[目的]对源自小麦品种蜀麦126的类病斑早衰突变体lmpsM4-17(lesion mimic and premature senescence M4-17)进行鉴定和基因定位。[方法]通过病斑发生观察、超微结构和组织化学特性研究明确类病斑突变体表型特征。将lmpsM4-17与正常小麦材料杂交构建遗传分离群体，对突变体进行遗传分析和基因定位。[结果]该突变体苗期叶片正常，孕穗期出现褪绿斑，且斑点数目随生育期逐渐增加并逐渐蔓延至叶鞘，灌浆期叶片黄化衰老。类病斑表型受光照诱导。与野生型相比，突变体lmpsM4-17对主要农艺性状有显著负效应。突变体叶片叶绿体数目和体积减小，过氧化物积累，类囊体片层结构严重受损;嗜锇小体数量增多，叶绿素含量下降。遗传分析表明突变体lmpsM4-17的类病斑早衰性状受1对隐性核基因控制。利用中国春与lmpsM4-17杂交所得分离群体和小麦55K SNP芯片标记，将目标基因定位于中国春染色体2BS的50。65～76。22 Mbp物理区间。[结论]lmpsM4-17的鉴定丰富了小麦类病斑突变体研究的基因资源;lmpsM4-17的定位为基因克隆和类病斑形成的分子机制解析奠定基础。
Phenotypic Characterization and Gene Mapping of A Lesion Mimic and Premature Senescence M4-17(lmpsM4-17)Mutant in Wheat
[Objective]This study aims to phenotypically identify and genetically map an EMS-induced lesion mimic and premature senescence mutant,M4-17(lmpsM4-17),derived from the wheat cultivar Shumail26.[Method]We analyzed the lesion-mimic development,leaf ultrastructure,and histochem-istry to reveal the phenotypic characteristics of lmpsM4-17.The mutant was crossed with common wheat cultivars to construct mapping populations for genetic analysis and gene mapping.[Result]lmpsM4-17 plants exhibited normal leaves at the seedling stage,but their leaves started to initiate chlorotic spots at the booting stage.The number of spots gradually increased and extended to the leaf sheath as the plants matured.Upon entering the grain-filling stage,the leaves became turned yellowish and started toinitiated premature senescence.The mutant phenotype of lmpsM4-17 was light induced and exhibited negative ef-fects on major agronomic traits compared to the wild type.Cellular observations revealed a reduction in chloroplast number and size,accumulation of peroxide,increase in osmiophilic granules,severe damage to the chloroplast thylakoid lamellar structure,and reduced chlorophyll content in lmpsM4-17.Genetic analysis indicated that the lesion mimic and premature senescence trait of lmpsM4-17 is governed by a single recessive nuclear gene.Utilizing an F2 population derived from the cross between Chinese Spring and lmpsM4-17,along with wheat 55K SNP markers,we mapped the target gene to a 50.65-76.22 Mbp physical interval on the short arm of chromosome 2B in wheat.[Conclusion]The investigation of lmpsM4-17 expands the gene resource for lesion mimic studies in wheat,and the mapping of the lmpsM4-17 provides the foundation for cloning the target gene and deciphering its molecular mechanism.
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