Peanut skins are a good source of polyphenols, which are a major source of dietary antioxidants. Therefore, the consumption of whole peanut seeds, including the skin, has been recommended by nutritional authorities. Here, the polyphenol contents of the skins of 22 experimental line, varying in skin color, and four Israeli cultivars were examined. The total phenolic (TPC), total flavonoid (TFC), total anthocyanin (TAC) contents and antioxidant capacity (AOC) of isolated skins were measured. Whereas significantly high correlation coefficients were found among the TPC, TFC and AOC, no significant correlations were found between any of these factors and skin color. On the other hand, TAC was significantly correlated with skin color. Our results clearly indicate that the AOC of peanut skins is not directly related to the intensity of their color and that the presence of colorless flavonoids might be the reason for the high AOC of peanut skins. PRACTICAL APPLICATIONSPeanut is the main summer legume crop in Israel. Recently, in response to strong demand among the European public for food products with added health value, breeders have considered developing peanut lines as functional foods. Peanut seed coats contain large amounts of important polyphenolic compounds. For this reason, peanuts are considered to be a good functional food when consumed as whole seeds. In order to determine the functional food potential of Israeli peanuts, the variability and relations of total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant capacity (AOC) among these and other imported peanut lines with a wide range of skin colors were evaluated. While significant correlations were found between TAC and skin color, no significant correlations were found between the other polyphenolic factors or AOC and peanut skin color. Actually, the Israeli cultivars that have light pink skins were found to have higher TPC, TFC and AOC than most of the lines with red, purple or white skins. This finding demonstrates that the high AOC of the Israeli cultivars is due to colorless compounds, a notion that should be taken into consideration in breeding programs aiming to integrate elevated AOC of the skin with other favorable traits.bs_bs_banner Journal of Food Biochemistry

The growth habit of lateral shoots (also termed “branching habit”) is an important descriptive and agronomic character of peanut. Yet, both the inheritance of branching habit and the genetic mechanism that controls it in this crop remain unclear. In addition, the low degree of polymorphism among cultivated peanut varieties hinders fine-mapping of this and other traits in non-homozygous genetic structures. Here, we combined high-throughput sequencing with a well-defined genetic system to study these issues in peanut. Initially, segregating F2 populations derived from a reciprocal cross between very closely related Virginia-type peanut cultivars with spreading and bunch growth habits were examined. The spreading/bunch trait was shown to be controlled by a single gene with no cytoplasmic effect. That gene was named Bunch1 and was significantly correlated with pod yield per plant, time to maturation and the ratio of “dead-end” pods. Subsequently, bulked segregant analysis was performed on 52 completely bunch, and 47 completely spreading F3 families. In order to facilitate the process of SNP detection and candidate-gene analysis, the transcriptome was used instead of genomic DNA. Young leaves were sampled and bulked. Reads from Illumina sequencing were aligned against the peanut reference transcriptome and the diploid genomes. Inter-varietal SNPs were detected, scored and quality-filtered. Thirty-four candidate SNPs were found to have a bulk frequency ratio value >10 and 6 of those SNPs were found to be located in the genomic region of linkage group B5. Three best hits from that over-represented region were further analyzed in the segregating population. The trait locus was found to be located in a ~1.1 Mbp segment between markers M875 (B5:145,553,897; 1.9 cM) and M255 (B5:146,649,943; 2.25 cM). The method was validated using a population of recombinant inbreed lines of the same cross and a new DNA SNP-array. This study demonstrates the relatively straight-forward utilization of bulk segregant analysis for trait fine-mapping in the low polymeric and heterozygous germplasm of cultivated peanut and provides a baseline for candidate gene discovery and map-based cloning of Bunch1.

The stearoyl-acyl carrier protein (ACP) desaturase (SAD) is a nuclear-encoded, plastid-localized soluble desaturase that catalyzes the conversion of stearoyl-ACP to oleoyl-ACP and plays a key role in the determination of the properties of the majority of cellular glycerolipids. Sad genes from a variety of plant species have been cloned and characterized. However, in peanut (Arachis hypogaea), an important edible and oilseed crop, these genes have not yet been characterized. By searching peanut expressed sequence tag (EST) and parallel sequencing (454) libraries, we have identified three members of the ahSad gene family. Among them, only one gene, ahSad3, was exclusively expressed during seed development and in a manner fully corresponding to oil accumulation. Both ahSad3 homeologous genes (ahSad3A and ahSad3B) were recovered from the allotetraploid peanut, and their mRNA expression levels were characterized. The open reading frames for ahSad3A and ahSad3B are 98% identical and consist of 1,158 bp, encoding a 386-full-amino-acid protein, with one intron in the coding sequence. Comparisons of the sequences of these two homeologous genes revealed seven singlenucleotide polymorphisms and one triplet insertion in the coding region. Southern blot analysis indicated that there are only two copies of the ahSad3 gene in the peanut genome. Homeolog-specific gene expression analysis showed that both ahSad3 homeologs are expressed in developing seeds, but gene expression is significantly biased toward the B genome. Our results point to ahSad3 as a possible target gene for manipulation of fatty acid saturation in A. hypogaea.

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Pod wart disease severely damages in‐shell peanut (Arachis hypogaea L.) production in areas in which peanut is routinely rotated with potato (Solanum tuberosum L.). It is caused by soil‐borne Streptomyces that cause unsightly scabs that render the affected pods unmarketable. Since all elite peanut cultivars are susceptible to pod wart, a new genetic source of resistance is required. Here, the identification and evaluation of a new genetic source of pod wart resistance is reported. The US mini‐core peanut collection was evaluated under field conditions, and the least susceptible genotypes were reevaluated in three locations. This led to the identification of two “landrace” genotypes that were significantly resistant to pod wart, with an average of 70% less infection than the control line. Two populations were prepared from crosses between these genotypes and an elite cultivar. Genetic analysis of segregating F2 populations showed that pod wart tolerance is polygenic with medium heritability estimations. No significant correlation was found between the incidence of pod wart and pod reticulation, indicating that the deep reticulation does not provide resistance. In addition, no significant correlation was found between the incidence of pod wart and pod yield, seed weight, or seed ratio. However, the incidence of disease was positively correlated with pod weight and pod length, indicating genetic linkage or a pleotropic effect on pod wart resistance. This study suggests that pod wart resistance can be selected in early generations of breeding pedigrees, but large populations are needed for optimal pyramiding of other pod‐ and yield‐related traits.