Premium
STERILITY BARRIERS OF SOME ARTIFICIAL F 1 ORCHID HYBRIDS: MALE STERILITY. I. MICROSPOROGENESIS AND POLLEN GERMINATION
Author(s) -
Stort Maria Neysa Silva
Publication year - 1984
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.1537-2197.1984.tb12519.x
Subject(s) - pollen , biology , pollen tube , germination , sterility , hybrid , botany , ovule , microspore , ovary , double fertilization , ploidy , gamete , gametophyte , stamen , gynoecium , pollination , genetics , sperm , gene
Microsporogenesis, pollen germination and fertility of males gametes were studied in 24 artificial intergeneric and interspecific F 1 hybrids of orchids. Although parental species had the same chromosome number (2 n = 40), microsporogenesis of the hybrids was irregular due to the lack of homology of the chromosomes of the parental species. This led to formation of tetrads of microspores without micronuclei, tetrads with 1–8 micronuclei, triads, dyads with and without micronuclei, and monads. Chromosomes numbers found in haploid microsporocytes ranged from 7 to 40; in micronuclei the chromosome number varied between 1 and 5. In terms of pollen germination, three situations were observed: 1) hybrids whose pollen grains did not germinate in the stigma; 2) hybrids in which the pollen tubes grew down in the style, but did not penetrate into the ovary; 3) hybrids in which the pollen tubes grew down normally through the ovary, reaching the ovules. When the pollen tubes did not penetrate the ovary no fruit was formed. Therefore germination tests carried out in vitro may not indicate pollen fertility, because pollen tube growth in the style of the flower may be insufficient to induce fruit formation or to accomplish fertilization.