Heat-induced changes in the abundance of wheat Rubisco activase isoforms

TheTriticum aestivum(wheat) genome encodes three isoforms of Rubisco activase (Rca) differing in thermostability, which could be exploited to improve the resilience of this crop to global warming. We hypothesized that elevated temperatures would cause an increase in the relative abundance of heat-stable Rca1 beta. Wheat plants were grown at 25 degrees C : 18 degrees C (day : night) and exposed to heat stress (38 degrees C : 22 degrees C) for up to 5 d at pre-anthesis. Carbon (C) assimilation, Rubisco activity, CA1Pase activity, transcripts of Rca1 beta, Rca2 beta, and Rca2 alpha, and the quantities of the corresponding protein products were measured during and after heat stress. The transcript ofRca1 beta increased 40-fold in 4 h at elevated temperatures and returned to the original level after 4 h upon return of plants to control temperatures. Rca1 beta comprised up to 2% of the total Rca protein in unstressed leaves but increased three-fold in leaves exposed to elevated temperatures for 5 d and remained high at 4 h after heat stress. These results show that elevated temperatures cause rapid changes inRcagene expression and adaptive changes in Rca isoform abundance. The improved understanding of the regulation of C assimilation under heat stress will inform efforts to improve wheat productivity and climate resilience.

Automated summary

The wheat genome encodes three isoforms of Rubisco activase with different thermostability, which can be utilized to enhance the crop's resilience to global warming. High temperatures lead to rapid changes in Rca gene expression and adaptive adjustments in the abundance of Rca isoforms in plants.