二氯喹啉酸诱导稗草EcDnaJ基因表达

Expression Profile of Quinclorac-induced EcDnaJ1 mRNA in Barnyardgrass( Echinochloa crus-galli)

DnaJ作为分子伴侣在植物抗逆中起重要作用．但目前在二氯喹啉酸逆境下，其在抗药性稗草中表达特点却鲜有报道．本研究采用RACE技术从抗二氯喹啉酸稗草中克隆了1个DnaJ基因，命名为EcDnaJl（GenBank登录号：JX518598），其cDNA全长为2154bp，开放阅读框为1350bp．编码449个氨基酸，理论分子量为48．4kD，等电点为9．5．该蛋白质氮端含有1个保守的J结构域，中部含有4个模式为CxxCxGxG的锌指结构．Real—timePCR分别测定EcDnaJl在二氯喹啉酸抗性和敏感的稗草生物型苗期叶、根及成株期根、茎、叶和种子中的表达，在感、抗生物型的相对表达量分别是0．8～20．9和7．4～30．2，其中在抗性稗草苗期叶片中相对表达量最高为30．2，而在敏感稗草种子中最低为0．8，抗性稗草是敏感稗草的1．4～9．2倍．受二氯喹啉酸诱导后，其在感、抗稗草的相对表达量分别为35．8～72．5和84．9～261．9，在抗性稗草苗期叶片中相对表达量最高为261．9，而在敏感稗草的种子中相对表达量最低为35．8，抗性稗草是敏感稗草的2．4～3．6倍．诱导前后，无论是在苗期根和叶中还是成株期的根、茎、叶和种子中，EcDnaJl表达量均是抗性稗草高于敏感稗草．抗、感稗草生物型的EcDnaJl在mRNA水平差异表达暗示，它可能参与了稗草对二氯喹啉酸的抗药性．

DnaJs, as molecular chaperones, play important roles in plant resistance or tolerance to various environmental stresses. But, little is known about expression profile of DnaJ1 mRNA in herbicide- resistant barnyardgrass （Echinochloa. crus-gaUi） under DnaJ was obtained from quinclora-resistant-identified E. quinclorac stress. A homologue sequence of crus-galli using RACE. The gene, designated EcDnaJ1 （GenBank No. JX518598） with full length 2 154 bp, has a 1 350 bp open reading frame predicted to encode a protein containing 449 amino acids with molecular weight 48.4 kD and isoelectrie point 9.5. The deduced protein possesses a J domain in N-terminus, and four CxxCxGxG zinc fingerdomains in the central regions. EcDnaJ1 expression was monitored in seedlings （leaves and roots） and adult plants （leaves, roots, stems and seeds） of quinclorac-resistant （R） and susceptible （S） biotypes of E. erus-galli via real-time PCR. EeDNAJ1 expression was 0. 8 ～20. 9 in S biotypes and 7.4 ～30.2 in R biotypes, such as 30.2 in leaves of seedling of R biotypes and 0. 8 in seeds of S biotypes, and 1.4 ～ 9.2 fold higher in the R plants than in the S plants. After exposure to quinclorac, its expression was 35.8 ～72.5 in S biotypes and 84.9 ～ 261.9 in R biotypes, such as 261.9 in leaves of seedling of R biotypes and 35.8 in seeds of S biotypes, and 2.4 ～ 3.6 fold higher in the R plants than in the S plants. Its expression was higher in all tissues tested of R biotypes than in that of S plants before or after quinclorae treatment. The difference expression of EcDNAJ1 mRNA in R and S biotypes suggested that EcDNAJ1 may be involved in resistance to ctuinclorac in E. crus-xalli.