Screening And Analysis Of Differential Genes Of Stipa Breviflora's Transcriptome During Its Flowering Phase Under Conditions Of Field Warming And Nitrogen Application

Climate change has a significant impact on grassland ecosystems.Forage grasses are very sensitive to climate change as the important parts of grassland ecosystems.Stipa breviflora is a high-quality pasture in desert steppe with the wide distribution in China,and belongs to Stipa capillata genus.The purpose of this research is to study the expression differences of flowering-related genes of Stipa breviflora under different treatments of warming and nitrogen addition,in order to reveal the molecular response mechanism under climate change condition.In this study,the Stipa breviflora under the artificial conditions of warming and nitrogen application in the field was used as the experimental material.The transcriptome of Stipa breviflora's fertile tillers were sequenced during different flowering stages,and differentially expressed genes were analyzed.The main results are as follows:1.The sequencing produced 4.39G high-quality data.There were 91.5Mb clean reads and 126583 unigene sequences.The total length of the sequence was 94542261bp,and the average length was 747bp.The N50 was 789bp.2.A total of 77,584 unigenes were successfully matched with known genes by homologous blasting.Among those unigenes,67,279 unigenes were annotated into the NR database,and 52,991 unigenes were assigned to 56 GO functional items.In another analysis,27,436 unigenes were assigned to 25 COG protein families,and 26,585 unigenes were annotated into the KEGG metabolic pathway.There were 48,999 unigenes with no matching sequences,and most of them are specific genes of Stipa breviflora.3.13 genes(PRR7-1?PRR7-2?COP1-1?COP1-2?FT-1?FT-2?HY5-1?HY5-2?CHS-2?CHS-3?LHY?PHYA?ELF3)which belonged to plant-circadian rhythm pathway were obtained by analyzing differential metabolic pathway enrichment and RPKM analysis of differential genes.Thees 13 differentially expressed genes in this pathway are related to plant flowering,and their expression trends were consistent with the sequencing results by RT-qPCR analysis.4.The expression of FT-2 and PRR7-2 genes increased under warming treatment,which may related to the premature senescence stage of Stipa breviflora's reproductive branches;the expression of PRR7-1?LHY and ELF3 genes decreased under nitrogen application from pre-stage to mid-stage of flowering,which may related to the delay of flowering period;the expression of PRR7-1?PRR7-2?COP1-1 and LHY were also changed under the treatment of warming&nitrogen addition,and these 4 genes may promote the expression of flowering related genes during mid-and later flowering stages of Stipa breviflora.