Auxin promotes Arabidopsis root growth by modulating gibberellin response

Modulation of sensitivity and selectivity in plant signaling by proteasomal destabilization

The ubiquitin (Ub) system of intracellular protein degradation regulates the abundance of numerous proteins that control plant growth and development. Recent advances have begun to illustrate how environmental and endogenous signals affect plant responses through Ub-related proteolysis, the importance of combinatorial control in regulated protein destruction and how multiprotein complexes confer sensitivity and selectivity to ubiquitination. Further insight into the cell biology of Ub-chain assembly and proteasomal degradation, as well as into the relationship between proteolysis and other regulatory modifications, will be essential for understanding the mechanistic basis of the integration of diverse plant signals.

Plants flex their skeletons

Recent work on the fragile fiber mutants of Arabidopsis has identified microtubule-associated proteins that affect the orientation of cellulose microfibrils in cell walls, a major determinant of plant elongation growth. These same proteins are implicated in responses to gibberellin, provoking fresh speculation about how this hormone affects cell elongation and growth.

Dispatch. Gibberellin signaling: GRASs growing roots dispatch

Gibberellins are important endogenous plant growth regulators. A new study has revealed an unexpected role for gibberellin-regulated transcription factors in promoting root growth; this depends on signaling from another plant hormone, auxin, suggesting that auxin promotes root growth by modulating the cellular response to gibberellins.