Development and cytometric evaluation of interspecific F1 hybrids Nicotiana tabacum × N. africana

Abstract

One of the most important threats to tobacco cultivation is the Potato virus Y (PVY). Sources of resistance to PVY are found both in Nicotiana tabacum cultivars and in wild Nicotiana species. The high variability of the virus and the ability to break the existing resistance make it necessary to search for new resistance sources or to combine the ones that are already known. The aim of the study was to combine va resistance of two cultivars VAM and Wiślica, showing resistance to most PVY isolates, with the wild Nicotiana africana species, which is immune to all known PVY isolates. Due to the significant genetic distance between these species, the seedlings of the obtained F1 hybrids were not viable. In order to obtain viable hybrids, cotyledon in vitro cultures were used. Growth and development of the callus, as well as plant regeneration were differentiated depending on the maternal component used in the crossing with N. africana. The cotyledons of hybrids derived from cultivar VAM regenerated more efficiently, as 88 amphihaploid hybrid plants were obtain from this maternal parent. In contrast, only 27 amphihaploid hybrid plants were derived from cultivar Wiślica. Infertility of amphihaploid plants hampered their use in the breeding process. In order to restore fertility, the process of organogenesis from stem piths under in vitro conditions, was used. The degree of ploidy of regenerated plants was determined using flow cytometry. Despite the use of the same in vitro culture conditions for all the objects, a significant influence of the maternal component on the number of obtained regenerants and on the degree of their ploidy level was observed.