AUTHOR=Martins Madlles Q. , Rodrigues Weverton P. , Fortunato Ana S. , Leitão António E. , Rodrigues Ana P. , Pais Isabel P. , Martins Lima D. , Silva Maria J. , Reboredo Fernando H. , Partelli Fábio L. , Campostrini Eliemar , Tomaz Marcelo A. , Scotti-Campos Paula , Ribeiro-Barros Ana I. , Lidon Fernando J. C. , DaMatta Fábio M. , Ramalho José C. 

TITLE=Protective Response Mechanisms to Heat Stress in Interaction with High [CO2] Conditions in Coffea spp.

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00947

DOI=10.3389/fpls.2016.00947

ISSN=1664-462X

ABSTRACT=<p>Modeling studies have predicted that coffee crop will be endangered by future global warming, but recent reports highlighted that high [CO<sub>2</sub>] can mitigate heat impacts on coffee. This work aimed at identifying heat protective mechanisms promoted by CO<sub>2</sub> in <italic>Coffea arabica</italic> (cv. Icatu and IPR108) and <italic>Coffea canephora</italic> cv. Conilon CL153. Plants were grown at 25/20°C (day/night), under 380 or 700 μL CO<sub>2</sub> L<sup>−1</sup>, and then gradually submitted to 31/25, 37/30, and 42/34°C. Relevant heat tolerance up to 37/30°C for both [CO<sub>2</sub>] and all coffee genotypes was observed, likely supported by the maintenance or increase of the pools of several protective molecules (neoxanthin, lutein, carotenes, α-tocopherol, HSP70, raffinose), activities of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), and the upregulated expression of some genes (<italic>ELIP, Chaperonin 20</italic>). However, at 42/34°C a tolerance threshold was reached, mostly in the 380-plants and Icatu. Adjustments in raffinose, lutein, β-carotene, α-tocopherol and HSP70 pools, and the upregulated expression of genes related to protective (<italic>ELIPS, HSP70, Chape 20</italic>, and <italic>60</italic>) and antioxidant (<italic>CAT, CuSOD2, APX Cyt, APX Chl</italic>) proteins were largely driven by temperature. However, enhanced [CO<sub>2</sub>] maintained higher activities of GR (Icatu) and CAT (Icatu and IPR108), kept (or even increased) the Cu,Zn-SOD, APX, and CAT activities, and promoted a greater upregulation of those enzyme genes, as well as those related to HSP70, ELIPs, Chaperonins in CL153, and Icatu. These changes likely favored the maintenance of reactive oxygen species (ROS) at controlled levels and contributed to mitigate of photosystem II photoinhibition at the highest temperature. Overall, our results highlighted the important role of enhanced [CO<sub>2</sub>] on the coffee crop acclimation and sustainability under predicted future global warming scenarios.</p>