Editors' ChoicePlant biology

EIN2, the Point of Convergence

Science's STKE  25 Jul 2000:
Vol. 2000, Issue 42, pp. tw9
DOI: 10.1126/stke.2000.42.tw9

Abscissic acid (ABA) and ethylene are plant hormones that regulate plant growth and development. Two groups (Beaudoin et al. and Ghassemian et al.) identified alleles of the ethylene response pathway that regulate ABA responsiveness in Arabidopsis. Plants expressing mutant alleles of the ethylene-insensitive2 gene (ein2) displayed an enhanced response to ABA in seeds, leading to decreased seed germination in the presence of low concentrations of ABA. However, ein2 mutants displayed a lack of ABA inhibition of root growth, suggesting that, in roots, the ABA and ethylene pathways interact to coregulate root growth. Other genes involved in ethylene signaling also interacted genetically with the ABA pathway mutants, confirming that the ein2 phenotypes arose from interaction between the ABA and ethylene pathways. For example, both groups identified alleles of ctr1, a negative regulator of the ethylene pathway, that enhanced the ability of seeds to germinate in the presence of ABA. Thus, there appears to cross talk between the ABA and ethylene pathways, the outcome of which is tissue specific: inhibitory in seeds and synergistic in roots.

Beaudoin, N., Serizet, C., Gosti, F., and Giraudat, J. (2000) Interactions between abscissic acid and ethylene signaling cascades. Plant Cell 12: 1103-1115. [Abstract] [Full Text]

Ghassemian, M., Nambara, E., Cutler, S., Kawaide, H., Kamiya, Y., and McCourt, P. (2000) Regulation of abscissic acid signaling by the ethylene response pathway in Arabidopsis. Plant Cell 12: 1117-1126. [Abstract] [Full Text]