High CO2 favors ionic homeostasis, photoprotection, and lower photorespiration in salt-stressed cashew plants

Author(s)

Souza, Naiara Celida S. ^[1] ; Silveira, Joaquim Albenisio G. ^[1] ; Silva, Evandro Nascimento ^[2] ; Lima Neto, Milton Costa ^[3] ; Lima, Cristina Silva ^[1] ; Aragao, Rafael Magalhaes ^[4] ; Ferreira-Silva, Sergio Luiz ^[5]

Affiliation

^[1] Univ Fed Ceara, Dept Bioquim & Biol Mol, Lab Metab Plantas, CP 6020, BR-60451970 Fortaleza, Ceara - Brazil

^[2] Univ Estadual Ceara, Fac Educ Ciencias & Letras Sertao Cent, BR-63900000 Quixada, Ceara - Brazil

^[3] Univ Estadual Paulista UNESP, Inst Biociencias, Campos Litoral Paulista, CP 73601, BR-11380972 Sao Paulo 11380972 - Brazil

^[4] UFRA, Campus Capanema, BR-68700030 Capanema, Para - Brazil

^[5] Univ Fed Rural Pernambuco, Unidade Acad Serra Talhada, Posgrad Prod Vegetal, CP 063, BR-56900000 Pernambuco - Brazil

• Document type: Journal article
• Source: ACTA PHYSIOLOGIAE PLANTARUM; v. 41, n. 9 AUG 8 2019.
• Web of Science Citations: 0

Abstract

The aim of this study was to evaluate the effects of elevated CO2 concentration on acclimation mechanisms related to gas exchange, photochemical activity, photorespiration, and oxidative protection in cashew plants exposed to salinity. Thirty-day-old cashew plants were irrigated with nutrient solution without (control) or with supplemental NaCl (100 mM) for 2 weeks in the greenhouse. Afterward, control and salt-stressed plants were transferred to the growth chamber and supplied with atmospheric (380 mu mol mol(-1)) or high CO2 (760 mu mol mol(-1)) concentrations for 15 days. The results show that elevated CO2 alone reduced the CO2 net assimilation rate (P-N) without affecting stomatal conductance (g(S)) and transpiration rate (E), whereas salinity and NaCl + high CO2 reduced the P-N associated with a decrease in g(S) and E. The potential quantum yield of photosystem II (Fv/Fm) was not altered, but a slight reduction in electron transport rate and photochemical quenching (qP) in response to high CO2 alone or combined with NaCl occurred. However, non-photochemical quenching increased due to the effects of high CO2 and NaCl alone and by their combination. High CO2 alleviated the toxic effects of Na+ favoring the K+/Na+ ratio under salinity. High CO2 coupled with salinity decreased glycolate oxidase activity and the contents of hydrogen peroxide (H2O2), NH4+, and glyoxylate. Furthermore, we observed increase in membrane damage associated with increased thiobarbituric acid-reactive substances levels under high CO2. High CO2 also decreased ascorbate peroxidase activity, but did not affect superoxide dismutase activity. In general, our data suggest that high CO2 could induce acclimation processes in plants independent of salinity, revealing a set of responses that are more associated with acclimation than with protective responses. (AU)

• FAPESP's process: 18/04258-6 - Impacts of the Photoinhibition of Photosystem I and its Photoprotective Mechanisms on the Photosynthetic Efficiency
• Grantee: Milton Costa Lima Neto
• Support Opportunities: Regular Research Grants