Abstract
Chilling and frost conditions impose major yield restraints to wheat crops in Australia and other temperate climate regions. Unpredictability and variability of field frost events are major impediments for cold tolerance breeding. Metabolome and lipidome profiling were used to compare the cold response in spikes of cold-tolerant Young and sensitive variety Wyalkatchem at the young microspore (YM) stage of pollen development. We aimed to identify metabolite markers that can reliably distinguish cold-tolerant and sensitive wheat varieties for future cold-tolerance phenotyping applications. We scored changes in spike metabolites and lipids for both varieties during cold acclimation after initial and prolonged exposure to combined chilling and freezing cycles (1 and 4 days, respectively) using controlled environment conditions. The two contrasting wheat varieties showed qualitative and quantitative differences in primary metabolites involved in osmoprotection, but differences in lipid accumulation most distinctively separated the cold response of the two wheat lines. These results resemble what we previously observed in flag leaves of the same two wheat varieties. The fact that this response occurs in tissue types with very different functions indicates that chilling and freezing tolerance in these wheat lines is associated with re-modelling of membrane lipid composition to maintain membrane fluidity.
Highlights
Frost events can cause major yield losses to cereal crops in many temperate climate regions in the world
The cold-tolerant wheat variety Young used in this study consistently performs better than the cold-sensitive variety Wyalkatchem in terms of spike grain yield in both field trials of the Australian National Frost Program (ANFP)
Profiling of primary metabolite and lipid changes in response to cold treatment of wheat spikes provided a better understanding about differences in cold acclimation of cold-tolerant Young and cold-sensitive Wyalkatchem
Summary
Frost events can cause major yield losses to cereal crops in many temperate climate regions in the world. Wheat crops in Australia are grown during winter and they flower in early spring to avoid the hot summers and to take advantage of available soil moisture. The annual yield loss due to frost events to the Australian grains industry is estimated to be A$360 million [1,2,3,4,5]. The problem is exacerbated by climate change. In China and Australia, spring frosts have become increasingly frequent since the 1960s and the length of the frost season has been extended by one month, leading to more frequent yield losses due to frost damage [5,6,7,8]
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