Inheritance Analysis and Identification of SSR Markers Linked to Late Blight Resistant Gene in Tomato

Late blight caused by Phytophthora infestans is the most serious disease of tomato production in China. Studies on the genetics of resistance and identification of molecular markers are very useful for breeding late blight resistant varieties. The objective of this paper was to study the inheritance of late blight resistance and identify simple sequence repeat （SSR） markers associated with resistance allele in tomato （Lycopersicon esculentum Mill）. The results came from an F2 progeny of 241 plants derived from a cross between 5~ inbred line that is susceptible to late blight and a resistant accession CLN2037E. The late blight responses of F2 plants were tested by artificially inoculation of detached-leaflets in plate and natural infection assayed under greenhouse conditions. Both methods showed that the resistance is dominant and inherited as monogenic trait. Genetic mapping and linkage analysis showed that the late blight resistance gene Ph-ROL was located on chromosome 9 with a genetic distance of 5.7 cM to the SSR marker TOM236.

SSR Molecular Marker for Late Blight Resistance Gene in Tomato CLN2037

[Objectives] The research aimed to investigate the genetic rule of the disease resistance of tomato CLN2037,find molecular markers linked with disease-resistant genes and locate the disease-resistant genes. [Methods] BCr,BCs and F2 were constructed from tomato CLN2037 and susceptible cultivar T2-03,and their resistance to late blight was identified and analyzed by inoculating the disease in the seedling stage of tomatoes. The genetic linkage analysis was made based on the genetic linkage map constructed by ICu GI using group segregation method and 90 pairs of tomato SSR primers. [Results]The resistance of CLN2037 to late blight was controlled by a single recessive gene. The polymorphic bands amplified by primer DM0231 had a linkage relationship with resistance genes. The size of the polymorphism fragment was 226 bp with the genetic linkage distance of 2. 67 c M,and the disease resistance gene was localized on CCPB272-03741.[Conclusions]DM0231 could be used as a molecular marker for molecular breeding of tomato against late blight,which laid the foundation for further fine localization of late blight resistance genes.

Molecular Markers Associated with <i>Ph</i>-3 Gene Conferring Late Blight Resistance in Tomato

Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to the chromosomes 7, 10 and 9, respectively. However, PCR-based molecular markers associated with these genes are limited. Molecular markers are extremely useful in the screening and selection of tomato lines for the development of LB resistant genotypes. The objective of this study was to identify molecular markers associated with Ph-3 gene conferring LB resistance in tomato. Four co-dominant markers were found to be associated with Ph-3, all of which were sequence characterized amplified region (SCAR) type. Breeding lines and cultivars were inoculated with a field isolate of Phytophthora infestans to collect phenotypic data on disease resistance. Genotypic data from molecular markers associated with Ph-3 were in close agreement with the phenotypic data for the lines tested. With the verification of genotypic data from novel molecular markers in known genotypes supported by phenotypic data, the novel molecular markers may be useful in screening tomato populations aiming to develop LB resistant genotypes or cloning the LB resistant genes.

马铃薯与致病疫霉互作研究进展与展望

马铃薯是重要的粮食作物,由致病疫霉侵染引发的晚疫病长期严重制约马铃薯产业的健康发展,因此,国内外均将马铃薯晚疫病列为重大病害。目前,抗病品种选育栽培、晚疫病预测预报和化学防治等相结合的晚疫病综合防治手段已得到普遍推广,但晚疫病局部大流行在全世界范围内仍时有发生,给粮食安全和生态安全带来巨大挑战。本文回顾了我国晚疫病的部分研究历史,集中关注致病疫霉与寄主的互作机制领域,梳理了近年来关于致病疫霉侵入机理、效应蛋白毒力功能、病原菌变异规律、马铃薯抗病机理等方面的重要研究结果并展望未来主要的研究方向,以期为晚疫病基础研究和防治技术革新提供参考。

番茄幼苗对接种晚疫病菌的生理响应

以番茄晚疫病抗病品系CLN2037E、感病品系5号自交系及其杂种一代F1为材料,人工接种番茄晚疫病菌生理小种T1、T2、T3,研究番茄苗期抵抗晚疫病的生理响应.结果显示:(1)感病品系的膜脂过氧化产物丙二醛(MDA)与过氧化氢(H2O2)的含量增加幅度较大,抗病品系的含量则相对稳定,F1代的变化趋势接近感病品系;(2)抗病品系和感病品系的多酚氧化酶(PPO)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性变化都呈先升高后下降,抗病品系的酶活性高峰出现早且峰值小于感病品系.研究发现,抗病番茄品系幼苗的多项生理指标在接种晚疫病菌后变化幅度小而稳定,并能在短时间内基本恢复到原来的正常状态,从而表现出较强的抗病性.

晚疫病诱导的番茄叶片cDNA文库构建及序列分析

以番茄抗病品系（CLN2037E）为研究材料,应用SMART技术构建晚疫病诱导的番茄叶片cDNA表达文库,并进行生物信息学分析。成功构建的cDNA文库的克隆数为2.3×109,重组率为96%,通过PCR检测,插入片段范围在0.1-2.0 kb之间。从文库中随机挑取110个克隆进行测序,最终得到107条差异表达ESTs序列。GenBank提交的序列号为GT742146-GT742150;GT865998-GT866099。利用BLAST进行同源性分析：75条ESTs与其他物种同源性较高,视为已知基因,功能涉及能量代谢的占42.7%、细胞内生命活动与信号传导的占10.7%、基因转录和翻译的占9.3%以及与抗性相关的占25.3%;另有32条ESTs无同源序列或同源性较低,预测是一些未知功能基因的占30%。本项研究应用SMART技术成功构建了高质量、信息丰富的晚疫病诱导的番茄叶片cDNA文库,为进一步筛选抗病相关候选基因奠定了基础。

PIAS对番茄晚疫病的诱导抗性及叶片内酶活性的研究

分别用6株番茄晚疫病菌弱毒菌株(简称:PIAS)在番茄幼苗2叶1心期对番茄幼苗进行诱导处理(叶片喷施),以研究弱毒菌株对番茄晚疫病的诱导抗性效果及叶片内酶活性的变化。结果表明:在接种后9~21 d的调查中PIAS-TR-dw处理植株的病情指数与对照有显著差异;在接种后21 d的调查中,PIAS-TR-dw、PIAS-TR-e、PIAS-TR-a、PIAS-TS-dw、PIAS-TL-e和PIAS-TL-a处理植株的病情指数均低于对照,各处理植株的诱导抗性效果分别为57.79%、21.29%、31.29%、48.18%、41.82%和18.32%,与PIAS-TL-a处理相比,PIAS-TR-dw、PIAS-TS-dw和PIAS-TL-e处理植株的诱导抗性效果均有显著差异。番茄晚疫病菌弱毒菌株诱导处理番茄叶片后12~132 h,各处理的PAL和POD活性与对照均有显著差异;诱导处理后36~84 h,各处理的APX、PPO和CAT活性均高于对照且有显著差异;诱导处理后84~132 h,各处理的APX、SOD和β-1,3-glucanase活性均高于对照且有显著差异。番茄叶片内的APX、SOD和β-1,3-glucanase活性与诱导抗性效果均为极显著正相关关系;PPO活性与诱导抗性效果为显著正相关关系;PAL、POD和CAT活性与诱导抗性效果均无显著相关关系。