Characterization and fine mapping of a semi-rolled leaf mutant srl3 in rice

Moderate leaf rolling can maintain leaf erectness,improve light transmittance in the population,and improve light energy utilization,thereby increasing rice yield.This study used ethyl methanesulfonate(EMS)to treat Yunjing 17(YJ17)and obtained a semi-rolled leaf mutant that was named semi-rolled leaf 3(srl3).We found that the rolled-leaf phenotype was due to the aberrant development of bulliform cells and the loss of sclerenchymatous cells.In addition,the shoot and root length of srl3 seedlings differed from the wild type.The srl3 mutant had significantly lower plant height and seed-setting rate but notably greater tiller number,panicle length,and primary branch number per panicle than the wild type.Genetic analysis showed that a single recessive nuclear gene defined the srl3 mutant,and it was precisely located in a 144-kb region between two insertion-deletion(InDel)markers,M8 and M19,on chromosome 2.In this region,no leaf-rollingrelated genes have been reported previously.Thus,the study indicated that SRL3 is a novel leaf-rolling-related gene,and the results laid the foundation for the cloning and functional analysis of the SRL3 gene.

NARROW AND ROLLED LEAF 2 regulates leaf shape,male fertility, and seed size in rice

Grain yield in rice （Oryza sativa L.） is closely related to leaf and flower development. Coordinative regulation of leaf, pollen, and seed development in rice as a critical biological and agricultural question should be addressed. Here we identified two allelic rice mutants with narrow and semi- rolled leaves, named narrow and rolled leaf2-1 （nrl2-1） and nr12- 2. Map-based molecular cloning revealed that NRL2 encodes a novel protein with unknown biochemical function. The mutation of NRL2 caused pleiotropic effects, including a reduction in the number of longitudinal veins, defective abaxial sclerenchymatous cell differentiation, abnormal tape- tum degeneration and microspore development, and the formation of more slender seeds compared with the wild type （WT）. The NRL2 protein interacted with Rolling-leaf （RL14）, causing the leaves of the nrl2 mutants to have a higher cellulose content and lower Iignin content than the WT, which may have been related to sclerenchymatous cell differentia- tion and tapetum degeneration. Thus, this gene is an essential developmental regulator controlling fundamental cellular and developmental processes, serving as a potential breeding target for high-yielding rice cultivars.