Cryptic Interspecific Introgression and Genetic Differentiation Within Gossypium Aridum (Malvaceae) and Its Relatives

Abstract

Interspecific gene flow is increasingly recognized as an important evolutionary phenomenon in plants. A surprising observation is that historical introgression is often inferred between species that presently have geographic and reproductive barriers that would appear to prohibit the inferred sexual exchange. A striking example concerns Gossypium aridum (subsection Erioxylum); previous analyses have shown that populations from Colima (southwestern Mexico) have a chloroplast genome (cpDNA) similar to that of a different taxonomic subsection (Integrifolia) that presently is confined to Baja California and the Galapagos Islands, whereas other G. aridum populations share a cpDNA lineage with each other and with other species in subsection Erioxylum. To evaluate further the possibility that this cpDNA evidence reflects introgression as opposed to some other evolutionary process, as well as to explore patterns of genetic diversity and similarity in both subsections, we conducted amplified fragment-length polymorphism (AFLP) analysis using 50 populations representing all seven species in the two subsections. Genetic diversity is high in G. aridum, and is strongly correlated with geography, as are similarities among the five species in subsection Erioxylum. This subsection is genetically distant from the two species in subsection Integrifolia, whose populations are highly similar inter se. Populations of G. aridum from Colima are genetically distinct from the remainder of the species, and exhibit a comparatively high frequency of AFLP fragments that otherwise are diagnostic of the Integrifolia lineage. These data implicate intersubsectional introgression between presently allopatric and genetically isolated clades, giving rise to a morphologically cryptic, introgressant entity. Biogeographic considerations suggest that this history was initiated following migration of one or more seeds from Baja California to the Colima coast, perhaps during the Pleistocene. We suggest that cryptic and seemingly improbable interspecific introgression and molecular differentiation may be more common than appreciated in angiosperm evolution.

Assessing genetic diversity in Gossypium arboreum L. cultivars using genomic and EST-derived microsatellites

“…Especially useful have been the PCR-based markers such as random amplified polymorphic DNA (RAPD) (Tatineni et al 1996;Xu et al 2001;Lu and Myers 2002), amplified fragment length polymorphism (AFLP) (Abdalla et al 2001;Alvarez and Wendel 2006), and simple sequence repeats aka microsatellites (SSRs) (Lui et al 2000b;Zhu et al 2003).…”

Molecular Markers and Cotton Genetic Improvement: Current Status and Future Prospects

“…Molecular marker technologies can be classified into hybridization based, PCR based, and sequenced based markers on the basis of their working mechanism. Among these, PCR-based markers, that is, random amplified polymorphic DNA (RAPD) [23, 31, 32], amplified fragment length polymorphism (AFLP) [17, 33], simple sequence repeats microsatellites (SSRs) [34, 35], and inter simple sequence repeats (ISSRs) [36], represent the major class of markers in cotton genomics due to their high utility and exploitation. The comparison of different aspects of generally used molecular markers is given in Table 1 and brief description of these three classes of molecular markers is described below with special reference to cotton genetic.…”

Genetic Diversity in Gossypium genus

“…The New World diploid Gossypium comprises of 14 (one undescribed taxon US-72) D genome species Alvarez and Wendel, 2006;Feng et al, 2011). Taxonomically, these species are recognized as the Houzingenia subgenus (Fryxell, 1979(Fryxell, , 1992 (Percival et al, 1999).…”

“…Studying a large number of accessions for D genome cotton such as G. aridum (D 4 (D 11 ) with AFLP markers Alvarez & Wendel (2006) have reported 7 to 54% genetic diversity among D-genome accessions studied. A wider range of genetic diversity was observed among 12 D-genome diploid cottons with the genetic similarity of 0.08-0.94 (Guo et al, 2007a), suggesting existence of diverse variations in D-genome cotton germplasm useful for breeding programs.…”