Identification Of Lipoxygenase Gene Family And Functional Study Of Brr Lox7 In Turnip (Brassica Rapa L.subsp.rapa)

Turnip(Brassica rapa L.subsp.rapa),also known as vetch,paniculata,or ’chamagu’ in Uyghur,is widely grown for its edible,medicinal and forage value.In Xinjiang,the South Xinjiang region is the main source of turnips;however,its environment is arid and the soil salinity is high,and turnips are often affected by abiotic stresses such as salinity and drought during growth,resulting in fluctuating yields and uneven quality.Lipoxygenase(LOX),as a multifunctional enzyme,plays an important role in the response to stress and growth development of plants.The identification of salt stress-responsive genes in the LOX family of turnips and the identification of their salt-resistant regulatory functions are of great significance for the molecular breeding of turnips for stress resistance.In this study,the gene Brr LOX7 was cloned from the turnip LOX family through the identification and q RT-PCR analysis of the gene.The main results of the study are as follows.(1)Fifteen Brr LOX genes were identified in the turnip genome through the identification of the turnip LOX family genes.Phylogenetic tree analysis revealed two subfamilies of turnip LOX family genes(9-LOX and 13-LOX type II).The results of the gene replication events showed that tandem and fragmental replication were the main modes of expansion of the turnip LOX genes.,transcriptome data analysis revealed that 13 Brr LOX genes were expressed in one or more periods of turnip flesh roots.In addition,q RT-PCR analysis showed that Brr LOX genes were involved in the response to four stresses(salt stress,drought stress,cold stress,heat stress)and three hormones(Me JA,SA,ABA)hormones.(2)A salt stress responsive gene,Brr LOX7,was cloned from turnip LOX family genes with an open reading frame of 2715 bp.subcellular localization showed that Brr LOX7 was mainly localized in chloroplasts.The results of yeast two-hybrid assays with Brr LOX7 co-expressed genes showed that Brr LOX7 did not have a direct reciprocal relationship with Brr TIFY3 B.(3)A Brr LOX7 overexpression vector was successfully constructed and 12 Brr LOX7 transgenic lines were obtained by using Agrobacterium transformation to transfer the turnip salt stress response gene Brr LOX7 into Arabidopsis thaliana.The effect of salt stress on the germination of turnip Brr LOX7 transgenic Arabidopsis seeds was analyzed,and the results showed that heterologous overexpression of the turnip salt-responsive Brr LOX7 gene in Arabidopsis improved the tolerance of seeds to salt stress.