59 research outputs found
Identification of QTLs for yield and its component traits, and downy mildrew (Sclerospora graminicola (Sacc.) J. Schrot.) resistance in pearl millet (Pennisetum glaucum (L.)R. Br)
No full textPhenotypic and molecular diversity-based prediction of heterosis in pearl millet (Pennisetum glaucum L. (R.) Br.)
No full textGenetic distances between hybrid parents based on phenotypic traits and molecular markers were investigated to assess their relationship with heterosis for grain and stover yield and other traits in pearl millet (Pennisetum glaucum [L.] R. Br.). Fifty-one hybrids developed using 101 hybrid parents (B and R lines) and showing a wide range of genetic distance between their parents based on eight phenotypic traits and 28–38 SSRs were evaluated in two sets for two seasons. The correlation between Euclidean distance (phenotypic distance, ED) and simple matching distance (molecular distance, SM) for parents of both sets was low but positive and significant (r = 0.2, P < 0.001).The correlation of ED in parents with better-parent heterosis for grain yield was similar in both sets (r = 0.38, P < 0.05). SM was not correlated with heterosis for grain yield in either set of hybrids. The results showed that phenotypic distance could be a better predictor of heterosis than molecular distance. The correlation between phenotypic distance and heterosis was not strong enough to permit the use of phenotypic diversity among parents as a major selection criterion for selection of parental lines displaying high levels of heterosis for grain and stover yield in pearl millet. Keywords: Hybrid parents, Agronomic traits, Euclidean distance, Molecular markers, Simple matching distanc
Patterns of Molecular Diversity in Current and Previously Developed Hybrid Parents of Pearl Millet [Pennisetum glaucum (L.) R. Br.]
No full textICRISAT’s pearl millet (Pennisetum glaucum (L.) R. Br.) breeding program at Patancheru, India, has developed genetically diverse hybrid parents since 1980s. The present study investigated genetic diversity pattern between two groups of parents in this program, bred till 2004 and developed during 2004-2010. Combined analysis of 379 hybrid parents (current 166 parents and 213 previously developed hybrid parents) carried out using a set of highly polymorphic 28 SSRs detected 12.7 alleles per locus. An average of 8.5 and 8.7 SSR alleles per locus were found in previously developed and current parents, respectively, indicating marginal improvement in the levels of genetic diversity of hybrid parents in this program. Distance matrix differentiated these current and previously developed hybrid parents into 2 separate clusters, indicating infusion of new genetic variability over time as reflected by development of more genotype-specific alleles. Also, the seed and restorer parents were found clearly separated from each other in both the sets with few crossovers, indicating existence of two diverse and broad-based pools in hybrid parents of pearl millet. Restorer parents (R-lines) were found more diverse than seed parents (B-lines), as higher average gene diversity was detected among R-lines (0.70) than B-lines (0.56), though variation between B- and R-lines was found reduced in newly developed lines to 9.22% from 16.98% in previously developed lines. Results suggested that newly developed lines were as much divergent when compared with previously developed lines, indicating that current ICRISAT pearl millet breeding program was moving towards development of diverse new hybrid parental lines. The study suggested use of trait-specific donors in B- and R-lines separately to maintain sufficient genetic distance between seed and restorer breeding lines. It was pointed out to cross parents having higher genetic distance within the seed (B-lines) and restorer (R-lines) breeding programs to derive diverse and productive hybrid parental lines in future
Within-line Genetic Variation for Quantitative Characters and SSRs in Long-time Maintained Inbreds in Pearl Millet [Pennisetum glaucum (L.) R. Br.]
No full textSix maintainer (B-) and restorer (R-) lines each from ICRISAT’s pearl millet hybrid parental line breeding program were investigated for within-line genetic variation for quantitative characters and simple sequence repeats (SSRs). Thirty two progenies of each inbred line were evaluated under two contrasting seasons and observed for 5 quantitative characters, and for 20 SSRs. Some B- and R- lines had small but significant within-line genetic variation for certain traits. Higher number of significant differences for within-line variation observed among progenies for B-lines (48%) than for R-lines (33%) indicated that ear-to-row procedure of line maintenance was more effective than bulking the phenotypically similar plants, for maintaining the genetic uniformity in inbreds. Amongst B-lines, ‘ICMB 89111’ had the maximum within-line variation for both quantitative characters and SSR markers. Amongst R-lines, ‘IPC 802’ and ‘IPC 909’ had within-line variation for maximum of 4 quantitative characters. Wide range of variability was observed for all the characters in both B- and R- lines, but genotypic coefficient of variation (GCV) was very low. SSRs were able to detect low level of residual heterozygosity in some of the inbred
Genetic Diversity in Maintainer and Restorer Lines of Pearl Millet
No full textMolecular markers facilitate rapid and environment-neutral characterization of the pattern of genetic diversity. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) at Patancheru, India, has developed a large number and diverse range of maintainer lines (B-lines) and restorer lines (R-lines) of pearl millet [Pennisetum glaucum (L.) R. Br.] in last three decades. In the present study, 213 lines (98 B-lines and 115 R-lines) were genotyped using high throughput assay and 38 polymorphic simple sequence repeat (SSR) markers, which detected 308 alleles averaging 8.1 alleles per locus. Restorer lines were genetically more diverse than B-lines, as higher average gene diversity was detected among R-lines (0.62) than among B-lines (0.50). A neighbor-joining tree based on simple matching dissimilarity distance matrix clearly differentiated B-lines from R-lines into two clusters, with further subdivision of B-lines into four subclusters and R-lines into five subclusters. Seven B-lines clustered with R-lines, and only two R-lines clustered with B-lines. Few unique alleles (1 to 3) were detected in 14 B- and 30 R-lines, which could be used to distinguish them from each other as well as from the remaining lines used in this study. The SSR alleles of each of the parental lines along with distinctness, uniformity, and stability (DUS) characterization may enable ICRISAT to protect these lines from any kind of infringement by the multiple users who have received these lines for hybrid development
Mapping Quantitative Trait Loci Controlling High Iron and Zinc Content in Self and Open Pollinated Grains of Pearl Millet [Pennisetum glaucum (L.) R. Br.]
No full textPearl millet is a multipurpose grain/fodder crop of the semi-arid tropics, feeding many
of the world’s poorest and most undernourished people. Genetic variation among
adapted pearl millet inbreds and hybrids suggests it will be possible to improve grain
micronutrient concentrations by selective breeding. Using 305 loci, a linkage map was
constructed to map QTLs for grain iron [Fe] and zinc [Zn] using replicated samples
of 106 pearl millet RILs (F6) derived from ICMB 841-P3 863B-P2. The grains of
the RIL population were evaluated for Fe and Zn content using atomic absorption
spectrophotometer. Grain mineral concentrations ranged from 28.4 to 124.0 ppm for
Fe and 28.7 to 119.8 ppm for Zn. Similarly, grain Fe and Zn in open pollinated seeds
ranged between 22.4–77.4 and 21.9–73.7 ppm, respectively. Mapping with 305 (96
SSRs; 208 DArT) markers detected seven linkage groups covering 1749 cM (Haldane)
with an average intermarker distance of 5.73 cM. On the basis of two environment
phenotypic data, two co-localized QTLs for Fe and Zn content on linkage group (LG) 3
were identified by composite interval mapping (CIM). Fe QTL explained 19% phenotypic
variation, whereas the Zn QTL explained 36% phenotypic variation. Likewise for open
pollinated seeds, the QTL analysis led to the identification of two QTLs for grain Fe
content on LG3 and 5, and two QTLs for grain Zn content on LG3 and 7. The total
phenotypic variance for Fe and Zn QTLs in open pollinated seeds was 16 and 42%,
respectively. Analysis of QTL QTL and QTL QTL environment interactions
indicated no major epistasis
Genetic Diversity in Maintainer and Restorer Lines of Pearl Millet
No full textMolecular markers facilitate rapid and environment-neutral characterization of the pattern of genetic diversity. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) at Patancheru, India, has developed a large number and diverse range of maintainer lines (B-lines) and restorer lines (R-lines) of pearl millet [Pennisetum glaucum (L.) R. Br.] in last three decades. In the present study, 213 lines (98 B-lines and 115 R-lines) were genotyped using high throughput assay and 38 polymorphic simple sequence repeat (SSR) markers, which detected 308 alleles averaging 8.1 alleles per locus. Restorer lines were genetically more diverse than B-lines, as
higher average gene diversity was detected among R-lines (0.62) than among B-lines (0.50). A neighbor-joining tree based on simple matching dissimilarity distance matrix clearly differentiated B-lines from R-lines into two
clusters, with further subdivision of B-lines into four subclusters and R-lines into five subclusters. Seven B-lines clustered with R-lines, and only two R-lines clustered with B-lines. Few unique alleles (1 to 3) were detected
in 14 B- and 30 R-lines, which could be used to distinguish them from each other as well as from the remaining lines used in this study. The SSR alleles of each of the parental lines along with distinctness, uniformity, and stability (DUS) characterization may enable ICRISAT to protect these lines from any kind of infringement by the multiple users who have received these lines for hybrid development
Bioefficacy of certain chemical and biofungicides against Hypoxylon spp. causing wood rot disease in tea
No full textWood rot disease caused by Hypoxylon serpens is the most widespread and serious stem disease in tea. Among the 350 bacterial and 35 fungal biocontrol isolates collected from several tea growing regions of southern India, three bacterial isolates produced higher antagonistic potential against this fungal pathogen. Two of the efficient strains were identified as Bacillus sp. (HBCWR-3 and WR46-2) and third one was Pseudomonas sp. (WR5-4). In case of fungal biocontrol agents, the type culture Trichoderma viride procured from Microbial Type Culture Collection (MTCC) performed better in controlling the pathogen over T. harzianum. Five systemic fungicides, hexaconazole, carbendazim, tebuconazole, tridemorph, benomyl and a contact fungicide, copper oxychloride were evaluated for studying their bioefficacy against wood rot pathogen. In this study, benomyl 50% WP or copper oxychloride at the lowest concentration (0.01%) completely inhibited the growth of the fungus in vitro. Moreover, bioefficacy of certain plant aqueous extracts of Azadirachta indica, acetone extracts of Pongamia pinnata, Cinnamom, Artemisia nilagirica, Lantana camera, Ageratum conyzoides and a bryophyte, Heteroscyphus argutus were also studied against H. serpens. Among them, A. nilagirica followed by H. argutus and A. indica were effective in controlling the wood rot pathogen. In the case of liquid biofungicides tested, ‘Expel’ controlled the tea pathogen efficiently. The present study revealed that, chemical fungicide (Benomyl or copper oxychloride at 0.01%), botanical extracts at 10% (A. nilagirica, H. argutus, Azadirachta and ‘Expel’) and biocontrol agents (Bacillus sp., Pseudomonas sp. and T. viride) were effective in controlling wood rot pathogen under in vitro condition
Quantitative trait loci for grain yield in pearl millet under variable postflowering moisture conditions
No full textPearl millet marker-assisted selection (MAS) programs targeting adaptation to variable postflowering moisture environments would benefit from quantitative trait loci (QTLs) that improve grain yield across the full range of postflowering moisture conditions, rather than just in drought-stressed environments. This research was undertaken to identify such QTLs from an extensive (12-environment) phenotyping data set that included both stressed and unstressed postflowering environments. Genetic materials were test crosses of 79 F2-derived F4 progenies from a mapping population based on a widely adapted maintainer line (ICMB 841) × a postfl owering drought-tolerant maintainer (863B). Three QTLs (on linkage group [LG] 2, LG 3, and LG 4) were identifi ed as primary candidates for MAS for improved grain yield across variable postflowering moisture environments. The QTLs on LG 2 and LG 3 (the most promising) explained a useful proportion (13-25%) of phenotypic variance for grain yield across environments. They also co-mapped with QTLs for harvest index across environments, and with QTLs for both grain number and individual grain mass under severe terminal stress. Neither had a significant QTL × environment interaction, indicating that their predicted effects should occur across a broad range of available moisture environments. We have estimated the benefi ts in grain yield and accompanying changes in yield components and partitioning indices that would be expected as a result of incorporating these QTLs into other genetic backgrounds by MAS
Pearl millet [Pennisetum glaucum (L.) R. Br.] consensus linkage map constructed using four RIL mapping populations and newly developed EST-SSRs
No full textPearl millet [Pennisetum glaucum (L.) R. Br.] is a widely cultivated drought- and high-temperature tolerant C4 cereal grown under dryland, rainfed and irrigated conditions in drought-prone regions of the tropics and sub-tropics of Africa, South Asia and the Americas. It is considered an orphan crop with relatively few genomic and genetic resources. This study was undertaken to increase the EST-based microsatellite marker and genetic resources for this crop to facilitate marker-assisted breeding
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