Abstract:
A new male sterile (MS) mutant was found in 1988 in an inbred
line of cucumber (Cucumis sativus L.) in the greenhouse of
Sunseeds Company. The mutant is characterized by normal
corolla in both male and female flowers, normal fertility in
the female, and absence of pollen in otherwise normal-appearing
male flowers. The inheritance of this pollen sterile
(PS) mutant was studied in F₂ segregates derived from crosses
between PS and male fertile (MF) plants, and by mating PS
plants with MF sib plants of the heterozygous genotype (PS
ps). Chi-square tests indicated that the PS character
controlled by a single recessive gene, assigned the tentative
designation ps.
Six reciprocal crosses made between heterozygous PS and
heterozygous apetalous (Ap) type produced a total 370 fertile
: 0 PS F₁ plants, indicating that there is no allelic
relationship between PS and Ap.
F₁ generations from each of gynoecious PS, and monoecious
PS crossed with monoecious, gynoecious (silver ion treated)
and hermaphroditic pollen parents had no PS plants. By
variance analysis and contrasting the individual effects of
three sex types, Gy, M and H, on PS, it was found that sex
types do not significantly influence PS levels in F₂ families
even though PS occurs in male flowers (a sexual character).
It was not possible to effect changes in the expression
of PS by application of cytokinin, indole acetic acid (IAA) or
gibberellin (GA₃), and there were likewise no changes in
response to temperature and fertilizer treatment. Unlike
gynoecy, which is responsive to some external factors, PS is
a stable characteristic.
MS-1, a previously reported male sterile, was studied in
different environments. It was found that MS-1 is heritable
but significantly affected by environmental factors. The study
indicated that MS-1 is a strong female sterile and semi-male
sterile type. The male flower buds of MS-1 plants are able to
open normally after the 10th to 15th node under greenhouse
conditions. All staminate flower buds aborted in the field.
The result of an allelism test indicated that MS-1 is not
allelic to Ap.
