The need to accelerate the selection of crop genotypes that are both resistant to and productive under abiotic stress is enhanced by global warming and the increase in demand for food by a growing world population. In this paper, we propose a new method for evaluation of wheat genotypes in terms of their resilience to stress and their production capacity. The method quantifies the components of a new index related to yield under abiotic stress based on previously developed stress indices, namely the stress susceptibility index, the stress tolerance index, the mean production index, the geometric mean production index, and the tolerance index, which were created originally to evaluate drought adaptation. The method, based on a scoring scale, offers simple and easy visualization and identification of resilient, productive and/or contrasting genotypes according to grain yield. This new selection method could help breeders and researchers by defining clear and strong criteria to identify genotypes with high resilience and high productivity and provide a clear visualization of contrasts in terms of grain yield production under stress. It is also expected that this methodology will reduce the time required for first selection and the number of first-selected genotypes for further evaluation by breeders and provide a basis for appropriate comparisons of genotypes that would help reveal the biology behind high stress productivity of crops.
Posts Tagged ‘Food security’
The International Center for Maize and Wheat Improvement (CIMMYT) leads the Global Wheat Program, whose main objective is to increase the productivity of wheat cropping systems to reduce poverty in developing countries. The priorities of the program are high grain yield, disease resistance, tolerance to abiotic stresses (drought and heat), and desirable quality. TheWheat Chemistry and Quality Laboratory has been continuously evolving to be able to analyze the largest number of samples possible, in the shortest time, at lowest cost, in order to deliver data on diverse quality traits on time to the breeders formaking selections for advancement in the breeding pipeline. The participation of wheat quality analysis/selection is carried out in two stages of the breeding process: evaluation of the parental
lines for new crosses and advanced lines in preliminary and elite yield trials. Thousands of lines are analyzed which requires a big investment in resources. Genomic selection has been proposed to assist in selecting for quality and other traits in breeding programs. Genomic selection can predict quantitative traits and is applicable to multiple quantitative traits in a breeding pipeline by attaining historical phenotypes and adding high-density genotypic information. Due to advances in sequencing technology, genome-wide single nucleotide polymorphism markers are available through genotyping-by-sequencing at a cost conducive to application for genomic selection. At CIMMYT, genomic selection has been applied to predict all of the processing and end-use quality traits regularly tested in the spring wheat breeding program. These traits have variable levels of prediction accuracy, however, they demonstrated thatmost expensive traits, dough rheology and baking final product, can be predicted with a high degree of confidence. Currently it is being explored howto combine both phenotypic and genomic selection to make more efficient the genetic improvement for quality traits at CIMMYT spring wheat breeding program.
Rusts, a fungal disease as old as its host plant wheat, an enemy as old as wheat, has caused havoc for over 8,000 years. As the rust pathogens can evolve into new virulent races which quickly defeat to qualitative or vertical the resistance that primarily rely on race specificity over time, adult plant resistance (APR) has often been found to be race non-specific and hence is considered have been proven to be a more to be a more reliable and durable strategy to combat this malady. Over decades sets of donor lines have been identified at International Maize and Wheat Improvement Center (CIMMYT) representing a wide range of APR sources in wheat. In this study, using nine donors and a common parent ‘PBW343’, a popular Green Revolution variety at CIMMYT, the nested association mapping (NAM) population of 1122 lines was constructed to understand the APR genetics underlying these founder lines. Thirty-four QTL were associated with APR to rusts, and 20 of 34 QTL had pleiotropic effects on SR, YR and LR resistance. Three chromosomal regions, associated with known APR genes (Sr58/Yr29/Lr46, Sr2/Yr30/Lr27, and Sr57/Yr18/Lr34), were also identified, 13 previously reported QTL regions were validated. Of the 18 QTL first detected in this study, 7 were pleiotropic QTL, distributing on chromosomes 3A, 3B, 6B, 3D, and 6D. The present investigation revealed the genetic relationship of historical APR donor lines, the novel knowledge on APR, as well as the new analytical methodologies to facilitate the applications of NAM design in crop genetics. Results shown in this study will aid the parental selection for hybridization in wheat breeding, and envision the future rust management breeding for addressing potential threat to wheat production and food security.
Developmental patterns strongly influence spike fertility and grain number, which are primarily deter-mined during the stem elongation period (i.e. time between terminal spikelet phase and anthesis). It has been proposed that the length of the stem elongation phase may, to an extent, affect grain number;thus it would be beneficial to identify genetic variation for the duration of this phase in elite germplasm. Variation in these developmental patterns was studied using 27 elite wheat lines in four experiments across three growing seasons. The results showed that the length of the stem elongation phase was (i)only slightly related to the period from seedling emergence to terminal spikelet, and (ii) more relevant than it for determining time to an thesis. Thus, phenological phases were largely independent and any particular time to an thesis may be reached with different combinations of component phases. Yield components were largely explained by fruiting efficiency of the elite lines used: the relationships were strongly positive and strongly negative with grain number and with grain weight, respectively. Although fruiting efficiency showed a positive trend with the duration of stem elongation that was not significant,a boundary function (which was highly significant) suggests that the length of this phase may impose an upper threshold for fruiting efficiency and grain number, and that maximum values of fruiting efficiency may require a relatively long stem elongation phase.
Evaluation of wheat for spot blotch disease resistance relies on various visual observation methods. The person evaluating the lines needs to be experienced in scoring disease severity. To facilitate
The wheat line ‘Chapio’ is resistant to leaf rust, caused by Puccinia triticinia, and was derived from a breeding programme that focuses on multi-genic resistance to provide durability. This line was crossed with the susceptible ‘Avocet’ to develop an F6 recombinant inbred line population. The population was phenotyped for leaf rust severity in two environments each in Mexico and China. There were significant differences in the loci providing resistance between the two intercontinental regions. The Lr34 locus had large effects in both Mexico and China, highlighting its importance in providing a basis for broad-spectrum resistance. The Lr46 locus on chromosome 1BL and a 3D locus had effects in Mexico but not in China. Presence of Sr2 was determined by the phenotypic marker of pseudo-black chaff and was mapped to chromosome 3BS. This region was associated with a QTL that had strong effects in China but no significant effect in Mexico, as did a locus on chromosome 4B. Seedling tests on the parents indicated that the 3B locus was not the complimentary gene Lr27, but the 4B locus was in the same position as Lr31 (or Lr12). Further investigations showed that these loci worked independently and additively in adult plants. Chapio was bred for quantitative, non-race-specific resistance under strong phenotypic selection for leaf rust in Mexico. It is interesting that different QTLs contribute to this resistance in another country, and these results suggest that environmental effects, as well as race specificity, can play a role in expression of resistance.
Published in: Frontiers in genetics, 2016, vol.7, no.201.
Wheat landraces in Turkey are an important genetic resource for wheat improvement. An exhaustive 5-year (2009–2014) effort made by the International Winter Wheat Improvement Programme (IWWIP), a cooperative program between the Ministry of Food, Agriculture and Livestock of Turkey, the International Center for Maize and Wheat Improvement (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA), led to the collection and documentation of around 2000 landrace populations from 55 provinces throughout Turkey. This study reports the genetic characterization of a subset of bread wheat landraces collected in 2010 from 11 diverse provinces using genotyping-by-sequencing (GBS) technology. The potential of this collection to identify loci determining grain yield and stripe rust resistance via genome-wide association (GWA) analysis was explored. A high genetic diversity (diversity index = 0.260) and a moderate population structure based on highly inherited spike traits was revealed in the panel. The linkage disequilibrium decayed at 10 cM across the whole genome and was slower as compared to other landrace collections. In addition to previously reported QTL, GWA analysis also identified new candidate genomic regions for stripe rust resistance, grain yield, and spike productivity components. New candidate genomic regions reflect the potential of this landrace collection to further increase genetic diversity in elite germplasm.
Published in : Ecology of Food and Nutrition, 2016, vol.55, no.2, p.209-230
The aim of this article was to investigate the food (in)security effect of household income generated from major economic activities in rural Swaziland. From a sample of 979 households, the results of a multinomial treatment regression model indicated that gender of household head, labor endowment, education, size of arable land, and location significantly influenced the households’ choice of primary economic activity. Further results suggested that off-farm-income-dependent households were less likely to be food insecure when compared with on-farm-income-dependent households. However, on-farm-income-dependent households had a better food security status than their counterparts who depended on remittances and nonfarm economic activities.
Kassie, M.; Adefris Teklewold; Marenya, P.; Jaleta Debello Moti; Erenstein, O.
Employing nationally representative data, we investigate the impact of Sustainable Intensification Practices (SIPs) on farm households’ food security, downside risk and the cost of risk in Malawi. The analysis relies on a flexible moment-based specification of a stochastic production function in a multinomial endogenous switching regression framework to correct for the selection bias stemming both from observed and unobserved heterogeneity. A quantile moment approach is used to estimate the cost of risk. After controlling for the effects of unobserved heterogeneity and several observable variables on maize production and downside risk functions, estimation results show that the adoption of SIPs increases food security and reduces downside risk exposure and the cost of risk. We estimate greater food security and larger reduction in downside risk from simultaneous adoption of both crop diversification (maize–legume intercropping and rotations) and minimum tillage, suggesting that there are complementary benefits from these practices. We find most of the cost of risk comes from exposure to downside risk. Our findings imply that in dealing with production risks development agents should encourage the adoption of agronomic and resource-management practices along with other risk mitigation and food security improving strategies.
12th Asian Maize Conference and Expert Consultation on maize for food, feed, nutrition and environmental security; Bangkok (Thailand), 30-1 Oct-Nov 2014 : proceedings. 2015. Paroda, R.; Prasanna, B.M.; Dasgupta, B.M.S.; Jat, M.L. (eds.). Bangkok (Thailand): APAARI / CIMMYT / FAO / Thailand Department of AGriculture xvii, 81 p.
Maize is a major food, feed and industrial crop and offers immense opportunities for attaining nutritional security in the developing countries of Asia. In fact, annual production growth rate in maize had been higher in Asia compared to global average, reflecting thereby tremendous potential for future upscaling and outscaling of innovations to have greater impact on livelihoods of smallholder farmers. The demand for maize is also expected to double by 2050. On the contrary, the maize production and productivity are severely constrained by an array of factors which need to be addressed urgently. For sustainable increase in yields and stabilizing prices, concerted efforts are required at the policy level to create enabling environment for long-term AR4D investments. The growing needs of the poultry and swine piggery sectors (especially in Southeast Asia and China), the expansion of maize seed industry, and the increasing interest of the consumers in nutritionally enriched and specialty maize products, require greater attention from both research and development viewpoints. Also, the CGIAR Research Program (CRP) on Maize “Global Alliance for Improving Food Security and the Livelihoods of the Resource-Poor in the Developing World” offers opportunities to catalyze stakeholder initiatives in the region to scale-out innovations in maize-based systems by building new public-private partnerships (PPPs).