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PHENOTYPIC VARIATION IN TRISOMICS OF CLARKIA UNGUICULATA
Author(s) -
Vasek Frank C.
Publication year - 1963
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.1537-2197.1963.tb07197.x
Subject(s) - biology , quantitative trait locus , heritability , pollen , genetics , trait , population , sepal , botany , stamen , gene , demography , sociology , computer science , programming language
V asek , F. C. (U. California, Riverside.) Phenotypic variation in trisomics of Clarkia unguiculata. Amer. Jour. Bot. 50(4): 308–314. 1963.—Progenies of 3 n × 2 n crosses included, in addition to diploids, plants trisomic for 1, 2, 3, 4, 5, 6 or 7 chromosomes. Means and variances were calculated for 15 phenotypic traits, including 3 width/length ratios, in one set of progenies, and for 10 of the traits, including 2 of the ratios, in another set of progenies. In 25 trait comparisons, including 15 different traits, the means for each chromosome number class were heterogeneous in 11 comparisons, which included 8 different traits. Single trisomics differed significantly from diploids in 5 comparisons (4 different traits). Despite these significant differences the variation followed no particular pattern except that sepal length increased and pollen fertility decreased with chromosome number, and trisomics, as a group, sometimes differed from diploids with regard to the width/length ratio of leaves or petals. The variances were heterogeneous in 5 comparisons (4 different traits). Sepal length and pollen fertility were the only traits for which single trisomics were more variable than diploids and for which the entire population was more variable than diploids. In addition, in 4 progenies of self‐pollinated trisomics, diploids and trisomics (which within each progeny were trisomic for the same Chromosome) differed significantly in mean value in only 3 traits (out of 60 trait comparisons). Variances were significantly different in 6 comparisons (4 different traits) but, surprisingly, diploids were more variable than trisomics in 3 of these 6 comparisons. Except for sepal length, pollen fertility and some width/length ratios, a wide variety and number of extra chromosomes rarely had a significant effect on the mean or variability of various phenotypic traits, and single specific extra chromosomes had very little effect except sometimes on pollen fertility or an occasional ratio. A large amount of variation, probably caused by the environment and the general genetic background, may obscure possible specific trisomic phenotypes. Morphological identification of specific trisomics is considered impractical in this species.