A homologous gene of OsREL2/ASP1, ASP-LSL regulates pleiotropic phenotype including long sterile lemma in rice

Tingkai Wu,Tingting Zhou,Xiaoqiong Chen,Yongxiang Liao,Jiahe Song,Hongyu Zhang,Yi Luo,Yutong Liu,Peizhou Xu,Jinhao Wang,Asif Ali,Xianjun Wu,Yongqiong Fang

doi:10.1186/s12870-021-03163-7

Tingkai Wu, Tingting Zhou + Show 11 more

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https://doi.org/10.1186/s12870-021-03163-7

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Abstract

BackgroundPanicle is a harvesting organ of rice, and its morphology and development are closely associated with grain yield. The current study was carried on a mutant screened through an EMS (ethyl-methane sulphonate) mutagenized population of a Japonica cultivar Kitaake (WT).ResultsA mutant, named as asp-lsl (aberrant spikelet-long sterile lemma), showed a significant decrease in plant height, number of tillers, thousand-grains weight, seed setting rate, spikelet length, kernel length and effective number of grains per panicle as compared to WT. Asp-lsl showed a pleiotropic phenotype coupled with the obvious presence of a long sterile lemma. Cross-sections of lemma showed an increase in the cell volume rather than the number of cells. Genetic segregation analysis revealed its phenotypic trait is controlled by a single recessive nuclear gene. Primary and fine mapping indicated that candidate gene controlling the phenotype of asp-lsl was located in an interval of 212 kb on the short arm of chromosome 8 between RM22445 and RM22453. Further sequencing and indels markers analysis revealed LOC_Os08g06480 harbors a single base substitution (G→A), resulting in a change of 521st amino acid(Gly→Glu. The homology comparison and phylogenetic tree analysis revealed mutation was occurred in a highly conserved domain and had a high degree of similarity in Arabidopsis, corn, and sorghum. The CRISPR/Cas9 mutant line of ASP-LSL produced a similar phenotype as that of asp-lsl. Subcellular localization of ASP-LSL revealed that its protein is localized in the nucleus. Relative expression analysis revealed ASP-LSL was preferentially expressed in panicle, stem, and leaves. The endogenous contents of GA, CTK, and IAA were found significantly decreased in asp-lsl as compared to WT.ConclusionsCurrent study presents the novel phenotype of asp-lsl and also validate the previously reported function of OsREL2 (ROMOSA ENHANCER LOCI2), / ASP1(ABERRANT SPIKELET AND PANICLE 1).

Highlights

Panicle is a harvesting organ of rice, and its morphology and development are closely associated with grain yield
The phenotypic observation and measurement of agronomic traits revealed pleiotropic effect of ASP-LSL Data of agronomic traits of asp-lsl and wild type (WT) (Kitaake) were measured and results revealed that plant height, length of panicle, grain length, number of seeds per panicle, thousand-grain weight, seed setting rate and length of sterile lemma were significantly different in asp-lsl
The glume length and width were 4.7 and 2.7 times increased in asp-lsl than that of WT, respectively

Summary

Introduction

Panicle is a harvesting organ of rice, and its morphology and development are closely associated with grain yield. Spikelet development is one of the most important traits for yield. Grasses spikelet consists of two sterile glumes (rudimentary glumes), empty glumes, and a pair of fertile glumes that are further called lemma and palea [1, 2]. Spikelet development can be roughly divided into the following eight stages: the first stage (Sp1) includes the formation of the incomplete rudimentary glume primordia. The formation of lodicule and stamen occur at the fifth (Sp5) and sixth (Sp6) stage of spikelet development, respectively. The seventh (Sp7) and eighth (Sp8) stages involve the formation of carpel primordium and development of ovule and pollen, respectively [3]. Mutants with abnormal spikelet development showing hindrance at various stages can be used as important materials for studying molecular mechanism

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