Calcium supply alters aquaporin transcription and enhances water deficit resilience in a Eucalyptus hybrid

Abstract

Key message Calcium plays a role in modulating aquaporin expression, reducing oxidative stress, preserving chlorophyll content, and maintaining membrane integrity, suggesting it may enhance eucalypt resilience to water restriction. Abstract Drought is a significant abiotic stress that severely impacts the growth and productivity of forests worldwide. This study investigates the role of calcium (Ca 2+ ) supply in modulating aquaporin (AQP) gene expression and mitigating oxidative stress in eucalypt ( Eucalyptus urophylla × Eucalyptus camaldulensis ) under water restriction. Three-month-old eucalypt seedlings were subjected to water restriction, with or without Ca 2+ supplementation. We measured mRNA expression levels of five aquaporin isoforms ( PIP1;2, PIP1;3, PIP2;1, PIP2;2, and PIP2;7 ), chlorophyll content, and markers of oxidative stress [e.g., hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and the activities of catalase (CAT) and superoxide dismutase (SOD)]. Our findings reveal that initial water restriction upregulated the expression of PIP1;2, PIP2;1, PIP2;2, and PIP2;7 in roots, which likely facilitated water uptake and maintained cellular hydration. However, under prolonged water limitation, plants supplemented with Ca 2+ showed downregulation of these PIPs, possibly as a protective mechanism to reduce water loss. In contrast, plants without Ca 2+ exhibited an upregulation of PIP1;2, PIP1;3 , and PIP2;7 under prolonged water deficit. Ca 2+ supplementation also played a crucial role in preserving chlorophyll content and reducing oxidative damage under water limitation. Plants supplemented with Ca 2+ had lower levels of H 2 O 2 and MDA, reduced oxidative damage and membrane permeability, alongside increased CAT activity, which suggests an enhanced oxidative response. Our results provide new insights into how Ca 2+ enhances eucalypt responses to water deprivation, enhancing our understanding of the function of Ca 2+ in drought responses.

Bibliographic Information