Plant type is an important composite trait associated with the yield potent
ial in rice and other cereal crops. Several characters associated with the
plant type of modern rice cultivars including tiller angle, leaf and flag l
eaf angle, were investigated using a complete linkage map with 115 well dis
tributed RFLP markers and progeny testing of 2418 F-2 derived F-4 lines fro
m a cross between O. sativa ssp. japonica cv. 'Lemont' and spp. indica cv.
'Teqing'. One major gene (Ta) and 11 QTLs were largely responsible for the
tremendous variation of the three plant type characters in the Lemont/Teqin
g F-2 population. The major gene, Ta, located between RZ228 and RG667 on ch
romosome 9, accounted for 47.5% of the phenotypic variation in tiller angle
and had large pleiotropic effects on both leaf and flag leaf angles. This
gene plus four QTLs accounted for 69.1% of the genotypic variation in tille
r angle. Eight additional QTLs for leaf and flag leaf angles were also iden
tified, which collectively explained 52.0 and 66.4% of the genotypic variat
ion of these traits. Ta and three QTLs (QFla2, QFla5 and QFla7) apparently
affected the related plant type characters differently, suggesting their po
ssible differential expression in different developmental stages of rice pl
ants or possibly clustering of different genes affecting these traits. Plan
t type, and consequently grain yield of rice, may be improved by deliberate
ly manipulating these QTLs in a marker-assisted selection program.