Screening Solanum Species for Heat Stress Tolerance (P-09)

Breeding climate-resilient potatoes is essential. The increased day and nighttime temperature affects tuber initiation, set, and early tuber bulking. Therefore, it is imperative to identify genetic resources for heat resistance breeding. This study aimed to use an in vitro screen to identify Solanum species with superior ability to tuberize under heat stress conditions and use a detached leaf bioassay to identify Solanum species. Based on previous work, we selected a set of Solanum species to test for heat tolerance. Trial 1 started with 40 wild accessions and five selected reference lines from MSU germplasm. We selected five individuals per accession as biological replicates. The in vitro plants underwent 32⁰C for day & night in darkness for 12 weeks. The number of tubers per replicate and the whole tuber weight of all replicates were measured. Another treatment was applied with a similar set of in vitro-grown plants at 20⁰C under the same conditions. In Trial 2, we selected 20 best accessions based on the Trial 1 data and five selected reference lines from MSU germplasm. In both trials, the accession PI 701941 (Salt Creek – Solanum jamesii) was the second-ranked accession regarding the number of tubers at 32⁰C (38 in Trial 1 and 34 in Trial 2). In Trial 1, the accession PI320265 (S. stenophyllidium) produced the highest mean number of tubers (41) and PI243503 (S. commersonii) produced the highest mean number of tubers (66) in Trial 2. In Trial 1, PI320265 also turned out to be the top-ranked variety regarding tuber weight. Currently, Trial 3 is underway with the same plant material set used in Trial 2 as well as drought tolerance evaluation with these 20 accessions. The results and germplasm will be made available to the US Potato Genebank to provide the basis for selecting heat-tolerant germplasm for breeding.