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Homeodomain - leucine zipper protein (homeodomain-leucine zipper protein, HD-Zip) is specific to a class of transcription factors in higher plants . The study showed that , HD-zip to play a crucial role in the early development of the plant , such as leaf development , the extension of the stem , and under stress conditions growth regulators , etc. . 4 encoding HD-Zip transcription factor genes from cotton cDNA library screening , molecular identification and expression analysis of the gene , and obtained the following results : 1 . 4 encoding HD-Zip transcription factor genes isolated from cotton (Gossypium hirsutum) , the named GhHB (Gossypium hirsutum homeobox) 1, GhHB2, GhHB3 and GhHB4 . Analysis of the protein primary structure display of 4 GhHB protein sequence contains a homeodomain ( homeodomain , HD) and leucine zipper region (lecuine zipper region), and contains a plurality of protein kinase C phosphorylation sites , casein kinase II phosphorylation sites. 2. Phylogenetic analysis showed that four of cotton and 40 HD-Zip proteins from different plants are located in the two clade and HD partial homology can be divided into two evolutionary branch GhHB1 GhHB2 , GhHB3 and GhHB4 comparative analysis also shows that the evolutionary conserved . GhHB1, GhHB 2, GhHB 3 and GhHB 4, respectively with OsHox3 , HAT4 PpHB3 and ANL2 recent genetic relationship . 3. Total RNA extracted cotton different organizations , reverse transcription cDNA . Using real-time quantitative PCR analysis of the expression of the four genes . The results show that the GhHB1 the , GhHB2 , GhHB3 beginning GhHB4 are root and hypocotyl strong expression which GhHB4 , also has a great expression level in the leaves . This indicates that these genes are related to the early development of cotton . At the same time , GhHB1 expression in the roots by NaCl, ABA and GA3 regulation . 4. The use of recombinant DNA technology , the gene was inserted into the GhHB3 the pPZP221 and pBI121 to build excessive expression vector (overexpression vector) and RNAi the carrier ( supression vector ) , respectively . Mediated transformation method using Agrobacterium (Agrobacterium LBA4404) , successfully GhHB3 transferred to cotton, now has been a conversion of a large number of seedlings , the portion has been identified as positive .
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