The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Janusz Zimny - One of the best experts on this subject based on the ideXlab platform.
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Direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×10^5 microspores and 2×10^5 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
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direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale triticosecale wittmack cv bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×105 microspores and 2×105 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
Sylwia Oleszczuk - One of the best experts on this subject based on the ideXlab platform.
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Direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×10^5 microspores and 2×10^5 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
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direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale triticosecale wittmack cv bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×105 microspores and 2×105 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
Sylwia Sowa - One of the best experts on this subject based on the ideXlab platform.
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Direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×10^5 microspores and 2×10^5 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
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direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale triticosecale wittmack cv bogo
Plant Cell Reports, 2004Co-Authors: Sylwia Oleszczuk, Sylwia Sowa, Janusz ZimnyAbstract:The use of Doubled Haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×105 microspores and 2×105 microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously Doubled Haploids.
Albrecht E. Melchinger - One of the best experts on this subject based on the ideXlab platform.
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Production of Haploids and Doubled Haploids in Maize
Methods in molecular biology (Clifton N.J.), 2012Co-Authors: Vanessa Prigge, Albrecht E. MelchingerAbstract:The in vivo haploid induction approach offers several advantages compared to the in vitro induction approach and recurrent self-pollination. It is currently the method of choice for inbred line development in many commercial maize breeding programs. Here, we describe the in vivo approach for generation of maternal Doubled Haploids (DHs). It involves four steps: (1) induction of haploidy by pollinating source germplasm with pollen of a haploid inducer; (2) identification of putative haploid seeds (seeds with a haploid embryo) using a seed coloration marker system; (3) doubling of chromosomes of putative Haploids by treating seedlings with a mitotic inhibitor; and (4) verification of putative Doubled Haploids with a stalk color marker and self-pollination of true Doubled haploid plants to multiply their seed.
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hybrid maize breeding with Doubled Haploids v selection strategies for testcross performance with variable sizes of crosses and s1 families
Theoretical and Applied Genetics, 2010Co-Authors: Thilo Wegenast, Friedrich H Utz, Friedrich C H Longin, Hans Peter Maurer, B S Dhillon, Albrecht E. MelchingerAbstract:In hybrid maize (Zea mays L.) breeding, Doubled Haploids (DH) are increasingly replacing inbreds developed by recurrent selfing. Doubled Haploids may be developed directly from S0 plants in the parental cross or via S1 families. In both these breeding schemes, we examined 2 two-stage selecting strategies, i.e., considering or ignoring cross and family structure while selection among and within parental crosses and S1 families. We examined the optimum allocation of resources to maximize the selection gain ΔG and the probability P(q) of identifying the q% best genotypes. Our specific objectives were to (1) determine the optimum number and size of crosses and S1 families, as well as the optimum number of test environments and (2) identify the superior selection strategy. Selection was based on the evaluation of testcross progenies of (1) DH lines in both stages (DHTC) and (2) S1 families in the first stage and of DH lines within S1 families in the second stage (S1TC-DHTC) with uniform and variable sizes of crosses and S1 families. We developed and employed simulation programs for selection with variable sizes of crosses and S1 families within crosses. The breeding schemes and selection strategies showed similar relative efficiency for both optimization criteria ΔG and P (0.1%). As compared with DHTC, S1TC-DHTC had larger ΔG and P (0.1%), but a higher standard deviation of ΔG. The superiority of S1TC-DHTC was increased when the selection was done among all DH lines ignoring their cross and family structure and using variable sizes of crosses and S1 families. In DHTC, the best selection strategy was to ignore cross structures and use uniform size of crosses.
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comparison of selection strategies and optimization criteria in hybrid maize breeding with Doubled Haploids
Maydica, 2009Co-Authors: Thilo Wegenast, C F H Longin, H F Utz, Hans Peter Maurer, B S Dhillon, Albrecht E. MelchingerAbstract:In hybrid maize (Zea mays L.) breeding, Doubled Haploids (DH) are increasingly replacing conventionally developed inbred lines. We considered two breeding schemes with selection based on the evaluation of testcross progenies of DH lines in two stages (DHTC) and of S 1 families in the first stage and of DH lines within S 1 families in the second stage (S 1 TC-DHTC). For both breeding schemes, we considered different selection strategies with or without optimum index at second stage and uniform or variable sizes of crosses and S 1 families. Our objectives were to (1) determine the optimum number of test environments as well as the optimum number and sizes of parental crosses and S 1 families for various variance component ratios and (2) identify the superior selection strategy for each breeding scheme with respect to the selection gain (ΔG) and the probability to select superior genotypes (P(q)) as well as to minimize their standard deviation. Breeding scheme S 1 TC-DHTC had larger ΔG and P(q) but a higher standard deviation of ΔG than DHTC. For breeding scheme S 1 TC-DHTC, strategies with selection among all DH lines led to larger progress than the strategy with sequential selection among and within crosses and S 1 families. The results for both optimization criteria in strategies with variable numbers of S 1 families and DH lines within crosses and S 1 families were larger than with uniform numbers. With decreasing contributions of the genetic variance, the number of test locations should be increased at the expense of the test candidates in both breeding schemes. Further, our study showed that a lower standard deviation of the expected values for both optimization criteria were feasible without a significant loss in ΔG or P(q) with an increased number of test locations.
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Hybrid maize breeding with Doubled Haploids: II. Optimum type and number of testers in two-stage selection for general combining ability
Theoretical and Applied Genetics, 2007Co-Authors: C F H Longin, Albrecht E. Melchinger, H F Utz, Jochen C ReifAbstract:Optimum allocation of test resources is of crucial importance for the efficiency of breeding programs. Our objectives were to (1) determine the optimum allocation of the number of lines, test locations, as well as number and type of testers in hybrid maize breeding using Doubled Haploids with two breeding strategies for improvement of general combining ability (GCA), (2) compare the maximum selection gain (Δ G ) achievable under both strategies, and (3) give recommendations for the optimum implementation of Doubled Haploids in commercial hybrid maize breeding. We calculated Δ G by numerical integration for two two-stage selection strategies with evaluation of (1) testcross performance in both stages (BS1) or (2) line per se performance in the first stage followed by testcross performance in the second stage (BS2). Different assumptions were made regarding the budget, variance components (VCs), and the correlation between line per se performance and GCA. Selection gain for GCA increased with a broader genetic base of the tester. Hence, testers combining a large number of divergent lines are advantageous. However, in applied breeding programs, the use of single- or double-cross testers in the first and inbred testers in the second selection stage may be a good compromise between theoretical and practical requirements. With a correlation between line per se performance and GCA of 0.50, Δ G for BS1 is about 5% higher than for BS2, if an economic weight of line per se performance is neglected. With increasing economic weight of line per se performance, relative efficiency of BS2 increased rapidly resulting in a superiority of BS2 over BS1 already for an economic weight for line per se performance larger than 0.1. Considering the importance of an economic seed production, an economic weight larger than 0.1 seems realistic indicating the necessity of separate breeding strategies for seed and pollen parent heterotic groups.
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hybrid maize breeding with Doubled Haploids comparison between selection criteria
Acta Agronomica Hungarica, 2006Co-Authors: C F H Longin, Albrecht E. Melchinger, H F Utz, Jochen C ReifAbstract:The optimum allocation of breeding resources is crucial for the efficiency of breeding programmes. The objectives were to (i) compare selection gain ΔGk for finite and infinite sample sizes, (ii) compare ΔGk and the probability of identifying superior hybrids (Pk), and (iii) determine the optimum allocation of the number of hybrids and test locations in hybrid maize breeding using Doubled Haploids. Infinite compared to finite sample sizes led to almost identical optimum allocation of test resources, but to an inflation of ΔGk. This inflation decreased as the budget and the number of finally selected hybrids increased. A reasonable Pk was reached for hybrids belonging to the q = 1% best of the population. The optimum allocations for Pk(q) and ΔGkwere similar, indicating that Pk(q) is promising for optimizing breeding programmes.
Friedrich C H Longin - One of the best experts on this subject based on the ideXlab platform.
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hybrid maize breeding with Doubled Haploids v selection strategies for testcross performance with variable sizes of crosses and s1 families
Theoretical and Applied Genetics, 2010Co-Authors: Thilo Wegenast, Friedrich H Utz, Friedrich C H Longin, Hans Peter Maurer, B S Dhillon, Albrecht E. MelchingerAbstract:In hybrid maize (Zea mays L.) breeding, Doubled Haploids (DH) are increasingly replacing inbreds developed by recurrent selfing. Doubled Haploids may be developed directly from S0 plants in the parental cross or via S1 families. In both these breeding schemes, we examined 2 two-stage selecting strategies, i.e., considering or ignoring cross and family structure while selection among and within parental crosses and S1 families. We examined the optimum allocation of resources to maximize the selection gain ΔG and the probability P(q) of identifying the q% best genotypes. Our specific objectives were to (1) determine the optimum number and size of crosses and S1 families, as well as the optimum number of test environments and (2) identify the superior selection strategy. Selection was based on the evaluation of testcross progenies of (1) DH lines in both stages (DHTC) and (2) S1 families in the first stage and of DH lines within S1 families in the second stage (S1TC-DHTC) with uniform and variable sizes of crosses and S1 families. We developed and employed simulation programs for selection with variable sizes of crosses and S1 families within crosses. The breeding schemes and selection strategies showed similar relative efficiency for both optimization criteria ΔG and P (0.1%). As compared with DHTC, S1TC-DHTC had larger ΔG and P (0.1%), but a higher standard deviation of ΔG. The superiority of S1TC-DHTC was increased when the selection was done among all DH lines ignoring their cross and family structure and using variable sizes of crosses and S1 families. In DHTC, the best selection strategy was to ignore cross structures and use uniform size of crosses.
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hybrid maize breeding with Doubled Haploids i one stage versus two stage selection for testcross performance
Theoretical and Applied Genetics, 2006Co-Authors: Friedrich C H Longin, Friedrich H Utz, Jochen C Reif, Wolfgang Schipprack, Albrecht E. MelchingerAbstract:Optimum allocation of resources is of fundamental importance for the efficiency of breeding programs. The objectives of our study were to (1) determine the optimum allocation for the number of lines and test locations in hybrid maize breeding with Doubled Haploids (DHs) regarding two optimization criteria, the selection gain ΔGk and the probability Pk of identifying superior genotypes, (2) compare both optimization criteria including their standard deviations (SDs), and (3) investigate the influence of production costs of DHs on the optimum allocation. For different budgets, number of finally selected lines, ratios of variance components, and production costs of DHs, the optimum allocation of test resources under one- and two-stage selection for testcross performance with a given tester was determined by using Monte Carlo simulations. In one-stage selection, lines are tested in field trials in a single year. In two-stage selection, optimum allocation of resources involves evaluation of (1) a large number of lines in a small number of test locations in the first year and (2) a small number of the selected superior lines in a large number of test locations in the second year, thereby maximizing both optimization criteria. Furthermore, to have a realistic chance of identifying a superior genotype, the probability Pk of identifying superior genotypes should be greater than 75%. For budgets between 200 and 5,000 field plot equivalents, Pk > 75% was reached only for genotypes belonging to the best 5% of the population. As the optimum allocation for Pk(5%) was similar to that for ΔGk, the choice of the optimization criterion was not crucial. The production costs of DHs had only a minor effect on the optimum number of locations and on values of the optimization criteria.