Functional Analysis Of Gossypium Hirsutum Transcription Factor GhRAV And GhMYB

Soil salinity effects production of global agriculture and stability of ecologicalenvironment, directly lead to decline of the crop yield. So the use of genetic engineering toimprove plant tolerance to salt is an effective method to utilize saline soil.Seed germination is a special growth process from embryonic stage to a seedling.Therefore, seed germination is very important, and is influenced by the plant intrinsic andenvironmental conditions. Salinity affects seed germination. Although the lower saltconcentration could promote seed germination, but the high concentration of salt is shown toinhibit seed germination. Cotton is one of the important economic crops. Its growth and yieldare affected by the salt stress, especially during seed germination stage and seedling growthstage. Therefore, studying the responsive mechanisms of the cotton to salt stress is veryimportant. Through Solexa sequence analysis, we found that two TAGs mathched toDW497477and TA42288₃635were upregulated by salt stress and selected for further strudy.The results are as follows:（1） Using RACE technology, we obtained the full-length sequence of DW497477andTA42288₃635. The BLAST analysis indicated that DW497477encoded a protein thatbelonged to the RAV subfamily of the AP2/ERF family. We named it as GhRAV. Thephylogenetic tree analysis and sequence alignments showed that GhRAV showed the highesthomology with CsRAV. The C terminal of protein that TA42288₃635encoded contains aconserved SANT domain belonged to MYB family. We named it as GhMYB.（2） Subcellular localization of GFP-tagged GhRAV in onion epidermal cells revealedthat GhRAV is exclusively localized in the nucleus.（3） During the germination and seedling stage, GhRAV overexpression transgenicArabidopsis showed insensitive to salt stress, osmotic stress and ABA.（4） Further analysis indicated that the insensitivity of GhRAV overexpression transgenic Arabidopsis to salt and osmotic stresses depended on ABA. The ABA content of WT andGhRAV overexpression transgenic Arabidopsis under high salt condition was in the similarlevel. These data suggested that GhRAV promoted seed germination through ABA signaling.（5） Under salt and osmotic stresses, genes of the key regulators of ABA signaling, suchas ABI3, ABI4and ABI5, were downregulated in GhRAV overexpression transgenicArabidopsis than those in wild-type plants by using qRT-PCR analysis. The results of westernbloting also indicated that the protein levels of ABI3and ABI5were significantly lower inGhRAV overexpression transgenic Arabidopsis than those in wild-type plants. These datafurther suggested that GhRAV promoted seed germination through ABA signaling.（6） GhMYB overexpression transgenic Arabidopsis also showed insensitivity to salt andosmotic stresses. But the mechanisms need to be further investigated.