Submitted to: Molecular Plant
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 2013
Publication Date: N/A
Interpretive Summary: A series of genes that regulate plant responses to drought stress were over-expressed in cotton. Two of these genes (RAV & ABI) improved plant resistance to imposed drought stress under greenhouse conditions and exhibited improved photosynthetic efficiencies, likely due to improved water absorption through a larger root system. This study showed these genes have the potential to impact sustainable cotton agriculture and potentially other crops under limited irrigation conditions.
Technical Abstract: Drought tolerance is an important trait being pursued by the agbiotech industry. Abscisic acid (ABA) is a stress hormone that mediates a multitude of processes in growth and development, water use efficiency, and gene expression during seed development and in response to environmental stresses. Arabidopsis B3-domain transcription factor Related to ABA-Insensitive3/Viviparous1 (namely, RAV2) and basic leucine zipper (bZIPs) ABI5 and ABF3 transactivated ABA- inducible promoter: GUS reporter expression in a maize mesophyll protoplast transient assay and showed synergies in reporter gene transactivation when co-expressed. Transgenic cotton (Gossypium hirsutum) expressing AtRAV1/2 and/or ABI5 showed resistance to imposed drought stress under greenhouse conditions and exhibited improved photosynthetic efficiencies, likely due to improved water absorption through a larger root system. We observed synergy for root biomass accumulation and drought tolerance in stacked AtRAV and AtABI5 double-transgenic cotton. We assessed AtABI5 and AtRAV1/2 involvement in drought stress adaptations though reactive oxygen species scavenging and osmotic adjustment by marker gene expression in cotton. Deficit irrigation-grown RAV1/2 and ABI5 transgenics had a “less stressed” phenotype, likely due to enhanced expression of antioxidant enzymes and proline biosynthetic genes. Overexpression of bZIP and RAV TFs can impact sustainable cotton agriculture and potentially other crops under limited irrigation conditions.