Ethylene‐insensitive floral senescence inSandersonia aurantiaca(Hook.)

Abstract

We have demonstrated that the senescence of Sandersonia aurantiaca (Hook.) flowers is insensitive to ethylene. Treating detached, physiologically mature flowers with propylene (0.5%, 24 h) did not alter the patterns of colour change, fresh weight, or respiration which normally occur as the flowers senesce. Silver thiosulphate (STS, 1 mM) did not extend the vase life of the flowers. Postharvest ethylene production by flowers was negligible, regardless of whether they had been exposed to propylene and or STS. Cycloheximide treatments (1 μM, 100 μM) inhibited the loss of pigment or fading associated with flower senescence. This suggests that de novo protein synthesis is required for pigment degradation in senescing sandersonia flowers. However, 100 μM cycloheximide also caused detached flowers to wilt prematurely, thereby changing the normal sequence of events that occur during senescence in this flower. Exposing flowers to actinomycin D caused a subtle change in their pattern of senescence and in vitro translation of RNA extracted from the flowers produced a pattern of translation products that differed from that of control flowers held in water. The data demonstrate that specific changes in both transcription and translation accompany the ethylene-insensitive senescence of sandersonia flowers. H95038

Identification of genes associated with perianth senescence in Daffodil (Narcissus pseudonarcissus L. ‘Dutch Master’)

“…S1-type endonucleases are glycoproteins that cleave single-stranded DNA and RNA. Their activity most likely causes the lower yields of RNA obtained from senescing tissues [28,29]. In daylily, single stranded nuclease activity was reported to increase at least 6 h prior to flower opening, which is 18 h before visible senescence of the cells [30].…”

“…This enhanced proteolytic activity most likely causes the changes in protein profiles and general decline in protein levels reported in senescing petals [34,29]. As well as having a role in recycling of nutrients, proteases may have important functions in inducing signals specific to programmed cell death by processing or releasing bioactive molecules or by activating cell surface receptors [35].…”

Protein synthesis inhibitors accelerate the postharvest senescence of asparagus and induce tiprot

“…For example, treatment of Sandersonia with actinomycin D delayed tepal fading and wilting (Eason & de Vre 1995). On the other hand, cycloheximide treatment also delayed tepal fading but, depending on the concentration, either accelerated or had no effect on wilting (Eason & de Vre 1995). This demonstrated that two characteristic features ofSandersonia senescencetepal fading and tepal wilting-are independent of each other.…”

“…Use of protein synthesis inhibitors has sometimes enabled senescence-related processes to be separated out from one another. For example, treatment of Sandersonia with actinomycin D delayed tepal fading and wilting (Eason & de Vre 1995). On the other hand, cycloheximide treatment also delayed tepal fading but, depending on the concentration, either accelerated or had no effect on wilting (Eason & de Vre 1995).…”

Molecular Mechanisms of Petal Senescence in Ornamental Plants

“…In these flowers, treatment with ethylene inhibitors does not improve flower longevity and exogenous ethylene does not accelerate petal senescence. Plants in this category include iris, daylily, gladiolus, Sandersonia, and chrysanthemum (Doi et al, 2003;Eason and de Vre, 1995;Lay-Yee et al, 1992;Serek et al, 1994;Woltering and van Doorn, 1988). In addition to ethylene-dependent and -independent senescence, there are intermediate or mixed patterns of senescence.…”