Phylogenetic analysis of the highland papayas (Vasconcellea) and allied genera (Caricaceae) using PCR-RFLP

Abstract

The chloroplast and mitochondrial DNA diversity of 61 genotypes belonging to 18 Vasconcellea species, the so-called highland papayas, was studied by PCR-RFLP analysis of two non-coding cpDNA regions ( trnM- rbcL and trnK1- trnK2) and one non-coding mtDNA region ( nad4/1- nad4/2). This sample set was supplemented with six genotypes belonging to three other Caricaceae genera: the monotypic genus Carica, including only the cultivated papaya, and the genera Jacaratia and Cylicomorpha. Moringa ovalifolia was added as an outgroup species. The PCR-amplified cpDNA regions were digested with 18 restriction endonucleases, the mtDNA region with 11. A total of 22 point mutations and four insertion/deletions were scored in the sample. A higher level of interspecific variation was detected in the two cpDNA regions in comparison to the analysis of the mtDNA. Wagner parsimony and Neighbor-Joining analysis resulted in dendrograms with similar topologies. PCR-RFLP analysis supported the monophyly of Caricaceae, but among the 26 mutations scored, an insufficient number of markers discriminated between the different Caricaceae genera included in this study. Hence the inference of the intergeneric relationships within Caricaceae was impossible. However, some conclusions can be noted at a lower taxonomic level. The Caricaceae species were divided into two lineages. One group included only Vasconcellea spp., whereas the second included the remaining Vasconcellea spp., together with the papaya genotypes and those from the other Caricaceae genera. This may indicate a higher level of inter-fertility for the Vasconcellea species from the latter clade in interspecific crossings with papaya. The putative progenitors of the natural sterile hybrid V. x heilbornii, i.e. V. stipulata and V. cundinamarcensis, were only distantly related to V. x heilbornii. This indicates that probably none of these species was involved as the maternal progenitor in the origin of V. x heilbornii. Surprisingly, V. x heilbornii had organellar genome patterns identical with V. weberbaueri, suggesting a possible involvement of this species in the origin of V. x heilbornii. On the basis of discrepancy between morphological traits and the cpDNA profiles of some pairs of Vasconcellea species, we believe that besides V. x heilbornii, some other species have originated through interspecific hybridization. A reticulate evolution for Vasconcellea has therefore been suggested. Finally, intraspecific cpDNA variation was detected in V. microcarpa, thus providing molecular evidence for the high diversity previously indicated by morphological observations.

A nuclear DNA barcode for eastern North American oaks and application to a study of hybridization in an Arboretum setting

“…In the past, markers such as restriction fragment length polymorphisms (RFLP), amplified fragment length polymorphisms (ALFP), and simple‐sequence repeats (SSR) have been used for population genetics, phylogenetics, and genotype/phenotype studies in a wide range of forest trees, including oaks (Chagné, Lalanne, Madur, Kumar, & Frigério, 2002; Curtu et al., 2007; Durand et al., 2010; Hipp & Weber, 2008; Hipp et al., 2014; Van Droogenbroeck et al., 2004). However, ascertainment bias (Putman & Carbone, 2014), reproducibility issues, and species specificity (Twyford & Ennos, 2012) often limit their utility across a range of species.…”

Moisture sorption isotherms and isosteric heat determination in Chilean papaya (Vasconcellea pubescens)

“…The Chilean papaya, Vasconcellea pubescens, which grows in a temperate climate regime, is a distant relative of the tropical papaya Carica papaya L. 1,2 Most of the Chilean papayas come from the (irrigated) region around La Serena, Chile (ca.30 ºS) which has a Mediterranean-type climate, typically overcast mornings and evenings, and an annual relative humidity normally over 80%. 3 The Chilean papaya is very different from the tropical papaya in that it is much smaller, and is consumed whole, only after cooking, with the seeds removed.…”

ISSR markers for genetic relationships in Caricaceae and sex differentiation in papaya

“…These data supported a recent rehabilitation of Vasconcellea as a genus category (Badillo 2000). On the other hand, Van Droogenbroeck et al (2004) analyzed the diversity of 18 Vasconcellea species and corroborated the monophyly of Caricaceae in the genera Carica, Jacaratia and Cylicomorpha by RFLP. According to these authors, Caricaceae species are divided into two lineage groups, one with some Vasconcellea spp., including V. monoica and V. goudotiana and the second with the other Vasconcellea species, C. papaya, Jacaratia and Cylicomorpha.…”

“…Some interspecific crosses using embryo rescue were successful (Magdalita et al 1996, Manshardt and Drew 1998. For a better understanding of the genetic relationships in Caricaceae, several molecular studies have been performed, suggesting a considerable genetic distance between Carica and Vasconcellea (Jobin-Decor et al 1997, Aradhya et al 1999, Olson 2002, Van Droogenbroeck et al 2004, Kyndt et al 2006 (Hofmeyr 1938, Storey 1938. Nevertheless, the sex can only be identified when plants are flowering.…”