AUTHOR=Zhou Qian , Zhang Zhifei , Liu Tiantian , Gao Bida , Xiong Xingyao 

TITLE=Identification and Map-Based Cloning of the Light-Induced Lesion Mimic Mutant 1 (LIL1) Gene in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.02122

DOI=10.3389/fpls.2017.02122

ISSN=1664-462X

ABSTRACT=<p>The hypersensitive response (HR) is a mechanism by which plants prevent the spread of pathogen. Despite extensive study, the molecular mechanisms underlying HR remain poorly understood. Lesion mimic mutants (LMMs), such as <italic>LIL1</italic> that was identified in an ethylmethane sulfonate mutagenized population of <italic>Indica</italic> rice (<italic>Oryza sativa</italic> L. ssp. <italic>Indica</italic>) 93-11, can be used to study the HR. Under natural field conditions, the leaves of <italic>LIL1</italic> mutant plants exhibited light-induced, small, rust-red lesions that first appeared at the leaf tips and subsequently expanded throughout the entire leaf blade to the leaf sheath. Histochemical staining indicated that <italic>LIL1</italic> lesions displayed an abnormal accumulation of reactive oxygen species (ROS) and resulted from programmed cell death (PCD). The <italic>LIL1</italic> mutants also displayed increased expression of defense-related genes and enhanced resistance to rice blast fungus (<italic>Magnaporthe grisea</italic>). Genetic analysis showed that mutation of <italic>LIL1</italic> created a semi-dominant allele. Using 1,758 individuals in the F<sub>2</sub> population, <italic>LIL1</italic> was mapped in a 222.3 kb region on the long arm of chromosome 7. That contains 12 predicted open reading frames (ORFs). Sequence analysis of these 12 candidate genes revealed a G to A base substitution in the fourth exon of LOC_Os07g30510, a putative cysteine-rich receptor-like kinase (CRK), which led to an amino acid change (Val 429 to Ile) in the LIL1 protein. Comparison of the transcript accumulation of the 12 candidate genes between <italic>LIL1</italic> and 93-11 revealed that LOC_Os07g30510 was up-regulated significantly in <italic>LIL1</italic>. Overexpression of the LOC_Os07g30510 gene from <italic>LIL1</italic> induced a <italic>LIL1</italic>-like lesion phenotype in Nipponbare. Thus, <italic>LIL1</italic> is a novel LMM in rice that will facilitate the further study of the molecular mechanisms of HR and the rice blast resistance.</p>