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ABSTRACT Waxy locus introns from 35 accessions of the species comprising the Capsicum annuum complex [C. annuum (7), C. frutescens (10), and C. chinense (11)], C. baccatum (5), C. chacoense [...]

The triploid genome of plantain (Musa spp., AA group) has been considered intractable to genetic improvement because of the production of putatively homogeneous 2n (= 3x) gametes. Plantain breeding schemes have been based on the hybridization of 2n megaspores from the triploid plantain and haploid microspores from a wild diploid banana. The resultant full-sib populations of tetraploid hybrids exhibited extreme variation in phenotypic characteristics. This study was conducted to analyze the genetic constitution of tetraploid hybrids in order to characterize the nature of the gametes from which they were derived. Parental genotypes were screened with 31 primer pairs specific to different Musa microsatellite loci. Primers which detected polymorphisms between the parental genotypes were used to screen a population of 14 full-sib tetraploid hybrids. A subset of primers was also used to screen a population generated by self-pollination of the parental diploid banana. During analysis of the tetraploid hybrid population, 75% of the alleles donated by the maternal genotype (Obino l'Ewai) were observed to segregate. These data demonstrate the occurrence of recombination during the formation of 2n megaspores in triploid plantain. Analysis of the paternal diploid banana accession (Calcutta 4) and its selfed progeny suggests that this accession is highly heterozygous. These data demonstrate the importance of genetic characterization to Musa breeding, and also indicate that microsatellite markers are well suited for marker-assisted selection systems in Musa., Plantain, a cultivated triploid (2n=3x=33) giant perennial herb, is a natural interspecific hybrid between the two wild species, M. acuminata Colla. and M. balbisiana Colla., which provided the A and [...]

The in trust sweetpotato collection housed by the International Center of Potato (CIP) is one of the largest assemblages of plant material representing the genetic resources of this important staple crop. The collection currently contains almost 6,000 accessions of Ipomoea batatas (cultivated sweetpotato) and over 1,000 accessions of sweetpotato crop wild relatives (CWRs). In this study, the entire cultivated collection (5,979 accessions) was genotyped with a panel of 20 simple sequence repeat (SSR) markers to assess genetic identity, diversity, and population structure. Genotyping and phenotyping of in vitro plantlets and mother plants were conducted simultaneously on 2,711 accessions (45% of the total collection) to identify and correct possible genetic identity errors which could have occurred at any time over the thirty plus years of maintenance in the in vitro collection. Within this group, 533 accessions (19.6%) had errors in identity. Field evaluations of morphological descriptors were carried out to confirm the marker data. A phylogenetic tree was constructed to reveal the intraspecific relationships in the population which uncovered high levels of redundancy in material from Peru and Latin America. These genotypic data were supported by morphological data. Population structure analysis demonstrated support for four ancestral populations with many of the accessions having lower levels of gene flow from the other populations. This was especially true of germplasm derived from Peru, Ecuador, and Africa. The set of 20 SSR markers was subsequently utilized to examine a subset of 189 accessions from the USDA sweetpotato germplasm collection and to identify and reconcile potential errors in the identification of clones shared between these collections. Marker analysis demonstrated that the USDA subset of material had 65 unique accessions that were not found in the larger CIP collection. As far as the authors are aware, this is the first report of genotyping an entire sweetpotato germplasm collection in its entirety. [ABSTRACT FROM AUTHOR]

The United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Plant Genetic Resources Conservation Unit in Griffin, GA maintains the United States germplasm collection for Ipomoea spp. (Convolvulaceae). During 2012-2014, 737 sweetpotato, Ipomoea batatas (L.) Lam., plant introductions (PI) were acquired as tissue-culture plantlets and then acclimated to greenhouse conditions at the USDA, ARS, U. S. Vegetable Laboratory (USVL), Charleston, SC. Single plants were transferred to plastic-covered plant beds to produce cuttings for replicated field trials. Storage roots were harvested from 690 PIs grown in the field and 695 PIs grown in pots. Color coordinates were obtained for each PI using a tristimulus colorimeter. Hue angle values (h*) ranged from 8.2° to 88.3° (x¯ = 54.9°) for the periderm (peel or skin) of field-grown storage roots (n = 690 PIs) and − 9.4° (= 350.6°) to 96.2° (x¯ = 51.3°) for pot-grown roots (n = 695 PIs). The red-green coordinate (a*) ranged from 0.8 to 30.7 (x¯ = 12.8) for the periderm of field-grown roots and − 2.0 to 44.9 (x¯ = 16.1) for pot-grown roots. The yellow-blue coordinate (b*) ranged from 2.8 to 33.1 (x¯ = 19.4) for the periderm of field-grown roots and − 7.4 to 38.1 (x¯ = 19.3) for pot-grown roots. Color saturation (chroma, C*) ranged from 13.7 to 35.8 (x¯ = 24.9) for the periderm of field-grown roots and 14.9-45.5 (x¯ = 29.3) for pot-grown roots. Lightness (white-black, L*) ranged from 32.6 to 81.7 (x¯ = 54.6) for the periderm of field-grown roots and 32.1-88.2 (x¯ = 64.0) for pot-grown roots. Hue angles ranged from − 13.1° (= 346.9°) to 100.9° (x¯ = 80.9°) for the stele (flesh) of field-grown storage roots (n = 672 PIs) and − 29.9° to 103.5° (x¯ = 81.6°) for pot-grown roots (n = 676 PIs); a* ranged from − 5.6 to 35.0 (x¯ = 8.0) for the stele of field-grown roots and − 6.0 to 41.0 (x¯ = 7.6) for pot-grown roots; and b* ranged from − 7.7 to 56.1 (x¯ = 34.6) for the stele of field-grown roots and − 12.6 to 56.1 (x¯ = 31.8) for pot-grown roots. C* ranged from 12.7 to 65.8 (x¯ = 37.2) for the stele of field-grown roots and 8.9-65.7 (x¯ = 34.5) for pot-grown roots; and L* ranged from 27.8 to 91.1 (x¯ = 77.7) for the stele of field-grown roots and 28.2-91.9 (x¯ = 80.4) for pot-grown roots. There were significant relationships between stele color (h*) and percent dry matter, with orange stele having a significantly lower % dry matter (x¯ = 25.6%, n = 183) compared with roots with cream/white stele (x¯ = 30.8%, n = 373). There appears to be wide genetic diversity for root color characteristics for the United States sweetpotato germplasm collection. [ABSTRACT FROM AUTHOR]