Th. He et al., MATING SYSTEM OF OPHIOPOGON XYLORRHIZUS (LILIACEAE), AN ENDANGERED SPECIES IN SOUTHWEST CHINA, International journal of plant sciences, 159(3), 1998, pp. 440-445
The mating system of Ophiopogon xylorrhizus Wang et Dai was studied in
three natural populations with allozyme electrophoresis. The outcross
ing rate was estimated by assaying eight enzyme loci. A mixed mating s
ystem model was used, and outcrossing rates were estimated for populat
ions and families. The multilocus outcrossing rates in three populatio
ns were 0.467, 0.323, and 0.091. The extent of outcrossing in populati
ons depended on the plant density (r = 0.9998; P < 0.02; df = 1). The
frequency distribution of family outcrossing rates was slightly bimoda
l. A mixed mating system with considerable complete selfing and comple
te outcrossing was found in this species. Positive correlations were o
bserved between family outcrossing rate and maternal heterozygosity (r
= 0.70-0.98) and between family outcrossing rate and fecundity (r = 0
.971; P < 0.0005; df = 7). Inbreeding depression was examined in popul
ations P3 and P4, both of which had high outcrossing rates. Inbreeding
depression was expressed mainly in seed production. Mating system pat
tern contributed to the high genetic variation in this species. Becaus
e of high inbreeding depression and habitat destruction, this species
is threatened with extinction. Conservation in situ by protecting the
habitat is the best way to conserve this species.