Growth in hot climates selectively alters potato tuber secondary metabolism-such as the anthocyanins, carotenoids, and glycoalkaloids-changing its nutritive value and the composition of health-promoting components. Potato breeding for improved nutritional value focuses mainly on increasing the health-promoting carotenoids and anthocyanins, and controlling toxic steroidal glycoalkaloids (SGAs). Metabolite levels are genetically determined, but developmental, tissue-specific, and environmental cues affect their final content. Transcriptomic and metabolomic approaches were applied to monitor carotenoid, anthocyanin, and SGA metabolite levels and their biosynthetic genes' expression under heat stress. The studied cultivars differed in tuber flesh carotenoid concentration and peel anthocyanin concentration. Gene expression studies showed heat-induced downregulation of specific genes for SGA, anthocyanin, and carotenoid biosynthesis. KEGG database mapping of the heat transcriptome indicated reduced gene expression for specific metabolic pathways rather than a global heat response. Targeted metabolomics indicated reduced SGA concentration, but anthocyanin pigments concentration remained unchanged, probably due to their stabilization in the vacuole. Total carotenoid level did not change significantly in potato tuber flesh, but their composition did. Results suggest that growth in hot climates selectively alters tuber secondary metabolism, changing its nutritive value and composition of health-promoting components.
Keywords: High growth temperature; Phelloderm; Secondary metabolite; Transcriptome; Tuber flesh.