Isolation And Functional Study Of Wheat NAC Transcriptional Factor Genes Related To ABA Signaling

Abiotic stress such as drought, salt, and alkalinity seriously affects the normal growth and development of plants, and plants have formed a serious of effective mechanisms including gene expression regulation related to adverse environment to cope with the bad outside world during the process of long-term evolution. We divided the genes induced with adversity stress into two categories:the genes encoding functional proteins and the genes encoding transcription regulatory proteins which participate in the process of signal transduction in adversity stress. The regulation of transcription factor is one of the effective mechanisms of plants to resist stress. It is produced by activation of adversity signal, then combined with cis element, to activate or inhibit downstream gene expression.NAC transcription factor is not only a larger family in plant but also a unique transcription factor family of it. It is involved in regulation of plant growth and development such as secondary growth, seed germination, flowering, senescence, etc.. In addition, it has participated in the process of biological and abiotic stress response. Wheat (Triticum aestivum L.) is one of the main food crops in China, which has been widely cultivated throughout the world. We chose three NAC genes to research by semi-quantitative PCR. The expression of three genes increased under ABA treatment. We found that TaNAM1 and TaNAC10 had NAM superfamily domain through analyzing conservation structure. After the yeast single hybridization experiment, we validated that TaNAC1, TaNAM1, and TaNAC10 had transcriptional activation activity. By constructing TaNACl-GFP、TaNAM1-GFP. TaNAC10-GFP fusing expression carriers using pBI 221 vector, the subcellular localization experiments showed that TaNAM1 and TaNAC10 were only located in nucleus, while TaNAC1 without NAC conservative structure domain, was located in nucleus and cytoplasm.We used Realtime PCR method to analyze TaNAC10 expression pattern under different wheat varieties. The results showed a trend of increasing expression both in leaves and roots of SR3 or JN177 after treating ABA. Under NaCl treatment, the expression of TaNAC10 was higher in leaves of JN177 and SR3, and higher in root of JN177 than the plants without treatment. Under H2O2 treatment, its expression was up-regulated in the root and leaf of JN177, while down-regulated in root of SR3. Measuring the expression level of transgenic Arabidopsis, the expression quantity of TaNAC10 in pure lines was far more than the wild type, and could be inherited stably.Through the phenotypic analysis of transgenic Arabidopsis, we knew that the germination rate of overexpression lines was not affected by ABA or NaCl in contrast with wild plants. But the root was significantly longer than the contrast in the high concentration of ABA and NaCl, which explained the salt resistance of TaNAC10 gene and not sensitive to ABA. With the treatment of H2O2, the lateral roots of overexpression lines were more than wild type, and the leaves were greener. From the detection of Marker genes which are related to ABA pathways, the quantity of RD29B, RAB18, ABA1 and NCED3 in OE lines was higher than the control group. But the expression of AtMYB2, CBF3 and ABA2 was lower. We found that GPX1 and APX2 which belonged to ROS pathways were induced, whereas SOD and CAT1 were restrained.All above results illustrated that TaNAC10 played multiple roles in abiotic stress, which provided important candidate gene for improving crops resistance with genetically engineered way in the future.