Adapting crop plants to abiotic stress via actin-mediated, stress-responsive membrane stabilisation

• Applicant: Dr. Sruthy Maria Augustine, Ph.D.
• Subject Area: Plant Breeding and Plant Pathology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442874779

Abiotic stresses are regarded as crucial factors restricting plant species from reaching their full genetic potential to deliver desired productivity. In crop improvement strategies, abiotic stress tolerance is gaining in importance due to the growing threat to food security because of climate change and environmental deterioration caused by human activity. In addition to current breeding practices for providing enhanced food security, there is great urgency to speed up crop improvement programs, for example by use of modern biotechnological tools to create novel diversity for stress responses. Wheat is one of the major cereal crops for one-third of the world population, and its yield and quality are severely affected by abiotic stress, especially drought (in combination with heat) and salinity. In a previous study we found that Erianthus aundinaceus, a wild relative of sugarcane showed higher Hsp70 gene expression under drought stress and the expression increases with increasing drought stress. The Hsp70 expression was correlating to the drought tolerance in E.arundinaceus. Further, we isolated the Hsp70 gene from E. arundinaceus and overexpress it in sugarcane results increased cortical actin accumulation, which leads to formation of interlocking marginal lobes (IML) and abiotic stress tolerance in sugarcane via cell membrane stability (Augustine et al., 2015a, 2015b). The Hsp70 orthologue from a drought-tolerant E. arundinaceus, driven by a drought-responsive ubiquitin promoter (Ubi 2.3) from Porteresia coarctata, induced Hsp70 expression nearly 2000-fold in sugarcane. The current project was conceived because of the importance of the cereal crop wheat and the problems arising from crop-improvement strategies relating to the development of multiple stress tolerances in a single plant species. Based on our previous encouraging results, the goal of the current project is to 1) identify and isolate the stress-responsive promoter (Ubi2.3) and Hsp70 orthologue from drought-tolerant wheat and sorghum genotypes; 2) identify the physiological and molecular basis of the role of actin in stress tolerance; 3) analyse the formation of IML and Hsp70 expression in Hsp70 donor genotypes; 4) identify whether the overexpression of Hsp70 in wheat leads to actin polymerization and IML formation on the cell membrane as a drought-tolerance response; 5) analyse the effects of Hsp70 overexpression in wheat; and 6) test and validate the IML selection marker for identification of stress-tolerant plants. Moreover, we hypothesise that actin plays a major role in drought stress tolerance and Hsp70 mediated cortical actin accumulation which leads to IML formation and stress tolerance via membrane stabilization is a general abiotic stress tolerance mechanism that can potentially be used to improve drought and salinity tolerance in monocotyledonous crop plants.

• DFG Programme: Research Grants