Drought is the major abiotic stress, which affects cotton productivity. Recently, a calcium oxalate (CaOx) crystal has been explored for its functional role in supplying carbon (CO2) for photosynthesis under drought stress conditions. Based on it, a hypothesis is put forward that CaOx could be used as a biochemical pump to collect C from the organ interior under drought stress conditions in cotton as well. Alternatively, metabolic changes under drought stress conditions in cotton will more clarify the mechanism to support the above as well as to identify the new metabolic indicator of drought in cotton

Fifty-one cotton genotypes were screened for in-gel oxalate oxidase (OxO) activity under control and drought conditions. The expression of OxO activity was higher in cotton under drought stress compared to control. Genome–wide identification of the GLP1 isoforms/oxalate oxidase was performed and 50 such isoforms were identified in G. arboreum. These were further characterized for their tissue-specific expression (leaves, squares, ovules and cotyledon). For qualitative and quantitative estimation of cotton metabolites through GC-MS, single solvent extraction followed by combination of solvents was found the most suitable method. Mid polar column followed by non-polar column was found th e best to identify cotton metabolites. Additionally, among identified 50 GLP (Germin Like Proteins) isoforms, nine GLP Isoforms were found to show more than four-fold expression under drought.