Knockdown of GhIQD31 and GhIQD32 increases drought and salt stress sensitivity in Gossypium hirsutum

Drought, salinity and cold stresses have a major impact on cotton production, thus identification and utilization of plant genes vital for plant improvement Whole-genome identification and functional characterizations of the IQ67-domain (IQD) protein family was carried out in which 148, 77, and 79 IQD genes were identified in Gossypium hirsutum, G. raimondii, and G. arboreum. The entire IQD proteins had varied physiochemical properties, however; their grand hydropathy values were negative, which demonstrated that the proteins were hydrophilic, a property common among the proteins encoded by various stresses responsive genes, such as the late embryogenesis abundant (LEA) proteins. The IQD proteins were predicted to be majorly sublocalized in the nucleus; moreover, various cis-regulatory elements with higher role in enhancing abiotic stress tolerance were detected. RNA-seq and RT-qPCR analysis revealed two key genes, Gh_D06G0014 and Gh_A09G1608 with significantly higher upregulation across the various tissues under drought, salt and cold stress. Knockdown of the two genes negatively affected the ability of G. hirsutum to tolerate the effects of the three stress factors, being all the antioxidant assayed were significantly low concentrations compared to the oxidizing enzymes in VIGS plants under stress, furthermore, morphological and physiological traits were all negatively affected in VIGS plants. Expression levels of GhLEA2, GhCDK_F4, GPCR (TOM1) and Gh_A05G2067 (TH), the stress responsive genes were all downregulated in the VIGS plants, but significantly upregulated in WT and positively controlled plants. The results demonstrated that the IQD genes could be responsible for enhancing drought, salt and cold stress tolerance in cotton.

Genome-wide analysis of the cotton G-coupled receptor proteins (GPCR) and functional analysis of GTOM1, a novel cotton GPCR gene under drought and cold stress

BACKGROUND

The efficient detection and initiation of appropriate response to abiotic stresses are important to plants survival. The plant G-protein coupled receptors (GPCRs) are diverse membranous proteins that are responsible for signal transduction.

RESULTS

In this research work, we identified a novel gene of the GPCR domain, transformed and carried out the functional analysis in Arabidopsis under drought and cold stresses. The transgenic lines exposed to drought and cold stress conditions showed higher germination rate, increased root length and higher fresh biomass accumulation. Besides, the levels of antioxidant enzymes, glutathione (GSH) and ascorbate peroxidase (APX) exhibited continuously increasing trends, with approximately threefold higher than the control, implying that these ROS-scavenging enzymes were responsible for the detoxification of ROS induced by drought and cold stresses. Similarly, the transgenic lines exhibited stable cell membrane stability (CMS), reduced water loss rate in the detached leaves and significant values for the saturated leaves compared to the wild types. Highly stress-responsive miRNAs were found to be targeted by the novel gene and based on GO analysis; the protein encoded by the gene was responsible for maintaining an integral component of membrane. In cotton, the virus-induced gene silencing (VIGS) plants exhibited a higher susceptibility to drought and cold stresses compared to the wild types.

CONCLUSION

The novel GPCR gene enhanced drought and cold stress tolerance in transgenic Arabidopsis plants by promoting root growth and induction of ROS scavenging enzymes. The outcome showed that the gene had a role in enhancing drought and cold stress tolerance, and can be further exploited in breeding for more stress-resilient and tolerant crops.