o.dauda@westernsydney.edu.au

*Corresponding author: z.chen@westernsydney.edu.au

Annexins are a multigene family linked to calcium ion (Ca2+) regulation under abiotic stress in plants. These genes bind to negatively charged phospholipids in membrane walls and are upregulated to signal calcium production under stress. Annexins have been studied under salinity, oxidative, drought, cold and abscisic acid stress conditions in diverse plants.

However, abiotic stresses occur simultaneously, and independent stress application is not enough to gauge plants response to these conditions thus the role of annexins in combined salinity and heat stress in wheat is unknown. In barley, we found HvANN8 confers salt tolerance in barley via the regulation of Ca2+ and-mediated ROS signalling. We also identified 25 annexins in wheat and this includes three annexin 8 gene (TaANN8s) in the A, B and D sub genomes.

This study evaluates the role of calcium-signalling annexin 8 gene in salinity and heat stress tolerance in wheat/barley crop (Triticeae). Here, we employed bioinformatics, physiological, biochemical, and molecular approaches to study the role of annexin in combined stress tolerance in wheat. Localisation analysis has shown diverse expression of this gene in the leaves and roots of wheat plants.

This study screened 319 wheat varieties including wild types for heat tolerance in the field at Hawkesbury River farm and greenhouse at Western Sydney University Hawkesbury campus (S35) to identify sensitive and tolerant cultivars by subjecting them to heat stress of 32°C for 5 days at the flowering stage to identify 16 heat tolerant and sensitive varieties.

The heat tolerant varieties were further screened for salinity stress against common bread wheat variety (fielder) by subjecting to salinity stress of 200 mM NaCl at the seedling stage to identify two salinity tolerant cultivars. The results showed that H-199 and H-031 were more tolerant to salt stress than the other cultivars.

These two cultivars along with fielder variety are currently being screened for combined salinity and heat stress tolerance in wheat with focus on the role of annexin 8 gene in inducing stomatal regulation under these stresses. Annexin 8 gene confers salinity and heat tolerance in wheat via calcium signalling for ROS scavenging.