Mesophyll CO2 conductance and leakiness are not responsive to short‐ and long‐term soil water limitations in the C4 plant Sorghum bicolor. (22nd July 2020)

• Record Type: Journal Article
• Authors: Sonawane, Balasaheb V.; Cousins, Asaph B.
• Is Part Of: Plant journal. Volume 103:Number 4(2020)
• Page Start: 1590
• Page End: 1602
• Publication Date: 2020-07-22
• Subjects: whole‐plant water‐use efficiency -- intrinsic water‐use efficiency -- water limitations -- leakiness -- C4 photosynthesis -- Sorghum bicolor -- carbon isotopes; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.14849
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: Breeding economically important C4 crops for enhanced whole‐plant water‐use efficiency ( WUE plant ) is needed for sustainable agriculture. WUE plant is a complex trait and an efficient phenotyping method that reports on components of WUE plant, such as intrinsic water‐use efficiency ( WUE i, the rate of leaf CO2 assimilation relative to water loss via stomatal conductance), is needed. In C4 plants, theoretical models suggest that leaf carbon isotope composition (δ 13 C), when the efficiency of the CO2 ‐concentrating mechanism (leakiness, ϕ) remains constant, can be used to screen for WUE i . The limited information about how ϕ responds to water limitations confines the application of δ 13 C for WUE i screening of C4 crops. The current research aimed to test the response of ϕ to short‐ or long‐term moderate water limitations, and the relationship of δ 13 C with WUE i and WUE plant, by addressing potential mesophyll CO2 conductance ( g m ) and biochemical limitations in the C4 plant Sorghum bicolor . We demonstrate that g m and ϕ are not responsive to short‐ or long‐term water limitations. Additionally, δ 13 C was not correlated with gas‐exchange estimates of WUE i under short‐ and long‐term water limitations, but showed a significant negative relationship with WUE plant . The observed association between the δ 13 C and WUE plant suggests an intrinsic link of δ 13 C with WUE i in this C4 plant, and can potentially be used as a screening tool for WUE plant in sorghum. Significance Statement: Plants such as Sorghum bicolor (sorghum) and Zea mays (maize) use a CO2 ‐concentrating mechanism (CCM) that increases rates of photosynthesis under environmental stress, such as drought; however, it is not clear how water limitations influence the efficiency of the CMM and whole‐plant water‐use efficiency. In the current study, the efficiency of the CCM was not responsive to soil water limitations, suggesting that whole‐plant water‐use efficiency was increased through reductions in leaf water loss without changes in photosynthesis.