ERECTA is required for protection against heat-stress in the AS1/AS2 pathway to regulate adaxial–abaxial leaf polarity in Arabidopsis
In seed plants, formation of the adaxial–abaxial polarity is of primary importance in leaf patterning. Since Arabidopsis thaliana (L.) Heynh. genes ASYMMETRIC LEAVES1 (AS1) and ASYMMETRIC LEAVES2 (AS2) are key regulators in specifying adaxial leaf identity, and ERECTA is involved in the AS1/AS2 pathway for regulating adaxial–abaxial polarity [L. Xu et al. (2003) Development 130:4097–4107], we studied the physiological functions of the ERECTA protein in plant development. We analyzed the effects of different environmental conditions on a special leaf structure in the as1 and as2 mutants. This structure, called the lotus-leaf, reflects a severe loss of adaxial–abaxial polarity in leaves. Higher concentrations of salt or other osmotic substance and lower temperature severely affected plant growth both in the wild type and the mutants, but did not affect lotus-leaf frequency in the as1 and as2 mutants. as1 and as2 mutants exhibited a very low lotus-leaf frequency at 22°C, a temperature that favors Arabidopsis growth. The lotus-leaf frequency rose significantly with an increase in growth temperature, and only in plants that are in the erecta mutation background. These results suggest that ERECTA function is required for reducing plant sensitivity to heat stress during adaxial–abaxial polarity formation in leaves.
KeywordsArabidopsis Asymmetric leaves1 (2) ERECTA Heat stress Leaf polarity
- AS1, AS2
ASYMMETRIC LEAVES1, 2
The authors thank the Ohio State University Arabidopsis Stock Center and the Nottingham Arabidopsis Stock Center for providing as1-1, CS2340, as2-1, N230 and Lan seeds. This work was supported by grants from the Chinese Administration of Science and Technology (863), the Chinese National Scientific Foundation, and Shanghai Scientific Committee, to H.H.
- Eshed Y, Baum SF, Perea LV, Bowman JL (2001) Establishment of polarity in lateral organs of plants. Curr Biol 11:1251–1260Google Scholar
- Estelle MA, Somerville CR (1987) Auxin-resistant mutants of Arabidopsis thaliana with an altered morphology. Mol Gen Genet 206:200–206Google Scholar
- Iwakawa H, Ueno Y, Semiarti E, Onouchi H, Kojima S, Tsukaya H, Hasebe M, Soma T, Ikezaki M, Machida C, Machida Y (2002) The ASYMMETRIC LEAVES2 gene of Arabidopsis thaliana, required for formation of a symmetric flat lamina, encodes a member of a novel family of proteins characterized by cysteine repeats and a leucine zipper. Plant Cell Physiol 43:467–478Google Scholar
- Redei GP (1965) Non-mendelian megagametogenesis in Arabidopsis. Genetics 51:857–872Google Scholar
- Sussex IM (1954) Experiments on the cause of dorsoventrality in leaves. Nature 174:351–352Google Scholar
- Sussex IM (1955) Morphogenesis in Solanum tuberosum L: Experimental investigation of leaf dorsoventrality and orientation in the juvenile shoot. Phytomorphology 5:286–300Google Scholar
- Waites R, Hudson A (1995) phantastica: a gene required for dorsoventrality of leaves in Antirrhinum majus. Development 121:2143–2154Google Scholar
- Xu Y, Sun Y, Liang W, Huang H (2002) The Arabidopsis AS2 gene encoding a predicted leucine-zipper protein is required for the leaf polarity formation. Acta Bot Sin 44:1194–1202Google Scholar