Carbon allocation patterns into proteins and lipids associated with superior tolerance of perennial grass to high soil temperature

Plant adaptation to heat stress may involve changes in C allocation within the plant. The objective of this study was to determine whether heat tolerance of C₃ perennial grass species was associated with the alteration of C allocation to proteins and lipids under heat stress. We study the patterns of allocation of newly fixed C through photosynthesis to proteins and lipids of heat-tolerant thermal Agrostis scabra Willd. and heat-sensitive creeping bent grass (A. stolonifera L. ‘Penncross’) exposed to high soil temperatures at 37°C or control temperature at 20°C. The allocation patterns of newly fixed C during heat stress into proteins and lipids in various plant organs (shoots, crowns, and roots) were examined using the¹⁴CO₂ pulsechase labeling technique. High soil temperature reduced the allocation of newly fixed C into proteins and lipids in shoots and roots, resulting in a lower protein and lipid content than control plants for both grass species. The decline in the protein and lipid content and the decrease in the¹⁴C allocation were less pronounced in thermal A. scabra than in A. stolonifera. The more efficient incorporation of newly fixed¹⁴C into lipids and proteins could support the superior tolerance of thermal A. scabra to prolonged periods of high soil temperatures.