Climate change impacts on crop breeding: Targeting interacting biotic and abiotic stresses for wheat improvement

Wheat (Triticum aestivum L.) as a staple crop is closely interwoven into the development of modern society. Its influence on culture and economic development is global. Recent instability in wheat markets has demonstrated its importance in guaranteeing food security across national borders. Climate change threatens food security as it interacts with a multitude of factors impacting wheat production. The challenge needs to be addressed with a multidisciplinary perspective delivered across research, private, and government sectors. Many experimental studies have identified the major biotic and abiotic stresses impacting wheat production, but fewer have addressed the combinations of stresses that occur simultaneously or sequentially during the wheat growth cycle. Here, we argue that biotic and abiotic stress interactions, and the genetics and genomics underlying them, have been insufficiently addressed by the crop science community. We propose this as a reason for the limited transfer of practical and feasible climate adaptation knowledge from research projects into routine farming practice. To address this gap, we propose that novel methodology integration can align large volumes of data available from crop breeding programs with increasingly cheaper omics tools to predict wheat performance under different climate change scenarios. Underlying this is our proposal that breeders design and deliver future wheat ideotypes based on new or enhanced understanding of the genetic and physiological processes that are triggered when wheat is subjected to combinations of stresses. By defining this to a trait and/or genetic level, new insights can be made for yield improvement under future climate conditions

Multi-location trials identify stable high yielding spring bread and durum wheat cultivars in Mexico

Determining the stability and consistency of grain yield performance requires accurate evaluation of genotypes in different environments. In Mexico, annual national spring wheat irrigated trials are conducted to assess elite bread and durum wheat performance in different testing environments (TEs) in the main wheat-growing areas. These trials provide data supporting release of new cultivars and aim to also address Mexican wheat value chain grain needs. In this study we analyzed 30 bread and durum wheat trial results from the 2012/13 and 2013/14 growing cycles conducted across TEs in northwest, north and central Mexico. Environmental variability (location, sowing timing, and irrigation schemes) across the national spring wheat irrigated trials enabled genotype by environment interaction to be effectively evaluated. We identified genotypes with high and stable grain yield across TEs of the wheat-growing areas of Mexico. The bread cultivars Bacorehuis F2015 and Borlaug100 F2014, and the durum cultivars Barobampo C2015, CONASIST C2015 and Anatoly C2011 were high yielding and gave stable performance in most of the TEs. This analysis demonstrates the utility of multi-year, multi-environment testing and analysis to identify improved wheat cultivars to meet wheat production demand in Mexico

Stem traits promote wheat climate-resilience

IntroductionWheat grain filling processes under post-anthesis stress scenarios depend mainly on stem traits and remobilization of stem water-soluble carbohydrates (WSC).MethodsA diverse panel of advanced semi-dwarf spring wheat lines, representing a natural variation in stem traits (WSC content, stem diameter, peduncle length, and stem wall width), was used to identify specific traits that reliably reflect the relationship between WSC and grain yield. The panel was phenotyped under various environmental conditions: well-watered, water-limited, and heat stress in Mexico, and terminal-drought in Israel.ResultsEnvironmental stresses reduced grain yield (from 626 g m−2 under well-watered to 213 g m−2 under heat), lower internode diameter, and peduncle length. However, stem-WSC generally peaked 3-4 weeks after heading under all environmental conditions except heat (where it peaked earlier) and expressed the highest values under water-limited and terminal-drought environments. Increased investment in internode diameter and peduncle length was associated with a higher accumulation of stem WSC, which showed a positive association with yield and kernel weight. Across all environments, there were no apparent trade-offs between increased crop investment in internode diameter, peduncle length, and grain yield. DiscussionOur results showed that selecting for genotypes with higher resource investment in stem structural biomass, WSC accumulation, and remobilization could be a valuable strategy to ameliorate grain size reduction under stress without compromising grain yield potential. Furthermore, easy-to-measure proxies for WSC (stem diameter at specific internodes and length of the last internode, i.e., the peduncle) could significantly increase throughput, potentially at the breeding scale

On-farm assessment of yield and quality traits in durum wheat

Durum wheat is key source of calories and nutrients for many regions of the world. Demand for it is predicted toincrease. Further efforts are therefore needed to develop new cultivars adapted to different future scenarios. Developing anovel cultivar takes, on average, 10 years and advanced lines are tested during the process, in general, under standardized con-ditions. Although evaluating candidate genotypes for commercial release under different on-farm conditions is a strategy thatis strongly recommended, its application for durum wheat and particularly for quality traits has been limited. This study eval-uated the grain yield and quality performance of eight different genotypes acrossfive contrasting farmers’fields over two sea-sons. Combining different analysis strategies, the most outstanding and stable genotypes were identified.RESULTS: The analyses revealed that some traits were mainly explained by the genotype effect (thousand kernel weight,flour sodiumdodecyl sulfate sedimentation volume, andflour yellowness), others by the management practices (yield and grain protein content),and others (test weight) by the year effect. In general, yield showed the highest range of variation across genotypes, managementpractices, and years and test weight the narrowest range. Flour yellowness was the most stable traitacross management conditions,while yield-related traits were the most unstable. We also determined the most representative and discriminativefield conditions,which is a beneficial strategy when breeders are constrained in their ability to develop multi-environment experiments.CONCLUSIONS: We concluded that assessing genotypes in different farming systems is a valid and complementary strategy foron-station trials for determining the performance of future commercial cultivars in heterogeneous environments to improvethe breeding process and resources.Fil: Tabbita, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; Argentina. Universidad de Córdoba, Departamento de Genética. Escuela Técnica Superior de Ingeniería Agronómica y de Montes; EspañaFil: Ortiz-Monasterio, Iván. International Maize and Wheat Improvement Center (CIMMYT); MéxicoFil: Piñera-Chávez, Francisco J. International Maize and Wheat Improvement Center (CIMMYT); MéxicoFil: Ibba, María Itria. International Maize and Wheat Improvement Center (CIMMYT); MéxicoFil: Guzman, Carlos. Universidad de Córdoba. Escuela Técnica Superior de Ingeniería Agronómica y de Montes. Departamento de Genética; Españ

Genotypic variation for lodging tolerance in spring wheat: wider and deeper root plates, a feature of low lodging, high yielding germplasm

Plant lodging reduces yield and quality of irrigated and rainfed spring wheats alike. Local and imported germplasm was screened to identify consistently higher-yielding genotypes with low plant lodging for the north-eastern Australian wheat belt. Using field level treatments, such as fertilisation and tactical overhead irrigation to consistently simulate scenarios leading to lodging in the target region, high reproducibility of lodging rankings was achieved in multi-environment experiments. In separate experiments in two years, detailed phenotyping of selected genotypes in field plots was implemented for traits underpinning stem and root type lodging. Multi-environment and phenotyping experiments ranked genotypes similarly in terms of lodging score. In the phenotyping experiments, root plate spread from field grown plants consistently emerged as a trait able to discriminate low lodging, high yielding germplasm from a multi-trait analysis quantifying genotypic correlations. If the root plate spread was greater than or equal to 5.5 cm, the lodging scores were small, and yield was high. Importantly, root plate spread phenotyped on plants growing at uniform planting density was found to be highly heritable (above 0.80), with a high genotypic correlation (0.80) across environments and strong association with structural rooting depth. A simplified phenotyping approach is discussed based on the main traits driving lodging tolerance and others routinely measured in breeding programs