Genome-Wide Identification Of Thiolase Gene Family And Drought Tolerance Function Analysis Of SiKAT1 In Foxtail Millet

Thiolase is widely found in prokaryotes and eukaryotes and play a role in the synthesis and degradation of fatty acid carbon chains.In plants,thiolase have an important role in growth and development and responses to abiotic stresses.Foxtail millet(Setaria italica.L)is an ideal model crop for studying drought tolerance mechanisms and gene functions owing to its small genome,self-pollination and short growth cycle.So far,there are few reports on the research of thiolase gene family identification and functional studies in Setaria italica.In this study,we identified the members of thiolase gene family in Setaria italica at the genome-wide level and analysed the physicochemical properties,sequence characteristics and tissue expression characteristics.The expression pattern of foxtail millet thiolase gene family members under drought stress was analyzed by q RT-PCR.Construction of CRISPR/Cas9 multi-Target knockout vector of SiKAT1 and SiKAT2 gene.The drought resistance function of SiKAT1,a key member of the thiolase gene family in Setaria italica,was analyzed by prokaryotic expression system.The main results are as follows:1.Five members coding for thiolase were identified in the whole genome,located on four chromosomes;the encoded proteins ranged from 401 to 461 aa in length,41 to 48 k Da in molecular weight and the isoelectric point was between 6.02 and 8.44;all members contained two conserved motifs specific to thioase and the cysteine active catalytic site of thiolase.2.Phylogenetic analysis revealed the thiolases in foxtail millet were divided into two subfamilies(KAT and ACAT);the proteins encoded by SiACAT2 and SiACAT3 are acidic proteins and the proteins encoded by SiACAT1,SiKAT1 and SiKAT2 are basic proteins;the genes encoding KAT-type thiolase have 14 exons and the genes encoding ACAT-type thiolase have 13 exons.The KAT isoform has a PTS2 sequence targeting the peroxisome,and SiKAT1 and SiKAT2 are homologous genes.3.The KAT-type thiolase was highly expressed in the root,stem,leaf and spike parts,while the ACAT-type thiolase was relatively less expressed in the root,stem,leaf and spike parts;the promoter region contained a variety of light-responsive elements,hormone responsive elements and stress-inducible elements.4.The expression of SiKAT1 in E.coli increased the colony number of E.coli under PEG treatment,suggesting SiKAT1 exerts drought-resistant function in vitro.