2020—2021年江苏省稻曲病菌对三唑类杀菌剂的抗药性监测

前期研究发现江苏省稻曲病菌对三唑类杀菌剂存在抗药性风险,为进一步明确江苏省稻曲病菌对三唑类杀菌剂的抗药性发展规律,指导全省三唑类杀菌剂的科学使用,利用菌丝生长速率法,测定了2020年江苏省6个地区和2021年江苏省7个地区共计219个稻曲病菌单孢菌株对三唑类杀菌剂的敏感性,并通过测定抗性菌株的生长速率和对水稻的致病力对其适合度进行了分析。结果表明,2020年采集的84株稻曲病菌对丙环唑均敏感;2021年,在靖江市监测到1株抗药性菌株,该市抗性频率为6.7%,全省抗性频率为0.7%;抗性水平2.2倍。进一步对筛选到的稻曲病菌抗药性菌株适合分析发现,抗药性菌株生长和致病力与敏感菌株相比均无显著差异,表明在三唑类杀菌剂的田间选择压下,抗药性可能会进一步发展。本研究明确了江苏省稻曲病菌对三唑类杀菌剂存在低抗药性风险,目前在做好抗药性监测的前提下,三唑类杀菌剂可继续作为江苏省防治稻曲病的主要药剂。

解淀粉芽胞杆菌Jt84防治水稻稻曲病田间应用技术研究

为了明确解淀粉芽胞杆菌Jt84防治水稻稻曲病田间应用技术,本文初步研究生防菌Jt84定殖规律以及不同喷施时期对水稻稻曲病的防效。结果显示:生防菌Jt84在水稻叶表能够有效定殖,7~16d时,叶表定殖菌量维持在10^(4) cfu/cm^(2),30 d仍可在水稻叶表检测到生防菌Jt84;生防菌Jt84防治水稻稻曲病的最佳防治时期为水稻叶枕平时期(旗叶与倒二叶的叶枕在同一处),田间试验表明在此时期防治,当解淀粉芽胞杆菌Jt84使用量为200~400 mL/667 m^(2)时,对水稻稻曲病防治效果为77.8%~89.5%。

5种杀菌剂防治稻曲病田间药效对比试验与评价

【目的】筛选防控稻曲病的有效药剂,并对早期报道有效药剂的稳定性作出评判,为稻曲病防控合理选择药剂提供科学依据。【方法】分别选用曾报道对稻曲病防效良好的3种杀菌剂和曾报道对稻曲病防效不佳的1种杀菌剂及未在稻曲病上试验过的1种杀菌剂,进行田间防效对比试验,测定其对稻曲病的防治效果。【结果】于水稻黄熟期调查,防效以125g/L氟环唑悬浮剂和24%腈苯唑悬浮剂较好,达80%以上;50%醚菌酯水分散粒剂次之,其他药剂防效不理想。【结论】24%腈苯唑悬浮剂与125g/L氟环唑悬浮剂这两种杀菌剂对稻曲病防效稳定,当前仍适宜作为稻曲病防治的主推药剂在生产上使用,50%醚菌酯水分散粒剂可考虑作为备用药剂酌情使用。

Genome-Wide Identification of Zn_(2)Cys_(6 ) Class Fungal-Specific Transcription Factors(ZnFTFs)and Functional Analysis of UvZnFTFI in Ustilaginoidea virens

Transcription factors(TFs)orchestrate the regulation of cellular gene expression and thereby determine cell functionality.In this study,we analyzed the distribution of TFs containing domains,which named as ZnFTFs,both in ascomycete and basidiomycete fungi.We found that ZnFTFs were widely distributed in these fungal species,but there was more expansion of the ZnFTF class in Ascomycota than Basidiomycota.We identified 40 ZnFTFs in Ustilaginoidea virens,and demonstrated the involvement of UvZnFTF1 in vegetative growth,conidiation,pigment biosynthesis and pathogenicity.RNA-Seq analysis suggested that UvZnFTF1 may regulate different nutrient metabolism pathways,the production of secondary metabolites,and the expression of pathogen-host interaction genes and secreted protein-encodi ng genes.Analysis of the distributi on of differe nt fungal TFs in U.virens further dem on strated that UvZnFTFs make up a large TF family and may play essential biological roles in U.virens.

UvSMEK1,a Suppressor of MEK Null,Regulates Pathogenicity,Conidiation and Conidial Germination in Rice False Smut Fungus Ustilaginoidea virens

Rice false smut,which is caused by Ustilaginoidea virens,is an emerging disease of rice spikelets in rice-growing areas worldwide.However,the infection mechanism of U.virens on rice spikelets is still unclear.Here,we characterized a suppressor of mitogen-activated protein kinase kinase or ERK kinase(MEK)null(UvSMEKI)in U.virens that is conserved among filamentous fungi.Compared with wild type U.virens strain P-1,UvSMEKI deletion mutants were defective in pathogenicity and conidial germination.In addition,conidiation of UvSMEKI deletion mutants was significantly reduced on yeast extract tryptone(YT)plates,but inc「eased in YT broth compared with the wild type.Compared with UvSMEKI expression level during the vegetative mycelia and conidiation stages,UvSMEKI dramatically increased during infection of rice florets.Surprisingly,the UvSMEKI deletion mutants exhibited higher tolerance to H_(2)O_(2) and NaCl.In summary,presented evidence suggested that UvSMEKI positively regulated pathogenicity,conidial germination and conidiation in YT broth,and negatively regulated conidiation on YT medium and tolerance to oxidative and osmotic stresses.The results enhanee our understanding of the regulatory mechanism of pathogenicity of U.virens,and present a potential molecular target for blocking rice infection by U.virens.

稻曲病菌转录因子UvZnFTF2参与稻曲病菌生长发育和致病性

转录因子通过调控生物体内不同基因的转录进而调控机体的生物学功能。ZnFTFs(Zn2Cys6class fungal-specific transcription factors)家族转录因子具有Zn_clus结构域和fungal_trans结构域,是一类真菌特异性转录因子。关于该转录因子在稻曲病菌中的作用及其机制报道较少。本研究分析了包含一个Zn_clus结构域和fungal_trans结构域的UvZnFTF2转录因子在稻曲病菌侵染不同时间点的转录表达模式,结果表明,在侵染3 d后,UvZnFTF2的表达开始上升,侵染7 d后下降。通过生物信息学分析发现,UvZnFTF2进化上与蝗缘殭菌(Metarhizium acridum)的ZnFTF2(KAG8424307.1)同源性最高。通过在稻曲病菌中沉默UvZnFTF2进行功能研究发现,UvZnFTF2沉默后,稻曲病菌菌丝生长和产孢量显著降低,并且致病性显著下降。RT-PCR分析表明,沉默UvZnFTF2后稻曲病菌中效应子SGP1的转录表达量显著低于野生型菌株。上述结果揭示了UvZnFTF2对稻曲病菌生长、发育和致病性的重要作用,为深入揭示稻曲病菌生长发育和致病分子机制奠定基础。

江苏省稻瘟病菌对稻瘟灵的抗药性监测及特性分析

近几年我国山东省、黑龙江省、辽宁省等多地稻瘟病菌(Magnaporthe oryzae)已对稻瘟灵杀菌剂产生了抗药性。江苏省是我国水稻生产大省,为明确江苏省稻瘟病菌对稻瘟灵的敏感性,本研究分离了2019年采自江苏省6个地区的稻瘟病菌单孢菌株101株,监测到13株稻瘟病菌为稻瘟灵的抗药性菌株,全省稻瘟病菌对稻瘟灵的抗性频率为12.9%。除仪征市未监测到抗药性菌株外,其他5个地区徐州市、淮安市、连云港市、东台市以及宜兴市稻瘟病菌对稻瘟灵的抗性频率分别为40.0%、33.3%、11.5%、5.0%和5.9%。利用菌丝生长速率法对其进行了敏感性测定,结果表明,这13株抗药性菌株的EC;值为15.0~20.6 mg·L^(-1),其抗性水平在3.6~5.0之间,均表现为低抗水平。进一步对筛选到的稻瘟灵抗性菌株适合度分析发现,只有2株抗性菌株2019-33和2019-45适合度降低,其余抗性菌株均无明显变化。这13株抗性菌株与嘧菌酯、咪鲜胺以及稻瘟酰胺均不存在交互抗性,且抗性相关基因MoIRR未发生任何位点突变。