RESUMO
Plant-specific TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors play crucial roles in development, but their functional mechanisms remain largely unknown. Here, we characterized the cellular functions of the class I TCP transcription factor GhTCP14 from upland cotton (Gossypium hirsutum). GhTCP14 is expressed predominantly in fiber cells, especially at the initiation and elongation stages of development, and its expression increased in response to exogenous auxin. Induced heterologous overexpression of GhTCP14 in Arabidopsis (Arabidopsis thaliana) enhanced initiation and elongation of trichomes and root hairs. In addition, root gravitropism was severely affected, similar to mutant of the auxin efflux carrier PIN-FORMED2 (PIN2) gene. Examination of auxin distribution in GhTCP14-expressing Arabidopsis by observation of auxin-responsive reporters revealed substantial alterations in auxin distribution in sepal trichomes and root cortical regions. Consistent with these changes, expression of the auxin uptake carrier AUXIN1 (AUX1) was up-regulated and PIN2 expression was down-regulated in the GhTCP14-expressing plants. The association of GhTCP14 with auxin responses was also evidenced by the enhanced expression of auxin response gene IAA3, a gene in the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) family. Electrophoretic mobility shift assays showed that GhTCP14 bound the promoters of PIN2, IAA3, and AUX1, and transactivation assays indicated that GhTCP14 had transcription activation activity. Taken together, these results demonstrate that GhTCP14 is a dual-function transcription factor able to positively or negatively regulate expression of auxin response and transporter genes, thus potentially acting as a crucial regulator in auxin-mediated differentiation and elongation of cotton fiber cells.
Assuntos
Gossypium/citologia , Gossypium/genética , Ácidos Indolacéticos/metabolismo , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Diferenciação Celular , Núcleo Celular/metabolismo , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Gossypium/metabolismo , Gravitropismo/genética , Dados de Sequência Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Tricomas/genética , Tricomas/metabolismoRESUMO
Using an estrogen-inducible expression XVE (LexA-VP16-Estragon Receptor) system, we have generated approximately 40 000 independent T-DNA insertion lines of Arabidopsis thaliana. Segregation analyses of about 18000 lines indicated that 51.6% of them contain single T-DNA insertions and that the average insertion number is 1.38 copies per line. Mutants displaying a variety of morphological alterations were identified, including those that affect development of roots,hypocotyls, leaves, floral organs and seeds as well as the flowering time.
