Abstract:

JAZ protein plays a key role in plant growth and development and stress signaling pathways.In order to explore the regulatory mechanism of JAZ protein in wheat late spring cold,TaJAZ6 gene was cloned from young spike of wheat,and its molecular characteristics,expression characteristics and subcellular localization were analyzed.The results showed that the full-length CDS sequence of the gene was 549 bp,encoding 178 amino acids.The predicted molecular weight of the encoded protein was 18.376 ku,the theoretical isoelectric point was 9.37,and the instability coefficient was 62.44,so it was an unstable protein.The protein encoded by this gene had a TIFY domain and a CCT_2 domain.Phylogenetic tree analysis showed that the protein had the closest relationship with TIFY 11b proteins of Triticum dicoccoides and Triticum urartu.In addition to the basic response elements such as CAAT-box and TATA-box,the promoter region of TaJAZ6 gene also contained hormone response elements,light response elements,low temperature response elements,defense and stress response elements.Real-time Quantitative PCR analysis showed that TaJAZ6 gene was expressed in roots,stems,leaves and young panicles,with the highest expression in roots.The expression of TaJAZ6 gene was also induced by low temperature and methyl jasmonate (MeJA).Under low temperature stress,the expression trends of TaJAZ6 in roots,stems and leaves of Aikang 58 (tolerant to late spring cold ) and Zhengmai 366 ( sensitive to late spring cold ) were the same trend,which significantly increased.After spraying 300,350 μmol/L MeJA,the expression of TaJAZ6 in plants treated with low temperature decreased significantly in both wheat varieties.The expression level of TaJAZ6 in the young panicles after low temperature stress showed an opposite trend.The expression level of TaJAZ6 in the young panicles of Aikang 58 decreased significantly,and increased significantly in the young panicles of Zhengmai 366.It was speculated that the gene might negatively regulate the defense response of wheat to late spring cold stress.By spraying MeJA,the relative expression of TaJAZ6 gene in young spikes of two wheat varieties under low temperature stress was significantly reduced,and the grain number of wheat was increased.Subcellular localization assay showed that TaJAZ6 protein was localized in the nucleus.The results above indicate that TaJAZ6 may play an important role in the response of wheat to late spring cold stress.

Key words: Wheat, TaJAZ6, Expression analysis, Cold stress, Subcellular localization