Genome-wide Analysis Of BZIP Family And Effects Of Different Sowing Dates And Temperatures On Seedling Growth And Development In Switchgrass

Switchgrass is a perennial warm-season pasture.Due to its high biomass and sustainable production capacity,switchgrass is considered to be an ideal biomass energy source.The seeds of switchgrass are small and difficult to build,and they are still in the primary introduction stage in China.Moreover,the area of cultivated land in China is limited.In order not to compete with the grain,switchgrass is often planted on the marginal land of barrenness,which seriously affects the growth and biomass accumulation of switchgrass.Therefore,the experiments were performed on the agronomic traits and physiological indexes of three lines to determined the appropriate sowing date and temperature conditions of switchgrass in this area and the same latitude.A large number of genes related to growth and development and stress were excavated through the genome-wide identification and analysis of the bZIP transcription factor family of switchgrass.Meantime,the cloning and expression analysis of the stress-related PvbZIP8 gene was carried out,and the biological function of the gene was preliminarily confirmed.The main research results were as follows:1.Genome-wide analysis of bZIP family related to abiotic stress in switchgrassIn the study,178 PvbZIPs were identified and distributed unevenly on 18 chromosomes in switchgrass.The PvbZIPs were divided into 10 subfamilies based on the evolutionary analysis.The gene structure and conserved motif analysis showed that the same subfamily members shared similar intron-exon model and motif composition,which supported the grouping of the PvbZIP family.111 switchgrass bZIPs and 70 rice bZIPs were identified as orthologs based on the phylogenetic and synteny analysis.In addition,these PvbZIPs showed diverse expression patterns in different tissues or developmental stages based on the expression altas.16 PvbZIPs were down-regulated significantly and 5 PvbZIPs were up-regulated dramatically with heat stress according to the data online.The expression pattern of the PvbZIPs in different tissues,organs and developmental stages were confirmed by qRT-PCR.At the same time,the response of some PvbZIPs to abiotic stress such as salt,cold,draught and heat were detected.The genome-wide identified and analysis of bZIP family in switchgrass provided multiple candidate PvbZIPs for the growth and stress response,and laid the foundation for the future functional studies.2.Cloning and Expression Analysis of PvbZIP8 Gene from SwitchgrassThe results showed that the length of open reading frame of PvbZIP8 gene was 468 bp,whose encoding 155 amino acids.In additional,PvbZIP8 was predicted as a hydrophilic protein,and the molecular formula was C761H1248N24O23S8 and the molecular weight was 17.81 kDa.Phylogenetic analysis indicated that the protein sequence was highly similar to Panicum hallii,Setaria italica and Panicum miliaceum,and which contained the typical conserved bZIP domain and belonged to the bZIP transcription factor family.Quantitative PCR results showed that PvbZIP8 gene was up-regulated under salt,drought,high temperature and low temperature stress,which played key roles in response to abiotic stress in switchgrass.Tissue-specific expression analysis showed that PvbZIP8 was detected in different tissues and organs,moreover,which had significantly high expressions in roots,stems and leaves.The investigation determined PvbZIP8 gene was related to abiotic stress tolerance and laid the foundation for further study.3.Effects of Different Sowing Dates and Temperatures on the Growth and Development of Switchgrass SeedlingsIn order to find out the suitable sowing date and temperature conditions of switchgrass in Guanzhong area and at the same latitude,we determined the agronomic traits and physiological indexes of three lines under different sowing dates and different temperatures.The results showed that the seedling rate of switchgrass planted on May 25 was the highest in the experiment of different sowing dates.Among the 30 days after emergence,the plant height of switchgrass planted on May 25 was the most significant,and planted on May 10.The dry weight value of switchgrass was significantly the largest,and the ratio of root to shoot was gradually decreasing with the delay of sowing date.The chlorophyll content of switchgrass planted on May 25 was the most significant.The root activity of switchgrass planted on March 25 was the highest;60 after emergence.Among the days,the plant height and dry weight of switchgrass planted on April 25 were significantly higher,and the ratio of root to shoot increased gradually with the delay of sowing date.The chlorophyll content of switchgrass planted on April 25 increased.Obviously,the root activity of switchgrass planted on March 25,April 10 and April 25 was significantly higher than that on May 10,May 25 and June 10;in different temperatures,the emergence rate With the increase of temperature,the plant height and dry weight of 25 °C treatment showed a large value.The root-shoot ratio and root activity value gradually decreased with the increase of temperature,and the chlorophyll content There is no significant difference.According to the comprehensive analysis,the growth and development of switchgrass at 25 °C is better,and the suitable sowing date of switchgrass is around April 25.