Abstract
Tiller of rice plants is corresponding to a lateral branch in dicots and its number is recognized as an important agricultural trait. It is well known that increment of tiller number is significantly repressed when rice plants are cultivated under dense planting. However, mechanism of the repression has been unclear yet. Based on results obtained from other plants, responses against dense planting are induced by high FR/R ratio in ambient light quality, which is monitored by phyB.
To clarify function of phytochromes in monitoring of dense planting, we examined tiller numbers of several phytochrome mutants grown either under sparse or dense planting. Not only Nipponbare but also all mutants examined (phyA, phyB, phyC, phyAphyC, phyBphyC) showed normal responses against dense planting. It is noteworthy that absence of phyB give no effect to monitoring of dense planting, suggesting that phyB is dispensable for these responses in rice plants.
