Volume 60 - Tomato Genetics Cooperative - University of Florida

Research Papers TGC REPORT VOLUME 60, 2010
Study of epidermal cell size of petals and stamens in tomato species and hybrids
using confocal laser-scanning microscopy
Christopher Lofty, Julian Smith, Pravda Stoeva-Popova
Department of Biology, Winthrop University, Rock Hill SC 29733
E-mail: stoevap@winthrop.edu
Introduction
The phenomenon of cytoplasmic male sterility (CMS) has been described and
the genetics underlying the phenomemon studied in many species. Whether arising
spontaneously, as the result of mutations, or through alloplasmic incompatibilities in
interspecific crosses, the main effect of CMS is on the development of stamens and
pollen, leading to aberrant stamens with no pollen or aborted pollen (Kaul 1988). Other
changes correlated with the CMS phenotype are changes in the second whorl affecting
petal size and color (Andersen 1963, 1964; Petrova et al. 1999; Farbos et al. 2001;
Leino et al. 2003)
In the tomato, CMS does not occur naturally. CMS has been reported in
interspecies hybrids. Andersen (1963, 1964) reported the emergence and increase of
pollen abortion in F1 and backcrosses of the crosses between Solanum lycopersicum,
S. cheesmaniiae (formerly L. chesmanii f. typicum and f. minor) or S. habrochaites
(formerly L. hirsutum f. glabratum) used as pistillate parents and S. pennellii as the
recurrent pollinating parent. Pleiotropic effects of the CMS phenotype included the
reduction of anther length and size, and the lengthening of the filaments. The anther
size was negatively correlated to the percent of aborted pollen.
Similar results were observed by Valkova-Atchkova (1980) in crosses involving
S. peruvianum as pistillate parent and S. pennellii and S. habrochaites (formerly L.
hirsutum f. typicum) as pollinating parents. Further introgression of the nuclear genome
of the recurrent parents confirmed the stability of the CMS phenotype over many
generations (Petrova et al. 1999, Stoeva et al. 2007).
As a preliminary step to dissecting morphological (and underlying genetic)
changes occurring in the CMS phenotype, this study has focused on the comparative
analysis of the size of epidermal cells from abaxial and adaxial sides of petals and
stamens of mature flowers from CMS-pennellii line (0% stainable pollen), the isonuclear
S. pennellii (100% pollen fertility), and the cultivated tomato S. lycopersicum.
Materials and methods
Plant material
In the study the following genotypes were used: Solanum lycopersicum (cv.
Merkurii), Solanum pennellii (LA716), and CMS-pennellii (CMS line) previously
described in Petrova et al. (1998) and Radkova (2002). To determine the size of the
epidermal cells, fully expanded flowers in stage 20 according to the classification of
Burkhin et al. (2003) were collected from plants grown in the same environmental
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