and cultivated melons is worldwide. A high level of molecular and morphological variability in leaf, plant, and fruit characteristics has been described in melon species ( Akashi et al., 2002 ; Burger et al., 2006 ; Goldman, 2002 ; Kirkbride, 1993
Emmanouil N. Tzitzikas, Antonio J. Monforte, Abdelhak Fatihi, Zacharias Kypriotakis, Tefkros A. Iacovides, Ioannis M. Ioannides, and Panagiotis Kalaitzis
Don La Bonte and Michael Courtney
Sweetpotato[Ipommabatatas (L.) Lam.] is a major subsistence crop in southern Africa, where iron and zinc deficiency in humans is an important health problem. A cultivar of sweetpotato that is suited for subsistence farming in this region and that is high in iron and zinc could be an important means of combatting these deficiencies. As part of a program of the International Potato Center (CIP) to develop such a cultivar, we are working to identify the high and low range of iron and zinc in sweetpotato cultivars grown throughout the world by testing a number of cultivars for these nutrients. Subsidiary objectives include determining the heritability of iron and zinc levels and surveying the variability in the levels of these nutrients from root to root on the same plant, from plant to plant of the same cultivar, from the proximal to the distal end of a given root, and from cambium to cortex.
Arthur Q. Villordon and Don R. LaBonte
Our research examined whether plants originating from adventitious sprouts from fleshy sweetpotato roots are genetically more variable than plants that arise from pre-existing meristematic regions, i.e., nodes. Our study compared one plant each of `Jewel', `Sumor', and L87-95 clonally propagated for seven generations both nodally and through adventitious sprouts. PCR-based analysis of 60 samples (10 nodal and 10 adventitiously derived plants/genotype) showed 20% polymorphism among adventitious materials vs. 6% among nodally derived plants. An “analysis of molecular variance” showed that differences between propagation methods accounted for 30% of the total marker variability. Our results support previous findings that, relative to non-meristematic materials, meristematic regions strictly control cell division and DNA synthesis that exclude DNA duplication and other irregularities.
Morshidi Maimunah, R.M. Manshardt, and Francis Zee
Populations of wild Carica papaya, previously designated as Carica peltata, were sampled from its native range on the Caribbean coast of Central America (Mexico, Belize, Guatemala, Honduras) and cultivated Carica papaya from both Central and South America were examined for isozyme variability. Thirteen loci from nine enzyme systems (Pgm, Pgi, Idh, Mdh, 6Pgd, Ugpp, Skdh, Aco, Tpi) were scored for all populations. Ten loci were polymorphic and a total of 31 alleles were detected. Isozyme genotypes as determined through segregation analysis were used in the genetic interpretation for eight loci and 18 alleles while six additional loci and 13 alleles were postulated on the basis of phenotypic variation found throughout the species. Nei's genetic identity, I, for both cultivated and wild Carica papaya was >0.9, which is consistent with conspecific populations. Wild papaya populations from different geographic areas appear more related to one another than to domesticates in the same geographic region.
R.S. Balardin and J.D. Kelly
Sixty-two genetically diverse modern and traditional Phaseolus vulgaris L. cultivars from Brazil, the Dominican Republic, Honduras, Mexico, the Netherlands, and the United States, representative of the Andean and Middle American gene pools, were selected to study the interaction with distinct races of Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib. Principal component and phenetic analyses were conducted on the disease reaction to inoculation with 34 races of C. lindemuthianum from Argentina, Brazil, Colombia, Costa Rica, the Dominican Republic, Honduras, Mexico, Peru, and the United States. The principal component analysis revealed four clusters in which only one cluster consisted of cultivars from both gene pools. Bean genotypes clustered based on the gene pool origin of the resistance genes present, regardless of the actual gene pool of the host genotype. Middle American genotypes in cluster A carried Andean resistance genes. Further grouping of genotypes based on overall level of resistance within each gene pool was observed. Clusters A and C consisted of the most resistant genotypes from both gene pools. The distribution of genotypes generated by the phenetic analysis, placed the most resistant and susceptible genotypes of the anthracnose differential series at the extremities of the phenogram, providing support for the range in genotypic resistance exhibited by members of the differential series. Races of C. lindemuthianum isolated from Middle American genotypes showed broad virulence on germplasm from both gene pools, whereas races with Andean reaction showed high virulence only on Andean germplasm. The reduced virulence of Andean races on Middle American genotypes suggests selection of virulence factors congruent with diversity in P. vulgaris. In addition, races of C. lindemuthianum formed two clusters corresponding to the Middle American and Andean reaction groups based on the phenetic analysis. In the principal component analysis, most races with the Andean reaction were observed in the clusters C and D, except races 15 and 23 which clustered with Middle American races in cluster B. Only races 38, 39 and 47 from the Dominican Republic showed high similarity in both multivariate analyses and clustered based on geographic origin. Races from other countries showed no geographic effect. The overlapping of specific races, however, with races from different reaction groups might indicate that this group of isolates possesses factors of virulence to both host gene pools. Data based on virulence supports variability in C. lindemuthianum structured with diversity in P. vulgaris.
Job Teixeira de Oliveira, Rubens Alves de Oliveira, Lucas Allan Almeida Oliveira, Paulo Teodoro, and Rafael Montanari
traits vs. any other characteristic serve as a basis for estimating the spatial variability of a particular variable by means of another easily measured ( Montanari et al., 2015 ). Recently, Viana et al. (2016) studied the productive components of
Long Ma, Kevin E. Kenworthy, Huangjun Lu, and Ronald Cherry
including stolon length, nodes, internodes, leaf length and width, density, turf visual quality, etc. ( Greene et al., 2008a , 2008b ; Skerman and Riveros, 1990 ; Turgeon, 2005 ), this is the first reporting of variability for percentage seed set in
Eric J. Votava and Paul W. Bosland
Random amplified polymorphic DNA (RAPD) analysis can provide a means of evaluating and comparing genetic variability within cultivars. The purpose of this study was to evaluate the relative genetic variability between accessions of two open-pollinated bell pepper cultivars: 'California Wonder', an heirloom cultivar, and 'Jupiter', a modern cultivar. RAPD molecular markers were used to assess the genetic variability between accessions of these two cultivars. The high levels of genetic variability found among accessions of 'California Wonder' may preclude its use as a standard cultivar in research.
Laurence Firmin, Didier Courtois, Vincent Pétiard, Charles Ehret, and Konrad Lerch
Rhizomes of Iris species used for perfume production do not contain scented irones immediately after harvest, precluding early selection of potentially high-producing genotypes. A recently developed technique involving a bacterial treatment (Rahnella aquatilis Izard, Gavini, Trinel, and Leclerc) of fresh rhizomes shortened the maturation time from 3 years to a few days. Variability in irone content among freshly harvested Iris species (76 clones) was evaluated, and three high-producing clones of Iris pallida Lam. were selected. Significant variability among clones was observed for irone content, growth, and yield.
Annick Moing, Nathalie Langlois, Laurence Svanella, Anne Zanetto, and Jean-Pierre Gaudillère
Sorbitol is a sugar alcohol, present with sucrose in Rosaceae trees, which seems to have a role in plant response to environmental stress. The aim of this study was to investigate variability in sorbitol : sucrose ratio in source leaves of 53 species or hybrids of Prunus. The studied taxa, representing three subgenera and 11 sections of the Prunus genus, were chosen from the Prunus collection at the Institut National de la Recherche Agronomique, Bordeaux, France. Young mature leaves were sampled on three dates in spring and summer and were analyzed for neutral soluble sugars using high-performance liquid chromatography. There were differences in sorbitol : sucrose ratio according to sampling date and according to taxon. Sorbitol content increased and sucrose content decreased from May to July, leading to an increase in sorbitol : sucrose ratio. For each date, there was a high variability within botanical sections for sorbitol : sucrose ratio. The highest variability between species for sorbitol : sucrose ratio was in July, with P. cocomilia having the lowest ratio (1.15, w/w) and P. fremontii having the highest ratio (5.59, w/w). When species were pooled according to their geographical zone of origin, species originating from Japan showed the lowest sorbitol : sucrose ratio for all sampling dates. In July, species originating from Japan, Europe, and central to western North America had sorbitol : sucrose ratio significantly lower than that of species originating from Europe to western Asia, China to eastern Asia, and central to eastern North America. These results indicate that variability in sorbitol : sucrose ratio exists in the Prunus germplasm and seems to be related to the geographical origin of the species. Moreover, variability in sorbitol to sucrose ratio is high in the germplasm of different Prunus taxa.