Dormancy and germination in wheat embryos: ribonucleases and hormonal control

Abstract

Acidic and neutral ribonucleases (RNases) were studied in embryos of Triticum durum cv. Cappelli and the effects of abscisic acid (ABA) and gibberellic acid (GA 3 ) 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 GA 3 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.

Responses to desiccation injury in developing wheat embryos from naturally- and artificially-dried grains

“…The presence of neutral ribonucleases seems to be correlated with grain water content. In fact, this enzymatic activity decreases progressively during maturation drying [8] and then rises again with the progressive increase in water content during imbibition [9]. This is further confirmed by the results of artificial drying, during which the pattern of neutral ribonucleases was mirrored by water content.…”

“…Specific RNases are associated with wheat embryo water content: its isozymes decrease during maturation drying [8] and reappear with the progressive increase in water content during imbibition [9]. The results of these studies also suggest the importance of physiological state, as these ribonucleases appear more precociously in dormant-than non-dormant-embryos during germination.…”

Durum wheat seedlings in saline conditions: Salt spray versus root-zone salinity

“…Fully viable grains (11% moisture content) were surface sterilised for 3 min in NaOCl (1%, v/v, available chlorine) and rinsed before use. Wheat grains were germinated as in Spanò et al (2008) in Petri dishes (10 replicates each of 100 grains) on water-moistened Whatman No. 2 filter paper at 23 ± 1°C in the dark for 72 hours.…”

Gibberellin retards chlorophyll degradation during senescence of Paris polyphylla

“…Gibberellins (GA) influence almost every aspect of the plant life cycle, including seed germination, leaf expansion, stem elongation, flower initiation and development, sex determination, and fruit development (Sun and Gubler 2004, Bogdanović et al 2008, Spanò et al 2008. Gibberellic acid (GA 3 ) treatment retards senescence and maintains the Chl content (Chin and Beevers 1970, Parmar and Hammond 1971, Rosenvasser et al 2006), but there have been few reports on the mechanism of the delaying of Chl degradation by GA 3 .…”