Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2004
Publication Date: 9/14/2004
Citation: Zhao, Y., Medrano, L., Ohashi, K., Fletcher, J.C., Yu, H., Sakai, H., Meyerowitz, E.M. 2004. HANABA TARANU is a GATA transcription factor that regulates shoot apical meristem and flower development in Arabidopsis. The Plant Cell,16:2586-2600. Interpretive Summary: This article reports the description of a mutant called hanaba taranu (han) that affects shoot and flower meristem development in Arabidopsis, and on the cloning and characterization of the HAN gene. Mutational analysis reveals that HAN meristems are smaller than wild type meristems, leading to reduced floral organ number and organ fusion events. We cloned the HAN gene and found that is encodes a transcriptional regulator that is active in embryos, vascular tissues, and at the boundaries of meristems and developing flowers and floral organs. Plants that make an excess of HAN protein have stunted growth and reduced meristem activity. Our results demonstrate that HAN is necessary to control cell division and meristem activity at the boundary between different tissues during Arabidopsis development.
Technical Abstract: We have isolated a new mutant, hanaba taranu (han), which affects both flower and shoot apical meristem (SAM) development in Arabidopsis thaliana. Mutants have fused sepals and reduced organ numbers in all four whorls, especially in the 2nd (petal) and 3rd (stamen) whorls. han meristems can become flatter or smaller than in the wild type. HAN encodes a GATA-3'like transcription factor with a single zinc finger domain. HAN is transcribed at the boundaries between the meristem and its newly initiated organ primordia and at the boundaries between different floral whorls. It is also expressed in vascular tissues, developing ovules and stamens, and in the embryo. han interacts strongly with clavata (clv) mutations (clv1, clv2, and clv3), resulting in highly fasciated SAMs, and we find that WUS expression is altered in han mutants from early embryogenesis. In addition, HAN is ectopically expressed both in clv1 and clv3 mutants. We propose that HAN is normally required for establishing organ boundaries in shoots and flowers and for controlling the number and position of WUS-expressing cells. Ectopic HAN expression causes growth retardation, aberrant cell division patterns, and loss of meristem activity, suggesting that HAN is involved in controlling cell proliferation and differentiation.