QTL characterization of resistance to leaf rust and stripe rust in the spring wheat line Francolin#1

Posted by Carelia Juarez on , in Journal Articles

Published in Molecular Breeding, 2014

Caixia Lan;Rosewarne, G.M.; Singh, R.P.; Herrera-Foessel, S.A.; Huerta-Espino, J.; Basnet, B.R.; Yelun Zhang; Ennian Yang.

Growing resistant wheat varieties is a key method of controlling two important wheat diseases, leaf rust and stripe rust. We analyzed quantitative trait loci (QTL) to investigate adult plant resistance (APR) to these rusts, using 141 F5 RILs derived from the cross ‘Avocet-YrA/Francolin#1’. Phenotyping of leaf rust resistance was conducted during two seasons at Ciudad Obregon, Mexico, whereas stripe rust was evaluated for two seasons in Toluca, Mexico, and one season in Chengdu, China. The genetic map was constructed with 581 markers, including diversity arrays technology and simple sequence repeat. Significant loci for reducing leaf rust severity were designated QLr.cim-1BLQLr.cim-3BS.1QLr.cim-3DC, and QLr.cim-7DS. The six QTL that reduced stripe rust severity were designated QYr.cim-1BLQYr.cim-2BSQYr.cim-2DSQYr.cim-3BS.2QYr.cim-5AL, andQYr.cim-6AL. All loci were conferred by Francolin#1, with the exception of QYr.cim-2DSQYr.cim-5AL, and QYr.cim-6AL, which were derived from Avocet-YrA. Closely linked markers indicated that the 1BL locus was the pleiotropic APR gene Lr46/Yr29QYr.cim-2BS was a seedling resistance gene designated as YrF that conferred intermediate seedling reactions and moderate resistance at the adult plant stage in both Mexican and Chinese environments. Significant additive interactions were detected between the six QTL for stripe rust, but not between the four QTL for leaf rust. Furthermore, we detected two new APR loci for leaf rust in common wheat: QLr.cim-3BS.1 andQLr.cim-7DS.

Inter-connection between land use/land cover change and herders’/farmers’ livestock feed resource management strategies: a case study from three Ethiopian eco-environments

Posted by Carelia Juarez on , in Journal Articles

Published in Agriculture, Ecosystems and Environment 188 : 150-162, 2014

Mekasha, A.; Gerard, B.; Kindie Tesfaye Fantaye;Nigatu, L.; Duncan, A.J.

We assessed land use/land cover changes from remotely sensed satellite imagery and compared this with community perceptions on availability/use of livestock feed resources and feed deficit management strategies since the 1973s in three districts representing the pastoral, agro-pastoral and mixed crop-livestock eco-environments of Ethiopia. We found that land use/land cover changes are proceeding in all eco-environments and that transitions are from grasslands, and forest lands to bush/shrub lands and crop lands in the pastoral site (Liben), from bush/shrub lands and grasslands to crop lands in agro-pastoral site (Mieso) and from bush/shrub lands, forest lands and grasslands to crop lands in the mixed crop-livestock site (Tiyo). The changes significantly affected livestock feed resources and feed deficit management strategies available to households. Over the last 30–40 years, grazing resources available to livestock keepers have been declining with resultant increase in the contribution of crop residues and other feeds from crop lands (weeds and crop thinnings) as compared to feeds from grasslands. The feed deficit management strategies of households are also changing significantly from mobility to herd management and feed conservation in the pastoral areas; from mobility to feed conservation and purchasing of feed in the agro-pastoral areas and from transhumance to feed conservation and purchase of feed in the mixed crop-livestock areas. Hence feed resources and their availability vary with time and eco-environments indicating the need for the development of eco-environment/site specific feed management strategies in order to support productive stock in the study areas and similar eco-environments.

Exploration of farmers’ preferences and perceptions of maize varieties: implications on development and adoption of quality protein maize (QPM) varieties in Zimbabwe

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Published in Journal of Sustainable Development  7 (2) : 194-207, 2014

Machida, L.; Derera, J.; Tongoona, P.; Langyintuo, A.; MacRobert, J.

Quality protein maize (QPM) technology is relatively new in Zimbabwe and farmer awareness of QPM was low. Participation of smallholder farmers in the development of QPM breeding objectives and dissemination strategies was solicited through participatory rural appraisal (PRA) techniques. Seventy two farmers participated; the farmers were involved in the Mother Baby Trial (MBT) projects in four selected villages from three districts of Zimbabwe. Data collection techniques included work-sharing, village or resource mapping, Venn diagramming, semi structured interviewing, matrix scoring and ranking and pairwise ranking. The results suggested that protein malnutrition was prevalent in the districts. Maize was the most important crop and farmers grew three types of maize, namely landrace (“Hickory King”), open pollinated varieties (OPV) and hybrid varieties all representing normal endosperm maize. Hybrids were dominant and produced mainly for sale, while “Hickory King”, although not supported by the formal seed system, continued to be produced for home consumption because of its superior taste, white kernel color, large kernel size, high kernel density, kernel hardness, and perceived weevil-resistance. Lateness and foliar disease susceptibility were the disadvantages of Hickory King. The ideal maize variety should be early-maturing, with a high yield potential, drought tolerant, foliar disease resistant and stem borer tolerant. For any QPM variety to be acceptable, farmers expected it to combine the agronomic attributes of hybrids and the grain quality characteristics of “Hickory King”, an “heirloom” variety. To effectively promote the adoption of QPM, the Agricultural Research and Extension (AREX) arm of government was the farmers’ choice compared to other modes of information dissemination which were radio, television, newspaper, church NGO and councillor.

Breeding progress in the pasta-making quality of durum wheat cultivars released in Italy and Spain during the 20th Century

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Published in Crop and Pasture Science 65 (1) : 16-26, 2014

Joan Subira; Peña Bautista, R.J.; Alvaro, F.; Ammar, K.; Ramdani, A.; Royo, C.

Genetic improvement of quality traits of durum wheat achieved in Italy and Spain during the 20th Century was investigated using an historical series of 12 cultivars from each country. The European Union durum wheat quality index increased by 6.25% (0.13% year–1 in Italian and 0.06% year–1 in Spanish cultivars). Protein content decreased by ~10% (–0.14% year–1 in Italian and –0.19% year–1 in Spanish cultivars) but protein per ha increased at a rate of 0.35% year–1 (0.41% year–1 in Spanish and 0.26% year–1 in Italian cultivars). Yellow colour index increased by 9.9% (0.15% year–1 in Italian and 0.10% year–1 in Spanish cultivars). Test weight and vitreousness did not suffer significant changes over time. Gluten strength increased by 32.1% or 0.54% year–1 in Italian, and 27.9% or 0.33% year–1 in Spanish cultivars. Much larger genetic control on gluten strength was found in Italian than in Spanish cultivars. Changes in sedimentation index (41.1% or 0.64% year–1 in Italy, and 41.6% or 0.49% year–1 in Spain) were the consequence of the progressive incorporation into recent cultivars of favourable low molecular weight glutenin subunits (LMW-GS). Breeding increased the frequency of the LMW-GS combination aaa, which was present in 75% of all intermediate cultivars and in 100% of the modern Italian cultivars. A LMW-GS combination not previously reported (d?b) was identified in two modern Spanish cultivars. Breeding programs were also successful in increasing the stability of gluten strength and the sedimentation index.

Molecular mapping across three populations reveals a QTL hotspot region on chromosome 3 for secondary traits associated with drought tolerance in tropical maize

Posted by Carelia Juarez on , in Journal Articles

Published in Molecular Breeding, 2014

Dias Almeida, G.; Nair, S.; Borem, A.; Cairns, J.; Trachsel, S.;Ribaut, J-M; Banziger, M.; Prasanna, B.M.; Crossa, J.; Babu, R.

Identifying quantitative trait loci (QTL) of sizeable effects that are expressed in diverse genetic backgrounds across contrasting water regimes particularly for secondary traits can significantly complement the conventional drought tolerance breeding efforts. We evaluated three tropical maize biparental populations under water-stressed and well-watered regimes for drought-related morpho-physiological traits, such as anthesis-silking interval (ASI), ears per plant (EPP), stay-green (SG) and plant-to-ear height ratio (PEH). In general, drought stress reduced the genetic variance of grain yield (GY), while that of morpho-physiological traits remained stable or even increased under drought conditions. We detected consistent genomic regions across different genetic backgrounds that could be target regions for marker-assisted introgression for drought tolerance in maize. A total of 203 QTL for ASI, EPP, SG and PEH were identified under both the water regimes. Meta-QTL analysis across the three populations identified six constitutive genomic regions with a minimum of two overlapping traits. Clusters of QTL were observed on chromosomes 1.06, 3.06, 4.09, 5.05, 7.03 and 10.04/06. Interestingly, a ~8-Mb region delimited in 3.06 harboured QTL for most of the morpho-physiological traits considered in the current study. This region contained two important candidate genes viz., zmm16 (MADS-domain transcription factor) and psbs1 (photosystem II unit) that are responsible for reproductive organ development and photosynthate accumulation, respectively. The genomic regions identified in this study partially explained the association of secondary traits with GY. Flanking single nucleotide polymorphism markers reported herein may be useful in marker-assisted introgression of drought tolerance in tropical maize.

Conservation agriculture in southern Africa: advances in knowledge

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Published in Renewable Agriculture and Food Systems, 2014

Thierfelder, C.; Rusinamhodzi, L.; Ngwira, A.R.;Mupangwa, W.; Isaiah, N.; Kassie, G.T.; Cairns, J.E.

The increasing demand for food from limited available land, in light of declining soil fertility and future threats of climate variability and change have increased the need for more sustainable crop management systems. Conservation agriculture (CA) is based on the three principles of minimum soil disturbance, surface crop residue retention and crop rotations, and is one of the available options. In Southern Africa, CA has been intensively promoted for more than a decade to combat declining soil fertility and to stabilize crop yields. The objective of this review is to summarize recent advances in knowledge about the benefits of CA and highlight constraints to its widespread adoption within Southern Africa. Research results from Southern Africa showed that CA generally increased water infiltration, reduced soil erosion and run-off, thereby increasing available soil moisture and deeper drainage. Physical, chemical and biological soil parameters were also improved under CA in the medium to long term. CA increased crop productivity and also reduced on-farm labor, especially when direct seeding techniques and herbicides were used. As with other cropping systems, CA has constraints at both the field and farm level. Challenges to adoption in Southern Africa include the retention of sufficient crop residues, crop rotations, weed control, pest and diseases, farmer perception and economic limitations, including poorly developed markets. It was concluded that CA is not a ‘one-size-fits-all’ solution and often needs significant adaptation and flexibility when implementing it across farming systems. However, CA may potentially reduce future soil fertility decline, the effects of seasonal dry-spells and may have a large impact on food security and farmers’ livelihoods if the challenges can be overcome.

Nutrient management and use efficiency in wheat systems of South Asia

Posted by Carelia Juarez on , in Journal Articles

Published in Advances in Agronomy  125 : 171-259, 2014

Jat, M.L.; Bijay-Singh; Gerard, B.

With the advent of Green Revolution era in the mid-1960s, high-yielding wheat (Triticum aestivum L.) varieties and chemical fertilizers were introduced in South Asia. Fertilizer consumption is continuously increasing since then, but the productivity of wheat is relatively stagnant during the last decade. In South Asia, fertilizers have been applied to wheat as blanket recommendations for regions with similar climate and landform. There exists a large variation in nutrient use efficiencies in wheat because of following blanket recommendations for nitrogen, phosphorus, and potassium in fields differing greatly in nutrient-supplying capacity of the soil. Research carried out in South Asia suggests that further improvement in nutrient use efficiency will become possible by balanced use of nitrogen, phosphorus, and potassium fertilizers, and by rational use of organic manures in wheat systems. Long-term fertility experiments also confirm the need of balanced use of nutrients to produce high sustainable yield levels of wheat. In saline alkali soils, wheat needs to be supplied with higher amounts of nutrients, particularly N, than in normal soils. Band placement of fertilizers, particularly phosphorus, leads to improved fertilizer use efficiency, but appropriate machinery is lacking. Recently introduced site-specific nutrient management strategies for wheat take into account field-to-field variability and can help increase fertilizer use efficiency more than that achieved by following blanket fertilizer recommendations. Conservation agricultural practices consisting of reduced tillage and residue retention in wheat fields have already been introduced in South Asia. Nutrient management strategies for these wheat-growing environments are also being actively worked out. Yield gap analysis shows that productivity of wheat as well as nutrient use efficiencies can be further improved.

Variation at glutenin subunit loci, single kernel characterization and evaluation of grain protein in East African bread wheat varieties

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Published in Euphytica, 2014

Macharia, G.K.; Peña Bautista, R.J.; Simsek, S.; Anderson, J.A.

Wheat breeding programs worldwide aim at developing cultivars that meet end user quality attributes demanded by producers, processors, and consumers. Selecting from breeding populations created from well characterized parental germplasm provides the best opportunity of identifying cultivars that combine the best alleles and grain phenotypes for the desired technological applications. In this study, 216 bread wheat lines associated with Ethiopian and Kenyan breeding programs including a few founder lines were profiled for high molecular weight glutenin subunits and low molecular weight glutenin subunits by SDS-PAGE. Additionally, total crude protein, relative puroindoline content by SDS-PAGE, kernel diameter, kernel weight and kernel hardness by SKCS were determined. Extensive allelic variation at the glutenin subunit loci was found, with Glu-B1 and Glu-B3 having highest diversity across subpopulations. Relative to wild type cultivar ‘Alpowa-1-soft’, the founder line BW21 had the lowest puroindoline content. The frequencies of soft and very soft wheat classes were lowest in the Ethiopian subpopulation and highest among the Kenyan lines. Accordingly, 12 lines considered to have optimal combinations of glutenin subunit alleles and kernel characteristics were highlighted and recommended for cultivar improvement.

Wheat seed storage proteins: Advances in molecular genetics, diversity and breeding applications

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Published in Journal of Cereal Science, 2014

Rasheed, A.; Xianchun Xia; Yueming Yan; Appels, R.; Mahmood, T.; He Zhonghu.

Wheat seed storage proteins, especially glutenins and gliadins, have unique functional properties giving rise to a wide array of food products for human consumption. The wheat seed storage proteins, however, are also the most common cause of food-related allergies and intolerances, and it has become crucially important to understand their composition, variation and functional properties and interface this knowledge with the grain handling industry as well as the breeders. This review focuses on advances in understanding the genetics and function of storage proteins and their application in wheat breeding programs. These include: (1) The development and validation of high-throughput molecular marker systems for defining the composition and variation of low molecular weight glutenin subunits (LMW-GS) genes and a summary of the more than 30 gene-specific markers for rapid screening in wheat breeding programs; (2) The identification of more than 100 alleles of storage proteins in wild species provide candidate genes for future quality improvement; (3) The documentation of quality effects of individual LMW-GS and HMW-GS for improving end-use quality; and (4) The analysis of α-gliadin genes on chromosomes 6A and 6D with non-toxic epitopes as potential targets to develop less toxic cultivars for people with celiac disease. Genomic and proteomic technologies that will continue to provide new tools for understanding variation and function of seed storage proteins in wheat are discussed.

Variability of grain-filling traits in early maturing CIMMYT tropical maize inbred lines

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Published in Crop Science 54 (2) : 530-536, 2014

Gasura, E.; Setimela, P.S.;Amsal Tesfaye Tarekegne; Icishahayo, D.; Edema, R.; Gibson, P.T.; Okori, P.

Grain-filling rate (GFR), effective grain-filling duration (EGFD), and total grain-filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yield (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is a prerequisite for improvement in early maturing maize. A study was conducted at CIMMYT-Zimbabwe using an α-lattice design with two replications in two environments to investigate the genetic variability of grain-filling traits in 18 early maturing tropical maize inbred lines derived from CIMMYT germplasm. Highly significant differences were observed for GY, thousand-grain weight (TGW), GFR, EGFD, TGFD, kernels per row (KR), and rows per cob (RC). The broad-sense coefficient of genetic determination (the fixed parent equivalent of broad-sense heritability) was above 70% for all of the traits. The highest GY was obtained from the inbred line T032-30 (79.2 g plant–1) and the lowest from inbred line CML506 (37.6 g plant–1), respectively. Therefore, selecting for higher GFR and longer TGFD, especially the EGFD, can increase GY of early maize without extending days to physiological maturity (DPM).