Function Of Four Transcription Factors(BnNF-YA2/3/9/12)from Coastal Salt-tolerant Canola(Brassica Napus L.) On Abiotic Stress Resistance

Canola(Brassica napus L.)is economic crop with highly adaptability.The new varieties with more resistantance to abiotic stress through modern molecular biology technology can be planted to increase agricultural income in the coastal beach and other soil which contains large amounts of inorganic salts.Previous study showed that four A subgroups of the nuclear transcription factor Y family(NF-YA)of Brassica napus L.,BnNF-YA2,BnNF-YA3,BnNF-YA9 and BnNF-YA12,had significant transcriptional changes under salt,drought and ABA treatments.The transgenic Arabidopsis that overexpressed individual BnNF-YA2/3/9/12 were got.Germination rate,root's growing rate and other physiological traits of transgenic Arabidopsis were determined under abiotic stress treatment such as NaCl,mannitol(simulated drought)and exogenous ABA.The response to abiotic stress of transgenic Arabidopsis was judged with wild type Arabidopsis.The results showed that Arabidopsis plants overexpressing BnNF-YA2/3/12 were sensitive to abiotic stress such as NaCl,mannitol and exogenous ABA compare with wild type Arabidopsis.The Arabidopsis of overexpressing BnNF-YA9 showed some resistance to abiotic stress such as NaCl,mannitol and exogenous ABA compare with wild type Arabidopsis.We find BnNF-YA2/3/9/12 were regulated by members of the microRNA169 family that belong to a kind of small RNA.Based on the interaction and relationship of regulation from bioinformatics prediction,we chose three members and named them as Bna-miR169m,Bna-miR169n,and Bna-miR169t,respectively.Canola and Arabidopsis both belong to cruciferous plants,so their genes have more homology.According to comparison and bioinformatics prediction of online database,Bna-miR169m's target gene maybe BnNF-YA3 in Brassica napus and AtNF-YA2/10 in Arabidopsis.Bna-miR169n's maybe targeted gene BnNF-YA9 in Brassica napus and AtNF-YA5/8 in Arabidopsis.Bna-miR169t's target gene maybe BnNF-YA2/12 in Brassica napus and AtNF-YA2/10 in Arabidopsis.We have constructed 3 overexpression plasmids of Bna-miR169s and transfered into wild type Arabidopsis.The results of the germination rate,the root growth rate and the growth of roots under abiotic stress showed that the Arabidopsis that contain three kinds of over-expression miRNA169s were sensitive to abiotic stress.The qPCR results revealed that the expression level of AtNF-YA2/10 in overexpressing Bna-miR169m of the Arabidopsis was reduced compared with wild-type Arabidopsis;the expression level of AtNF-YA5/8 in overexpressing Bna-miR169n of the Arabidopsis was reduced compared with wild-type Arabidopsis and the expression level of AtNF-YA2/10 in overexpressing Bna-miR169t of the Arabidopsis was reduced compared with wild-type Arabidopsis.