Hahb-4, a sunflower homeobox-leucine zipper gene, is a developmental regulator and confers drought tolerance to Arabidopsis thaliana plants.
Homeodomain-leucine zipper proteins constitute a family of transcription factors found only in plants. Hahb-4 is a member of Helianthus annuus (sunflower) subfamily I. It is regulated at the transcriptional level by water availability and abscisic acid. In order to establish if this gene plays a functional role in drought responses, transgenic Arabidopsis thaliana plants that overexpress Hahb-4 under the control of the 35S Cauliflower Mosaic Virus promoter were obtained. Transformed plants show a specific phenotype: they develop shorter stems and internodes, rounder leaves and more compact inflorescences than their non-transformed counterparts. Shorter stems and internodes are due to a lower rate in cell elongation rather than to a stop in cell division. Transgenic plants were more tolerant to water stress conditions, showing improved development, a healthier appearance and higher survival rates than wild-type plants. Indeed, either under normal or drought conditions, they produce approximately the same seed weight per plant as wild-type plants under normal growth conditions. Plants transformed with a construct that bears the Hahb-4 promoter fused to gusA show reporter gene expression in defined cell-types and developmental stages and are induced by drought and abscisic acid. Since Hahb-4 is a transcription factor, we propose that it may participate in the regulation of the expression of genes involved in developmental responses of plants to desiccation.
Dezar
Carlos Alberto
CA
Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina.
Gago
Gabriela Marisa
GM
Gonzalez
Daniel Héctor
DH
Chan
Raquel Lía
RL
D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018556:Crops, Agricultural / Q000235:genetics / Q000502:physiology; D018744:DNA, Plant / Q000302:isolation & purification; D004190:Disasters; D018506:Gene Expression Regulation, Plant; D005801:Genes, Homeobox / Q000502:physiology*; D017343:Genes, Plant; D006368:Helianthus / Q000235:genetics; D018398:Homeodomain Proteins; D016350:Leucine Zippers / Q000235:genetics*; D010641:Phenotype; D010937:Plant Growth Regulators / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000302:isolation & purification / Q000378:metabolism; D014157:Transcription Factors
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018398:Homeodomain Proteins; D010937:Plant Growth Regulators; D018749:RNA, Plant; D014157:Transcription Factors