Photochemical efficiency correlated with candidate gene expression promote coffee drought tolerance

Abstract

The aim of this study was to identify the correlation between photochemical efficiency and candidate genes expression to elucidate the drought tolerance mechanisms in coffee progenies (Icatu Vermelho IAC 3851-2 × Catimor UFV 1602-215) previously identified as tolerant in field conditions. Four progenies (2, 5, 12 and 15) were evaluated under water-deficit conditions (water deficit imposed 8 months after transplanting seedlings to the pots) and under irrigated system. Evaluations of physiological parameters and expression of candidate genes for drought tolerance were performed. Progeny 5 showed capacity to maintain water potential, which contributed to lower qP variation between irrigated and deficit conditions. However, the increases of qN and NPQ in response to stress indicate that this progeny is photochemically responsive to small variations of Ψam protecting the photosystem and maintaining qP. Data obtained for progeny 12 indicated a lower water status maintenance capacity, but with increased qN and NPQ providing maintenance of the ɸPSII and ETR parameters. A PCA analysis revealed that the genes coding regulatory proteins, ABA-synthesis, cellular protectors, isoforms of ascorbate peroxidase clearly displayed a major response to drought stress and discriminated the progenies 5 and 12 which showed a better photochemical response. The genes CaMYB1, CaERF017, CaEDR2, CaNCED, CaAPX1, CaAPX5, CaGolS3, CaDHN1 and CaPYL8a were up-regulated in the arabica coffee progenies with greater photochemical efficiency under deficit and therefore contributing to efficiency of the photosynthesis in drought tolerant progenies.

Next-Generation Proteomics Reveals a Greater Antioxidative Response to Drought in Coffea arabica Than in Coffea canephora

“…Bourbon Vermelho that was further crossed with C. arabica cv. Mundo Novo and has a very high tolerance to drought under environmentally controlled conditions [20,33,44] and under field conditions [32]. Understanding the proteomic response of these genotypes to drought complements physiological, biochemical, and transcriptional leaf studies, previously performed under the same plants and the conditions studied here [19,20,42,44].…”

“…Nevertheless, both inadequate temperatures and water availability conditions are the main environmental constraints to plant development and production [27]. However, some cultivars show a significant resilience under drought, extreme temperatures, and full sunlight, triggering a wide number of energy dissipation and antioxidant mechanisms [19,[30][31][32][33] as well as by changing the lipid matrix of their chloroplast membranes [34][35][36]. For instance, genotypes of both C. arabica and C. canephora can display different drought tolerance levels, although in general, C. canephora is thought to be more tolerant than C. arabica to prolonged periods of drought, as empirically observed in coffee plantations [28].…”

Understanding the Impact of Drought in Coffea Genotypes: Transcriptomic Analysis Supports a Common High Resilience to Moderate Water Deficit but a Genotype Dependent Sensitivity to Severe Water Deficit

“…At the molecular level, several studies have identified candidate genes for drought tolerance in C. canephora (e.g., [29,76,[99][100][101]) and C. arabica (e.g., [52,76,102]). These candidate genes mainly encompass TFs as the DREB-like genes DREB1D, ERF017, EDR2 [29,74,76,102], genes related to ABA synthase, ABA receptors, and protein phosphatases such as PYL8a, PYR1, SNRK2.8 [29,103], and mainly protective genes, including those associated with ROS control and removal, such as CuSOD1, CuSOD2, APX1, APX5, APX6, HSP70, ELIP, Chape20, and Chape60 [29,48,100,[104][105][106].…”

“…At the molecular level, several studies have identified candidate genes for drought tolerance in C. canephora (e.g., [29,76,[99][100][101]) and C. arabica (e.g., [52,76,102]). These candidate genes mainly encompass TFs as the DREB-like genes DREB1D, ERF017, EDR2 [29,74,76,102], genes related to ABA synthase, ABA receptors, and protein phosphatases such as PYL8a, PYR1, SNRK2.8 [29,103], and mainly protective genes, including those associated with ROS control and removal, such as CuSOD1, CuSOD2, APX1, APX5, APX6, HSP70, ELIP, Chape20, and Chape60 [29,48,100,[104][105][106]. Additionally, drought studies also found increases in protective proteins that could improve thermal dissipation processes (PsbS) and promote the protective cyclic electron transport around photosystems I and II when CO 2 supply to the carboxylation sites in the chloroplast is greatly diminished due to stomata closure [24,25].…”

“…Additionally, drought studies also found increases in protective proteins that could improve thermal dissipation processes (PsbS) and promote the protective cyclic electron transport around photosystems I and II when CO 2 supply to the carboxylation sites in the chloroplast is greatly diminished due to stomata closure [24,25]. These genes (and proteins) are usually overexpressed in coffee genotypes and are assumed to contribute to maintaining the photochemical efficiency under stress, at least in some genotypes [34,48,102].…”