Effects of high temperature on in vitro tuberization and accumulation of stress-responsive proteins in potato

Potato ( Solanum tuberosum L.) plants are highly vulnerable to heat stress. Even moderately elevated temperatures can disturb the process of tuberization in this important crop, causing a decline in tuber initiation, a reduction in tuber bulking, and tuber disorders. In the present study, we investigated the effects of heat stress on tuberization in two potato cultivars, the heat-sensitive cultivar Désirée and the heat-tolerant cultivar Festival, using an in vitro system. A temperature of 29 °C reduced tuber initiation and tuber bulking, and stimulated shoot elongation in cv. Désirée, while this temperature treatment did not significantly alter tuberization or shoot elongation in cv. Festival. In addition, high temperature interfered with the onset of microtuber dormancy and promoted growth of tuber apical buds during the tuber bulking stage in both cultivars. Stress-responsive proteins HSP17.6-CI, HSP101, and eEF1A showed heat-induced accumulation patterns in shoots and microtubers of these two cultivars, with the exception of a decline in the abundance of eEF1A in cv. Désirée microtubers under heat stress. High levels of HSP17.6-CI in microtubers of cv. Désirée did not ameliorate the effects of heat stress on tuberization of this relatively heat-sensitive cultivar. Conversely, a higher level of eEF1A under heat stress in microtubers of the heat-tolerant cv. Festival indicated a possible function of this protein in alleviating the negative effects of high temperature on potato tuberization. This study suggested that analysis of stress-responsive proteins in potato microtubers combined with assessment of tuberization parameters in vitro may represent a useful screening procedure for selection of heat-tolerant potato genotypes.