Acquisition of desiccation tolerance by cultured carrot cells upon ectopic expression of C-ABI3, a carrot homolog of ABI3
JOURNAL OF PLANT PHYSIOLOGY
Authors: Shiota, H; Kamada, H
Abstract
To obtain direct evidence for the involvement of C-ABI3, a carrot (Daucus carota L.) homolog of VP1/ ABI3, seed-specific transcription factor, in the acquisition of desiccation tolerance, we prepared transgenic carrot non-embryogenic cells (NC) in which the C-ABI3 gene was expressed ectopically. Non-transgenic NC, in which expression of C-ABI3 was not detected, did not exhibit desiccation tolerance even after treatment with abscisic acid (ABA). In transgenic NC that expressed C-ABI3, embryo-specific ABA-inducible genes (ECP genes) were expressed upon ABA-treatment. Furthermore, the transgenic NC became desiccation-tolerant upon ABA-treatment, but did not tolerate desiccation without ABA-treatment.
Transcripts of Vp-1 homoeologues are alternatively spliced within the Triticeae tribe
EUPHYTICA
Authors: Wilkinson, M; Lenton, J; Holdsworth, M
Abstract
Hexaploid bread wheat (Triticum aestivum) caryopses are characterised by relatively weak embryo dormancy and display pre-harvest sprouting (PHS) under cool moist conditions. The phenotype of sprouted wheat is very similar to that of the maize seed-specific mutation viviparous 1 (vp1) and to abi3 in Arabidopsis. VP1 has been shown to be a transcription factor that functions both in the activation of genes involved in the maturation program and in the repression of genes involved in germination. Our analysis of the three wheat Vp-1 gene homoeologues has shown that each gene produces a set of cytoplasmic mRNAs, the majority of which are alternatively spliced, containing unedited intron sequences and deletion of coding region. These transcripts do not have the capacity to encode full-length proteins. The analysis of these Vp-1 transcripts has been extended to look at their structure in the presumed progenitors of wheat and species within the triticeae tribe, which may allow us to determine when alterations in transcript structures evolved. Results using transgenic plants have shown that expression of the Avena fatua VP1 protein in wheat has a positive effect in the reduction of PHS. In addition, there was a clear reduction in the germination indices of transgenic seeds compared to the control under conditions that would promote PHS.