Jp. Gibson et Pk. Diggle, FLOWER DEVELOPMENT AND MALE-STERILITY IN OCOTEA-TENERA (LAURACEAE) - A GYNODIOECIOUS TROPICAL TREE, International journal of plant sciences, 159(3), 1998, pp. 405-417
Androecium development and gynoecium development were compared among h
ermaphroditic flowers from non-fruiting (NF) and low-fruiting (LF) tre
es and female flowers from high-fruiting (KF) trees of gynodioecious O
cotea tenera Met & J.D. Smith ex Met. Dramatic qualitative differences
in androecium development were identified between gender classes. Ant
hers in all flowers initiated microsporogenesis, with flowers from NF
and LF trees eventually producing pollen, although some pollen from LF
trees was slightly malformed. In anthers from HF trees, pollen develo
pment terminated after microspore tetrads developed, and the immature
pollen grains eventually degenerated. Allometric relationships between
flower growth and gynoecium growth differed among gender classes, wit
h flowers from HF trees having a significantly greater slope. Allometr
ic relationships between androecium and whole-flower growth were not d
ifferent, but androecium size was reduced in female flowers. We argue
that the gene, or genes, causing abortion of pollen grains in flowers
of HF trees not only causes male sterility but also has a cascade of e
ffects on stamen and corolla development. In contrast, gynoecium devel
opment appears to be uncoupled from androecial and corolla development
. The uncoupling may allow natural selection to shape specific structu
ral attributes of female flowers and functionally male flowers separat
ely.