Cloning And Expression Characterization Of GhHB In Cotton

Homeodomain leucine zipper (HD-Zip) is one type of transcriptional factor. Its structures consist of a homeodomain and a leucine zipper region. HD-Zip encoding genes are identified only in plant. HD-Zip plays an important role in morphological changes of plant, such as leaf development, stem elongtion, hormone response and so on. In our study, we isolate four HD-Zip encoding genes. Structure, conservation and function four genes are investigated. The results as follows:1. We isolate four HD-Zip protein-encoding genes, named GhHB1 (Gossypium hirsutum homeobox) 1, GhHB2, GhHB3 and GhHB4. The elementary anlysis of four HD-Zip protein sequences from cotton (Gossypium hirsutum) show that all of them have many PKC_PHOSPHO_SITEs and CK2_PHOSPHO_SITEs. The analysis also shows that they possess homedomain and leucine zipper region.2. Phylogenetic analysis indicates that all 44 HD-Zip proteins from different plant are divided into two clades. GhHB1, GhHB2, GhHB3 and GhHB4 are belonged to those two clades, suggesting that those genes may have very close evolutionary relationship. GhHB1, GhHB2, GhHB3 and GhHB4 have the closest relationship with OsHox3, HAT4, PpHB3 and ANL2, respectly.3. RNA was extracted from cotton tissues; we analyzed the expression patterns of GhHB1, GhHB2, GhHB3 and GhHB4 by realtime SYBR-Green fluorescence quantity PCR. The results indicate that GhHB1, GhHB2, GhHB3 and GhHB4 are predominantly expressed in roots and hypocotyls, suggesting that it may function in roots and hypocotyls development. GhHB4 is also expressed in cotyledon. GhHBl expression in roots and hypocotyls is also up-regulated by NaCl, GA3 and ABA, suggestting that the GhHB1 may play an important role in response to salt-stresses and to different phytohormone signalings.4. Different GhHB3 fragment was cloned into pPZP221 and pBI121 to obtain overexpression vector and supression vector respectively. GhHB3 fragment was transformed into cotton by Agrobacterium-mediated transformation method. A great number of transformed seedlings have been obtained. Some seedlings have been indentified.