独脚金内酯(SLs)是一种调控分枝的新型植物激素，其合成及信号传导途径是当今植物激素领域的研究热点之一。目前SLs途径中已发现的基因较少，其与另一种调控植物分枝的激素即生长素的互作机制亦无定论。本项目从水稻半显性矮化多分蘖突变体hd103中图位克隆了目标基因OsIAA16，并初步证明其处于SLs信号传导途径中。OsIAA16属于Aux/IAA基因家族，该家族成员不仅是生长素信号传导过程中的重要抑制因子，往往还介导生长素与其他植物激素的相互作用，但OsIAA16的生物学功能还未见报道。本研究将采用生理、生化和分子生物学等实验手段研究水稻OsIAA16在SLs和生长素途径中的作用，并探讨其在介导两种植物激素互作中的作用机制。本研究不仅可以完善SLs的信号传导途径，还可能发现SLs与生长素互作的新途径。本研究涉及水稻分蘖和根系等重要农艺性状，不仅具有重要理论意义，而且具有潜在应用价值。

Strigolactones (SLs) are a group of newly identified phytohormones that control plant shoot branching. The SLs biosynthesis and signal transduction pathway is currently one of the hotspots in the phytohormone research. Up to now, only a few genes have been identified in the SLs biosynthetic and signaling pathway. The underlying mechanism of cross-talks between SLs and auxin, another phytohormone.controlling shoot branching, also remains to be unveiled. We have isolated the OsIAA16 gene from the semi-dominant high-tillering dwarf rice mutant hd103 by a map-based cloning approach. Our preliminary studies have shown that OsIAA16 participates in the SLs signaling pathway. OsIAA16 is a member of the Aux/IAA gene superfamily, members of which are not only important repressors of auxin signaling but also mediators of the cross-talks between auxin and other hormones. However, the biological functions of OsIAA16 have not been reported. In this proposed project, physiological, biochemical and molecular approaches will be taken to elucidate how OsIAA16 works in the SLs and auxin signaling pathways and how it mediates the interaction between SLs and auxin. This research will improve our understanding of the SLs signal transduction pathway and establish a new model of the cross-talks between SLs and auxin. Objects of this study are tiller and root, both of which are important agronomic traits in rice production. Thus, this study has not only important theoretical significance, but also potential application value in the agricultural production.