Geographical Distribution of Genetic Diversity in <i>Arachis hypogaea</i>

Holbrook, C. C.; Isleib, T. G.

doi:10.3146/i0095-3679-28-2-8

Cited by 15 publications

(14 citation statements)

References 8 publications

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“…Use of this mini core collection would not have significantly improved the efficiency of identifying resistance to the peanut root‐knot nematode in the core collection (Table 4) This was unexpected since we had previously demonstrated that some geographical areas are rich sources of resistance to the peanut root‐knot nematode (Holbrook et al, 2000a; Holbrook and Isleib, 2001) and shown that the clusters used to develop the core collection improved the efficiency of identifying nematode resistance in the entire collection (Holbrook et al, 2000b). An examination of the mean data for accessions showed similar grouping in the clusters used to select this core of the core collection.…”

Section: Resultsmentioning

confidence: 98%

Development and Evaluation of a Mini Core Collection for the U.S. Peanut Germplasm Collection

Holbrook¹,

2005

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examining all accessions in the core collection for a desired characteristic. This information is then used to A core collection (831 accessions) has been developed to represent determine which clusters of accessions in the entire germthe U.S. Arachis hypogaea L. germplasm collection. This core collection has been shown to be effective in improving the efficiency of plasm collection should be examined during the secidentifying genes of interest in the entire germplasm collection. How-ond stage of screening. Theoretically, the probability of ever, an even smaller subset of germplasm is needed for traits which finding additional accessions with a desired characterisare difficult and/or expensive to measure. The objectives of this study tic would be highest in these clusters. Holbrook and were to select a core of the core collection and to evaluate the use-Anderson (1995) used data on resistance to late leaf fulness of this subset of germplasm to identify genes of interest in spot that was available for the entire peanut germplasm peanut. Data for eight above ground and eight below ground morphocollection to determine retrospectively how effective logical characteristics were measured for each accession in the core the use of a core collection approach would have been collection. Cluster analysis was used on these data to partition the core for identifying sources of resistance in the entire collecaccessions into groups which, theoretically, are genetically similar. tion. Holbrook et al. (2000b) evaluated the effectivenessRandom sampling was then used to select a 10% sample from each group. The result was a core of the core collection (mini core) con-

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Section: Resultsmentioning

confidence: 98%

Development and Evaluation of a Mini Core Collection for the U.S. Peanut Germplasm Collection

Holbrook¹,

2005

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“…Core (representing 10% of total collection) and mini-core (representing 10% of core collection) collections were made for the groundnut genetic resources available in USDA/ARS (Holbrook et al, 1993; Holbrook and Dong, 2005), ICRISAT (Upadhyaya et al, 2002, 2003), and China (Jiang et al, 2008, 2010). Holbrook and Isleib (2001) observed that the resistance genes were cluster geographically and accessions with multiple disease resistance were most common in India, Mozambique, and Senegal.…”

Section: Groundnut Improvement Using Conventional Approachesmentioning

confidence: 99%

Groundnut improvement: use of genetic and genomic tools

Janila¹,

Nigam²,

Pandey³

et al. 2013

Front. Plant Sci.

175

135

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Groundnut (Arachis hypogaea L.), a self-pollinated legume is an important crop cultivated in 24 million ha world over for extraction of edible oil and food uses. The kernels are rich in oil (48–50%) and protein (25–28%), and are source of several vitamins, minerals, antioxidants, biologically active polyphenols, flavonoids, and isoflavones. Improved varieties of groundnut with high yield potential were developed and released for cultivation world over. The improved varieties belong to different maturity durations and possess resistance to diseases, tolerance to drought, enhanced oil content, and improved quality traits for food uses. Conventional breeding procedures along with the tools for phenotyping were largely used in groundnut improvement programs. Mutations were used to induce variability and wide hybridization was attempted to tap variability from wild species. Low genetic variability has been a bottleneck for groundnut improvement. The vast potential of wild species, reservoir of new alleles remains under-utilized. Development of linkage maps of groundnut during the last decade was followed by identification of markers and quantitative trait loci for the target traits. Consequently, the last decade has witnessed the deployment of molecular breeding approaches to complement the ongoing groundnut improvement programs in USA, China, India, and Japan. The other potential advantages of molecular breeding are the feasibility to target multiple traits for improvement and provide tools to tap new alleles from wild species. The first groundnut variety developed through marker-assisted back-crossing is a root-knot nematode-resistant variety, NemaTAM in USA. The uptake of molecular breeding approaches in groundnut improvement programs by NARS partners in India and many African countries is slow or needs to be initiated in part due to inadequate infrastructure, high genotyping costs, and human capacities. Availability of draft genome sequence for diploid (AA and BB) and tetraploid, AABB genome species of Arachis in coming years is expected to bring low-cost genotyping to the groundnut community that will facilitate use of modern genetics and breeding approaches such as genome-wide association studies for trait mapping and genomic selection for crop improvement.

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“…This germplasm collection has served as a valuable source of diversity for resistance to many pathogens of peanut (Holbrook and Isleib, 2001). However, it is not feasible to evaluate this collection, in its entirety, for resistance to PAC using currently available screening techniques.…”

Section: Screening For Sources Of Resistancementioning

confidence: 99%

The U.S. Breeding Program to Develop Peanut with Drought Tolerance and Reduced Aflatoxin Contamination

Holbrook¹,

Guo²,

Wilson³

et al. 2009

Peanut Science

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Aflatoxin contamination costs the U.S. peanut (Arachis hypogaea L.) industry over $20 million annually. The development of peanut cultivars with resistance to preharvest aflatoxin contamination (PAC) would reduce these costs. Screening techniques have been developed that can measure genetic differences in aflatoxin contamination and they have been used to identify accessions that exhibited relatively low PAC in multiple environments. Significant reductions in PAC have been identified in peanut genotypes with drought tolerance. These sources of resistance to PAC have been crossed with cultivars and breeding lines that have high yield, acceptable grade, and resistance to spotted wilt caused by Tomato spotted wilt tospovirus (TSWV). Due to the large environmental variation in PAC, breeding populations can only be evaluated in late generations when there is less heterozygosity and adequate numbers of seed are available for field testing using multiple replications. Evaluation of numerous breeding populations has identified several families and individual breeding lines with relatively low PAC, relatively high yield, and acceptable levels of resistance to TSWV. To increase breeding efficiency, studies on mechanisms of resistance to PAC are being conducted. The most promising mechanisms identified thus far are resistance to drought and resistance to the peanut rootknot nematode. Late generation breeding lines have been developed with resistance to drought, several of which also exhibited reduced aflatoxin contamination in multiple environments. Tifguard, the first cultivar with high levels of resistance to both TSWV and the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] was released from this program. Testing is ongoing to determine if this cultivar can be used to reduce aflatoxin contamination in nematode infested fields.

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Geographical Distribution of Genetic Diversity in Arachis hypogaea

Cited by 15 publications

References 8 publications

Development and Evaluation of a Mini Core Collection for the U.S. Peanut Germplasm Collection

Development and Evaluation of a Mini Core Collection for the U.S. Peanut Germplasm Collection

Groundnut improvement: use of genetic and genomic tools

The U.S. Breeding Program to Develop Peanut with Drought Tolerance and Reduced Aflatoxin Contamination

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