Cloning Of Dsep1 Controlling The Phenotype Of Drought-sensitive Enclosed Panicle In Rice

The phenotype of panicle enclosure in rice has close relations with several important agronomic traits such as plant height,fertility and stress tolerance.And it has significance for the growing development of the inter node in identify ing the genes to control panicle enclosure,improvement of male sterile line breeding without panicle enclosure and creating new germplasm for an improved adaptability to abiotic stress.This paper focused on a drought-sensitive enclosed panicle mutant named dsep1,which was identified from indica maintainer line T98B treated with⁶⁰Co-gamma irradiation.Its characteristics were investigated from morphological,physiological,genetic and transcriptional level,and the results were shown as follows:?1?Phenotypic observation showed that,by contrast of T98B,dsep1 was significantly shortened on upper internodes with a decrease of 87.94%in length,and its morphology of longitudinal cells on the upper internodes showed that the cell extension was blocked and the cells were reduced in height by nearly 1/4 to 1/3,leading to a little dwarfism.Hormone analysis found that the content of abscisic acid in flag leaves,upper internodes,spike branches and grains were all increased significantly,as was 13.0 times of T98B in the grains.While,the gibberellins content in those parts were declined,even at a decreased degree by nearly 70%in flag leaves.In the meanwhile,dsep1 seemed insensitive to exogenous gibberellins,suggesting gibberellins signal transduction would be impaired in dsep1.?2?A F₂ population from dsep1 and Nipponbare an indica/japonica crossing was constructed for mapping dsep1.It was fine mapped on chromosome 1 by map-based gene cloning.The gene of LOC_Os01g02890,was inferred the candidate for dsep1,which was named OsPSS1 encoding phosphatidylserine synthase?PSS?.Through sequencing,dsep1 was confirmed mutate on exon 6 with a deletion of T,thus shifting the open reading frame?ORF?and terminating the transcription.Moreover,by way of CRISPR/Cas9-mediated system,a vector for targeting site at 405bp to 425bp downstream from initiation codon ATG?located at the upstream of the mutation point?on DSEP1 was constructed and transformed into Nipponbare.The homozygous T ₁lines displayed a phenotype of panicle enclosure,the candidate genes were validated.?3?Through transcriptome analysis on upper internodes at heading stage under drought condition,it found that dsep1 and T98B differently expressed for those genes involving in single cell metabolism of biological process and catalytic-activity reactions,function of molecular processes.The regulation process of genes would be up-regulated or down-regulated especially for stress responding i.e Calmodulin-mediated?Calmodulin,CaM?ones,Protein kinase?Protein Kinases,PK?ones,as well as hormone biosynthesis and signal transduction of gibberellin?GAs?.Our results provide a basis for the further understanding of the biological function of OsPSS1 and a novel mechanism underlying responding aga inst drought in rice.