Solanum malmeanum, um parente silvestre promissor para o melhoramento da batata

Abstract

Solanum malmeanum (Solanum sect. Petota, Solanaceae) is a wild relative of the cultivated potato (S. tuberosum), native from the Southern Cone of South America and distributed in Argentina, Brazil, Paraguay and Uruguay. S. malmeanum was historically mistakenly identified or traditionally considered as conspecific with S. commersonii, becoming a neglected genetic resource regarding its applied uses in breeding. To elucidade the potential of this species towards the use in potato breeding, this dissertation is organized into two chapters. Chapter 1 presents a review of literature, specimens from herbaria and gene banks. The available information was updated to allow the recognition and aid the applied use of this wild potato in breeding. Data on taxonomy, geographic distribution, ecology, reproductive biology, and information about resistance to address abiotic and biotic stresses are provided. Moreover, methods to overcome barriers of reproduction and hybridization are discussed, for the efficient application in potato breeding program. Chapter 2 present studies on reproductive biology and cross-ability relationship based on intra- and interspecific crosses under controlled conditions using plant accessions of Embrapa Clima Temperado Potato Gene Bank. The essays demonstrated that five diploid accessions of S. malmeanum (BGB015, BGB017, BGB446, BGB447, BGB471) and three triploids (BGB021, BGB080, BGB448) produce fertile pollen, while two triploid accessions (BGB084, BGB448) do not produce pollen. Two triploid accessions (BGB021, BGB448) produce spontaneous and induced parthenocarpic fruits. Self-pollination and apomixis are absent in all evaluated accessions. Five diploid accessions (BGB015, BGB017, B446, BGB447, BGB471) and two triploid ones (BGB080 and BGB448) are allogamous and fertile as female genitor when bulk pollinated, while three triploid accessions (BGB021, BGB081, BGB084) do not produce seeds from same conditions and reproduce only vegetatively. The reconize of a self-compatible accession (BGB447) with potential for the development of diploid inbred lines is highlighted. The diploid accessions of S. malmeanum easily hibridize with BGB1 2x (1EBN) S. commersonii, producing normal and viable seeds. The accessions BGB017, BGB021, BGB080, BGB446, BGB447 and BGB448 also hybridize with BGB444 2x (2EBN) S. chacoense, but the number of seeds and germination were limited. Direct crosses between S. malmeanum (1EBN) and 4 (4EBN) S. tuberosum (cultivar BRSANA and breeding line C1750-15-95) fails and confirms the expected reproductive incompatibility. However, the partial success of S. malmeanum when crossed with S. chacoense suggests the presence of mechanisms that could help to overcomes barriers of hybridization residing on EBN and facilitates the introgression of genes via bridge-crossings.