Study On The Stress Resistance Of Tobacco Of Transgenic LpNAC5 And LpNAC13 From Lilium Pumilum

Lilium pumilum with bright red color is an important parent for Lilium resistance breeding because of its salt and alkali tolerance and strong cold resistance.In this study,LpNAC5 and LpNAC13 from L.pumilum were analyzed by bioinformatics.At the same time,their spatiotemporal expression characteristics and expression pattern under abiotic stress were analyzed by real-time PCR.In addition,to further study the function of LpNAC5 and LpNAC13 under abiotic stress,the differences between transgenic and wild-type tobacco in growth and development stages were compared under drought,salt and alkali stress.The main results are as follows:1.Bioinformatics analysis indicated that the proteins encoded by the ORF regions of the LpNAC5 and LpNAC13 genes were belong to the NAC family,encoding 181 and 208 amino acids,respectively.These proteins were hydrophilic proteins without a transmembrane domain,and contained a conserved DNA-binding domain in the N-terminal region,which was further divided into five subdomains(A-E).Sequence homology analysis indicated that the proteins encoded by LpNAC5 and LpNAC13 had the highest homology with Aquilegia coerulea and Phoenix dactylifera,respectively.Phylogenetic tree analysis indicated that LpNAC5 and LpNAC13 gene clusters were in the same clade as NAC083,a gene belonging to the SENU5 subfamily.2.The tissue expression characteristics of LpNAC5 and LpNAC13 genes were analyzed by real-time PCR.The result indicated that LpNAC5 and LpNAC13 were expressed in various tissue,and there were differences in spatiotemporal expression.At the mature stage,LpNAC5 was highest expressed in roots and lowest in stems;LpNAC13 was highest expressed in bulbs and lowest in roots.However,at the seedling stage,the expression levels of LpNAC5 was highest expressed in leaves and lowest in bulbs;the expression levels of LpNAC13 was highest expressed in bulbs and lowest in bulbs.LpNAC5 and LpNAC13 genes were involved in the development of L.pumilum.3.Real-time PCR analysis showed that there were differences in the expression levels of LpNAC5 and LpNAC13 under various abiotic stresses.In addition,the expression patterns were different in various tissues and organs.Under salt stress treatment,LpNAC5 in bulbs and roots and LpNAC13 in leaves and roots were up-regulated.Under drought stress,LpNAC13 was up-regulated in bulbs and leaves.Under ABA stress treatment,LpNAC5 in bulbs and LpNAC13 in leaves were up-regulated.These fully proved that LpNAC5 and LpNAC13 were involved in the stress response of L.pumilum.4.ABA sensitivity experiment results showed that overexpressed LpNAC5 increased the sensitivity of tobacco to ABA at the seed and seedling stage,such as inhibiting seed germination,root length elongation and fresh weight increase.However,overexpressed LpNAC13 decreased the sensitivity of tobacco to ABA at the seed and seedling stage,such as promoting seed germination,root length elongation and fresh weight increase.5.Analysis of drought resistance showed that heterologous overexpression of LpNAC5 could improve tobacco drought resistance at the seed and seedling stage,such as promoting seed germination,root length elongation and fresh weight increase.In addition,overexpression of LpNAC5 enhanced the drought resistance of tobacco at mature seedling stage.Heterologous overexpression of LpNAC13 could decrease tobacco drought resistance at the seed and seedling stage,such as inhibiting seed germination,root length elongation and fresh weight increase.In addition,overexpression of LpNAC13 reduced the drought resistance of tobacco at mature seedling stage.6.Heterologous overexpression of LpNAC5 and LpNAC13 could improve the salt and alkali resistance of tobacco,such as promoting seed germination and enhancing the salt and alkali tolerance of tobacco at mature seedling stage.