Functional Identification Of DELLA GAI4Gene In Gossypium Hirsutum L.

Objective: Cotton is the most important fiber crop, is an important oil crops, but also withhigh-protein food crops, textiles, fine chemical raw materials and important strategicmaterial.The cotton fiber is a special testa cells by a variety of hormonal regulation of growthand development. It has been confirmed applied gibberellin can increase the yield of cottonfiber. But the molecular mechanism of Gibberellin on the cotton fiber cell initiation anddevelopment is unclear. The gibberellin almost have an impact on plant growth anddevelopment process, including seed germination, stem elongation, hypocotyl elongation,floral organ formation and seed development, seed development and light regulation. DELLAprotein is the conservative inhibitor of GA signaling pathways, the N-terminal domain ofDELLA play a very important role in protein stability, it can rapidly response to the GA signal.To explore the influence of DELLA proteins GhGAI4a to Arabidopsis growth anddevelopment and the role of the gibberellin pathway, And thus lay the foundation for thefollow-up to understand the impact of the gene on cotton development.Method: Constructing the plant expression vector pBP35S:GhGAI4a and pBP35S:Ghgai4aand converting them into Col of Arabidopsis with the method of Agrobacterium-mediatedinflorescence infection. By PCR detection and the kanamycin screening obtainedhomozygous transgenic lines. By semi-quantitative RT-PCR analysis of target geneexpression. Observe the germination rate of transgenic Arabidopsis Analyzing theArabidopsis germination rate, hypocotyl and root length on GA treatment. The differentconcentrations of PEG6000and NaCl were used to explore the abiotic stress tolerance oftransgenic Arabidopsis To observe the germination rate and the length of hypocotyl ofArabidopsis light cycles on photoperiod To analysis the bolting time, flowering time, thenumber of rosette leaves and final plant height of transgenic Arabidopsis under long-day(16hlight/8h dark) conditions. To analysis the function of GhGAI4a by morphology preliminaryConstructing the functional complementation experiments vector pMP35S:GhGAI4a theArabidopsis DELLA mutant Tetra. To identify GhGAI4a function further.Result and Conclusion: Constructed plant expression vector pBP35S:GhGAI4a andpBP35S:Ghgai4a double digestion with Xma I and Sac I, result with the expected size ofexactly the purpose of bands.The results of the amino acid sequence comparison show thatcompared with GhGAI4a, Ghgai4a lack of the DELLA domain. Each of them obtained6transgenic Arabidopsis homozygous lines. Compared to wild-type Arabidopsis,48hours ofgermination rate of transgenic Arabidopsis of GhGAI4a and Ghgai4a were significantly lower,the germination rate of Ghgai4a Arabidopsis was very low. The taproot length of GhGAI4a and Ghgai4a transgenic Arabidopsis is shorter than wild type. Compared to wild-typeArabidopsis, seed germination and taproot growth of have been greatly improved with1μmolGA treatment, while Ghgai4a did not change significantly. The plant height of GhGAI4a andGhgai4a was significantly shorter than wild type. Bolting and flowering time of GhGAI4awere significantly later than the wild-type. GhGAI4a have a large number of rosette leavesand large rosette radius. GhGAI4a transgenic Arabidopsis has a lower ability of drought andsalt tolerance. Converting pMP35S:GhGAI4a into Tetra, by the kanamycin screening obtained3T1hygromycin-resistant plants. The plant is not detected the target fragment. It had a Longthin silique and plant height was significantly increased.