Unravelling the regulatory network involved in heat-stress tolerance of potato plants (Pot-HotNet)
Final Report Abstract
Potato (Solanum tuberosum) is one of the most important crops worldwide. Its popularity increases steadily due to its relatively easy cultivation and the high nutritional value of potato tubers. Increasing temperatures due to global warming threat its production and impair tuber yield and quality. Hence, there is is an urgent need to breed heat-stress tolerant cultivars to ensure yield stability. This challenge requires a detailed knowledge and understanding of the underlying biological processes and gene regulatory networks. Within the project we explored a broad spectrum of European cultivars to elucidate the molecular mechanisms of heat tolerance and susceptibility. We monitored morpho-physiological alterations of around 180 different potato cultivars in response to elevated temperatures (30°C). The results confirmed that heat stress impairs tuber growth and starch accumulation and showed that the heat-mediated increase in shoot length negatively correlates with tuber weight. However, there was large variation in the degree of responses between individual genotypes. To unravel the underlying genetic basis of these differences a genome-wide association study (GWAS) was conducted. To facilitate this, the genomic information of all cultivars was gathered by a genotyping-by-sequencing approach (GBS) and a pipeline was developed to perform these analyses in tetraploid potato plants. A set of 20K single nucleotide polymorphisms (SNPs) was identified and exploited for GWAS using the morpho-physiological parameters as input traits. Several QTL associated with heat-induced changes in plant height, aboveground biomass accumulation and distribution as well as in tuber weight and starch content were identified which need further investigations, but may contribute to the development of molecular markers for heat stress resilience. Two contrasting genotypes were selected for more detailed studies how elevated temperatures affect potato plants at physiological, metabolic and transcriptional level. Our investigations revealed that the susceptible cultivar (Cecile) exhibited a stronger heat-induced shoot elongation and decrease in photosynthesis, an activation of stress-related genes and an induction of senescence. These changes were not or to a lower extent observed in the tolerant variety (Solara). Moreover, the susceptible cultivar accumulated significant amounts of salicylic acid and ethylene, which most likely contribute to the impairment of photosynthesis and the induction of premature senescence. Consequently, this reduces plant fitness and impairs tuber development and starch accumulation. In contrast, the more tolerant cultivar showed an increased expression of several heat-tolerance associated genes and produced higher levels of osmolytes. Ongoing and future work will verify and further investigate candidate genes that were identified by both the genetic approach and the comparative transcriptome study.
Publications
-
Tuber and Tuberous Root Development. Annual Review of Plant Biology, 72(1), 551-580.
Zierer, Wolfgang; Rüscher, David; Sonnewald, Uwe & Sonnewald, Sophia
-
Knollen unter Hitzestress, Zeitschrift Kartoffelbau 05/2023
Sonnewald S.
