Populus Simonii×P. Nigra AP1 Gene’s Clone And Genetic Transformation Into Tobacco And Arabidopsis Thaliana

AP1 is a floral meristem identity gene and plays an important role in floral organ development. In this study, PsnAP1-1 and PsnAP1-2 were isolated from the male reproductive buds of Populus simonii×P. nigra, which are the orthologs of AP1 in Arabidopsis.By sequence analysis, PsnAP1-1 contains a 726 bp open reading frame (ORF) corresponding to a deduced protein of 241 amino acids, and the estimated molecular weight and isoelectric point of the putative protein were 28.1 kD and 8.19. PsnAP1-2 contains an ORF of 750 bp, encoding 249 amino acids with a predicted molecular mass of 28.7 kD and a pI of 9.07.Northern blot and qRT-PCR analysis showed that PsnAP1-1 and PsnAP1-2 exhibited high expression level in early inflorescence development of Populus simonii×P. nigra. Subcellular localization showed the PsnAP1-1 and PsnAP1-2 proteins were localized in the nucleus.Overexpression of PsnAP1-1 and PsnAP1-2 in tobacco under the control of a CaMV 35S promoter significantly enhanced early flowering. These transgenic plants also showed much earlier in stem initiation and higher rates in photosynthesis than they did in wild-type tobacco.qRT-PCR analysis indicated that overexpression of PsnAP1-1 and PsnAP1-2 regulated such genes with up-regulation. These up-regulation genes included NtMADS4, NtMADS5 and NtMADS11, which were related to flowering process.Overexpression of PsnAP1-1 and PsnAP1-2 in Arabidopsis also induced early flowering, but the morphological changes of the mutant ap1-10 were not significantly changed.This study indicated that PsnAP1-1 and PsnAP1-2 played important roles in floral transition of Populus simonii×P. nigra.