Cloning And Expression Analysis Of Photoperiodic Flowering Related Genes HcCOL4 And HcGI In Kenaf

With the effect of photoperiodism, elements such as Northern seeds germinating in the south or continued raining could shorten the vegetative period of kenaf, thus will reduce the yield and quality of the fiber. Research of photoperiodic genes can help us understand the mechanism of photoperiodic induction, and guide for the seeding of kenaf.GI and CO play a promote role of photoperiodic flowering in Arabidopsis by the pathway of GI-CO-FT. The kenaf laboratory of FAFU breed a photoperiod insensitive cultivar Zanyin-1. Does the photoperiod insensitive character of this cultivar exit in the conserved GI-CO-FT pathway? Thus, we use the photoperiod sensitive cultivar 85-132 and photoperiod insensitive cultivar Zanyin-1 as materials, clone the GI and CO genes, and analysis the expression of these two genes under short day condition. The main results as the following:1. Use the homology-based cloning and race technology, clone the CO and GI homologic gene in kenaf, through the alignment with homologous gene in Arabidopsis, named the genes HcCOL4 and HcGI. HcCOL4 gene is the hinge of the circadian clock and the following flowering genes. The CDS of HcCOL4 has 996bp, and translate 331 Aa. The HcCOL4 gene of 85-132 has a full genomic length of 1106bp, it has two intron, intron 1 has 104bp and intron 2 has 6bp; the full genomic length of Zanyin-1 is 1129bp, it also has two introns, one is 103bp, another is 30bp. The intron 1 of these two cultivar is in the same place and intron 2 in the different place. The similarity of CDS in these two cultivar is 90.16%, genomic similarity is 84.55%, and protein is 88.82%. Clone the upstream gene HcGI 3397bp, the CDS has 3507bp, translate 1168 Aa.2. In order to search the expression pattern of HcGI and HcCOL4 gene, we use the qRT-PCR to analysis the expression variation of HcGI and HcCOL4 gene in different cultivars, different periods and under different day-length condition.The result show that:under short-day condition, the expression of HcCOL4 rises remarkable, In Arabidopsis, long-day condition promote the expression of CO and lead to flowering. It suggest that although the expression pattern is different in these two species, the function of CO to promote flowering may be the same. Under squaring stage, the expression of GI gene is higher under short-day condition than under long-day condition, but before squaring stage is the opposite, it suggest that, GI gene maybe take plays in the photoperiodic flowering and in other place at the growth of the plant. In conclusion, photoperiodic flowering mechanism of kenaf maybe has a conserved GI-CO-FT pathway, under short-day condition, the expression of GI rises and promote the expression of CO, and finally promote the plant flowering, further more, GI gene maybe has other function. The expression of HcCOL4 and HcGI gene have remarkable difference in 85-132 and Zanyin-1, it suggest that GI-CO-FT pathway plays an important role in photoperiodic flowering difference between 85-132 and Zanyin-1.