scholarly journals Association analysis for resistance to Striga hermonthica in diverse tropical maize inbred lines

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. E. Stanley ◽  
A. Menkir ◽  
B. Ifie ◽  
A. A. Paterne ◽  
N. N. Unachukwu ◽  
...  
Keyword(s):  
Grain Yield ◽  
Candidate Genes ◽  
Phenotypic Variation ◽  
Resistance Breeding ◽  
Inbred Lines ◽  
Sub Saharan Africa ◽  
Striga Hermonthica ◽  
Small Scale ◽  
Total Phenotypic Variation ◽  
Maize Inbred Lines

AbstractStriga hermonthica is a widespread, destructive parasitic plant that causes substantial yield loss to maize productivity in sub-Saharan Africa. Under severe Striga infestation, yield losses can range from 60 to 100% resulting in abandonment of farmers’ lands. Diverse methods have been proposed for Striga management; however, host plant resistance is considered the most effective and affordable to small-scale famers. Thus, conducting a genome-wide association study to identify quantitative trait nucleotides controlling S. hermonthica resistance and mining of relevant candidate genes will expedite the improvement of Striga resistance breeding through marker-assisted breeding. For this study, 150 diverse maize inbred lines were evaluated under Striga infested and non-infested conditions for two years and genotyped using the genotyping-by-sequencing platform. Heritability estimates of Striga damage ratings, emerged Striga plants and grain yield, hereafter referred to as Striga resistance-related traits, were high under Striga infested condition. The mixed linear model (MLM) identified thirty SNPs associated with the three Striga resistance-related traits based on the multi-locus approaches (mrMLM, FASTmrMLM, FASTmrEMMA and pLARmEB). These SNPs explained up to 14% of the total phenotypic variation. Under non-infested condition, four SNPs were associated with grain yield, and these SNPs explained up to 17% of the total phenotypic variation. Gene annotation of significant SNPs identified candidate genes (Leucine-rich repeats, putative disease resistance protein and VQ proteins) with functions related to plant growth, development, and defense mechanisms. The marker-effect prediction was able to identify alleles responsible for predicting high yield and low Striga damage rating in the breeding panel. This study provides valuable insight for marker validation and deployment for Striga resistance breeding in maize.

scholarly journals Response of Assorted Maize Germplasm to the Maize Lethal Necrosis Disease in Kenya

2017 ◽  
Vol 6 (2) ◽  
pp. 65
Author(s):  
Sitta J. ◽  
Nzuve F. M. ◽  
Olubayo F. M. ◽  
Mutinda C. ◽  
Muiru W. M. ◽  
...  
Keyword(s):  
Inbred Lines ◽  
Sub Saharan Africa ◽  
Eastern Africa ◽  
Small Scale ◽  
Maize Productivity ◽  
Maize Genotypes ◽  
Severity Scores ◽  
Chlorotic Mottle Virus ◽  
Maize Chlorotic Mottle Virus ◽  
Chlorotic Mottle

Maize (Zea mays L.) is the most widely grown staple food crop in Sub Saharan Africa (SSA) and occupies more than 33 million hectares each year. The recent outbreak and rapid spread of the Maize Lethal Necrosis (MLN) disease has emerged as a great challenge to maize production, threatening food security for the majority of households in the Eastern Africa region with yield loss estimated to be 50-90%. The disease is a result of synergistic interaction between two viruses, Sugarcane mosaic virus (SCMV) and Maize chlorotic mottle virus (MCMV). The objective of this study was to identify maize genotypes with resistance to MLN. In season one, 73 maize genotypes comprising 25 inbred lines from research institutes, 30 lines from the International Maize and Wheat Improvement Centre (CIMMYT) and 18 farmer varieties were screened for resistance to MLN. In season 2, only 48 genotypes were screened after some of the inbred lines showed complete susceptibility to MLN. These genotypes were grown in three replications in a completely randomized design in polythene bags in the greenhouse at the University of Nairobi. The plants were artificially inoculated using a mixture of SCMV and MCMV. .Weekly MLN disease severity scores using a scale of 1 to 5 (1 = highly resistant and 5 = highly susceptible) and % MLN incidence were recorded and eventually converted into Area under Disease Progress Curve (AUDPC) to give an indication of the disease intensity over time. The plants were allowed to grow to flowering stage to observe the effect of the MLN on the maize productivity. Analysis of Variance revealed wide genetic variation among the genotypes ranging from resistant to highly susceptible. In season 1, three farmer varieties namely MLR2, MLR11 and MLR13 showed resistance to MLN with a mean severity score of 2. In season 2, MLN12, MLN17, MLN18, MLN19, and MLR4 showed low MLN severity ranging from 2-3. The genotypes MLR6, MLR9, MLR16 and MLR18 showed MLN severity of 3 and early maturity traits. This study also validated the presence of MLN resistance among some CIMMYT lines depicted to show resistance in previous studies. These resistant genotypes could serve as donors in the introgression of the resistance into the adapted Kenyan maize backgrounds. This will go a long way in ensuring sustainable maize productivity while improving the livelihoods of the small-scale farmers who form the bulk of the major maize producers in Kenya.

scholarly journals Partial diallel and genetic divergence analyses in maize inbred lines

2020 ◽  
Vol 43 ◽  
pp. e53540
Author(s):  
Maria Fernanda de Souza Dias Maioli ◽  
Ronald José Barth Pinto ◽  
Tereza Aparecida da Silva ◽  
Diego Ary Rizzardi ◽  
Robson Akira Matsuzaki ◽  
...  
Keyword(s):  
Grain Yield ◽  
Genetic Divergence ◽  
Block Design ◽  
Inbred Lines ◽  
Group Method ◽  
Arithmetic Average ◽  
Pair Group ◽  
Maize Inbred Lines ◽  
Randomized Block Design ◽  
Partial Diallel

In this study, we aimed to estimate general and specific combining abilities (GCA and SCA, respectively) and to verify genetic divergence (Rogers distance, Unweighted Pair-Group Method Using Arithmetic Average - UPGMA) using microsatellite markers in maize inbred lines. Using a partial diallel scheme, a total of 19 inbred lines were crossed as (9 x 10), which were derived from the single hybrids SG6015 and P30F53, respectively. The 90 hybrids were evaluated in an incomplete randomized block design with common checks and three replications during the 2017-2018 growing season. Flowering time, average plant height, ear height insertion, average ear diameter, ear length, number of lodged and broken plants, mass of 100 grains and grain yield were measured. According to the analysis of variance, GCA, and SCA were significant (p < 0.05) in all the measured traits; inbred line B as well as 1 and 8, derived from the single hybrids SG6015 and P30F53, respectively, were selected due to their higher GCA values in grain yield to be used in crosses as testers, while the single cross hybrid (B x 1) was selected due to their higher SCA value in grain yield to be used in future breeding programs. The molecular marker analysis divided the inbred lines into two groups, where the highest dissimilarity (0.74) was observed between lines A and 9; however, these did not result in a high SCA value, therefore the hybrids obtained by such crossings were not selected for grain yield.

Heterosis and combining ability for grain yield and its components in selected maize inbred lines

2007 ◽  
Vol 24 (3) ◽  
pp. 133-137 ◽  
Author(s):  
D. W. Gissa ◽  
H. Zelleke ◽  
M. T. Labuschagne ◽  
T. Hussien ◽  
H. Singh
Keyword(s):  
Grain Yield ◽  
Combining Ability ◽  
Inbred Lines ◽  
Maize Inbred Lines

Diallel analysis of acid soil tolerant and susceptible maize inbred lines for grain yield under acid and non-acid soil conditions

Euphytica ◽  
2017 ◽  
Vol 213 (4) ◽  
Author(s):  
Charles Mutimaamba ◽  
John MacRobert ◽  
Jill E. Cairns ◽  
Cosmos E. Magorokosho ◽  
Thokozile Ndhlela ◽  
...  
Keyword(s):  
Grain Yield ◽  
Acid Soil ◽  
Diallel Analysis ◽  
Inbred Lines ◽  
Soil Conditions ◽  
Maize Inbred Lines

scholarly journals Evaluation of Yield-Based Low Nitrogen Tolerance Indices for Screening Maize (Zea mays L.) Inbred Lines

Agronomy ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 240 ◽  
Author(s):  
Zhixin Zhao ◽  
Kunhui He ◽  
Zhiqian Feng ◽  
Yanan Li ◽  
Liguo Chang ◽  
...  
Keyword(s):  
Grain Yield ◽  
Geometric Mean ◽  
Inbred Lines ◽  
Shaanxi Province ◽  
High Yield ◽  
Tolerance Index ◽  
Heterotic Groups ◽  
Maize Inbred Lines ◽  
Low Nitrogen Tolerance ◽  
Low Nitrogen

To screen the desired criterion to identify desirable genotypes and select genotypes best suited to limited nitrogen availability in order to facilitate the practice of low-nitrogen-tolerant breeding in maize, the response of 31 maize inbred lines, containing four control inbred lines (PH6WC, PH4CV, Zheng58, and Chang7-2) and others selected from the Shaan A and Shaan B heterotic groups cultivated at Northwest A&F University (Yangling, Shaanxi, China), were evaluated. The experiment was conducted following a split plot design with two replications during three growing seasons (2015, 2016, and 2017) under both high nitrogen (HN) and low nitrogen (LN) conditions at the Yulin and Yangling in Shaanxi Province, China. Seven screening indices, based on grain yield under two contrasting nitrogen (N) conditions, the stress susceptibility index (SSI), yield stability index (YSI), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), harmonic mean (HM), and low nitrogen tolerance index (LNTI), were computed to assess the overall index that accurately screened the desirable genotypes. The results of the correlation analyses and principal component analysis showed that MP, GMP, HM and STI were correlated with grain yield significantly and positively under contrasting N conditions, and were able to accurately discriminate the desirable genotypes. Compared with the control inbred lines, many inbred lines selected from the Shaan A and Shaan B groups showed a higher LN tolerance. This shows that we can effectively improve the LN tolerance of maize inbred lines through LN screening. Based on the screening indices, the three-dimensional diagram and genotype and genotype × environment (GGE) biplots are agreed with this results, and we identified KA105, KB081, KA225, 91227, and 2013KB-47 as the desired genotypes that have the potential to be used to breed a high yield and stable hybrid.

scholarly journals Agronomic and molecular evaluation of maize inbred lines for drought tolerance

2016 ◽  
Vol 14 (4) ◽  
pp. e0711 ◽  
Author(s):  
Sanja Mikić ◽  
Miroslav Zorić ◽  
Dušan Stanisavljević ◽  
Ankica Kondić-Špika ◽  
Ljiljana Brbaklić ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Grain Yield ◽  
Maize Yield ◽  
Field Trials ◽  
Inbred Lines ◽  
Partial Least Square ◽  
Least Square ◽  
Maize Breeding ◽  
Heterotic Groups ◽  
Maize Inbred Lines

Drought is a severe threat to maize yield stability in Serbia and other temperate Southeast European countries occurring occasionally but with significant yield losses. The development of resilient genotypes that perform well under drought is one of the main focuses of maize breeding programmes. To test the tolerance of newly developed elite maize inbred lines to drought stress, field trials for grain yield performance and anthesis silk interval (ASI) were set in drought stressed environments in 2011 and 2012. Inbred lines performing well under drought, clustered into a group with short ASI and a smaller group with long ASI, were considered as a potential source for tolerance. The former contained inbreds from different heterotic groups and with a proportion of local germplasm. The latter consisted of genotypes with mixed exotic and Lancaster germplasm, which performed better in more drought-affected environments. Three inbreds were selected for their potential drought tolerance, showing an above-average yield and small ASI in all environments. Association analysis indicated significant correlations between ASI and grain yield and three microsatellites (bnlg1525, bnlg238 and umc1025). Eight alleles were selected for their favourable concurrent effect on yield increase and ASI decrease. The proportion of phenotypic variation explained by the markers varied across environments from 5.7% to 22.4% and from 4.6% to 8.1% for ASI and yield, respectively. The alleles with strongest effect on performance of particular genotypes and their interactions in specific environments were identified by the mean of partial least square interactions analysis indicating potential suitability of the makers for tolerant genotype selection.

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