The breeding of cereals with altered gibberellin (GA) signaling propelled the ‘Green Revolution’ by generating semidwarf plants with increased tiller number. The mechanism by which GAs promote shoot height has been studied extensively, but it is not known what causes the inverse relationship between plant height and tiller number. Here we show that rice tiller number regulator MONOCULM 1 (MOC1) is protected from degradation by binding to the DELLA protein SLENDER RICE 1 (SLR1). GAs trigger the degradation of SLR1, leading to stem elongation and also to the degradation of MOC1, and hence a decrease in tiller number. This discovery provides a molecular explanation for the coordinated control of plant height and tiller number in rice by GAs, SLR1 and MOC1.

赤霉素（GA）信号改变的谷物的育种产生了分till数增加的半矮植株，从而推动了“绿色革命”。遗传算法促进苗高的机理已被广泛研究，但尚不清楚是什么原因导致株高与分till数成反比。在这里，我们显示水稻分number数调节剂MONOCULM 1（MOC1）通过与DELLA蛋白SLENDER RICE 1（SLR1）结合而受到保护，免受降解。GAs触发SLR1的降解，导致茎伸长，也导致MOC1降解，因此分number数减少。这一发现为利用GA，SLR1和MOC1协调控制水稻株高和分till数提供了分子解释。