L. Chen et al., SELF-INCOMPATIBILITY, SEED ABORTION AND CLONALITY IN THE BREEDING SYSTEMS OF SEVERAL WESTERN-AUSTRALIAN DROSERA SPECIES (DROSERACEAE), Australian Journal of Botany, 45(1), 1997, pp. 191-201
Western Australian Drosera L. species include one annual and many tube
rous and pygmy perennials. In 20 species or subspecies, 17 taxa were s
elf-incompatible (SI) and three were self-compatible (SC), as assessed
by patterns of seed set and pollen tube growth. All SI species were c
lonal (tubers or gemmae), but two SC species were clonal (gemmae) and
one was annual. Self-pollen tube inhibition confirmed that SI species
were pre-zygotically self-sterile. The sites of SI pollen tube inhibit
ion varied from early (stigmatic) to fate (stylar, placental, ovular),
which suggests continuing evolution in the expression of the SI respo
nse. Self-compatible species showed little inbreeding depression, but
SI species showed considerable inbreeding depression as measured by se
ed abortion. In the three species tested, open-pollinated capsules wer
e typically more fecund than hand-pollinated capsules. In D. glandulig
era Lehm., this might represent position effects in an inflorescence t
hat were reflected in the sampling method. In other species, however,
this might also reflect biparental inbreeding depression in the glassh
ouse plants. Interspecific crosses between D. tubaestylis N.Marchant &
A.Lowrie (n = 14) and D. rosulata Lehm. (n = 13) were slightly succes
sful, with no pollen-pistil incompatibility interaction, but with exte
nsive seed abortion. This is the first report of SI in Droseraceae.