Abstract:

Lesion mimic mutant (LMM) was a class of plant mutant, similar to allergic reaction, and was of significant importance for studying the mechanism of plant pathogens against outside dissemination. In this study, a lesion-mimic mutant derived from Rice mutant library, was designated lm1. Physiological indicators was analyzed and measured between mutant and wild-type. Compared with wild-type plants, malondialdehyde (MDA) accumulation in the mutant plant leaf cells was significantly increased, and the chlorophyll content, Fv/Fm ratio in mutant plants were significantly decreased compared with the wild-type plants. Genetic analysis indicated that the lm1 mutant was controlled by a single recessive gene. LM1 gene was isolated by map-based cloning method. The LM1 gene was narrowed on the short arm of chromosome 12 and it was controlled by LOC_Os12g16720. Protein sequence showed that LM1 encodes a P450 monooxygenase, which was allele with the SPL1 gene. The P450 monooxygenase was an essential enzyme involving in plant serotonin biosynthesis pathway.

Key words: rice, lesion mimic mutant, map-based cloning, P450 monooxygenase

摘要：

类病斑坏死突变体（lesion mimic mutant,LMM）是一类表型类似于植物过敏反应的突变体，对植物抵御外界病原菌浸染的抗病机理研究具有重有意义。以水稻突变体库中类病斑突变体lm1为材料，经图位克隆获得突变基因LM1，同时测定了相关生理指标。分析结果表明：与野生型相比，突变体叶片细胞中的丙二醛（MDA）积累水平明显升高，而叶绿素含量、Fv/Fm却显著低于野生型。遗传分析及精细定位显示，lm1突变体表型受一对隐性核基因LOC_Os12g16720控制，并将该基因命名为LM1，LM1位于水稻第12号染色体短臂的着丝粒附近，是SPL1的等位基因, 编码细胞色素P450单加氧酶；LM1突变导致其功能缺失，使植物体内活性氧得到累积，引发细胞程序性死亡并诱导病斑形成。

关键词: 水稻；类病斑坏死突变体；图位克隆；P450单加氧酶