Identification of TaRPL36 Gene Family in Wheat and Development of Functional Markers for Drought-response Gene TaRPL36-8

Purpose To investigate the characteristics of wheat (Triticum aestivum) ribosomal large subunit protein TaRPL36 gene family and its expression response to drought stress, thereby providing a theoretical basis for the study of its biological functions.

Methods Bioinformatics methods were used to identify the TaRPL36 gene family members in wheat, and analyze their phylogenetic evolution tree, gene structures and cis-acting elements. RNA-Seq data and quantitative real-time PCR (qRT-PCR) were employed to investigate TaRPL36 expression patterns under drought stress. Kompetitive allele-specific PCR (KASP) markers were developed for TaRPL36-8 gene, and correlation analysis was performed on the drought survival rate (DSR) phenotype of wheat seedlings in a natural population.

Results A total of nine TaRPL36 gene family members were identified in wheat genome, distributed across chromosomes 1A, 1B, 1D, 3A, 3B, 3D, 5A, 5B, and 5D, respectively. These family members exhibited similar conserved domains and gene structures. A total of 18 tandemly duplicated gene pairs were identified through intraspecific synteny analysis, while interspecific analysis revealed 12 homologous gene pairs each with rice and maize. Cis-acting element analysis demonstrated that the promoters of TaRPL36 genes contained abundant hormone-responsive and stress-responsive elements. Transcriptome and qRT-PCR analyses indicated that the expression levels of TaRPL36 were downregulated under drought stress. A KASP marker was developed for TaRPL36-8 gene, identifying two haplotypes. Notably, TaRPL36-8-HapⅠ exhibited an extremely significantly higher DSR than TaRPL36-8-HapⅡ, and had undergone positive selection during wheat breeding in China.

Conclusion A total of nine genes were identified in wheat TaRPL36 gene family, all of which share similar conserved domains and gene structures. These genes exhibit downregulated expression under drought stress. TaRPL36-8 gene can be classified into two haplotypes, which are significantly associated with DSR. Among them, TaRPL36-8-HapⅠ is the superior haplotype, having been positively selected in Chinese wheat breeding. The findings provide valuable genetic resources for molecular breeding of drought-resistant wheat.