Pepper, Capsicum spp., is a worldwide crop valued for heat, nutrition, and rich pigment content. Carotenoids, the largest group of plant pigments, function as antioxidants and as vitamin A precursors. The most abundant carotenoids in ripe pepper fruits are β-carotene, capsanthin, and capsorubin. In this study, the carotenoid composition of orange fruited Capsicum lines was defined along with the allelic variability of the biosynthetic enzymes. The carotenoid chemical profiles present in seven orange pepper varieties were determined using a novel UPLC method. The orange appearance of the fruit was due either to the accumulation of β-carotene, or in two cases, due to only the accumulation of red and yellow carotenoids. Four carotenoid biosynthetic genes, Psy, Lcyb, CrtZ-2, and Ccs were cloned and sequenced from these cultivars. This data tested the hypothesis that different alleles for specific carotenoid biosynthetic enzymes are associated with specific carotenoid profiles in orange peppers. While the coding regions within Psy and CrtZ-2 did not change in any of the lines, the genomic sequence contained introns not previously reported. Lcyb and Ccs contained no introns but did exhibit polymorphisms resulting in amino acid changes; a new Ccs variant was found. When selectively breeding for high provitamin A levels, phenotypic recurrent selection based on fruit color is not sufficient, carotenoid chemical composition should also be conducted. Based on these results, specific alleles are candidate molecular markers for selection of orange pepper lines with high β-carotene and therefore high pro-vitamin A levels.
Accumulation of capsaicinoids in the placental tissue of ripening chile (Capsicum spp.) fruit follows the coordinated expression of multiple biosynthetic enzymes producing the substrates for capsaicin synthase. Transcription factors are likely agents to regulate expression of these biosynthetic genes. Placental RNAs from habanero fruit (C. chinense) were screened for expression of candidate transcription factors; with two candidate genes identified, both in the ERF family of transcription factors. Characterization of these transcription factors, Erf and Jerf, in nine chile cultivars with distinct capsaicinoid contents demonstrated a correlation of expression with pungency. Amino acid variants were observed in both ERF and JERF from different chile cultivars; none of these changes involved the DNA binding domains. Little to no transcription of Erf was detected in non-pungent C. annuum or C. chinense mutants. This correlation was characterized at an individual fruit level in a set of jalapeño (C. annuum) lines again with distinct and variable capsaicinoid contents. Both Erf and Jerf are expressed early in fruit development, 16–20 days post-anthesis, at times prior to the accumulation of capsaicinoids in the placental tissues. These data support the hypothesis that these two members of the complex ERF family participate in regulation of the pungency phenotype in chile.
Onions are an important crop for New Mexico with 7,700 acres (3,116 ha) harvested in the state in 2003 (3). In 2002, onions of several cultivars were first noticed with diamond-shaped chlorotic or bleached lesions on seed stalks or leaves, typical of those reported for Iris yellow spot virus (IYSV). A more widespread survey of breeding stocks and commercial onion fields revealed similar symptoms on thrips-infested onions in Dona Ana and Rio Arriba counties. Incidence of disease symptoms ranged from <0.5 to nearly 30%. Symptomatic leaves were assayed for the presence of IYSV using enzyme-linked immunosorbent assay (ELISA; Agdia, Elkhart, IN) and antisera acquired from Agdia. Symptomatic leaves from breeding and commercial fields tested positive for IYSV. The virus was transmitted by Thrips tabaci from symptomatic onions to three onion cvs. New Mex Mesa, New Mex Vado, and New Mex Cryspy in growth chamber tests. All three cultivars showed symptoms of IYSV and tested positive for the disease using ELISA. However, New Mex Vado and New Mex Cryspy cultivars each showed 24% infection (4 infected plants of 17 tested) compared with 59% infection (10 infected plants of 17 tested) for New Mex Mesa, suggesting that not all cultivars are equally susceptible to the virus. To our knowledge, this is the first report of IYSV in onions in New Mexico, which has also been reported in the western United States in Idaho, Oregon, Colorado, and Washington (1,2,4). References: (1) L. J. du Toit et al. Plant Dis. 88:222, 2004. (2) J. M. Hall et al. Plant Dis. 77:952, 1993. (3) National Agricultural Statistics Service, On-line publication. USDA, 2004. (4) H. F. Schwartz et al. Plant Dis. 86:560, 2002.
From 1999 to 2002, field surveys were conducted in the legume-growing areas of Spain including Ávila, Badajoz, Cádiz, Córdoba, León, Málaga, Murcia, Salamanca, and Zamora provinces. Leaf tissue from 35 asymptomatic and 224 virus symptomatic plants was sampled and analyzed by indirect-ELISA with a specific monoclonal antibody against the potyvirus group (Adgia, Elkhart, IN). All symptomatic plants of bean (Phaseolus vulgaris L.), broad bean (Vicia faba L.), lentils (Lens culinaris L.), and chickpea (Cicer arietinum L.) were positive for potyvirus infection. Identification as Bean yellow mosaic virus (BYMV) was obtained by double-antibody sandwich (DAS)-ELISA with a polyclonal antiserum (Loewe Biochemica Gmbh, Sauerlach, Germany). To analyze the genetic variability of BYMV Spanish isolates, 33 Spanish isolates were selected at random from our BYMV collection, and extracts from these plants were used with primers 1985 (5′-gagagaatgatacacatactgaa-3′) and 1984 (5′-caaggtgagtggacaatgatgg-3′) to amplify by immunocapture (IC)-reverse transcription (RT)-PCR a 524-nt fragment of the BYMV genome that includes the C-terminal 417 nt of the coat protein and 107 nt from the 3′ untranslated region. The IC-RT-PCR products were cloned into pGEM-T easy vector (Promega, Madison, WI) and a minimum of three clones from each PCR amplification were sequenced. BLAST analysis showed that the sequences of 30 samples were 96 to 98% identical to BYMV, but three samples (GenBank Accession Nos. EU860364–66) from bean, broad bean, and lentils had a high (98%) identity with Clover yellow vein virus (ClYVV). Sequence alignments of the ClYVV Spanish isolates and 14 ClYVV isolates from the GenBank (Accession Nos. AB03308, AB004545, AB011819, AF185959, AF203536, D86044, S77521, D95538–94) were obtained using the Clustal X software. Genetic distances were estimated using the Kimura two-parameter method. Within-population and between-population nucleotide diversities were estimated from the genetic distances (2). ClYVV sequences were phylogenetically separated into two clades: one with the three isolates from Japan (Accession Nos. D89542, D89543, and D89544) and the other with the remaining isolates. Molecular clustering coincides with biology and serological variations of strains 1 and 2 (3). Phylogenetic distances were independent of geographic origin, host, or time of sampling. The nucleotide diversity value among populations (0.18) was higher than within the subpopulations (0.017 and 0.029). dNS/dS in the ClYVV population was 0.031 (<1) and we can conclude that negative selection is occurring in the gene in study and that the population of ClYVV present in Spain is homogenous. In Spain, ClYVV was reported infecting borage (Borago officinalis L.) (1). To our knowledge, this is the first report of natural infection of bean, broad bean, and lentils with ClYVV in Spain. ClYVV might cause important economic losses in grain legumes since it causes an important viral disease of legumes worldwide. References: (1) M. Luis-Arteaga et al. Plant Pathol. 45:38, 1996. (2) M. Nei and T. Gojobori. Mol. Biol. Evol. 3:418, 1986. (3) T. Sasaya et al. Virology 87:1014, 1987.
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