Variation over time in morphological phenotypes and reproductive behavior in a natural wild potato population from Tucumán, Argentina

Abstract

The common potato, Solanum tuberosum ssp. tuberosum (tbr, 2n = 4x = 48, 4EBN), has a large number of wild relatives (known as “wild potatoes”) with wide geographic and ecological distribution in the Americas. They form a polyploid series with 2n = 2x to 6x (x = 12), have scarce chromosome differentiation, and can reproduce both sexually (by seeds) and asexually (by tubers and stolons). In nature, wild potatoes can be isolated by external and/or internal hybridization barriers; when incomplete, internal barriers allow for gene flow and introgression between sympatric populations. To develop appropriate strategies to in situ maintain the available genetic diversity and to capture a large part of this diversity for ex situ conservation, it is of utmost importance to understand the reproductive behavior of wild potatoes in their natural environments, and to explore possible over time changes. Information in this regard is lacking. Thus, an integrated analysis of morphological phenotypes and breeding relationships was carried out in a natural population from Tucumán province, Argentina. This population was sampled in two consecutive years following a field design and, ex situ, controlled crosses were carried out between plants derived from the sampled propagules. High morphological variability and absence of relationships between morphological phenotypes and breeding behavior was observed, in addition to changes in the predominant mode of reproduction (either sexual or asexual) over time. These results highlight the necessity of resampling wild potato populations and of applying the gene reservoir concept in natural populations -irrespective of individual plant morphological phenotypes- for both conservation and use of their genetic diversity.