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Discs of cortical and perimedullary tissue from tubers of potato (Solanum tuberosum L. cv. Superior) formed adventitious shoots when cultured on a medium containing Murashige and Skoog's salts, myo-inositol, 100 mg/l; folic acid, 0.5 mg/l: D-biotin, (0.05 mg/l; gibberellic acid (GA3), 0.5 mg/l; thiamine HCl, 0.1 mg/l; glycine, 2.0 mg/l; pyridoxine HCl, 0.5 mg/l; nicotinic acid, 0.5 mg/l; sucrose, 25 g/l; casein hydrolysate, 1 g/l Bacto agar, 9.0 g/l; and a cytokinin [N6-benzylaminopurine (BAP), N6-γ,γ-dimethylallylaminopurine (2iP), or N6-furfurylaminopurine (kinetin)]. Discs of pith tissue either failed to survive or produced callus but did not undergo morphogenesis. Cytokinin was essential for explant survival, while BAP at 3.0 mg/l was most efficacious in promoting shoot initiation. Auxin was not essential for shoot initiation or development; however, a low concentration (0.03 mg/l) of α-naphthaleneacetic acid (NAA) stimulated both explant survival and the number of shoots produced per disc. Indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) did not stimulate shoot initiation. GA3 was essential for both shoot initiation and subsequent shoot development. The highest incidence of morphogenesis (over 100 shoots in 12 weeks) occurred from tuber discs cultured at 18°C constant and under a photon flux density of 60 μE m-2s-1. No difference in regenerative ability was found in explants taken from source tubers stored for 0 to 20 weeks at 4°C. A histological examination indicated that shoots developed from small clusters of meristematic cells which were initiated from within small protuberances on the surface of the tuber disc 3 weeks after transfer. [ABSTRACT FROM AUTHOR]

During 2012-14, 737 sweetpotato, Ipomoea batatas (L.) Lam. (Convolvulaceae), plant introduction (PI) accessions from the U.S. Department of Agriculture, Agricultural Research Service (USDA, ARS) sweetpotato germplasm collection were evaluated for several phenotypic leaf and plant characteristics, and a photographic record of each accession was made. Data were prepared for placement in the USDA, ARS Germplasm Resources Information Network (GRIN) database and the sweetpotato ontology. The parameters recorded for each genotype were canopy coverage, vine length, general leaf outline, leaf lobing, shape of the central leaf lobe, number of leaf points, leaf petiole length, leaf width, leaf length, leaf width 3 length, and leaf width/length (aspect ratio). The data indicate that there is wide genetic diversity for vegetative phenotypic characteristics within the USDA, ARS sweetpotato germplasm collection. This study provides important phenotype information for the USDA, ARS sweetpotato collection that has been lacking and can be used for curation of the collection and by researchers and breeders working with this important global food crop. [ABSTRACT FROM AUTHOR]

Elevated concentrations of heavy metals in edible plants could expose consumers to excessive levels of potentially hazardous chemicals. Sixty-three accessions (genotypes) of Capsicum chinense Jacq, collected from 8 countries of origin were grown in a silty-loam soil under field conditions. At maturity, fruits were collected and analyzed for seven heavy metals (Cd, Cr, Ni, Pb, Zn, Cu, and Mo) concentrations. The main objectives of this investigation were: 1) to determine the concentrations of seven heavy metals in the soil and monitor their accumulation in mature fruits, 2) to categorize the pepper accessions as low or high heavy metal accumulators, and 3) to determine if heavy metal content of the pepper fruit was lower than the permitted limits. Concentrations and relative proportions of heavy metals in pepper fruits of C. chinense varied among accessions. Fruits of Plant Introduction (PI) 355820 accumulated significant concentrations of Cd (0.47 μg g(-1) dry fruit). PI-260522 accumulated the highest concentration of Pb (2.12 μg g(-1) dry fruit) among the 63 accessions tested. This accession (PI-260522) contained about twice the Pb limit on a fresh weight basis. Among the 63 accessions analyzed, PI-238051 contained the highest levels of Ni (17.2 μg g(-1)). We concluded that high accumulator genotypes may be useful for phytoremediation, while, low accumulator accessions might be appropriate selections for growing on Cd-, Pb-, or Ni-contaminated soils to prevent potential human exposure to heavy metals and health hazards through the food chain.

The main objective of this investigation was to evaluate fruits of C. chinense accessions for their concentration of beta -carotene, ascorbic acid, and phenols for use as parents in breeding for these phytochemicals. Mature fruits of 63 accessions of C. chinense originally acquired from Belize, Brazil, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and the United States were analyzed for their chemical composition. Fruits of C. chinense accessions PI-152452 (Brazil) and PI-360726 (Ecuador) contained the greatest concentrations of ascorbic acid (1.2 and 1.1 mg g(-1) fresh fruit, respectively), while PI-438648 (Mexico) contained the greatest concentration of total phenols content (349 micro g g(-1) fresh fruit) among the other 63 accessions tested. Accession PI-355817 from Ecuador contained the greatest concentrations of beta -carotene (8 mg g(-1)fresh fruit). These accessions were identified as potential candidates for mass production of antioxidants with health-promoting properties.

Fruits of 63 accessions of Capsicum chinense Jacq. from the USDA/ARS Capsicum germplasm collection were analyzed for two major capsaicinoids, capsaicin and dihydrocapsaicin, using gas chromatography with nitrogen phosphorus detection (GC/NPD). The objectives of the present investigation were: (i) to quantify the major capsaicinoids (capsaicin and dihydrocapsaicin) in fruits of Capsicum chinense accessions and (ii) to identify accessions containing great concentrations of capsaicinoids among countries of hot pepper origin. Seeds of C. chinense accessions received from Belize, Brazil, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and United States were field grown in a silty-loam soil. Mature fruits were analyzed for major capsaicinoids content. Capsaicin concentrations were generally greater than dihydrocapsaicin. Fruits of C. chinense accession PI640900 (USA) contained the greatest concentration of capsaicin (1.52 mg g(- 1) fruit) and dihydrocapsaicin (1.16 mg g(- 1) fruit), while total major capsaicinoids in the fruits of PI438648 (Mexico) averaged 2 mg g(- 1) fruit. These two accessions were identified as potential candidates for mass production of major capsaicinoids that have health-promoting properties and for use as a source of pest control agents in agricultural fields.

Ninety Capsicum accessions selected from the USDA Capsicum germplasm collection were screened for their capsaicinoids content using gas hromatography with nitrogen phosphorus detection (GC/NPD). Fresh fruits of Capsicum chinense, C. frutescens, C. baccatum, C. annuum, and C. pubescens were extracted with methanol and analyzed for capsaicin, dihydrocapsaicin, and nordihydrocapsaicin. Mass spectrometry of the fruit crude extracts indicated that the molecular ions at m/z 305, 307, and 293, which correspond to capsaicin, dihydrocapsaicin, and nordihydrocapsaicin, respectively, have a common benzyl cation fragment at m/z 137 that can be used for monitoring capsaicinoids in pepper fruit extracts. Capsaicin and dihydrocapsaicin were the dominant capsaicinoids detected. Capsaicin concentrations were typically greater than dihydrocapsaicin. Concentrations of total capsaicinoids varied from not detectable to 11.2 mg fruit(-1). Statistical analysis revealed that accession PI-441624 (C. chinense) had the highest capsaicin content (2.9 mg g(-1) fresh fruit) and accession PI-497984 (C. frutescens) had the highest dihydrocapsaicin content (2.3 mg g(-1) fresh fruit). Genebank accessions PI-439522 (C. frutescens) and PI-497984 contained the highest concentrations of total capsaicinoids.