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CHROMOSOME HOMOLOGY IN SOME INTERCONTINENTAL HYBRIDS IN HIBISCUS SECT. FURCARIA
Author(s) -
Menzel Margaret Y.,
Martin Diana W.
Publication year - 1971
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.1537-2197.1971.tb09962.x
Subject(s) - biology , hybrid , genome , genetics , botany , pollen , gene
Ten kinds of interspecific hybrids were obtained involving the following species: H. surattensis L. (2x, genome constitution BB), H. sudanensis Hochr. (2x, GG), and H. rostellatus Guill. and Perr. (4x, GGHH) from Africa; H. furcatus Roxb. non Willd. (8x) from India and Ceylon; H. furcellatus Lam. and H. bifurcatus Cav. (both 4x, PPQQ) from South America; and H. heterophyllus Vent. (6x) from Australia. Chromosome pairing in pollen mother cells (PMC's) at metaphase I in the 4x hybrids H. bifurcatus‐rostellatus and H. furcellatus‐rostellatus indicated that the parents have one genome in common (Q = G or H). Hibiscus furcatus was shown earlier to have a B genome; hybrids of H. surattensis‐sudanensis F 1 X furcatus were hexaploid, having received an unreduced gamete from their hybrid parent, and had approximately 36 II, 36 I in PMC's. The genome formula of H. furcatus may therefore be designated BBGGWWZZ. The hybrid H. rostellatus‐furcatus (BGGHWZ) confirmed that H. furcatus has a G genome in common with H. rostellatus ; pairing of the other three genomes was inconsistent, as was that in H. rostellatus‐heterophyllus . Some samples of the latter approached 36 II, 36 I, expected if H. heterophyllus were GGHHJJ; other samples had less pairing. Hibiscus furcatus‐heterophyllus hybrids apparently arose from unreduced gametes of H. heterophyllus and originated as decaploids rather than heptaploids; chromosome number was unstable in PMC's. Nevertheless, multivalents, especially trivalents, were frequent enough to suggest that H. furcatus and H. heterophyllus share G genomes. On the other hand, an 8x H. bifurcatus‐furcatus hybrid, which apparently arose from an unreduced gamete of H. bifurcatus , had a low multivalent frequency. Hybrids were obtained of H. heterophyllus X sudanensis and H. surattensis‐sudanensis X heterophyllus , but the plants were weak and were not analyzed cytologically. We suggest that the New World, African, Indian, and Australian genomes which retain a considerable degree of homology (G or H or both) were distributed by land prior to separation of the southern continents by continental drift.