Comparison of proteomic and metabolomic profiles of two contrasting ecotypes of sweetpotato (Ipomoea batata L.).

UNLABELLED: Sweetpotato has long been acknowledged as a significant contributor of global caloric needs, which continues to be of remarkable economic value. It is an important staple and emergency food in many countries and its annual world production hovers to about 130 million tons. The tubers act as sink and compete for the available photoassimilates eventually leading to the acquisition of nutrients and phytochemicals. Differential display of genes or gene-products, and metabolites causes differences in nutritive value of closely related ecotypes. To better understand the molecular basis for differential nutrient availability and phytochemicals, and exploit the natural genetic variation(s), we aimed at developing proteometabolic profiles of two contrasting ecotypes of sweetpotato. Proteomic analyses led to the identification of 1541 and 1201 proteins in orange fleshed and white fleshed sweetpotato ecotypes, respectively, presumably associated with binding, followed by catalytic, transferase, hydrolase, kinase and transporter activities. Furthermore, metabolome profiling revealed 148 and 126 metabolites in cv. OFSP and WFSP, respectively. This study would provide a basis for future comparative proteometabolomic efforts for sweetpotato, in particular and tuber crops in general. The results would expand our understanding of the proteome as well as metabolome and give new insights into how ecotype-specific traits are developed.

BIOLOGICAL SIGNIFICANCE: Sweetpotato, the potato of the tropics, is the seventh most important crop worldwide in terms of production for food and additional industrial resources. Over 95% of the global sweet potato is produced in developing countries where it is considered as emergency food. It is also a vegetable, a snack food and confectionery item in most countries. It greatly contributes as a phytochemical source of nutrition and can produce more edible energy per hectare per day than wheat or rice. The adaptability to a wide range of agroecological conditions with least growth requirements makes it a preferred tuber crop of high commercial significance. Despite its nutritional merits, it has always remained outside the realm of large-scale functional genomics. Therefore, this study was aimed at constructing the proteomics and metabolomics shared resource for sweetpotato. These data are particularly significant, at least partially due to the fact that the currently available information about sweet potato is under-represented.