| Cotton(Gossypium hirsutum L.)occupies an important position in the agricultural development in China,but its limitless growth characteristics often lead to reduction in cotton yields and quality.As one of the important hormones,Auxin was widely involved in plant growth and development,and Aux/IAAs protein is the key to regulate auxin signaling pathway.However,there is little research in cotton,and its regulation mechanism is unclear.This research is about the function of Aux/IAA family genes during cotton vegetative growth phase.1.We constructed the recombinant plasmid viral vectors successfully,which combined pTRV-RNA2 vector and four AUX/IAA family genes: GhAux1,GhAux3,GhAux6 and GhAux7.We detected the expression level of the four genes in the buds of silent cotton strain by Real-time PCR,and results show that four genes were extremely significantly lower than control group,which means the vectors we constructed in this study were successful and effective,and four GhAuxs had different degree of silencing in cotton.2.This study analyzed the growth condition of the above cotton.Compared with the control of the empty vector,the silence of both GhAux1 and GhAux6 promoted the growth of cotton seedlings,and the length of GhAux1 silent cotton seedlings were significantly increased 21.4% especially after injecting 27 days.However,the silence of GhAux3 and GhAux7 inhibited the growth of the cotton seedlings,especially after injecting 27 days,the length of GhAux3 silence cotton was decreased significantly about 17.1%,while the length of internode and petiole was decreased significantly.Moreover,the length and the second and the third internodal length of GhAux7 silent cotton seedlings had the same situation.So the result indicated that the decreasing expression level of the four GhAuxs effected the growth of the cotton seedlings in different degree.3.This study detected the responses of the four genes(GhAux1,GhAux3,GhAux6 and GhAux7)after spraying different concentration of DPC(N,N-dimethylpiperidinium chloride,DPC)on wild type cotton leaves.It indicated that the expression of GhAux1,GhAux3 and GhAux6 was inhibited by DPC significantly,while the expression level of GhAux7 induced by DPC was increased significantly.The four silent cotton seedlings by VIGS were treated with 80 mg/L of the DPC and then observed the phenotypes.We found that the GhAux1 silent seedlings were more sensitive to DPC than the control group of the empty vector.4.We researched the influence on GhAux1-silenced cotton seedlings by salt stress.The results showed that the dry weight and fresh weight of the silent cotton seedlings were increased.Moreover,POD and CAT activity were increased,too.These results suggested that the GhAux1 silent cotton had certain salt resistance.This results showed that GhAux1,GhAux3,GhAux6 and GhAux7 may participate in cotton vegetative growth.The four GhAuxs genes were regulated by DPC,in which GhAux1 may be the key gene. |
