A Dissociation insertion causes a semidominant mutation that increases expression of TINY, an Arabidopsis gene related to APETALA2.

Abstract

A novel transposon-tagging strategy designed to recover dominant gain-of-function alleles was performed with Arabidopsis by using a Dissociation element with a cauliflower mosaic virus 35s promoter transcribing outward over one terminus.Lines containing transposed copies of this transposon were screened for mutants, and a semidominant mutation affecting plant height, hypocotyl elongation, and fertility was recovered. The pleiotropic effects of this mutation appear to result from a general reduction in cell expansion, and some of the effects are similar to those caused by supplying exogenous ethylene or cytokinin to wild-type seedlings. In addition, the arrangement of cells in some organs, such as the etiolated hypocotyl, is disoqanized. The mutation was called tiny, and the affected gene was cloned by first using transposon sequences to isolate the mutant allele. The predicted protein product of the TlNY gene shows strong homology with the DNA binding domain of a recently identified class of plant transcription factors. This domain, called the APETALAS domain, was initially identified as a duplicated region within the APETALAP gene of Arabidopsis and then as a conserved region between APETALAS and the ethylene responsive element binding proteins of tobacco. In the mutant allele, the Dissociation element is inserted in the untranslated leader of the TlNY gene, 35 bp from the ATG, and the mutant contains a novel transcript that initiates from the cauliflower mosaic virus 35s promoter within the transposon. This transcript is present in greater abundance than the wild-type TlNY transcript; therefore, the semidominant tiny mutation most likely results from increased, or ectopic, expression of the gene.

Overexpression of the Tobacco Tsi1 Gene Encoding an EREBP/AP2-Type Transcription Factor Enhances Resistance against Pathogen Attack and Osmotic Stress in Tobacco

“…The EREBP/AP2 domain (Jofuku et al, 1994). Recently, the EREBP/AP2 DNA binding motif has been found in various plant regulatory genes, such as Arabidopsis TINY (Wilson et al, 1996), CBF1 (Stockinger et al, 1997), AtEBP (Büttner and Singh, 1997), DREBPs (Liu et al, 1998), AINTEGU-MENTA (Elliott et al, 1996;Klucher et al, 1996), maize Glossy15 (Moose and Sisco, 1996), and tomato Ptis (Zhou et al, 1997). These genes are divided into two classes based on the number of EREBP/AP2 motifs.…”

The Cytokinin Type-B Response Regulator PtRR13 Is a Negative Regulator of Adventitious Root Development inPopulus

“…Among ERF/AP2 family members, the DREB and ERF (for ethylene-responsive elementbinding factor) subfamilies participate in responses to abiotic stress, such as mechanical injury and reduced water availability (Shinozaki and Yamaguchi-Shinozaki, 2000;Lorenzo et al, 2003). TINY appears to be a positive effector of ethylene action based on its transcript induction in response to ethylene treatment and the triple response phenotype observed when TINY is overexpressed in seedlings (Wilson et al, 1996;Sun et al, 2008). Genes encoding other members of the AP2/ERF family, PLETHORA1 and PLETHORA2, and BABY BOOM are up-regulated during the actual formation of adventitious roots in culture (Imin et al, 2007).…”

Arabidopsis RAV1 is down-regulated by brassinosteroid and may act as a negative regulator during plant development

“…The number of different proteins containing the AP2 domain appears to be quite large in plants [28,29]. Some of them, such as Arabidopsis ANT, TINY and CBF1, have been shown to be involved in flower development, cell proliferation, and plant responses to hormones and stresses [27,30,31]. VP1/B3 is another DNA binding domain conserved in a number of DNA binding proteins, such as VP1, ABI3 and ARF1, which have been shown to mediate the plant responses to ABA and auxin [32][33][34].…”