GRP (glycine-rich protein) is characterized by glycine-rich and conserved motifs that include (Gly) N-X repeats. This superfamily is generally divided into five major subclasses. Although GRP has been found to be involved in the stress response in many model plants and nonmodel plant species, little is known about the key physiological processes and molecular mechanisms involved in these proteins. In this study, we identified and analyzed the GhGRP genes of five subgroups of Gossypium hirsutum for the first time. Our research showed that GRP overexpression could enhance the salt stress tolerance of Arabidopsis thaliana and cotton, which would play a very promising role in cotton genetic engineering breeding. The GRP gene had make some progress in rice, Arabidopsis thaliana, maize, tobacco and other plants. In cotton, only Gossypium arboreum and Gossypium raimondii had been analyzed and identified into subgroup IV[(](#ref-0038)W. Yang et al., 2019), also known as the RB-GRP. VIGS and Arabidopsis thaliana overexpression experiments showed that the expression of GRP42 gene could indeed improve plant salt tolerance. The results of TEM showed that GRP42 gene maight act on the cell wall of plant vascular tissue and played a supporting role.

ZAT (ZINC FINGER OF ARABIDOPSIS THALIANA) proteins are composed of a plant-specific transcription factor family, which play an important role in plant growth, development and resistance to stress. To study the potential function of ZAT family in cotton, the whole genome identification, expression and structure analysis of ZAT gene family were carried out. In this study, our analysis revealed the presence of 115, 56, 59, 115 ZAT genes in Gossypium hirsutum, Gossypium raimondii, Gossypium arboreum and Gossypium barbadense, respectively. According to the number of domains and phylogenetic characteristics, we divided ZAT genes of four Gossypium species into 4 different classes, and further divided them into 11 subfamilies. The results of collinearity analysis showed that segmental duplication was the main method to amplify cotton ZAT gene family. Analysis of cis-elements of promoter indicated that most GhZATs genes contained cis-elements related to plant hormones and abiotic stress. According to heatmap analysis, the expression patterns of GhZATs genes under different stress treatments indicated that GhZATs genes were significantly involved in the response to cold, heat, salt, and PEG stress, possibly through different mechanisms. Among the highly expressed genes, we cloned an Gossypium hirsutum gene GhZAT67. Through virus-induced gene silencing (VIGS), we found that its expression decreased significantly after being silenced. After alkaline treatment, the wilting degree of silencing plants (VIGS) was even greater than WT, which proved that GhZAT12 gene was involved in the response to alkaline stress.