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  • Prasanna, Boddupalli M.  (22)
  • 1
    In: Theoretical and Applied Genetics, Springer Science and Business Media LLC, Vol. 134, No. 6 ( 2021-06), p. 1729-1752
    Kurzfassung: Intensive public sector breeding efforts and public-private partnerships have led to the increase in genetic gains, and deployment of elite climate-resilient maize cultivars for the stress-prone environments in the tropics. Abstract Maize ( Zea mays L.) plays a critical role in ensuring food and nutritional security, and livelihoods of millions of resource-constrained smallholders. However, maize yields in the tropical rainfed environments are now increasingly vulnerable to various climate-induced stresses, especially drought, heat, waterlogging, salinity, cold, diseases, and insect pests, which often come in combinations to severely impact maize crops. The International Maize and Wheat Improvement Center (CIMMYT), in partnership with several public and private sector institutions, has been intensively engaged over the last four decades in breeding elite tropical maize germplasm with tolerance to key abiotic and biotic stresses, using an extensive managed stress screening network and on-farm testing system. This has led to the successful development and deployment of an array of elite stress-tolerant maize cultivars across sub-Saharan Africa, Asia, and Latin America. Further increasing genetic gains in the tropical maize breeding programs demands judicious integration of doubled haploidy, high-throughput and precise phenotyping, genomics-assisted breeding, breeding data management, and more effective decision support tools. Multi-institutional efforts, especially public–private alliances, are key to ensure that the improved maize varieties effectively reach the climate-vulnerable farming communities in the tropics, including accelerated replacement of old/obsolete varieties.
    Materialart: Online-Ressource
    ISSN: 0040-5752 , 1432-2242
    RVK:
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2021
    ZDB Id: 1478966-8
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Crop Science, Wiley, Vol. 57, No. 5 ( 2017-09), p. 2395-2404
    Kurzfassung: Genetic gain within the CIMMYT Eastern and Southern Africa (ESA) hybrid maize ( Zea mays L.) breeding program from 2000 to 2010 was recently estimated at 0.85 to 2.2% yr −1 under various environmental conditions. Over 100 varieties were disseminated from CIMMYT to farmers in ESA, hence the need to check genetic diversity and frequency of use of parents to avoid potential narrowing down of the genetic base. Fifty‐five parents from CIMMYT ESA used in the hybrids were fingerprinted using genotyping‐by‐sequencing. Data analysis in TASSEL and MEGA6 generated pairwise genetic distances between parents of 0.004 to 0.4005. Unweighted pair group method with arithmetic mean (UPGMA) analysis produced two clusters (I and II) with two subclusters each (A and B) and two sub‐subclusters (IAi and IAii). Principal coordinate analysis produced three clusters where IAi and IIA from the UPGMA analysis formed independent clusters while IAii, IB, and IIB clustered together. Lines were separated by pedigree and origin. Ninety‐five percent frequency of pairwise genetic distances ranged between 0.2001 and 0.4000. However, only four of the 55 parents (CML444, CML395, CML312, and CML442) were each used in 15 to 30 of the 52 hybrids evaluated in the genetic gain study. The remaining 51 were used in one to four hybrids. Frequent use of the four parents gave 29 to 58% of the hybrids a narrow genetic base, posing risk in case of pest or disease outbreaks. Parents evaluated do not represent the genetic base of CIMMYT ESA but parents of the best‐performing hybrids selected from 2000 to 2010. Breeders should ensure a wide genetic base for released varieties to avoid breakdown in case of pest or disease outbreaks.
    Materialart: Online-Ressource
    ISSN: 0011-183X , 1435-0653
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2017
    ZDB Id: 1480918-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 21, No. 18 ( 2020-09-06), p. 6518-
    Kurzfassung: Common rust (CR) caused by Puccina sorghi is one of the destructive fungal foliar diseases of maize and has been reported to cause moderate to high yield losses. Providing CR resistant germplasm has the potential to increase yields. To dissect the genetic architecture of CR resistance in maize, association mapping, in conjunction with linkage mapping, joint linkage association mapping (JLAM), and genomic prediction (GP) was conducted on an association-mapping panel and five F3 biparental populations using genotyping-by-sequencing (GBS) single-nucleotide polymorphisms (SNPs). Analysis of variance for the biparental populations and the association panel showed significant genotypic and genotype x environment (GXE) interaction variances except for GXE of Pop4. Heritability (h2) estimates were moderate with 0.37–0.45 for the individual F3 populations, 0.45 across five populations and 0.65 for the association panel. Genome-wide association study (GWAS) analyses revealed 14 significant marker-trait associations which individually explained 6–10% of the total phenotypic variances. Individual population-based linkage analysis revealed 26 QTLs associated with CR resistance and together explained 14–40% of the total phenotypic variances. Linkage mapping revealed seven QTLs in pop1, nine QTL in pop2, four QTL in pop3, five QTL in pop4, and one QTL in pop5, distributed on all chromosomes except chromosome 10. JLAM for the 921 F3 families from five populations detected 18 QTLs distributed in all chromosomes except on chromosome 8. These QTLs individually explained 0.3 to 3.1% and together explained 45% of the total phenotypic variance. Among the 18 QTL detected through JLAM, six QTLs, qCR1-78, qCR1-227, qCR3-172, qCR3-186, qCR4-171, and qCR7-137 were also detected in linkage mapping. GP within population revealed low to moderate correlations with a range from 0.19 to 0.51. Prediction correlation was high with r = 0.78 for combined analysis of the five F3 populations. Prediction of biparental populations by using association panel as training set reveals positive correlations ranging from 0.05 to 0.22, which encourages to develop an independent but related population as a training set which can be used to predict diverse but related populations. The findings of this study provide valuable information on understanding the genetic basis of CR resistance and the obtained information can be used for developing functional molecular markers for marker-assisted selection and for implementing GP to improve CR resistance in tropical maize.
    Materialart: Online-Ressource
    ISSN: 1422-0067
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2019364-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: Euphytica, Springer Science and Business Media LLC, Vol. 211, No. 3 ( 2016-10), p. 395-409
    Kurzfassung: Maize production constraints in sub-Saharan Africa (SSA) are being addressed by CIMMYT and partners through an array of projects, focusing on developing and evaluating parental inbred lines and single-crosses as well as formulating, evaluating and releasing high-yielding and stress resilient hybrids adapted to different agro-ecologies. The objectives of the present study were to (1) evaluate the grain yield performance of parental elite inbred lines developed over the years, and single crosses; and (2) ascertain the flowering synchrony among inbred lines and single-cross hybrid parents. Parental inbred lines and single-crosses were evaluated at seven locations in two countries in 2014. Combined analysis of variance revealed differences ( P   〈  0.01) among genotypes for grain yield (GY) and among different years/era of release of the inbred lines. The improvement in GY of inbred lines was estimated to be 1.4 % per year. Under irrigated conditions GY of some single-cross hybrids was over 16 t ha −1 . Some single-cross and inbred line parents showed acceptable flowering synchrony, good producibility, and stable performance across testing environments, suggesting that these have high potential for seed production. Further research is needed to determine the physiological and morphological characteristics that contributed to the GY improvement in the parental inbred lines. Information generated from this study will enhance the use of CIMMYT’s tropical mid-altitude parental germplasm by breeders working in both private and public breeding programs for developing and deploying high-yielding maize hybrids for the benefit of small-scale farmers in SSA.
    Materialart: Online-Ressource
    ISSN: 0014-2336 , 1573-5060
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2016
    ZDB Id: 2012322-X
    SSG: 12
    SSG: 21
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Genes, MDPI AG, Vol. 11, No. 1 ( 2019-12-23), p. 16-
    Kurzfassung: Maize lethal necrosis (MLN), caused by co-infection of maize chlorotic mottle virus and sugarcane mosaic virus, can lead up to 100% yield loss. Identification and validation of genomic regions can facilitate marker assisted breeding for resistance to MLN. Our objectives were to identify marker-trait associations using genome wide association study and assess the potential of genomic prediction for MLN resistance in a large panel of diverse maize lines. A set of 1400 diverse maize tropical inbred lines were evaluated for their response to MLN under artificial inoculation by measuring disease severity or incidence and area under disease progress curve (AUDPC). All lines were genotyped with genotyping by sequencing (GBS) SNPs. The phenotypic variation was significant for all traits and the heritability estimates were moderate to high. GWAS revealed 32 significantly associated SNPs for MLN resistance (at p 〈 1.0 × 10−6). For disease severity, these significantly associated SNPs individually explained 3–5% of the total phenotypic variance, whereas for AUDPC they explained 3–12% of the total proportion of phenotypic variance. Most of significant SNPs were consistent with the previous studies and assists to validate and fine map the big quantitative trait locus (QTL) regions into few markers’ specific regions. A set of putative candidate genes associated with the significant markers were identified and their functions revealed to be directly or indirectly involved in plant defense responses. Genomic prediction revealed reasonable prediction accuracies. The prediction accuracies significantly increased with increasing marker densities and training population size. These results support that MLN is a complex trait controlled by few major and many minor effect genes.
    Materialart: Online-Ressource
    ISSN: 2073-4425
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2019
    ZDB Id: 2527218-4
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Frontiers Media SA ; 2023
    In:  Frontiers in Plant Science Vol. 14 ( 2023-1-20)
    In: Frontiers in Plant Science, Frontiers Media SA, Vol. 14 ( 2023-1-20)
    Kurzfassung: Development and deployment of high-yielding maize varieties with native resistance to Fall armyworm (FAW), turcicum leaf blight (TLB), and gray leaf spot (GLS) infestation is critical for addressing the food insecurity in sub-Saharan Africa. The objectives of this study were to determine the inheritance of resistance for FAW, identity hybrids which in addition to FAW resistance, also show resistance to TLB and GLS, and investigate the usefulness of models based on general combining ability (GCA) and SNP markers in predicting the performance of new untested hybrids. Half-diallel mating scheme was used to generate 105 F 1 hybrids from 15 parents and another 55 F 1 hybrids from 11 parents. These were evaluated in two experiments, each with commercial checks in multiple locations under FAW artificial infestation and optimum management in Kenya. Under artificial FAW infestation, significant mean squares among hybrids and hybrids x environment were observed for most traits in both experiments, including at least one of the three assessments carried out for foliar damage caused by FAW. Interaction of GCA x environment and specific combining ability (SCA) x environment interactions were significant for all traits under FAW infestation and optimal conditions. Moderate to high heritability estimates were observed for GY under both management conditions. Correlation between GY and two of the three scorings (one and three weeks after infestation) for foliar damage caused by FAW were negative (-0.27 and -0.38) and significant. Positive and significant correlation (0.84) was observed between FAW-inflicted ear damage and the percentage of rotten ears. We identified many superior-performing hybrids compared to the best commercial checks for both GY and FAW resistance associated traits. Inbred lines CML312, CML567, CML488, DTPYC9-F46-1-2-1-2, CKDHL164288, CKDHL166062, and CLRCY039 had significant and positive GCA for GY (positive) and FAW resistance-associated traits (negative). CML567 was a parent in four of the top ten hybrids under optimum and FAW conditions. Both additive and non-additive gene action were important in the inheritance of FAW resistance. Both GCA and marker-based models showed high correlation with field performance, but marker-based models exhibited considerably higher correlation. The best performing hybrids identified in this study could be used as potential single cross testers in the development of three-way FAW resistance hybrids. Overall, our results provide insights that help breeders to design effective breeding strategies to develop FAW resistant hybrids that are high yielding under FAW and optimum conditions.
    Materialart: Online-Ressource
    ISSN: 1664-462X
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2023
    ZDB Id: 2687947-5
    ZDB Id: 2613694-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Plants, MDPI AG, Vol. 9, No. 4 ( 2020-04-08), p. 468-
    Kurzfassung: Prior knowledge on heterosis and quantitative genetic parameters on maize lethal necrosis (MLN) can help the breeders to develop numerous resistant or tolerant hybrids with optimum resources. Our objectives were to (1) estimate the quantitative genetic parameters for MLN disease severity, (2) investigate the efficiency of the prediction of hybrid performance based on parental per se and general combining ability (GCA) effects, and (3) examine the potential of hybrid prediction for MLN resistance or tolerance based on markers. Fifty elite maize inbred lines were selected based on their response to MLN under artificial inoculation. Crosses were made in a half diallel mating design to produce 307 F1 hybrids. All hybrids were evaluated in MLN quarantine facility in Naivasha, Kenya for two seasons under artificial inoculation. All 50 inbreds were genotyped with genotyping-by-sequencing (GBS) SNPs. The phenotypic variation was significant for all traits and the heritability was moderate to high. We observed that hybrids were superior to the mean performance of the parents for disease severity (−14.57%) and area under disease progress curve (AUDPC) (14.9%). Correlations were significant and moderate between line per se and GCA; and mean of parental value with hybrid performance for both disease severity and AUDPC value. Very low and negative correlation was observed between parental lines marker based genetic distance and heterosis. Nevertheless, the correlation of GCA effects was very high with hybrid performance which can suggests as a good predictor of MLN resistance. Genomic prediction of hybrid performance for MLN is high for both traits. We therefore conclude that there is potential for prediction of hybrid performance for MLN. Overall, the estimated quantitative genetic parameters suggest that through targeted approach, it is possible to develop outstanding lines and hybrids for MLN resistance.
    Materialart: Online-Ressource
    ISSN: 2223-7747
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2704341-1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    In: Plants, MDPI AG, Vol. 11, No. 22 ( 2022-11-14), p. 3092-
    Kurzfassung: CIMMYT maize lines (CMLs), which represent the tropical maize germplasm, are freely available worldwide. All currently released 615 CMLs and fourteen temperate maize inbred lines were genotyped with 180 kompetitive allele-specific PCR single nucleotide polymorphisms to develop a reference fingerprinting SNP dataset that can be used to perform quality control (QC) and genetic diversity analyses. The QC analysis identified 25 CMLs with purity, identity, or mislabeling issues. Further field observation, purification, and re-genotyping of these CMLs are required. The reference fingerprinting SNP dataset was developed for all of the currently released CMLs with 152 high-quality SNPs. The results of principal component analysis and average genetic distances between subgroups showed a clear genetic divergence between temperate and tropical maize, whereas the three tropical subgroups partially overlapped with one another. More than 99% of the pairs of CMLs had genetic distances greater than 0.30, showing their high genetic diversity, and most CMLs are distantly related. The heterotic patterns, estimated with the molecular markers, are consistent with those estimated using pedigree information in two major maize breeding programs at CIMMYT. These research findings are helpful for ensuring the regeneration and distribution of the true CMLs, via QC analysis, and for facilitating the effective utilization of the CMLs, globally.
    Materialart: Online-Ressource
    ISSN: 2223-7747
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2704341-1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    In: Theoretical and Applied Genetics, Springer Science and Business Media LLC, Vol. 128, No. 10 ( 2015-10), p. 1957-1968
    Materialart: Online-Ressource
    ISSN: 0040-5752 , 1432-2242
    RVK:
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2015
    ZDB Id: 1478966-8
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    In: Molecular Breeding, Springer Science and Business Media LLC, Vol. 38, No. 5 ( 2018-5)
    Materialart: Online-Ressource
    ISSN: 1380-3743 , 1572-9788
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2018
    ZDB Id: 1478220-0
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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