Estación Experimental Agropecuaria Balcarce, Instituto Nacional de Tecnología Agropecuaria (INTA), Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Balcorce, Argentina.
Plant Biol (Stuttg). 2012 Jul;14(4):543-54. doi: 10.1111/j.1438-8677.2012.00563.x. Epub 2012 Feb 28.
Wild potatoes are native to the Americas, where they present very wide geographical and ecological distribution. Most are diploid, obligate out-crossers due to a multiallelic gametophytic self-incompatibility (S) locus that prevents self-fertilisation and crossing between individuals carrying identical S-alleles. They have two alternative modes of reproduction: sexual (by seeds) and asexual (by stolons and tubers), which provide, respectively, for genetic flexibility in changing environments and high fitness of adapted genotypes under stable conditions. Since the early twentieth century, their taxonomic classification has been mostly based on morphological phenotypes (Taxonomic Species Concept). More recently, attempts have been made to establish phylogenetic relationships, applying molecular tools in samples of populations (accessions) with a previously assigned specific category. However, neither the reproductive biology and breeding relations among spontaneous populations nor the morphological and genetic variability expected in obligate allogamous populations are considered when the taxonomic species concept is applied. In nature, wild potato populations are isolated through external and internal hybridisation barriers; the latter, which are genetically determined, can be either pre-zygotic (pollen-pistil incompatibility) or post-zygotic (abortion of embryo, endosperm or both tissues, sterility, and hybrid weakness and breakdown in segregating generations). The internal barriers, however, can be incomplete, providing opportunities for hybridisation and introgression within and between populations and ploidy levels in areas of overlap. The widespread occurrence of spontaneous hybrids in nature was recognised in the mid-twentieth century. Using genetic approaches, results have been obtained that provide strong support to the assertion that populations are at different stages of genetic divergence and are not at the end of the evolutionary process, as presupposed by the Taxonomic Species Concept. Furthermore, since wild potatoes have uniparental and biparental overlapping generations, the Biological Species Concept - developed for sexually reproducing biparental organisms - cannot be applied to them. In this paper, morphological, genetic, molecular and taxonomic studies in wild potato are reviewed, considering the genetic consequences of their reproductive biology, in an attempt to shed light on the species problem, because of its relevance in germplasm conservation and breeding.
野生马铃薯原产于美洲，那里的地理和生态分布非常广泛。大多数野生马铃薯是二倍体，是强制异交的，这是由于多等位基因的配子体自交不亲和（S）基因座，它阻止了自花授粉和携带相同 S 等位基因的个体之间的杂交。它们有两种替代的繁殖方式：有性（通过种子）和无性（通过匍匐茎和块茎），分别为在不断变化的环境中提供遗传灵活性和在稳定条件下适应基因型的高适应性。自 20 世纪初以来，它们的分类学分类主要基于形态表型（分类物种概念）。最近，人们试图应用分子工具在预先指定特定类别的种群（样本）中建立系统发育关系。然而，在应用分类物种概念时，既没有考虑到自然条件下野生马铃薯种群的繁殖生物学和繁殖关系，也没有考虑到强制异交种群中预期的形态和遗传多样性。在自然界中，野生马铃薯种群通过外部和内部杂交障碍而隔离；后者是由遗传决定的，可以是前合子（花粉-柱头不亲和）或后合子（胚胎、胚乳或两者组织的流产、不育以及在分离世代中的杂种脆弱性和崩溃）。然而，内部障碍可能不完全，为种群内部和种群之间以及重叠区域的多倍体水平的杂交和基因渗入提供了机会。20 世纪中期，人们认识到自然中广泛存在自发杂交种。利用遗传方法，得到的结果为种群处于不同遗传分化阶段而不是处于分类物种概念所假设的进化过程结束的结论提供了强有力的支持。此外，由于野生马铃薯具有单亲性和双亲性重叠世代，因此不能将生物物种概念——为有性繁殖的双亲生物开发的概念——应用于它们。本文综述了野生马铃薯的形态学、遗传学、分子学和分类学研究，考虑了它们繁殖生物学的遗传后果，试图阐明物种问题，因为它与种质保存和繁殖有关。
