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P ollen H eteromorphism in N icotiana tabacum (S olanaceae )
Author(s) -
TillBottraud Irène,
Mignot Agnès,
De Paepe Rosine,
Dajoz Isabelle
Publication year - 1995
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1995.tb11569.x
Subject(s) - selfing , biology , pollen , cultivar , nicotiana tabacum , botany , hybrid , stamen , population , genetics , gene , demography , sociology
Pollen heteromorphism is defined as the production by a single plant of different fertile pollen types in all its anthers, and thus all flowers, throughout its life cycle. Eight cultivars of Nicotiana tabacum , as well as its ancestors ( N. tabacum is an amphiploid hybrid 4 × from a cross between N. sylvestris and N. tomentosiformis ) and recent hybrids were analyzed. Most cultivars and the hybrids are heteromorphic (producing 3‐ and 4‐aperturate pollen grains), whereas both parent species are homomorphic (3‐aperturate). Heteromorphism is a common consequence of polyploidization and these results agree with this interpretation. There is a significant variation in the proportions of the two pollen types among cultivars (genetic component), but also (with a much lower component of variance) within each cultivar, between plants (genets), flowers of a plant, and even anthers of a flower. This is interpreted as a release of the selective pressure: the cultivars of N. tabacum were obtained after several generations of selfing and are themselves selfers. Selfing, by removing pollen mixtures on a stigma, removes pollen competition, which is the drive for heteromorphism, and allows for a large variation of the proportions of the different pollen types.