Mechanisms of abiotic stress responses in tomato (Solanum lycopersicum)

点击翻译按钮获取中文摘要

The long-term goal of this project is to advance our understanding of the molecular mechanisms and the underlying genetic components that function in heat and salt stress tolerance in tomato. During the last funding period we have confirmed and initially characterized a generative heat tolerance trait of the Palestinian tomato cultivar P2. Moreover, we obtained evidence that this cultivar appears to exhibit also exceptional salt tolerance with respect to fertilization and fruit set. An emerging new concept during the last funding period was based on the identification of a transpiration dependent salt tolerance pathway in Arabidopsis. In this regard we identified not only a CBL-CIPK complex but also a ROP GTPase as so far unknown components of this pathway. We succeeded in identifying and assembling a homologous CBL-CIPK-RBOHF module from tomato and initiated genetic approaches to enable the study of the molecular and physiological function of these proteins. Based on our identification of ROP11 from Arabidopsis as a component of transpiration dependent salt tolerance we similarly performed the characterization of the small GTPase SlROP9 (the homolog of AtROP11) from tomato. Based on these achievements we intend to pursue two specific aims during the requested extension period:(i) We intend to further phenotypically characterize the heat tolerant generative trait of the P2 variety (midday heat tolerance and potential tolerance to elevated night temperatures) and to genetically identify the underlying genetic cause(s) for this abiotic stress trait(s). Similarly, we want to elucidate the characteristics and genetic causes of the generative salt tolerance that we observed in this variety. To this end we will combine in vitro and in vivo approaches, like pistil feeding assays, for detailed characterization of the heat and salt tolerant phenotypes of P2. Subsequently, we will use the already existing F2 populations for a large-scale phenotyping, initial RAPD based QTL mapping/verification and finally a map-based cloning using NGS approaches. (ii) Moreover, we will investigate the molecular mechanisms and physiological function of the tomato CBL-CIPK-RBOH-ROP module that we have assembled during the last funding period. Here the focus will be on the further generation and characterization of genetically modified tomato lines that allow to elucidate the function and physiological roles of these proteins. Together, these approaches should significantly enhance our understanding of the mechanisms and signaling networks that underlie heat and salt tolerance in tomato.