Dynamics of nonstructural carbohydrates in a deciduous woody species from tropical dry forests under recurrent water deficit

Abstract

In tropical dry forests, both the dry and the short rainy seasons have become increasingly irregular. This study replicated these conditions to investigate the effects of two water deficit cycles on Cenostigma microphyllum seedlings. Impacts were assessed by measuring growth traits, water relations, gas exchange, and dynamics of nonstructural carbohydrate (NSC) content in the whole plant under greenhouse conditions in potted plants. In the first water deficit cycle, the leaf relative water content (RWC) was maintained at the expense of a rapid drop in gas exchange. Furthermore, there was a slight accumulation of NSC, mainly soluble sugars (SS) in the stem wood and roots, to the detriment of height and stem diameter growth. In the second cycle, the leaf RWC remained 40% higher than the lowest level measured in the first water deficit, and CO 2 assimilation remained twice as long in previously stressed plants.The SS content of the stems and roots was strongly correlated with the predawn leaf RWC. No strong reduction was observed in the bark stock even with the gradual increase of SS in the wood. Our data suggest that under recurrent water deficit prior to leaf drop, CO 2 assimilation is maintained, with the highest possible leaf RWC, under reduced stomatal conductance. This assists in SS transport to wood and root, which is no longer used to support the growth of the aboveground parts.

Seasonal Responses of Hydraulic Function and Carbon Dynamics in Spruce Seedlings to Continuous Drought

“…It is possible that seedlings sacrificed growth to maintain higher NSC for subsequent C use (e.g., osmoregulation) (Huang et al, 2021 ; Luo et al, 2021 ). In addition, as a drought-defoliation species, Jezo spruce fell off leaves to protect the hydraulic system, which may also stimulate C accumulation in branches and roots (Santos et al, 2022 ). However, C reserve may be unavailable under drought stress, and less change at the time of death (Sala et al, 2010 ; Jin et al, 2018 ; Wiley et al, 2019 ), which may lead to high-level NSC in drought and dead seedlings ( Figure 5 ).…”

Plant sugar metabolism, transport and signalling in challenging environments

“…In summary, there is a need to improve our knowledge further of how these different processes are coordinated and regulated in response to abiotic stresses to design new strategies for enhancing plant response to climate change. This special issue includes research articles and reviews on different aspects of sugar metabolism (Khattak et al, 2022;Krämer et al, 2022;Morin, Kadi, et al, 2022a;Samkumar et al, 2022;Santos et al, 2022;Seydel et al, 2022;Khanzada et al, 2022), sugar transport (Li & Vincent, 2022;Meuriot et al, 2022;Morabito et al, 2022;Morin, Maurousset, et al, 2022b;Okooboh et al, 2022;Salvi et al, 2022) and sugar signalling (Choudhary et al, 2022;Wingler & Henriques, 2022), and the crosstalk between sugars and phytohormones (Mishra et al, 2022) in response to a changing environment. More generally, the role of sugars in plant growth and development is also addressed (Dinant & Le Hir, 2022).…”