Pattern of genetic variability of Solanum habrochaites in its natural area of distribution

Abstract

The tomato wild relative species Solanum habrochaites (previously known as Lycopersicon hirsutum) is a potential source of novel genes for tomato breeding. It shows resistance to many diseases and pests, cold tolerance and fruit quality traits. This species inhabits the western Andean slopes at high elevations from central Ecuador to central Peru. In this study the genetic variation of S. habrochaites was studied using 91 accessions from the whole range of distribution of this species. To this end, we employed two kinds of markers: 9 SSRs and 6 AFLP combinations. The Principal Coordinate Analysis based on AFLP data showed the existence of clinal genetic variation from north to south. The accessions of the different geographic groups were sequentially arranged in the first axis from north to south and a clear separation between them was found. The groups from the centre of the area of distribution showed the highest variation and heterozygosis. The ones from the margins showed lower variability and presented higher homozygosis. The morphotypes typicum and glabratum considered by Müller constituted the extreme forms of the continuous variation in the pubescence grade. These differences in pubescence were not associated with the homozygosis grade.

Genetic diversity of cultivated and wild tomatoes revealed by morphological traits and SSR markers

“…This is indicated by the high similarity coefficient of the 29 cultivated tomatoes (0.845) in this study. By contrast, wild tomatoes, with a lot of valuable genes, are important resources for improving the tolerance to both biotic and abiotic stress, such as S. habrochaites (Hanson et al, 2007;Sifres et al, 2011), which could expand the genetic base of cultivated tomatoes. The 14 wild tomatoes that were included in this study enriched the genetic diversity as indicated by i) their scattered distribution in the three-dimensional PCA plot ( Figure 1); ii) the large genetic distance between them and the cultivated tomatoes ( Figure 3); and iii) the lower similarity coefficient of the wild tomatoes (0.627) as compared to the similarity coefficient of the cultivated tomatoes.…”

Striking Natural Diversity in Glandular Trichome Acylsugar Composition Is Shaped by Variation at the Acyltransferase2 Locus in the Wild Tomato Solanum habrochaites

“…Despite an interest in the possible antimicrobial or insecticidal roles of these metabolites, relatively little is known about their structural diversity or biosynthesis (Ghangas and Steffens, 1993). To document acylsugar diversity within a single species, we analyzed 80 S. habrochaites accessions collected from throughout the range of the species (Supplemental Table S1; Sifres et al, 2011) and M82 cultivated tomato (S. lycopersicum).…”

Transcriptomic analysis links gene expression to unilateral pollen-pistil reproductive barriers

“…The loss of SI at the northern range margin is correlated with the loss of pistil-side SI factor S-RNase [6, 31, 46]; whereas southern S. habrochaites SC populations express an S-RNase protein with little or no RNase activity [31]. The genetic structure of S. habrochaites is consistent with the spread of populations both north and south from a central origin, with central SI populations showing the highest levels of diversity [45, 47]. Interestingly, the types and strengths of reproductive barriers displayed by a number of populations also follow this same latitudinal axis of divergence [6, 45].…”