A family of transcripts encoding water channel proteins: tissue-specific expression in the common ice plant.

摘要: Seawater-strength salt stress of the ice plant (Mesembryanthemum crystallinum) initially results in wilting, but full turgor is restored within approximately 2 days. We are interested a mechanistic explanation for this behavior and, as requisite in-depth biochemical studies, have begun to analyze gene expression changes roots coincident with onset stress. cDNAs that suggested mRNA amount under were found; their deduced amino acid sequences share homologies proteins Mip (major intrinsic protein) family and potentially encode aquaporins. One transcript, MipB, was found only root RNA, whereas two other transcripts, MipA MipC, detected leaves. Transcript levels MipB low abundance. All transcripts declined during later recovered at least prestress level. The most drastic decline MipC transcripts. distribution by situ hybridization indicated transcript present all cells tip. In expansion zone where vascular bundles differentiate, amounts abundant endodermis. older roots, which had undergone secondary growth, highly expressed cell layers surrounding individual xylem strands. also localized leaf tissue lower amounts, mesophyll cells. Transcripts seemed be exclusively tip root, before possibly development system. MipA- MipB-encoded Xenopus oocytes led increased water permeability. fluctuations coincided leaves As regained turgor, these channel increased.