Identification of anti-senescence candidate genes TaSGR2 and TaSGRL1 and development of molecular marker related to chlorophyll degradation in wheat (Triticum aestivum L.)

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STAY-GREEN (SGR) genes play crucial roles in chlorophyll degradation and are considered promising candidates for developing leaf anti-senescence crops. However, their characterization in wheat remains unclear. In this study, we performed a genome-wide identification of TaSGR genes and analyzed their phylogeny, gene structure, transcriptional profiles, protein interaction networks, and genetic variations. Six TaSGR genes, grouped into two subclasses based on phylogenetic analysis and sequence homology, were identified and mapped to chromosomes 2A, 2B, 2D, 5A, 5B, and 5D. Expression analysis revealed that TaSGR1–3 are responsive to heat and drought stresses, whereas TaSGRL1–3 are induced under phosphorus starvation. We also predicted one putative miRNA and nineteen candidate genes targeting TaSGRs . Furthermore, CHLG and CAO were predicted to interact with TaSGR2 and showed decreased expression during leaf senescence. Most SGR genes exhibited high expression levels in senescent leaves, while TaSGR2 displayed relatively low expression and TaSGRL1 showed elevated expression in the stay-green cultivar CN18. Promoter variations in TaSGR2 and both promoter and coding-region variations in TaSGRL1 were associated with delayed senescence. Haplotype TaSGRL1 -HapI was identified as an allele significantly associated with leaf anti-senescence, whereas TaSGR2 -HapII showed a similar but non-significant trend. These haplotypes were phylogenetically associated with Aegilops speltoides and Triticum urartu , respectively. These findings highlight functional variations in TaSGR2 and TaSGRL1 and provide valuable targets for breeding wheat varieties with enhanced leaf longevity.

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