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Ribonucleases in roots of seedlings of Triticum durum and xHaynaldoticum sardoum grown at low temperatures
No full textDormancy and germination in wheat embryos: ribonucleases and hormonal control
No full textAcidic and neutral ribonucleases (RNases) were studied in embryos of Triticum durum cv. Cappelli and the effects of
abscisic acid (ABA) and gibberellic acid (GA3) were analysed. RNases activities increased during germination and were
comparable in dormant and non-dormant embryos imbibed for 24 h. ABA generally inhibited ribonucleolytic activities,
while GA3 only affected dormant embryos. To assess whether changes in RNase activities during germination or
following hormonal treatment required new transcriptional or translational action, cycloheximide or cordycepin were
used. The action of inhibitors of acidic RNase activity was found only in non-dormant-embryos. Findings obtained in
the present work concur with a change of the ribonucleolytic pattern in the shift from dormant to non dormant
metabolism
Ribonucleases during ripening and after-ripening in Triticum durum embryos
No full textTotal and polyadenylated RNA content changes during ripening and after-ripening in embryos of Triticum
durum cv. Cappelli. In this work, RNase activity was studied by means of enzymatic assays and
activity staining SDS-PAGE in embryos at different stages of maturation and after-ripening. Qualitative
and quantitative changes of RNases were found. Of particular interest was the continuous presence of
acidic RNase in embryos, and the disappearance of neutral RNase activities during after ripening. Saltinhibited
RNases disappeared 42 days after anthesis, while salt-stimulated RNases with higher mobility
disappeared in fully ripened embryos. Salt-stimulated RNases with lower mobility disappeared during
after-ripening. The disappearance of neutral RNase activities during ripening may be related to the different
physiological status induced by dehydration
Poly (A) polymerase activity: product characterization and levels in aged embryos of Triticum durum.
No full textNatural ageing of wheat seeds
No full textSeed natural ageing is accompanied by the loss of the ability to germinate and by a reduction in viability. Viability loss is associated with damage to the DNA, changes in the synthesis of RNA and in enzymatic patterns. The loss of viability, in Triticum durum, is accompanied in imbibed seeds, among other components, by a reduced synthesis and poly(A) polymerase activity. Both young and aged germinating endosperms showed a different pattern of proteolytic activities.
Among the factors which influence the longevity of seeds, the most important ones are temperature and moisture content, thus seed ageing is closely linked to storage conditions. In Triticum durum the protective action of low temperature against the degradation process during storage has been shown. A close correlation between the germination rate and capability to synthesise poly(A)+RNA and the integrity of the rRNA molecules may be considered to exist in embryos. Recent data show that the seed viability loss is associated with a progressive membrane deterioration in parallel with changes in RNases and nucleases activities. The damage observed in embryos and endosperms of aged seeds is not found in the cold stored seeds of the same age
Poly (A) polymerase activity: product characterization and levels in aged embryos of Triticum durum
No full textRibonucleases in leaves and roots of Triticum durum and x Haynaldoticum sardoum submitted to low non freezing temperatures
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