Jasper Lamers & Mariam Awalia - Salinity Session

1) Title: How Plants Sense and Respond to Salinity
By: Jasper Lamers (Wageningen University & Research)

Plants use several different strategies to deal with high soil salinity. However, these adaptations are often not understood at the cellular level. Part of our research is to link early salt signalling to developmental plasticity. Hence, we work on a variety of topics including sodium sensing, root architecture and coordination of root and shoot growth under stress. Today, I will give an overview of the latest developments in our lab, with a focus on how we untangle ionic signalling from osmotic signalling.

2) Title: Genetic Mapping of the Early Responses to Salt Stress in A. thaliana
By: Mariam Awlia (University of Cape Town)

Salt stress severely and rapidly reduces plant growth prior to shoot ion accumulation. The genetic components of this early response to salt stress are largely unknown. Using high-throughput non-destructive phenotyping with RGB and chlorophyll fluorescence imaging, the early salt stress responses of 191 Arabidopsis accessions were screened within one hour after salt treatment and up to seven consecutive days, capturing traits related to rosette growth, shape, colour and photosynthetic activity. Multivariate analysis and machine learning models identified that photosynthetic activity in the light-adapted state (Fv´/Fm´) is a major determinant of plant performance during the early responses to salt stress, while dark-adapted maximum quantum yield (QY max) contributed to plant performance at a later stage. Genome-wide association study (GWAS) identified over one thousand associations specific to salt stress across 29 unique traits measured through time yielding a total of 438 traits. Two loci associated with QY max and Fv´/Fm´ were validated using T-DNA insertion lines, where an unknown protein kinase was identified that seems to affect Fv´/Fm´ under salt stress, thereby reducing plant growth and performance under salinity. Our work demonstrates how the combination of high-throughput phenotyping, multivariate analysis and GWAS can lead to new insights in studying temporal stress responses, identifying associations among different traits, and identifying new genetic components of salinity tolerance.