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Thiruvananthapuram, India

Chakrabarti S.K.,Central Potato Research Institute | Chakrabarti S.K.,Central Tuber Crop Research Institute | Singh B.P.,Central Potato Research Institute | Thakur G.,Central Potato Research Institute | And 5 more authors.
Potato Research | Year: 2014

Several quantitative trait loci (QTL) for resistance to late blight have been reported in diploid potatoes. The diploid wild potato species Solanum chacoense possesses a high degree of horizontal resistance to late blight. In the present study, we report on QTL mapping for late blight resistance in a diploid mapping population of 126 F1 of Solanum spegazzinii (susceptible) × S. chacoense (resistant). The area under the disease progress curve (AUDPC) values for late blight resistance using the "whole plant in vitro assay" and the "detached leaf assay" on the mapping population displayed quantitative variation. Out of 64 AFLP primer-pairs combinations and SSR markers, a total of 209 significant AFLP loci were placed onto the 12 linkage group of potato covering a total map length of 6548.1 cM. QTL analysis based on the AUDPC dataset of the "whole plant in vitro assay" using the interval-mapping option identified two QTL (LOD > 2.5) located on linkage groups IX and X, which explained 14.70 and 3.40% variation, respectively. The present study revealed the presence of potential new genetic loci in the diploid potato family contributing to quantitative resistance against late blight. © 2014 EAPR. Source


Kaushik S.K.,Central Potato Research Institute Campus | Sharma R.,Central Potato Research Institute | Garg I.D.,Central Potato Research Institute | Singh B.P.,Central Potato Research Institute | And 3 more authors.
Journal of Horticultural Science and Biotechnology | Year: 2013

The present study was undertaken to validate a sequence characterised amplified region (SCAR) marker tightlylinked to the potato virus Y (PVY) resistant gene (Ryadg) and its further use to develop a triplex parental line using marker assisted selection (MAS). The expected SCAR marker was detected in 11 PVY-resistant genotypes, including putative duplex clones, and was absent in PVY-susceptible genotypes. The resistant genotypes were also screened by double-anitbody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and the results agreed with the SCAR marker data. Based on having a high marker band intensity, three putative duplex clones (YY-3, YY-6, and YY-13) were selected and were inter-crossed to ascertain their duplex status. Based on the PVY resistant (R): PVY susceptible (S) segregation ratio of their three respective progenies, the three clones were confirmed to be duplex clones. Similarly, five putative triplex clones were selected from the segregating progenies of two diploid clones based on having a higher marker band intensity. These were test-crossed with PVY-susceptible, nulliplex clones. The expected segregation ratio (27:1) following random chromatid assortment was tested for in the progenies. The triplex clone, YY-6/3 C11 was identified as carrying the extreme resistance gene to PVY. Use of this elite parental line in potato breeding programmes would ensure that 96% of the progeny carried at least one copy of the Ryadg gene, thus having extreme resistance to PVY. This would eliminate the need to screen using DAS-ELISA and would also reduce the widespread degeneration of potato seed by reducing the incidence of co-infections in which PVY is more damaging with Potato Virus X (PVX) and/or Potato Leaf Roll Virus (PLRV) on the sub-tropical plains of India where approx. 90% of potatoes are grown.This study showed that MAS can be used to speed-up a conventional breeding programme to develop a desired genotype. Source


Das A.B.,Orissa University of Agriculture and Technology | Das A.B.,Utkal University | Das A.,Orissa University of Agriculture and Technology | Pradhan C.,Utkal University | Naskar S.K.,Central Tuber Crop Research Institute
Caryologia | Year: 2015

Detailed karyotype, genome size and RAPD marker analysis were employed to assess genetic diversity in Taro (Colocasia esculenta var antiquorom Schott.). Karyotype analysis revealed genotype specific chromosomal characteristics and structural alterations in chromosome with variations of ploidy from 2n = 2x = 28 (cv. Mothan, cv. Muktakeshi, cv. Sree Kiran, cv. Sree Pallavi, cv. Sunajhili) to 3n = 3x = 42 (cv. Banky, cv. DP-25, cv. Duradin, cv. H-3, cv. Telia) in the genome. Highly significant variations in the genomic length, volume and total form (TF) % were noted at variety level. Total genomic chromosome length varied from 46.96μm in cv. Sree Kiran to 100.49μm in cv. Duradin. Total genomic chromosome volume varied from 18.22μm3 in cv. Sunajhili to 38.22μm3 in cv. Duradin. Total form percentage was varied from 24.94% in cv. Sree Kiran to 39.04% in cv. H-3 confirming near metacentric to metacentric chromosomes in the karyotype. Significant variations in the 4C DNA content noted among the cultivars that ranged from 7.24 pg in cv. Sree Kiran to 18.24 pg in cv. Duradin; accordingly, genome size varied from ~7095 to 17875 Mbp. High genome size in all the triplod varieties with 3x = 42 chromosomes could be due to the presence of extra set of chromosomes in the genome or high amount of repetitive DNA. The variation in the genome size at the variety level might be attributed to loss or addition of highly repetitive sequences in the genome. Amplification of genomic DNA in 10 genotypes using Operon primers yielded 230 amplified DNA fragments, ranging in size from 200 to 2500bp out of which 79 bands were polymorphic. A total of 8 unique RAPD bands were observed among 10 taro genotypes that revealed primer wise polymorphism ranged from 16.66 to 47.36% with an average polymorphic percentage of 34.34%. Whereas, among the cultivars the polymorphic percentage varied from 3.70% between cv. DR-25 & cv. Duradin and cv. Telia & cv. H-3 to 41.94% between cv. Mothan & cv. Muktakeshi. Genetic similarity based on Jaccard’s coefficient varied from 0.54 to 0.96, indicating wide genetic variability among the varieties based on RAPD markers. Similarity measures and cluster analysis generally reflected the expected trends in relationships of diploid and triplod taro varieties. Dendrogram obtained from the genetic distances among the varieties could be useful for breeders to choose the diverse parents for breeding programme aimed at varietal improvement. © 2015 Dipartimento di Biologia Evoluzionistica, Università di Firenze. Source


Tiwari J.K.,Central Potato Research Institute | Siddappa S.,Central Potato Research Institute | Singh B.P.,Central Potato Research Institute | Kaushik S.K.,Central Potato Research Institute Campus | And 4 more authors.
Plant Breeding | Year: 2013

Late blight is the most devastating disease of the potato crop that can be effectively managed by growing resistant cultivars. Introgression of resistance (R) genes/quantitative trait loci (QTLs) from the Solanum germplasm into common potato is one of the plausible approaches to breed resistant cultivars. Although the conventional method of breeding will continue to play a primary role in potato improvement, molecular marker technology is becoming one of its integral components. To achieve rapid success, from the past to recent years, several R genes/QTLs that originated from wild/cultivated Solanum species were mapped on the potato genome and a few genes were cloned using molecular approaches. As a result, molecular markers closely linked to resistance genes or QTLs offer a quicker potato breeding option through marker-assisted selection (MAS). However, limited progress has been achieved so far through MAS in potato breeding. In near future, new resistance genes/QTLs are expected to be discovered from wild Solanum gene pools and linked molecular markers would be available for MAS. This article presents an update on the development of molecular markers linked to late blight resistance genes or QTLs by utilization of Solanum species for MAS in potato. © 2013 Blackwell Verlag GmbH. Source


Choudhary V.K.,Indian Council of Agricultural Research | Kumar P.S.,Central Tuber Crop Research Institute
Communications in Soil Science and Plant Analysis | Year: 2014

Low availability of phosphorus (P) and potassium (K) in acidic soil is a major constraint for crop production. Therefore, a field study was conducted to determine the effects of K and P on nodulation, productivity, and nutrient uptake of cowpea (Vigna unguiculata L. Walp) under rainfed conditions. The K and P were subjected to main and subplots, respectively with 100, 75, and 50% of fertilizer application. The growth and yield attributes were better using 100% K with 100% P. However, 100% K resulted in 20.9 and 16.9% greater green pod and stover yield than 50% K. Similarly, 100% P recorded 20.2 and 15.6% greater green pod and stover yield than 50% P. Uptake of nutrients such as nitrogen (N), P, and K followed the trend of greater to lower, 100% > 75% > 50%, in order for K and P. Similarly, nutrient-use efficiencies and production efficiency followed the trend of nutrient uptake. © 2014 Copyright Taylor and Francis Group, LLC. Source

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