growth of atrazine-sensitive crops(i.e.,soybean)was significantly increased in the FH-1-treated soil.Interestingly,we found that FH-1 could promote soybean growth and induce resistance to S.sclerotiorum.In our study,strain FH-1 could grow in a nitrogen-free environment,dissolve inorganic phosphorus and potassium,and produce indoleacetic acid and a siderophore.The results of pot experiments showed that K.variicola FH-1 promoted soybean plant development,substantially improving plant height,fresh weight,and root length,and induced resistance against S.sclerotiorum infection in soybean leaves.The area under the disease progression curve(AUDPC)for treatment with strain FH-1 was significantly lower than the control and was reduced by up to 42.2%within 48 h(P<0.001).Moreover,strain FH-1 rcovered the activities of catalase,superoxide dismutase,peroxidase,phenylalanine ammonia lyase,and polyphenol oxidase,which are involved in plant protection,and reduced malondialdehyde accumulation in the leaves.The mechanism of induction of resistance appeared to be primarily resulted from the enhancement of transcript levels of PR10,PR12,AOS,CHS,and PDF1.2 genes.The colonization of FH-1 on soybean root,determined using CLSM and SEM,revealed that FH-1 colonized soybean root surfaces,root hairs,and exodermis to form biofilms.In summary,K.variicola FH-1 exhibited the biological control potential by inducing resistance in soybean against S.sclerotiorum infection,providing new suggestions for green prevention and control.

Relationships between Microsclerotia Content and Hyperspectral Reflectance Data in Soybean Tissue Infected by Macrophomina phaseolina

Alternative methods are needed to assess the severity of charcoal rot disease [Macrophomina phaseolina (Tassi) Goid] in soybean [Glycine max (L.)] plant tissue. The objective of this study was to define the relationship between light reflectance properties and microsclerotia content of soybean stem and root tissue. Understanding that relationship could lead to using spectral reflectance data as a tool to assess the severity of charcoal rot disease in soybean plants, thus reducing human bias associated with qualitative analysis of soybean plant tissue and cost and time issues connected with quantitative analysis. Hyperspectral reflectance measurements (400-2490 nm) were obtained with a non-imaging spectroradiometer of non-diseased and charcoal rot diseased ground stem and root tissue samples of six soybean genotypes (“Clark”, “LD00-3309”, “LG03- 4561-14”, “LG03-4561-19”, “Saline”, and “Y227-1”). Relationships between the reflectance measurements and tissue microsclerotia content were evaluated with Spearman correlation (rs) analysis (p < 0.05). Moderate (rs = ±0.40 to ±0.59), strong (rs = ±0.60 to ±0.79), and very strong (rs = ±0.80 to ±1.00) negative and positive statistically significant (p < 0.05) monotonic relationships were observed between tissue spectral reflectance values and tissue microsclerotia content. Near-infrared and shortwave-infrared wavelengths had the best relationships with microsclerotia content in the ground tissue samples, with consistent results obtained with near-infrared wavelengths in that decreases in near-infrared spectral reflectance values were associated with increases in microsclerotia content in the stem and root tissue of the soybean plants. The findings of this study provided evidence that relationships exist between tissue spectral reflectance and tissue microsclerotia content of soybean plants, supporting spectral reflectance data as a means for assessing variation of microsclerotia content in soybean plants. Future research should focus on the modelling capabilities of the selected wavelengths and on the feasibility of using these wavelengths in machine learning algorithms to differentiate non-diseased from charcoal rot diseased tissue.

Conidia of one Fusarium solani isolate from a soybean-production field enable to be virulent to soybean and make soybean seedlings wilted

Fusarium is usually thought to cause soybean root rot, which results in a large quantity of annual yield loss in soybean production, by its secretions including Fusarium toxins and cell wall degrading enzymes, but not by the conidia themselves that do not underlie any virulence so far. Here we report that the conidia of one Fusarium solani isolate are able to be virulent to soybean and make soybean seedlings wilted alone. We isolated them from the wilted plants in a soybean-production field and molecularly identified 17 Fusarium isolates through phylogenetic analysis. Of them, except for one isolate that showed diversity of virulence to different soybeans （virulent to one soybean whereas avirulent to another soybean）, the others were all virulent to the two tested soybeans： both conidia cultures and secretions could make soybean seedlings wilted at 5 days post infection, and their virulence had dosage effects that only conidia cultures of at least 5×10^6 conidia mL-1 could show virulence to soybean; however, the sole conidia of the F. solani isolate #4 also exhibited virulence to soybean and could make soybean seedlings wilted. Finally, we developed the specific cleaved amplified polymorphic sequences （CAPS） markers to easily differentiate Fusarium isolates. The isolate #4 in this work will likely be used to investigate the new mechanism of virulence of Fusarium to soybean.

Occurrence of Root Rot Caused by Phytophthora cryptogea on Common Sage （Salvia officinalis） in Turkey

Common sage or Dalmatian sage （Salvia officinalis L.） is a perennial plant （subshrub）, native to the Mediterranean region. This research was conducted to identify the fungi species which cause a sudden damping-off disease in some common sage plantation, in the coastal experimental areas of Antalya and Izmir provinces of Turkey. The infected plant materials were collected from Mediterranean and Eagean regions which showed root and crown rots typical ofPhytophthora sp. symptoms. Ten plants having those symptoms were used for identification of the causal agent by Phytophthora selective medium. A new Phytophthora species was isolated and identified as P. cryptogea as a result of morphological and molecular characteristics of DNA base sequences of internal transcribed spacer （ITS） regions. Pathogenicity of P. cryptogea was proved on rooted cuttings of common sage. This is the first report of P. cryptogea on common sage in Turkey.

Phytophthora Root and Crown Rot on Fruit Trees in Bulgaria

Phytophthora root and crown rot was found on the fruit trees in Bulgaria for the first time in the period 1998-1999. Monitoring of the disease spread from 2000 to 2007 points out incidence between 2 and 14 per cent, in some orchards and nurseries in the Southern part of Bulgaria. The following Phytophthora species were identified based on morphological and cultural characteristics, and temperature requirements： Phytophthora cactorum, Phytophthora citrophthora, Phytophthora drechsleri, Phytophthora cryptogea, Phytophthora hybrid specie and Pythium. Prevailing specie was P. cactorum. P. cryptogea and P. cactorum were confirmed by application of molecular methods. Nutritional requirements of P. cactorum and P. citrophthora were studied. Most Nitrogen sources stimulated the mycelial growth of P. cactorum to a higher extend, and reduced the colony size ofP. citrophthora. Different Carbon sources were utilized well by P. cactorum, and only saccharose and maltose had a stimulating effect on the mycelial growth of P. citrophthora. MgSO4.7H20 was the preferred sulfur source for both fungi, as L-cysteine and L-methionine only for P. cactorum. Phytophthora infection leads to physiological changes in the.host plant tissues. The tendency traced out is： about disorders in the amino acid metabolism, increase in the total sugars and slight reduction of the cellulose content. The total nitrogen, phosphorus and potassium content are reduced and the calcium and magnesium are increased. Photosynthesis of inoculated plants was suppressed and transpiration was increased.

Fusarium-produced vitamin B6 promotes the evasion of soybean resistance by Phytophthora sojae

Plants can be infected by multiple pathogens concurrently in natural systems. However,pathogen–pathogen interactions have rarely been studied. In addition to the oomycete Phytophthora sojae, fungi such as Fusarium spp. also cause soybean root rot. In a 3-year field investigation, we discovered that P. sojae and Fusarium spp. frequently coexisted in diseased soybean roots. Out of 336 P. sojae–soybean–Fusarium combinations,more than 80% aggravated disease. Different Fusarium species all enhanced P. sojae infection when co-inoculated on soybean. Treatment with Fusarium secreted non-proteinaceous metabolites had an effect equal to the direct pathogen coinoculation. By screening a Fusarium graminearum mutant library, we identified Fusarium promoting factor of Phytophthora sojae infection 1(Fpp1),encoding a zinc alcohol dehydrogenase. Fpp1 is functionally conserved in Fusarium and contributes to metabolite-mediated infection promotion, in which vitamin B6(VB6) produced by Fusarium is key. Transcriptional and functional analyses revealed that Fpp1 regulates two VB6 metabolism genes, and VB6 suppresses expression of soybean disease resistance-related genes. These results reveal that co-infection with Fusarium promotes loss of P. sojae resistance in soybean, information that will inform the sustainable use of diseaseresistant crop varieties and provide new strategies to control soybean root rot.

Distribution and Virulence Diversity of Phytophthora sojae in China

By investigating occurrence of Phytophthora root rot in fields and isolating P.sojae fromdiseased plants and soils, the distribution of P.sojae in China was surveyed. In addition tonortheast region, P.sojae existed in Huanghe-Huaihe basin and Yangtze basin too. Eighty- threeisolates of P.sojae isolated from different areas were identified on virulence using 13differential soybean cultivars, abundant virulence diversity was found in P.sojae. The greaterdiversity in virulence of P.sojae was in isolates from soil than from plants. And the greatestvirulence diversity of P.sojae was found in Yangtze basin.

Study on Identification of RAPD Marker of Phytophthora sojae Associated with Rps1-k

A near-isogenic lines(NILs) -Williams and Williams82 is used to identify molecular marker linked to the resistance gene Rps1-k by RAPD. Genomic DNAs extracted from soybean leaves of the NILs were analyzed by RAPD using 160 different 10-nt random primers. Some specific DNA fragments were amplified from Williams82 with 4 primer(OPF-16, OPB-05, OPD-06 and OPH-05) which contains Rps1-k. All these specific DNA fragments were not detected in Williams. The experiment with OPH-05 was repeated 3 times and the results were the same. Using primer- OPH-05 to detect other resistance cultivars with Rps1-k, almost everyone can amplify the specific DNA fragment. So it is inferred that the specific DNA fragment is probably linked to Rps1-k.

The disease reactions of heirloom bell pepper “California Wonder” to <i>Phytophthora capsici</i>

Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.

大豆镰刀菌根腐病拮抗菌的筛选及生防效果

【目的】镰刀菌根腐病是世界范围内大豆生产上最具破坏性的土传病害之一,为获得对禾谷镰刀菌Fusarium graminearum具有较好拮抗效果的生防菌株。【方法】从健康大豆根际土壤分离细菌,平板对峙法筛选拮抗菌株,通过形态观察、生理生化特性、胞外酶活性及促生特性对菌株进行鉴定分析,采用盆栽试验进一步测定菌株生防及促生效果。【结果】筛选出的4株芽孢杆菌和1株假单胞杆菌对F.graminearum的抑菌率均达到60%以上,对F.oxysporum,F.solani,F.longifundum以及F.equiseti也均有一定的抑制作用,其发酵液及挥发代谢物均会影响F.graminearum的生长。5株拮抗菌具有产蛋白酶、纤维素酶以及葡聚糖酶的活性,解磷、解钾、固氮以及产铁载体的能力。综合以上测试结果,菌株20-8具有较强的抑菌及大豆促生效果。根据形态特征及16S rRNA序列分析,将菌株20-8鉴定为暹罗芽孢杆菌(Bacillus siamensis)。该菌株的发酵上清液可以破坏F.graminearum菌丝体结构,无细胞发酵上清液可以显著抑制孢子萌发。室内盆栽防效测定结果表明,20-8的稀释发酵液对F.graminearum引起大豆根腐病的防效可达46.08%,并且促进大豆植株生长。【结论】筛选鉴定的暹罗芽孢杆菌20-8具有解磷、解钾、固氮以及产铁载体及多种胞外酶功能,其稀释发酵液具有较强的抗真菌活性及大豆促生能力,菌株20-8可以用于防治F.graminearum引起的大豆根腐病。

番茄疫霉根腐病菌拮抗细菌HP8-1的鉴定及生物防治潜力

【目的】探究HP8-1在番茄上的生物防治潜力,为番茄疫霉根腐病的生物防治提供优良生物防治资源。【方法】通过形态学观察、生理生化特性检测并结合16S rRNA序列分析鉴定HP8-1菌株,探讨其对植物病原菌的抑菌效果和生物学功能及在番茄根际的定殖能力,并通过盆栽试验测定其对番茄疫霉根腐病的防治效果和对番茄生长的影响。【结果】HP8-1为多粘类芽孢杆菌(Paenibacillus polymyxa),对多种植物病原菌具有抑菌效果,具有解磷、分解蛋白、分解纤维素、产嗜铁素和产吲哚乙酸等生物学功能;HP8-1在番茄根系和根际土壤具有稳定的定殖能力,尤其是在接种疫霉菌的条件下其定殖量趋于增加并显著高于未接种疫霉菌的条件;HP8-1处理对番茄疫霉根腐病具有明显的防治效果,防治效果达到57.41%;同时,HP8-1处理显著促进番茄植株生长、提高叶绿素含量和根系活力。【结论】HP8-1菌株稳定定殖在番茄根系和根际土壤,防治番茄疫霉根腐病,促进番茄生长,是对番茄疫霉根腐病具有生物防治潜力的资源。

浅析黑龙江省大豆根腐病研究现状

大豆根腐病为大豆主要病害之一,具有发病范围广、卵孢子存活时间长、危害重等特点,严重制约黑龙江省大豆产业发展。为提高黑龙江省大豆根腐病防控技术水平,文章综述黑龙江省大豆根腐病致病菌种类及分布、发病症状及特点、抗病品种鉴定及防治措施,以期为黑龙江省大豆根腐病防治及研究提供理论依据,助力黑龙江省大豆产业振兴。

镰孢菌引发的大豆根腐病及其生物防治研究进展

大豆是我国主要粮食和经济作物之一,但其产量和品质极易受病害影响。大豆根腐病是世界范围内较为常见的大豆病害类型。镰孢菌(Fusarium)是大豆根腐病的主要致病菌之一。本文综述了由镰孢菌引发的大豆根腐病的发生条件、发病症状及病害影响,并分析了镰孢菌引发大豆根腐病的致病性与发病机理。通过尖孢镰孢菌(F.oxysporum)和禾谷镰孢菌(F.graminearum)的致病性研究发现,镰孢菌属菌株可以通过破坏宿主植物免疫应答系统或分泌真菌毒素破坏植物细胞等方式引发大豆根腐病。同时不同病原菌之间还存在协同互作机制,可通过分泌促侵染关键物质协同逃脱宿主植物防御。本文总结了镰孢菌引发的大豆根腐病的生物防治研究进展。生物防治手段集合多个作用靶点于一体,通过转录组学技术能够揭示生物防治的作用机理,而生防微生物固有的活体属性所带来的应用局限性则可通过与农业田间管理、化学防治相结合等方式加以攻破。本文还对关于大豆根腐病乃至各类农业生产病害的生物防治未来研究方向进行了展望。

黑龙江省北部地区大豆种质对疫霉根腐病抗性评价

为了明确黑龙江省北部地区大豆种质资源对大豆疫霉根腐病的抗耐情况,采用下胚轴创伤接种法,对适宜该地区种植的113份大豆育成品种或育种材料的大豆疫霉根腐病抗性开展鉴定。结果显示:共鉴定出7份抗病种质,占鉴定总数的6.19%;5份中间类型种质,占鉴定总数的4.42%。其中,从第三积温带种质中鉴定出1份抗病种质,中间类型种质1份;从第四积温带种质中鉴定出抗性种质3份,中间类型种质2份;从第五积温带种质中鉴定出抗性种质1份,中间类型种质2份;从第六积温带种质中鉴定出抗性种质2份,未见中间类型种质。结果表明在不同积温带参试材料中均存在抗性种质。该研究结果为黑龙江省北部地区培育和利用抗疫霉根腐病大豆种质提供了参考。

大豆根腐病致病病原菌及其抗性研究进展

文章综述大豆根腐病病原菌鉴定与分布、抗病性鉴定与抗病基因挖掘研究现状,从栽培措施、化学防治、定向育种、生物防治方面总结根腐病防治方法,展望未来研究方向,旨在为提高大豆产量提供科学依据。

番茄疫霉根腐病病原菌鉴定及药剂敏感性分析

[目的]番茄是内蒙古自治区重要的优势特色蔬菜,近年来因连年重茬、种植品种单一,土传病害发生率增加,制约着番茄产业的健康发展。2021年8月在内蒙古呼和浩特地区番茄苗期出现了一种茎基部变黑、溢缩,纵切维管束褐变的症状,疑似根腐病,为了明确病原菌的种类并为科学防治提供依据,开展了病原菌鉴定及7种药剂的室内敏感性试验。[方法]通过采集20株发病植株,开展了组织分离及病原菌培养、形态学观察、分子生物学鉴定、生理小种鉴定,柯赫氏法则验证以及防治药剂筛选。[结果]从20份发病植株样本中分离得到10个分离株,菌落白色短绒毛状、光照诱导条件下可产生孢子囊,利用ITS测序并构建系统发育树确定其为辣椒疫霉菌;分离株能够侵染苗期番茄植株,产生疫霉根腐病的典型症状,与田间发病症状一致,验证了柯赫氏法则,说明其为番茄疫霉根腐病的病原菌,并且病原菌中2号生理小种占70%,其余为3号生理小种。此外,室内培养条件下7种常用杀菌剂对辣椒疫霉菌的菌丝生长均有抑制作用,其中烯酰吗啉、甲霜灵和嘧菌酯的抑制效果最好。[结论]侵染内蒙古呼和浩特地区番茄植株的辣椒疫霉菌以2号生理小种为主,2号生理小种的化学防治推荐使用烯酰吗啉、甲霜灵和嘧菌酯,使用药剂防治时注意轮换用药以延缓抗药性的产生。