Strigolactones (SLs) are fundamental phytohormones that suppress tillering, whereas sugars act as both energy source and signaling molecules to promote tillering. However, the molecular interplay between SLs and sugars remains largely underexplored. Here, through iTRAQ-based quantitative proteomic analysis, we identified two highly homologous monosaccharide transporters OsMST3 and OsMST6 showing increased protein abundance in the SLs signaling mutant
d3s2-215 and biosynthesis mutant
d10XJ1705. Through feeding with fluorescence- or isotope-labelled sugars, we demonstrated that OsMST3/6 functioned as influx transporters of glucose and fructose, facilitating their translocation from leaf blades to tiller buds to promote bud outgrowth. Interestingly, glucose and fructose induced
OsMST3/
6 expression and polarized plasma membrane localization, a process essential for bud outgrowth, whereas SLs suppressed their expression and counteracted sugars-induced polarized localization. OsTB1, a key transcription factor downstream of SLs signaling, directly bound the
OsMST3/
6 promoters to inhibit their transcription. Tiller bud outgrowth of the
tb1SG0312 mutant was severely inhibited by a non-metabolizable glucose analog (2-Deoxy-D-glucose) and an inhibitor of sugar transporters (CCCP). Moreover, simultaneous knockout of
OsMST3/6 rescued the high-tillering phenotype of the
d3s2-215,
d10XJ1705 and
tb1SG0312mutants. Together, we found a novel mechanism by which SLs control tillering by limiting sugars allocation to buds through suppressing monosaccharide transporters OsMST3/6.
研究者从SL突变体筛出OsMST3/6，再用遗传、转运、同位素示踪、亚细胞定位和启动子结合实验，闭合“SL—OsTB1—糖运输—分蘖芽伸长”的因果链。
OsTB1直接压低OsMST3/6表达，SLs又阻断其糖诱导极性定位；同时证明葡萄糖也能直接长距离进入分蘖芽。
