Toward a New Use for Carbon Isotope Discrimination in Wheat Breeding

Abstract

A major obstacle in the effort to develop drought tolerant varieties of wheat (Triticum aestivum L.) is phenotyping. Traits known to contribute to improved drought tolerance, such as water-use behavior, reliance on stem reserve carbohydrates, and the ability to develop deep roots, require time and resource-intensive screening techniques. Plant breeding programs often have many thousands of experimental genotypes, which makes testing for each of these traits impractical. This work proposes that carbon isotope discrimination (∆) analysis of mature grains may serve as a relatively high-throughput approach to identify genotypes exhibiting traits associated with drought tolerance. Using ∆ as a proxy for stomatal conductance and photosynthetic capacity, assumptions can be made regarding fundamental plant physiological responses. When combined with knowledge of the terminal drought severity experienced in a particular environment, genotypes exhibiting conservative and rapid water use, deep roots, and reliance on stem reserve carbohydrates may be identified. Preliminary data in support of this idea are presented. Further verification of this use for grain ∆ will better equip wheat breeding programs to develop more drought tolerant varieties.

Genetic Variation in Drought-Tolerance Traits and Their Relationships to Growth in Pinus radiata D. Don Under Water Stress

“…Leaf δ 13 C is an attractive parameter that provides a spatial and temporal measure of essential traits related to carbon gain and plant water use (e.g., photosynthesis and stomatal conductance). Plant δ 13 C has been often used as a screening tool in breeding programs to select genotypes with greater WUE and productivity under drought conditions ( Richards and Condon, 1993 ; Dixon and Carter, 2019 ; Famula et al, 2019 ). A rapid, accurate and non-destructive method (i.e., high-throughput phenotyping) to identify drought-tolerant woody plants for future breeding programs is also required.…”

Genetics components of rice root architecture and carbon isotopic fractionation parameters: a tracer for breeding in a water-saving irrigation management

“…Carbon isotope discrimination (CID) has been extensively used as a proxy for physiological breeding of many plant species, aiming to improve its water use e ciency or its effective capacity of water use under dryland condition (Farquhar and Richards 1984;Farquhar et al 1989;Brito et al 2014;Dixon and Carter 2019). Nevertheless, there is scarce knowledge about its usability to identify desirable genotypes when AWD is adopted; especially considering the soil dynamic changes created by AWD and its complex interactions among genotypes.…”

“…This is strongly impacted by stomatal conductance and photosynthetic performance, what allow researchers to make conclusions regarding principles of plant physiology from CID analysis (Brugnoli et al 1988). When considered gas exchange performance over time, especially for photosynthesis and stomatal conductance in the tissue, where these parameters are analyzed, a high CID in leaf may be assumed to have experienced high stomatal conductance with low photosynthetic capacity or high performance for stomatal conductance and high photosynthesis, whereas the opposite may be assumed for low CID in plant tissue (Dixon and Carter 2019). Taken together, these assumptions and mode of dynamic progress of ooding and drying cycles via AWD, could lead to identify and classify genotypes based in traits known to be related to water de cit tolerance.…”