Person: Pixley, K.V.
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Pixley
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K.V.
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Pixley, K.V.
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0000-0003-4068-743624 results
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- Translational research for climate resilient, higher yielding crops(Hapres, 2019) Reynolds, M.P.; Borrell, A.; Braun, H.J.; Edmeades, G.O.; Flavell, R.; Gwyn, J.; Jordan, D.; Pixley, K.V.; Rebetzke, G.J.
Publication - Genome editing, gene drives, and synthetic biology: will they contribute to disease-resistance crops, and who will benefit?(Annual Reviews Inc., 2019) Pixley, K.V.; Falck-Zepeda, J.B.; Giller, K.E.; Glenna, L.L.; Gould, F.; Mallory-Smith, C.; Stelly, D.M.; Stewart Jr, C.N.Genetically engineered crops have been grown for more than 20 years, resulting in widespread albeit variable benefits for farmers and consumers. We review current, likely, and potential genetic engineering (GE) applications for the development of disease-resistant crop cultivars. Gene editing, gene drives, and synthetic biology offer novel opportunities to control viral, bacterial, and fungal pathogens, parasitic weeds, and insect vectors of plant pathogens. We conclude that there will be no shortage of GE applications to tackle disease resistance and other farmer and consumer priorities for agricultural crops. Beyond reviewing scientific prospects for genetically engineered crops, we address the social institutional forces that are commonly overlooked by biological scientists. Intellectual property regimes, technology regulatory frameworks, the balance of funding between public- and private-sector research, and advocacy by concerned civil society groups interact to define who uses which GE technologies, on which crops, and for the benefit of whom. Ensuring equitable access to the benefits of genetically engineered crops requires affirmative policies, targeted investments, and excellent science.
Publication - Provitamin A carotenoids in grain reduce aflatoxin contamination of maize while combating vitamin A deficiency(Frontiers, 2019) Suwarno, W.B.; Hannok, P.; Palacios-Rojas, N.; Windham, G.L.; Crossa, J.; Pixley, K.V.Aflatoxin contamination of maize grain and products causes serious health problems for consumers worldwide, and especially in low- and middle-income countries where monitoring and safety standards are inconsistently implemented. Vitamin A deficiency (VAD) also compromises the health of millions of maize consumers in several regions of the world including large parts of sub-Saharan Africa. We investigated whether provitamin A (proVA) enriched maize can simultaneously contribute to alleviate both of these health concerns. We studied aflatoxin accumulation in grain of 120 maize hybrids formed by crossing 3 Aspergillus flavus resistant and three susceptible lines with 20 orange maize lines with low to high carotenoids concentrations. The hybrids were grown in replicated, artificially-inoculated field trials at five environments. Grain of hybrids with larger concentrations of beta-carotene (BC), beta-cryptoxanthin (BCX) and total proVA had significantly less aflatoxin contamination than hybrids with lower carotenoids concentrations. Aflatoxin contamination had negative genetic correlation with BCX (-0.28, p < 0.01), BC (-0.18, p < 0.05), and proVA (-0.23, p < 0.05). The relative ease of breeding for increased proVA carotenoid concentrations as compared to breeding for aflatoxin resistance in maize suggests using the former as a component of strategies to combat aflatoxin contamination problems for maize. Our findings indicate that proVA enriched maize can be particularly beneficial where the health burdens of exposure to aflatoxin and prevalence of VAD converge with high rates of maize consumption.
Publication - Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security(Nature Publishing Group, 2018) Singh, S.; Vikram, P.; Sehgal, D.; Burgueño, J.; Sharma, A.R.; Singh, S.K.; Sansaloni, C.; Joynson, R.; Brabbs, T.; Ortiz, C.; Solís Moya, E.; Velu, G.; Gupta, N.; Sidhu, H.S.; Basandrai, A.K.; Basandrai, D.; Ledesma-Ramires, L.; Suaste-Franco, M.P.; Fuentes Dávila, G.; Ireta Moreno, J.; Sonder, K.; Vaibhav K. Singh; Sajid Shokat; Shokat, S.; Mian A. R. Arif; Khalil A. Laghari; Puja Srivastava; Bhavani, S.; Satish Kumar; Pal, D.; Jaiswal, J.P.; Kumar, U.; Harinder K. Chaudhary; Crossa, J.; Payne, T.S.; Imtiaz, M.; Sohu, V.S.; Singh, G.P.; Bains, N.; Hall, A.J.W.; Pixley, K.V.The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios.
Publication - Maize milling method affects growth and zinc status but not provitamin A carotenoid bioefficacy in male Mongolian gerbils(American Society for Nutrition, 2017) Gannon, B.M.; Pixley, K.V.; Tanumihardjo, S.A.Background: Vitamin A (VA) and zinc deficiencies are prevalent. Maize is a common staple, and milling affects nutrient and nutrient-modifier profiles. Objective: We investigated the interaction of maize milling methods (i.e., whole grain compared with refined) in male Mongolian gerbils aged 29–35 d with conventionally bred provitamin A–biofortified (orange) or white maize on VA and zinc status. Methods: Study 1 (n = 67) was a 2 × 3 milling (whole compared with refined) by VA [no–vitamin A placebo group (VA−), orange, and VA-supplemented group (VA+)] design, with 4 wk of VA depletion followed by six 4-wk treatments (n = 10/treatment). Study 2 (n = 33) was a 2 × 2 milling-by-zinc [no-zinc placebo group (Zn−) compared with zinc-supplemented group (Zn+)] design, including 2 wk of VA depletion followed by four 3-wk treatments (n = 8–9/treatment). For study 1, positive and negative control groups were given supplemental VA at equimolar amounts to β-carotene equivalents consumed by the orange groups (74 ± 5 nmol/d) or placebo, respectively. For study 2, positive and negative control groups were given 152 μg Zn/d or placebo, respectively. Results: Milling significantly affected zinc concentration, providing 44–45% (whole grain) or 9–14% (refined) NRC requirements. In study 1, orange maize improved liver VA concentrations (mean ± SD: 0.28 ± 0.08 μmol/g) compared with the white maize groups (0.072 ± 0.054 μmol/g). Provitamin A bioefficacy was similar. In study 2, neither zinc nor milling influenced liver retinol. Refined Zn− gerbils weighed less than others by day 14 (46.6 ± 7.1 compared with 56.5 ± 3.5 g, respectively; P < 0.0001). Milling affected pancreas zinc concentrations (refined Zn−: 21.1 ± 1.8 μg Zn/g; whole Zn−: 32.5 ± 5.8 μg Zn/g). Conclusions: Whole-grain intake improved zinc and did not affect provitamin A bioefficacy. Other factors affected by milling (e.g., shelf life, preference, aflatoxin fractioning) need to be considered to maximize health.
Publication - SeeD DivSeek: from germplasm bank to application of alleles in effective breeding programs(CIMMYT, 2017) Hearne, S.; Pixley, K.V.
Publication - Gains in maize genetic improvement in Eastern and Southern Africa: II. CIMMYT open-pollinated variety breeding pipeline(Crop Science Society of America (CSSA), 2017) Masuka, B.; Magorokosho, C.; Olsen, M.; Atlin, G.; Banziger, M.; Pixley, K.V.; Vivek, B.; Labuschagne, M.; Matemba-Mutasa, R.; Burgueño, J.; MacRobert, J.; Prasanna, B.M.; Das, B.; Makumbi, D.; Tarekegne, A.T.; Crossa, J.; Zaman-Allah, M.; Biljon, A.; Cairns, J.E.Open-pollinated varieties (OP Vs) still represent a significant proportion of the maize (Zea mays L.) seed system in many countries of sub- Saharan Africa. The International Maize and Wheat Improvement Centre (CIMMYT) has been breeding improved maize varieties for the stress-prone environments experienced by most smallholder farmers in eastern and southern Africa for over 30 yr. Hybrid breeding is now the major focus of the CIMMYT breeding pipeline. However, OP Vs are generated within the hybrid pipeline. This is the first study to document genetic gain for maize grain yield under both optimal and stress (random and managed drought, low nitrogen [N], and maize streak virus [MSV]) conditions within the CIMMYT eastern and southern African OP V breeding pipeline. Genetic gain was estimated using the slope of the regression on the year of OP V release in regional trials over a 12-yr period (1999–2011). Open-pollinated varieties were separated into two maturity groups, early (<70 d to anthesis) and intermediate-late (>70 d to anthesis). Genetic gain in the early maturity group under optimal conditions, random drought, low N, and MSV was 109.9, 29.2, 84.8, and 192.9 kg ha−1 yr−1. In the intermediate-late maturity group, genetic gain under optimal conditions, random drought, low N, and MSV was 79.1, 42.3, 53.0 and 108.7 kg ha−1 yr−1. No significant yield gains were made under managed drought stress for both maturity groups. Our results show continued improvement in OP Vs for both yield potential and stress tolerance.
Publication - Harnessing crop genetic resources to meet the challenges of feeding the world in 2050 and beyond(CIMMYT, 2016) Pixley, K.V.; Costich, D.E.
Publication - MasAgro Biodiversidad: a learning model towards effective and equitableuse of genetic resources(CIMMYT, 2016) Pixley, K.V.
Publication - Worldwide and local programs to preserve, characterize and utilize maize genetic diversity(CIMMYT, 2016) Pixley, K.V.
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