Drought and high salinity are key limiting factors for cotton production. Therefore, research is increasingly focused on the underlying stress response mechanisms of cotton. We first identified and cloned a novel gene encoding the 525 amino acids in cotton, namely GhWRKY6 . qRT-PCR analysis indicated that GhWRKY6 was induced by NaCl, PEG 6000 and ABA. Analyses of germination rate and root length indicated that overexpression of GhWRKY6 in Arabidopsis resulted in hypersensitivity to ABA, NaCl, and PEG 6000. In contrast, the loss-of-function mutant wrky6 was insensitive and had slightly longer roots than the wild-type did under these treatment conditions. Furthermore, GhWRKY6 overexpression in Arabidopsis modulated salt- and drought-sensitive phenotypes and stomatal aperture by regulating ABA signaling pathways, and reduced plant tolerance to abiotic stress through reactive oxygen species (ROS) enrichment, reduced proline content, and increased electrolytes and malondialdehyde (MDA). The expression levels of a series of ABA-, salt- and drought-related marker genes were altered in overexpression seedlings. Virus-induced gene silencing (VIGS) technology revealed that down-regulation of GhWRKY6 increased salt tolerance in cotton. These results demonstrate that GhWRKY6 is a negative regulator of plant responses to abiotic stress via the ABA signaling pathway.

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Upland cotton is an important global cash crop for its long seed fibers and high edible oil and protein content. Progress in cotton genomics promotes the advancement of cotton genetics, evolutionary studies, functional genetics, and breeding, and has ushered cotton research and breeding into a new era. Here, we summarize high‐impact genomics studies for cotton from the last 10 years. The diploid Gossypium arboreum and allotetraploid Gossypium hirsutum are the main focus of most genetic and genomic studies. We next review recent progress in cotton molecular biology and genetics, which builds on cotton genome sequencing efforts, population studies, and functional genomics, to provide insights into the mechanisms shaping abiotic and biotic stress tolerance, plant architecture, seed oil content, and fiber development. We also suggest the application of novel technologies and strategies to facilitate genome‐based crop breeding. Explosive growth in the amount of novel genomic data, identified genes, gene modules, and pathways is now enabling researchers to utilize multidisciplinary genomics‐enabled breeding strategies to cultivate “super cotton”, synergistically improving multiple traits. These strategies must rise to meet urgent demands for a sustainable cotton industry.