Metabolomic Analysis of Drought Response in Guar (Cyamopsis tetragonoloba (L.) Taub.) Seeds

Guar (Cyamopsis tetragonoloba (L.) Taub.) is a legume crop valued for the gum (carbohydrate galactomannan) found in its seeds, which is widely used in the oil and mining industries. In this study, we assessed changes in seed metabolite content caused by drought stress in three guar genotypes (tolerant, neutral, and sensitive to drought) in order to gain an insight into molecular mechanisms of guar tolerance to drought. The most intense response to drought was observed in seeds of the tolerant genotype. In response to drought, the content of sugars and their derivatives in the seeds of all three genotypes changed: monosaccharide content increased and glycoside content decreased. However, the tolerant genotype accumulated a specific set of sugars and their derivatives, including galactinol, and demonstrated higher levels of tocopherols. The neutral genotype was characterized by higher content of glycosides and pentoses, while the sensitive genotype had higher accumulation of some specific sugars and derivatives, major phytosterols, and unsaturated C18 fatty acids. Overall, the accumulation of galactinol, phytol, and alpha-tocopherol in seeds was associated with guar drought tolerance. This finding expands the understanding of the molecular mechanisms of drought tolerance in guar and paves the way for breeding drought-tolerant guar varieties.