The role of genetic diversity and pre-breeding traits to improve drought and heat tolerance of bread wheat at the reproductive stage

Authors: SHOKAT, SAJID - University Of Copenhagen; GROSSKINSKY, DOMINIK - Austrian Institute Of Technology (AIT); Singh, Sukhwinder; LIU, FULAI - University Of Copenhagen

Submitted to: Food and Energy Security
Publication Type: Review Article
Publication Acceptance Date: 5/31/2023
Publication Date: 8/12/2023
Citation: Shokat, S., Grosskinsky, D.K., Singh, S., Liu, F. 2023. The role of genetic diversity and pre-breeding traits to improve drought and heat tolerance of bread wheat at the reproductive stage. Food and Energy Security. 00.e478. https://doi.org/10.1002/fes3.478.
DOI: https://doi.org/10.1002/fes3.478

Interpretive Summary: Extreme weather events including heat waves and drought episodes are likely to increase in intensity and duration due to climate change (Salinger, Stigter, & Das, 2000). Since 1900 drought has caused more than 11 million causalities and more than 2 billion people have been affected (4th UN World Water Development Report, 2012); while heat stress is reported to affect 1.2 billion people on the globe (Li, Yuan, & Kopp, 2020). After rice and maize, wheat is the third most produced crop (FAO Statistics, 2018) and is being grown in more than 85 countries. Its global cultivated area is 215 million ha (FAO, 2017) and wheat is consumed by more than 30% of the world population, providing 20% calories to 4.5 billion people (Lucas, 2012). Increasing CO2 is one of the main drivers of global warming. The rising temperature is causing melting of glaciers and uneven patterns of precipitation, which can result in floods and acute water shortage even in the same areas. Being one of the most important crops for food security, wheat is intensely cultivated in large monocultures across different areas of the world made it more prone to high temperature and acute water shortage. These stresses can occur throughout the plant growth season and generally have adverse effects on plant growth and productivity. Drought and heat at anthesis can directly reduce spike length, grain number and weight (Shokat et al., 2021; Shokat et al., 2020a; Akter and Rafiqul Islam, 2017). Thus, wheat cultivation will become more challenging in future with rising temperature and decreasing water availability and it will be a serious concern for sustainable food production to ensure food and nutritional security. During the first green revolution, wheat was changed to semi-dwarf and input responsive crop which significantly eliminate global hunger (Syme, 1969). Since then, plant scientists are making continuous efforts to understand the mechanisms of drought and heat tolerance to improve wheat against these stresses. Current genetic gain through plant improvement efforts is hovering around one percent, and this rate could not meet the required food demand of the growing world population (Ray et al., 2012; Sehgal et al., 2017). This is particularly true with the increased unpredictability of climate and with decreasing arable land indicating future farming can face challenges requiring novel strategies to cope with water shortage and high temperature at the reproductive stage (Rosenqvist et al., 2019). Phenotyping in the target environments have contributed to greater extent to develop drought and heat tolerant wheat genotypes (Reynolds et al., 2020). These phenotyping facilities varies from field observations to physiology where high resolution as well as breeder friendly machines have been adopted (Reynolds et al., 2020) to successfully screen the plant material tolerant to these stresses. However, this review addresses the potential of genetically diverse wheat germplasm in climate change scenario with special focus on drought and heat stresses at reproductive stage. Further, it will explain the role of diverse wheat germplasm derived from landraces and interspecific crosses to sustain grain yield at reproductive stage stresses. Likewise, potential of certain eco-physiological traits, carbohydrate metabolic and antioxidant enzymes, and endogenous concentration of phytohormones to predict the yield related traits at reproductive stage drought and heat stresses are explored, and discriminating traits are identified to select as pre-breeding traits for wheat improvement.

Technical Abstract: Extreme weather events including heat waves and drought episodes are expected to increase in intensity and duration due to climate change. Wheat, being a major crop is under extreme threat to these stresses especially at the reproductive stage. This review addresses the potential of diverse wheat germplasm (originated from landraces and synthetic derivatives) to cope with drought and heat stress at the flowering stage. Here, important marker-trait associations were reported for sustainable grain production under drought and heat stress at anthesis. Likewise, the mechanisms of drought and heat resilience including gene expression and physiological traits (activities of carbohydrate metabolic and antioxidant enzymes, and endogenous hormonal responses) were explored. These studies helped to understand the genetic and physiological basis of drought and heat tolerance and certain pre-breeding traits related to osmotic adjustment, phytohormonal regulation, antioxidant metabolism and the expression of novel gene were identified. Moreover, identified pre-breeding traits and genotypes can be utilized in breeding new wheat cultivars resilient to future adverse environments.