Cloning, Expression And Function Analysis Of Some Floral Genes In Betula Luminifera H. Winkl.

Betula luminifera H. Winkl. is a precious timber tree with excellent material, which widely distribute in south of China. Cloning of the flowering related genes in Betula luminifer has significant meaning to indicate their functions and molecular mechanisms. On the other hand, it will lay a foundation for regulating flowering by using molecular biological methods and serving improved variety selection.Here, BlLFY, BlMADS1 and BlSPL1 were cloned by homologous cloning and RACE methods respectively, using the designed degenerate primers according to the conserved domains. BlLFY was 1305 bp and encoded a 321 aa protein. Protein homology analyses showed BlLFY had the highest identity to Castanea mollissima and Juglans regia LFY both with 88% identity. BlMADS1 had two different transcription versions: the frist was 1150 bp and encoded a typical MADS-box protein which belonged to AP1/SQUA subfamily, while the second contained a 162 bp insertion senquences in 3′terminal region and thus encoded a MADS-box protein with truncated C terminal. Two proteins of BlMADS1 were most smilar to Betula pendula BpMADS4 with 99% and 95% identity respectively. BlSPL1 was 838 bp andencoded a 134 aa protein which had high identity to Betula pendula BpSPL1 with 99% identity.Real-time Expression analysis for BlLFY, BlMADS1 and BlSPL1 genes were performed in different development stages of male flowers, female flowers, leaves and buds. The results showed that BlLFY was highly expressed in reproductive organs, especially in initial female flowers and germinating male flowers. And also relatively higher in young and developing phenotypes of the same organs. BlMADS1 expression was nearly undetectable in female flowers, and showed higher expression levels in germinating male flowers, buds and leaves. And along with the developing, expression of BlMADS1 was decrease. BlSPL1 was expressed in reproductive and vegetative organs, with the highest expression in initial female flowers, and leaves buds. And with the development, its expression was different. These suggested that BlLFY gene may involved in the development of female and male inflorescences. BlMADS1 gene was connected to the initiation of female inflorescences, but none business with its development, and may involved in the development of leaves. BlSPL1 gene may had relationship with the development of female and male inflorescences.To characterize BlLFY, BlMADS1 and BlSPL1 genes, we constructed overexpression vectors, and transformed them into Arabidopsis. We had got the transgenic seeds, and we are conducting screening of transgenic plants at present, functional analysis will be carried out in future.