Reference "QTLs for branching, floret formation, and pre-flowering floret abortion of rice panicle in a temperate japonica x tropical japonica cross"

Reference ID

8343

Title

QTLs for branching, floret formation, and pre-flowering floret abortion of rice panicle in a temperate japonica x tropical japonica cross

Source

Theoretical and applied genetics, 2004, vol. 109, pp. 1555-1561

Authors (5)

Yamagishi-J	Miyamoto-N
Hirotsu-S	Laza-R-C
Nemoto-K

Abstract

A large panicle with numerous florets is essential for improving rice ( Oryza
sativa L.) yield. Rice panicle size is determined by such underlying
morphogenetic processes as: (1) primary branch formation on the panicle axis;
(2) floret formation on the primary branches (mainly determined by the secondary
branch formation); and (3) pre-flowering abortion of florets in the panicle. We
examined QTLs for these processes to understand how they are integrated into
panicle size. We developed 106 backcross-inbred lines (BC(1)F(4)) from a cross
between 'Akihikari' (a temperate japonica) and 'IRAT109' (a tropical japonica)
and constructed a genetic map. One QTL detected on chromosome 2, with a large
effect ( R=0.30) on the number of florets per panicle, affected both primary
branch formation on the panicle axis and floret formation on the primary
branches. In addition, three QTLs that affect only one of these two processes
were identified on chromosomes 4, 9, and 11, each having a subsidiary effect on
the number of florets per panicle ( R(2)=0.04-0.07). QTLs for pre-flowering
floret abortion were detected at three different regions of the genome
(chromosomes 1, 10, and 11). This is the first report on QTLs for pre-flowering
floret abortion in grasses. The absence of a co-location between QTLs suggests
that floret formation and abortion are not directly linked causally. These
results demonstrate that studying the partitioning of panicle size into these
underlying morphogenetic components would be helpful in understanding the
complicated genetic control of panicle size.