role of maturation drying in the transition from seed development to germination. VI. Desiccation-induced changes in messenger RNA populations within the endosperm of Ricinus communis L. seeds

• Published in: Journal of experimental botany 1989, Vol.40 (210), p.33-41
• Main Authors: Kermode, A.R, Pramanik, S.K, Bewley, J.D
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; desiccation; Developmental biology; Drying; Endosperm; Fructification and ripening; Fundamental and applied biological sciences. Psychology; gene expression; genetic techniques and protocols; Germination; Imbibition; Messenger RNA; Oral rehydration; plant development; Plant physiology and development; protein synthesis; Ricinus communis; RNA; Seed development; seed germination; Seeds; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0022-0957; 1460-2431

From 30 to 50 d after pollination (DAP) the total RNA content declines in the developing endosperm of castor bean and only a small amount is present in the mature dry (60 DAP) endosperm. During and following germination of the mature seed the RNA content of the endosperm increases up to 72 h after imbibition (HAI). A similar decline in RNA in the endosperm occurs when the seed is prematurely dried at 35 DAP and there is an increase again upon subsequent rehydration, although not to the level achieved in the endosperm of germinated mature seed. Quantitative and qualitative changes in the mRNA complement of the endosperm occur during development. In particular, messages coding for high mol. wt. proteins (putative storage protein precursors) decline substantially during maturation drying (50-60 DAP). A similar decline occurs as a consequence of premature desiccation at 35 DAP. Following rehydration of these dried seeds the pattern of proteins synthesized in vitro by the mRNAs extracted from the endosperm is very similar to that catalysed by messages from the mature seed endosperm during germination and growth. Some mRNAs associated with development, which persist in the endosperm following natural and imposed desiccation, decline during early imbibition. During germination and growth of mature and prematurely dried seeds a similar complement of mRNAs arise in the endosperm, in an identical temporal sequence. The mRNA for ricin D, a protein synthesized predominantly during development at 30-40 DAP, declines to a low level in the mature dry endosperm (60 DAP) and in that of the prematurely dried seed and does not increase substantially during germination or growth. Thus the changes in protein synthesis effected by drying in the endosperm of castor bean are mediated primarily through changes in their mRNAs, as a result of transcriptional control. Drying, whether occurring naturally or imposed prematurely, results in the permanent suppression of transcription of most developmentally-related messages and, upon subsequent rehydration, the induction of those associated with germination and growth. Some residual mRNAs for developmental proteins which are present in the dry seed are selectively degraded during germination. Thus there are some post-transcriptional changes to the mRNA population following drying, in addition to the transcriptional modifications.