Identification And Functional Study Of LncRNAs Related To Rice Seed Development

Rice seed development is a complicated and precisely regulated biological process that involves transcriptional regulation of multiple genes.The endosperm as the main component of the seed,its development is closely related to rice yield and quality.In this study,we analyzed the transcription data of nipponbare pistils,5DAP and 7DAP in the endosperm,and obtained 52 lncRNAs that were specifically expressed in the endosperm or differentially expressed in the endosperm.BLAST was performed on the lncRNA sequence using the Rice Genome Annotation Project Pseudomolecules database.The non-coding characteristics of the lncRNA were identified by semi-quantitative RT-PCR.A total of 12 lncRNAs were specifically expressed in the endosperm.RNAi interference technology was used to study the mechanism of lncRNAs regulating seed development.The analysis of agronomic traits of the T₀ transgenic lineage showed that,except for the appearance quality,the 1000-grain weight of some lines increased significantly,and their grain length and grain width increased accordingly,suggesting that lncRNAs may be involved in regulating the development of seed size and ultimately affecting yield.The high temperature of grain-filling stage affected the filling rate of rice and shortened the grouting period,resulting in insufficient filling,abnormal grain development,and reduced yield and quality.In this study,the high temperature treatment of the conventional japonica rice Ningjing No.1from the booting stage to the maturity stage resulted in a significant decrease in grain length,grain width,grain thickness,and 1000-grain weight.The results of scanning electron microscopy showed that the starch grains of the seed treated with high temperature were small and round,and the arrangement was loose,while the starch grains of the seed treated with normal temperature showed the irregular polygonal structure and dense arrangement.Physicochemical properties revealed that the total starch content and amylose content of the seed treated with high temperature was significantly reduced,and the protein content was significantly increased.The initial gelatinization temperature,peak gelatinization temperature,and final gelatinization temperature of the DSC were all significantly increased,indicating high temperatures significantly affects the development of seed and leads to deterioration of rice quality.LncRNA transcriptome sequencing was performed on endosperm 10 days after pollination under high temperature treatment and normal temperature treatment.A total of 578novel lncRNAs were identified.Structural analysis showed that the transcripts were mainly distributed in the range of 200bp-1000bp compared to mRNA and had with fewer exon numbers and shorter ORF lengths,differential expression analysis showed that 59 lncRNAs responded to high temperature stress,14 lncRNAs were significantly up-regulated,and 45 lncRNAs were significantly down-regulated.Among these differentially expressed lncRNAs,there were 32 lncRNAs and 5 the mRNA forms a complex regulatory network involved in starch anabolic pathways under high temperature stress.