Intraspecific plasticity in hydraulic and stomatal regulation under drought is linked to aridity at the seed source in a wild pear species

Abstract

Adaptations of fruit trees to future climate are a current research priority due to the rapid increase in air temperature and changes in precipitation patterns. This is aimed at securing sustainable food production for our growing populations. Key physiological traits in trees conferring drought tolerance are resistance to embolism and stomatal control over water loss. Recently, we have shown in the field that a native wild pear species performs better under drought than two cultivated pear species. A comparative greenhouse study was conducted to investigate traits associated with drought tolerance in four ecotypes of a wild pear species (Pyrus syriaca Boiss), compared with a wild pear species (Pyrus betulifolia Bunge) commonly used as a pear rootstock. Seed sources were collected from semi-arid, sub-humid and humid sites across northern Israel. Measurements of water relations, leaf physiology, hydraulic conductivity and percent loss of hydraulic conductivity (PLC) were conducted under standard irrigation, drought and recovery from drought. The four P. syriaca ecotypes maintained significantly higher leaf gas exchange values and water-use efficiency and had lower PLC than the rootstock species under prolonged drought as well as during recovery. Across the four ecotypes, stomatal closure occurred at stem water potential (Ψ) around −3.5 MPa; however, Ψ at 50% PLC ranged from −4.1 MPa in the humid ecotype to −5.2 MPa in one of the semi-arid ecotypes, rendering the latter with a higher hydraulic safety margin (the Ψ difference between stomatal closure and 50% PLC). Divergence of the ecotypes in xylem vulnerability to embolism closely matched the mean annual precipitation at their seed sources. Thus, selection of pear ecotypes from populations in semi-arid sites may be better than the currently used plant material for preparing our cultivated species for hotter and drier future climate.

Orchard Management and Incorporation of Biochemical and Molecular Strategies for Improving Drought Tolerance in Fruit Tree Crops

“…Using wild varieties as rootstocks is also recommended for pome fruit trees [ 7 ]. As a case in point, Al Maarri et al [ 28 ] showed that the Syrian pear ( Pyrus syriaca ), the only wild species in Lebanon and Turkey, is drought tolerant and has higher grafting compatibility with Pyrus communis than quince ( Cydonia oblonga ) rootstocks [ 7 ].…”

“…Many orchard irrigation systems are not optimized for severe abiotic conditions, so the water requirements for plant growth are not supplied at the critical stages of growth [ 6 ]. The ultimate aim of commercial goals is fruit yield; to produce a successful yield, basic conditions must be met [ 7 ]. Water shortage is more problematic in the final period of fruit growth and can result in fruits that are smaller than usual and not suitable for the market [ 8 ].…”

“…As global human population growth has increased, cropland expansion has risen as well; this expansion imposes intense pressure on water resources [ 7 ]. In order to sustain the growing world population, efficient water management strategies and systems are vital [ 18 ].…”

Plant-Based Methodologies and Approaches for Estimating Plant Water Status of Mediterranean Tree Species: A Semi-Systematic Review

“…Another limitation is that the sensors used to measure g s are not automated. The sensitivity of g s to PWS changes was shown to be a good irrigation indicator for several crops [32,157,158]. It was studied in the application of an irrigation schedule in olives [159], grapefruit [160], and grapevines [161], among many others.…”

Melatonin Enhances Drought Tolerance by Regulating Leaf Stomatal Behavior, Carbon and Nitrogen Metabolism, and Related Gene Expression in Maize Plants

“…Drought is complex abiotic stress, and a series of morphological, physiological, and biochemical changes take place during the response of plants to drought stress ( Shah et al, 2020 ), which include plant growth ( Todaka et al, 2017 ), leaf stomatal behavior ( Indira et al, 2021 ), photosynthetic activity ( Zhou et al, 2019 ), cellular redox homeostasis ( Zhang et al, 2019 ), and metabolism homeostasis ( Pinheiro and Chaves, 2011 ). These changes are usually interconnected.…”