Differential Accumulation of Sunflower Tetraubiquitin mRNAs during Zygotic Embryogenesis and Developmental Regulation of Their Heat-Shock Response.

AUTOR(ES)

Almoguera, C.

RESUMO

We have isolated and sequenced Ha UbiS, a cDNA for a dry-seed-stored mRNA that encodes tetraubiquitin. We have observed differential accumulation of tetraubiquitin mRNAs during sunflower (Helianthus annuus L.) zygotic embryogenesis. These mRNAs were up-regulated during late embryogenesis and reached higher prevalence in the dry seed, where they were found to be associated mainly with provascular tissue. UbiS mRNA, as confirmed by Rnase A protection experiments, accumulated also in response to heat shock, but only in leaves and later during postgerminative development. These novel observations demonstrate expression during seed maturation of specific plant polyubiquitin transcripts and developmental regulation of their heat-shock response. Using ubiquitin antibodies we also detected discrete, seed-specific proteins with distinct temporal expression patterns during zygotic embryogenesis. Some of these patterns were concurrent with UbiS mRNA accumulation in seeds. The most abundant ubiquitin-reacting proteins found in mature seeds were small (16-22 kD) and acidic (isoelectric points of 6.1-7.4). Possible functional implications for UbiS expression elicited from these observations are discussed.

Documentos Relacionados

• Evidence for protection by heat-shock proteins against photoinhibition during heat-shock
• Initiation-mediated mRNA decay in yeast affects heat-shock mRNAs, and works through decapping and 5′-to-3′ hydrolysis
• Tissue-Type-Specific Heat-Shock Response and Immunolocalization of Class I Low-Molecular-Weight Heat-Shock Proteins in Soybean.
• Archaebacterial heat-shock proteins
• Heat-Shock Response in Heat-Tolerant and Nontolerant Variants of Agrostis palustris Huds.