Figure 8

A proposed model of GA regulated TW formation. (a) The poplar DELLA protein PtRGA1 inhibits the expression of PtFLAs under normal growth, and then represses the TW formation. (b) When submitted to mechanical or gravity stress, more GA3 will be produced on the upper side of the bended or tilted poplar stems, and then triggers the degradation of PtRGA1 proteins, which promotes PtFLAs transcription to facilitate TW formation.