TY - JOUR

T1 - Heat tolerance in a wild Oryza species is attributed to maintenance of Rubisco activation by a thermally stable Rubisco activase ortholog

AU - Scafaro, Andrew

AU - Gallé, Alexander

AU - van Rie, Jeroen

AU - Carmo-Silva, Ana Elizabete

AU - Salvucci, Michael E.

AU - Atwell, Brian J.

N1 - This is the peer reviewed version of the following article: Scafaro, A. P., Gallé, A., Van Rie, J., Carmo-Silva, E., Salvucci, M. E. and Atwell, B. J. (2016), Heat tolerance in a wild Oryza species is attributed to maintenance of Rubisco activation by a thermally stable Rubisco activase ortholog. New Phytol, 211: 899–911. doi:10.1111/nph.13963 which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/nph.13963/abstract This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

PY - 2016/8

Y1 - 2016/8

N2 - • The response of photosynthesis and plant growth to short periods of supra-optimal heat was tested in rice (Oryza sativa) and two wild Oryza species from the Australian savanna, O. meridionalis and O. australiensis. The mechanism of heat tolerance in the wild species was explored, particularly focusing on the heat-labile protein Rubisco activase (RCA).• We compared leaf elongation rates, net photosynthesis and Rubisco activation state at moderate (28°C) and high temperature (45°C). Sequence analysis followed by enzyme kinetics of RCA was used to identify structural differences and thermal stability.• Oryza australiensis was the most heat-tolerant species. Rubisco activation state was positively correlated with leaf elongation rates across all three species at four times following exposure to 45°C. Oryza australiensis had multiple polymorphisms in the RCA primary protein sequence, and the protein was thermally stable up to 42°C relative to RCA from O. sativa which became inhibited at 36°C. • We attribute the heat tolerance of growth and photosynthesis in these wild species to thermal stability of RCA, enabling Rubisco to remain active. Because thermal stability of RCA in O. australiensis co-occurs with reduced enzyme specific activity, an increased RCA to Rubisco ratio is required in vivo to maintain high Rubisco activation.

AB - • The response of photosynthesis and plant growth to short periods of supra-optimal heat was tested in rice (Oryza sativa) and two wild Oryza species from the Australian savanna, O. meridionalis and O. australiensis. The mechanism of heat tolerance in the wild species was explored, particularly focusing on the heat-labile protein Rubisco activase (RCA).• We compared leaf elongation rates, net photosynthesis and Rubisco activation state at moderate (28°C) and high temperature (45°C). Sequence analysis followed by enzyme kinetics of RCA was used to identify structural differences and thermal stability.• Oryza australiensis was the most heat-tolerant species. Rubisco activation state was positively correlated with leaf elongation rates across all three species at four times following exposure to 45°C. Oryza australiensis had multiple polymorphisms in the RCA primary protein sequence, and the protein was thermally stable up to 42°C relative to RCA from O. sativa which became inhibited at 36°C. • We attribute the heat tolerance of growth and photosynthesis in these wild species to thermal stability of RCA, enabling Rubisco to remain active. Because thermal stability of RCA in O. australiensis co-occurs with reduced enzyme specific activity, an increased RCA to Rubisco ratio is required in vivo to maintain high Rubisco activation.

KW - Rubisco

KW - Rubisco activase

KW - Rice

KW - Heat stress

U2 - 10.1111/nph.13963

DO - 10.1111/nph.13963

M3 - Journal article

VL - 211

SP - 899

EP - 911

JO - New Phytologist

JF - New Phytologist

SN - 0028-646X

IS - 3

ER -