Relationship between Auxin and Membrane-Integrity in Tissue Senescence and Abscission

Sacher, Joseph A.

doi:10.1126/science.125.3259.1199

Cited by 60 publications

(32 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concept that membrane failure may be involved in leaf senescence was first suggested by Sacher (18). Eilam (3) showed that senescence of bean leaves was associated with a leakage of potassium from the leaves and an associated increase in apparent free space.…”

Section: Discussionmentioning

confidence: 99%

“…A general concept of endogenous regulation of senescence by hormones is, however, made less attractive by the difficulties of bringing about major alterations in senescence development through applications of hormones to intact plants. Recent work in our laboratory has shown that calcium ions can alter appreciably some aspects of senescence development in petiole explants (16); this finding together with the earlier theory that senescence may relate to deterioration of membrane integrity (18) and the evidence that calcium may sustain membrane integrity (13) leads us to examine the possible effectiveness of calcium in deferring leaf senescence.…”

mentioning

confidence: 88%

See 1 more Smart Citation

Deferral of Leaf Senescence with Calcium

Poovaiah¹,

Leopold²

1973

Plant Physiol.

169

View full text Add to dashboard Cite

In view of the possibility that senescence may be a consequence of the deterioration of membrane compartments in the cells of leaves, calcium was studied as a possible agent which might defer senescence. The senescence of corn leaf discs was deferred by added calcium, and the effect was additive to the cytokinin deferral of senescence. Likewise, the senescence of Rumex leaf discs was deferred by added calcium, and the effect was additive to the gibberellin deferral of senescence.Detailed experiments with corn leaf discs established that the increase in apparent free space associated with senescence was completely prevented by calcium. An increase in hydraulic permeability during senescence was likewise demonstrated, and this increase was deferred by calcium; calcium plus benzyladenine was even more effective. Each of the measured functions of leaf senescence (chlorophyll content, protein decrease, apparent free space increase, and hydraulic permeability increase) was suppressed by calcium, and the interpretation is offered that the effects are a consequence of the calcium function in maintaining cellular membranes.Since the discovery by Richmond and Lang (17) growth chamber (2000 ft-c, 16 hr daily) at a temperature close to 22 C. At 8 to 10 days, leaf discs measuring 1 cm in size were taken from the primary leaf with the aid of a cork borer. The discs were floated in 10 ml of test solution, 10 discs per Petri dish in darkness at 25 C for 3 to 5 days.For the Rumex assay (Rumex obtusifolius L.), following the procedure of Whyte and Luckwill (27), old leaves which were uniformly green were selected from matured plants in the greenhouse, and they were allowed to stand overnight at 25 C in the dark with petiole in water. Leaf discs (1 cm) were cut with a cork borer and randomized, and 10 discs were floated in each Petri dish containing 10 ml of solution to be tested in the darkroom at 25 C for 4 or 5 days. Chlorophyll was extracted in ethanol. Ten leaf discs were transferred to 10 ml of ethanol in a closed vial and allowed to stand overnight, and absorbance was read at 665 nm. Experiments were repeated 4 to 6 times.For protein measurement 20 leaf discs were ground in a mortar and pestle with phosphate buffer at pH 6.5 and centrifuged at 800g to discard cellular debris. Protein was precipitated from the supernatant with 10% trichloroacetic acid and centrifuged at 10,000g for 10 min. The precipitate was dissolved in 5 ml of 0.1 N NaOH, and a 0.1-ml aliquot was used for protein analysis by the method of Lowry et al. (12).Apparent free space was determined by the method of Epstein (5). Twelve leaf discs were blotted on a paper towel to remove solution adhering to the surface. To initiate the absorption, the leaf discs were transferred to a salt solution (1 mm KCl) containing a radioactively labeled ion . At the end of the absorption period (90 min), the solution containing the radioactively labeled ion was decanted, and the leaf discs were blotted on a paper towel. Some leaf discs were used to determine the ini...

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 88%

Deferral of Leaf Senescence with Calcium

Poovaiah¹,

Leopold²

1973

Plant Physiol.

169

View full text Add to dashboard Cite

show abstract

“…For some experiments (table I) seg-mlenits of the pods of KentuckyvW:onder (9,11) in water or solutions containiing auxin (a-naphthalene acetic acid, \ A) aind/or kinetin (6-furfurylaminopurine) for 24 or 48 hours. Replicates (1.5 g fr wt) were removed from b)oth fresh (control) and aged segments, washed and( assayed for RNA and protein as describedl following.…”

Section: Methodsmentioning

confidence: 99%

Senescence: Action of Auxin and Kinetin in Control of RNA and Protein Synthesis in Subcellular Fractions of Bean Endocarp

Sacher

1967

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…PLANT PHYSIOLOGY RESPIRATORY STUDIES: When bean segments are prepared without asepsis the water-treated segments succumb to bacterial contamination after 5 days, or 2 days after the completion of water-logging. In contrast, auxin-treated segments do not become contaminated until 12 to 20 days elapse (22), again following the ultimate change in membrane properties. It seems that contamination results from the favorable substratum provided by the leakage of cellular substances.…”

Section: Plasmolytic Studiesmentioning

confidence: 95%

“…DEPARTMENT OF BIOLOGICAL SCIENCES, Los ANGELES STATE COLLEGE, Los ANGELES, CALIFORNIA In a previous paper (22) (19).…”

mentioning

confidence: 99%