Peanut composition is influenced by several groups of factors: environmental, genetic, and their interaction. This study evaluated the relative contributions of these factors using data from the USDA-ARS quality testing program using samples from the multi-state Uniform Peanut Performance Tests (UPPT). Data were subjected to restricted maximum likelihood estimation of variance components reflecting the main effects of year, production region, location within region, genotype (cultivar or breeding line), and kernel grade (''seed size'') within genotype, and the interactions among these main effects. Genetic variation in oil content was low (9% of total variation); however, fatty acid composition of the oil was highly influenced by genotype (34-77%) with the exception of lignoceric acid (1%). Genetic influence on tocopherols was generally less than that of fatty acids. Environmental variation of tocopherols was greater than the variation attributable to genotype-by-environment interaction. The lowest genetic variation was observed in sugar content; however, environmental variation was high (68%). The magnitude of genetic influence on oil content and fatty acid concentrations suggests that these traits are amenable to improvement through breeding.

The sensory attributes that make up roasted peanut flavor quality are important traits to evaluate in the development of new cultivars. Recent publications have characterized the variation in sensory attributes in U.S. peanuts (Arachis hypogaea L.), however, no estimates of the effects of lines asparents in a breeding program have been calculated. Best linear unbiased prediction (BLUP) is a method for predicting the breeding value of a parent based on the performance of its relatives. Commonly used in animal and tree breeding, the method is rarely applied in annual crop species. The method was applied to a set of data collected on the three sensory attributes roasted peanut, sweet, and bitter for 250 peanut genotypes evaluated in 53 environments. BLUP solutions computed usingdifferent estimates ofnarrow-sense heritability (h 2) were highly correlated (r > 0.9), suggesting that precise estimates ofh 2 are not necessary. Correlations of values predicted by BLUP with observed values were moderate (0.63 < r < 0.71) for individual lines, but strong (0.85 < r < 0.92) for means of crosses. BLUPs ofbreeding "The research reported in this publication was a cooperative effort of the Agric. Res. Servo ofthe U.S. Dept. of Agric. and the North Carolina Agric. Res. Serv., Raleigh, NC 27695-7643. The use of trade names in this publication neitherimplies endorsement by the USDAor the NCARS of the products named nor criticism of similar ones not mentioned.

Early and late leaf spots are the major foliar diseases of peanut responsible for severely decreased yield in the absence of intensive fungicide spray programs. Pyramiding host resistance to leaf spots in elite cultivars is a sustainable solution to mitigate the diseases. In order to determine the genetic control of leaf spot disease resistance in peanut, a recombinant inbred line population (Florida-07 x GP-NC WS16) segregating for resistance to both diseases was used to construct a SNP-based linkage map consisting of 855 loci. QTL mapping revealed three resistance QTLs for late leaf spot qLLSA05 (phenotypic variation explained, PVE=7-10%), qLLSB03 (PVE=5-7%), and qLLSB05 (PVE=15-41%) that were consistently expressed over multi-year analysis. Two QTL, qLLSA05 and qLLSB05, confirmed our previously published QTL-seq results. For early leaf spot, three resistance QTLs were identified in multiple years, two on chromosome A03 (PVE=8-12%) and one on chromosome B03 (PVE=13-20%), with the locus qELSA03_1.1 coinciding with the previously published genomic region for LLS resistance in GPBD4. Comparative analysis of the genomic regions spanning the QTLs suggests that resistance to early and late leaf spots are largely genetically independent. In addition, QTL analysis on yield showed that the presence of resistance allele in qLLSB03 and qLLSB05 loci might result in protection from yield loss caused by LLS disease damage. Finally, post hoc analysis of the RIL subpopulation that was not utilized in the QTL mapping revealed that the flanking markers for these QTLs can successfully select for resistant and susceptible lines, confirming the effectiveness of pyramiding these resistance loci to improve host-plant resistance in peanut breeding programs using marker-assisted selection.

The U.S. maintains a large (&gt; 8000 accessions) and genetically diverse collection of peanut (Arachis hypogaea L.) germplasm. It is costly to screen all accessions within this collection for traits that could be useful in cultivar development. The objective of this research was to identify countries of origin that are rich sources of resistance to important peanut diseases. This would allow peanut breeders to focus their efforts on smaller subsets of the germplasm collection. Accessions in the peanut core collection were evaluated for resistance to late (Cercosporidium personatum Berk. & M. A. Curtis) and early (Cercospora arachidicola Hori) leaf spot, tomato spotted wilt Tospovirus (TSWV), the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1], and Cylindrocladium black rot (CBR)[Cylindrocladium crotalarie (Loos) Bell & Sobers]. These data then were examined to determine if genes for resistance clustered geographically. Several geographical areas that appear to be rich sources for disease-resistant genes were identified. China had a relatively large number of accessions with resistance to the peanut root-knot nematode. Peru appeared to be a rich source of material with resistance to CBR. Resistance to late leaf spot was more frequent than expected in accessions from Bolivia and Ecuador. Bolivia was also a valuable source of resistance to early leaf spot. Early leaf spot resistance also was more prevalent than expected in accessions from India, Nigeria, and Sudan. India, Israel, and Sudan were valuable origins for material with resistance to TSWV. Accessions with multiple disease resistance were most common in India, Mozambique, and Senegal. This information should enable plant breeders to utilize more efficiently the genes for disease resistance that are available in the U.S. germplasm collection.

The scientific community has long assumed that plant breeding activities decrease genetic diversity in crop species. To determine the influence of plant breeding on peanut, this study was designed to assess allelic diversity changes among peanut (Arachis hypogaea L.) cultivars of the runner market type using simple sequence repeat (SSR) markers. All runner‐type cultivars released to date were included with the exception of ten cultivars released in the 2000s. Thirty‐four SSR primer pairs amplified a total of 154 alleles. The results indicated that (i) at the gene level, allelic diversity has increased significantly through decades of breeding, (ii) at the population level, genetic diversity was at its lowest during the pre‐1980s time period and gradually increased in each subsequent decade, and (iii) most of the observed SSR variation occurred within, rather than among time periods. A principal coordinate analysis (PCO) clearly demonstrated increases in the variation present in each subsequent breeding decade, reaching its maximum in the 2000s. Therefore, it appears that runner‐type peanut breeders have been successful at developing improved peanut cultivars while increasing levels of diversity in the last three decades of breeding. In addition, genetic relationships among cultivars reported in this study might be of use for peanut breeders when selecting parents for establishment of breeding populations.

No abstract

A full diallel cross among four diverse homozygous strains of dry edible beans (Phaseolus vulgaris L.) was evaluated for yield, protein content, and culinary quality traits in the F2 and F3 generations in two locations. Interpretation of diallel effects [Method 1 Model I] using a fixed-effect genetic model made it possible to combine data from two generations into a single analysis and quantify the relative contributions of additive and dominance genetic effects to general (GCA) and specific (SCA) combining abilities. GCA was found to arise from three potential sources: additive effects, dominance interactions at homozygous loci, and average dominance interactions in hybrids involving the parent in question. SCA was found to be a function solely of dominance. Additive effects were the primary determinant of GCA and were highly significant. Specific dominance interactions were significant for seed yield, cooked bean moisture content, and texture but not for protein content. Texture was the only trait for which the additive-dominance model failed to provide an adequate fit to the data, suggesting that texture is significantly affected by epistatic interaction. One cross ('Brazil-2' × 'Sanilac') was identified that exhibited a large heterotic effect for seed yield although the parents' additive effects were nonsignificant. Such a "nicking" effect was attributed to complementation between the two parents.

Georgia Green has become the dominant runner market-type peanut cultivar in the United States because of its high yield and superior disease resistance to tomato spotted wilt virus. However, the roasted peanut flavor quality of Georgia Green has not been formally reported, and questions regarding its flavor quality have been expressed by the peanut industry. The objective of this study was to compare the roasted peanut flavorqualities of Georgia Green to those of the long-time industry standard Florunner. This study also provided an opportunity to further expand investigations into the parent selection effects on progeny roasted peanut flavor quality. A total of 192 samples of cultivars Florunner, Georgia Green, and Georgia Green's parents, Southern Runner and Sunbelt Runner, were collected from 1986 to 2000 from the Southeast, Southwest, and Virginia-Carolina peanut production regions. A descriptive sensory panel evaluated flavor attributes of a roasted sound mature kernel (SMK) sample from each plot. The sensory attributes of the four genotypes were compared directly, and the data were included in a Best Linear Unbiased Prediction (BLUP) model of breeding value of 112 peanut cultivars and breeding lines. Georgia Green was not significantly different from the industry standard cultivar Florunner in the sensory attributes roasted peanut [4.5 vs. 4.1 flavor intensity units (flu), ns], bitter (3.2 vs. 3.3 fiu, ns), and astringent (3.3 vs. 3.4 fiu, ns). It was significantly sweeter than Florunner (3.3 vs 3.0 fiu, P < 0.05). The BLUPs of breeding value for roasted peanut and sweet attributes of Georgia Green were among the highest of any peanut lines included in the analysis. Based on this finding, widespread use of Georgia Green as a parent should contribute to flavor improvement in peanut breeding programs.