Identification of Drought, Heat, and Combined Drought and Heat Tolerant Donors in Maize

Abstract

Low maize (Zea maysL.) yields and the impacts of climate change on maize production highlight the need to improve yields in eastern and southern Africa. Climate projections suggest higher temperatures within drought‐prone areas. Research in model species suggests that tolerance to combined drought and heat stress is genetically distinct from tolerance to either stress alone, but this has not been confirmed in maize. In this study we evaluated 300 maize inbred lines testcrossed to CML539. Experiments were conducted under optimal conditions, reproductive stage drought stress, heat stress, and combined drought and heat stress. Lines with high levels of tolerance to drought and combined drought and heat stress were identified. Significant genotype × trial interaction and very large plot residuals were observed; consequently, the repeatability of individual managed stress trials was low. Tolerance to combined drought and heat stress in maize was genetically distinct from tolerance to individual stresses, and tolerance to either stress alone did not confer tolerance to combined drought and heat stress. This finding has major implications for maize drought breeding. Many current drought donors and key inbreds used in widely grown African hybrids were susceptible to drought stress at elevated temperatures. Several donors tolerant to drought and combined drought and heat stress, notably La Posta Sequia C7‐F64‐2‐6‐2‐2 and DTPYC9‐F46‐1‐2‐1‐2, need to be incorporated into maize breeding pipelines.

Adapting maize production to climate change in sub-Saharan Africa

“…In the field, delayed planting can be used to screen for tolerance to heat stress by ensuring higher temperatures are experienced during critical stages of plant growth (Craufurd et al 2013). Using this method Cairns et al (2013) recently reported large genetic variability for tolerance to heat stress in sub-tropical and tropical maize suggesting gains in maize tolerance to heat stress could be achieved through conventional breeding.…”

Climate Change: Seed Production and Options for Adaptation

“…However, plant breeders have been actively working towards producing cultivars better able to cope with climate change. The Drought Tolerant Maize for Africa project [145] has produced new drought tolerant hybrids [148], and drought tolerant germplasm which also has a higher level of tolerance to higher temperatures is also available [149]. Similarly, the Program for Africa's Seed Systems is seeking to promote the development of seed systems that deliver improved, locally adapted crop varieties to small-scale farmers and the uptake and use of released cultivars [150].…”

Metabolite profiles of maize leaves in drought, heat and combined stress field trials reveal the relationship between metabolism and grain yield

“…Additionally, simulation studies indicate that maize yield in Africa is likely to be significantly impaired by heat stress (HS; Lobell and Burke, 2010;Lobell et al, 2011), such as can be anticipated as a result of the changes in climate predicted for the coming decades . Moreover, the sensitivity of maize yield to heat is exacerbated under drought conditions (Lobell et al, 2011;Cairns et al, 2012aCairns et al, , 2012bCairns et al, , 2013. Therefore, the development of maize germplasm tolerant to drought and heat conditions is of utmost importance to both increase yields and offset predicted yield losses under projected climate change scenarios (Easterling et al, 2007), especially in sub-Saharan Africa.…”

“…Therefore, the development of maize germplasm tolerant to drought and heat conditions is of utmost importance to both increase yields and offset predicted yield losses under projected climate change scenarios (Easterling et al, 2007), especially in sub-Saharan Africa. While direct selection for grain yield under DS has resulted in admirable gains in grain yield under stress (Bänziger et al, 2006;Cairns et al, 2013), further improvement requires the incorporation of additional selection traits (Cairns et al, 2012a(Cairns et al, , 2012b. In recent years, genetic and phenotypic markers have been searched extensively for drought tolerance of maize by high-throughput genomic and phenotyping approaches, respectively (Tuberosa and Salvi, 2006;Wen et al, 2011;Araus et al, 2012;Cairns et al, 2013;Prasanna et al, 2013;Araus and Cairns, 2014;Tsonev et al, 2014).…”

“…While direct selection for grain yield under DS has resulted in admirable gains in grain yield under stress (Bänziger et al, 2006;Cairns et al, 2013), further improvement requires the incorporation of additional selection traits (Cairns et al, 2012a(Cairns et al, , 2012b. In recent years, genetic and phenotypic markers have been searched extensively for drought tolerance of maize by high-throughput genomic and phenotyping approaches, respectively (Tuberosa and Salvi, 2006;Wen et al, 2011;Araus et al, 2012;Cairns et al, 2013;Prasanna et al, 2013;Araus and Cairns, 2014;Tsonev et al, 2014). Moreover, metabolic markers started to draw attention due to their close relationship with yield phenotypes (Fernie and Schauer, 2009;Redestig et al, 2011;Riedelsheimer et al, 2012aRiedelsheimer et al, , 2012bWitt et al, 2012;Degenkolbe et al, 2013).…”