一种新型水稻穗叶类病斑突变体pls1的基因克隆和功能分析

打开文本图片集

Abstract：Rice lesion mimic mutants playan important role in studying programmed cell death and broadspectrum disease resistance. Previously reported rice lesion mimics mainly occur on leaves and occasionally on glumes.In this study，we report a novel panicle and leaf spot mutant，pls1 （Panicle and leaf spot 1），which exhibits reddish-brown lesions starting from thethree-leaf stage.The lesions expand with developmental progression and spread to other organs. Unlike previously reported lesion mimic mutants，plsl develops reddishbrown spots on panicle branches and glumes after heading，leading to severe panicle withering at maturity and significant yield reduction，representing a new type of rice lesion mimic mutant. Map-based cloning combined with whole-genome resequencing revealed a large 173403 bp deletion in the pls1 mutant，resulting in the loss of seven genes and the promoter region of one gene.Among these eight genes，four encode prolamin proteins， while the other three exhibit low expression levels in leaves and panicles. Only Osl2g0268000 shows relatively higher expression in leaves and panicles compared to other organs.These results suggest that PLS1 corresponds to Osl2g0268000 ，and functional annotation reveals that it encodes a tryptamine 5-hydroxylase.The pls1 mutant exhibited excessive accumulation of reactive oxygen species，hydrogen peroxide，and superoxide anions，along with increased activity of antioxidant enzymes，including superoxide dismutase，ascorbate peroxidase，catalase， and glutathione reductase. These changes triggered programmed celldeath and chloroplast degradation，reducing photosynthetic capacity.Melatonin plays a crucial role in plant salt tolerance.Further functional analysis showed that the loss of PLS1 suppressed the expression of melatonin biosynthesis-related genes （OsTDC1，OsTDC3， OsSNAT1，OsASMT1，and OsCOMT ），leading to reduced salt tolerance in pls1. In summary，pls1 is a novel type of rice lesion mimic mutant that willprovide new germplasm for studying rice lesion mimics. The salt tolerance analysis reveals a new function of tryptamine 5-hydroxylase，ofering insights into its role in programmed cell death and salt stress resistance.

Keywords：rice;panicle and leafspot;pls1 ;melanin;salt tolerance

类病斑是在无生物或非生物胁迫的情况下，植物叶和叶鞘上自发产生，由细胞程序性死亡引起的各种病斑。（剩余17715字）