Background Leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous trees of the temperate region. Various plant hormones are involved in the timing of abscission. For example, ethylene signaling is required to induce hydrolysis of cell walls, while an auxin gradient [1] was suggested to act upstream of ethylene on the onset of leaf abscission. Besides ...

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H2O2 significantly diminishing the responsiveness to 2 mM N...

Leaf abscission is a common response of plants to drought stress. Some species, such as citrus, have evolved a specific behaviour in this respect, keeping their leaves attached to the plant body during water stress until this is released by irrigation or rain. This study successfully reproduced this phenomenon under controlled conditions (24h of water stress followed by 24h of rehydration) and ...

A comprehensive review of work pertinent to changes in the separation zone prior to abscission is presented. Since these changes are largely pectic in nature the involvement of pectic enzymes is suggested. The results obtained for the role of pectin methylesterase ( PME) in abscission arc as follows: ( 1 ) A localization of PME activity in the abscission zone of tobacco pedicels was established...

Shedding of organs by abscission is a key terminal step in plant development and stress responses. Cell wall (CW) loosening at the abscission zone can occur through a combination chain breakage of apoplastic polysaccharides and tension release of cellulose microfibrils. Two distinctly regulated abscission cleavage events are amenable to study in small water ferns of the genus Azolla; one is a r...

In a screen for delayed floral organ abscission in Arabidopsis, we have identified a novel mutant of CORONATINE INSENSITIVE 1 (COI1), the F-box protein that has been shown to be the jasmonic acid (JA) co-receptor. While JA has been shown to have an important role in senescence, root development, pollen dehiscence and defense responses, there has been little focus on its critical role in floral ...

When cuttings or seedlings of Phaseolus aureus were treated proximally with malformin for 2 days in continuous white light, resistance to subsequent leaf abscission in the dark resulted. The amount of resistance diminished as the concentration of malformin decreased from 10 to 0.1 micromolar. Resistance to dark abscission persisted for 7 days in continuous light. Little resistance was obtained ...

Initiation of abscission at the pedicel-fruit zone in the sour cherry (Prunus cerasus L. cv. Montmorency) occurs near the transition of Stage II to Stage III of fruit growth. The preinitiation phase is characterized by a high fruit removal force (FRF) and explants prepared from fruits during this period do not undergo abscission as indexed by a reduction in FRF. Ethylene does not cause a signif...

Summer fruit drop (June drop) is one of the main reasons for low yield in some citrus varieties in northern Iran. Recognition of physiological changes in fruit abscission zone (calyx) and application of suitable treatments would reduce or control abscission. Hence, the changes of auxin, cellulose, and polygalacturonase in calyx of Thomson navel fruitlets were measured and their relations with a...

Virus-induced gene silencing (VIGS) was used as a tool for functional analysis of cell wall-associated genes that have been suggested to be involved in leaf abscission. Tobacco rattle virus is an effective vector for VIGS in tomato (Lycopersicon esculentum). Silencing was more efficient when the plants were grown at 22 degrees C than when they were grown at 20 degrees C or 25 degrees C. The pho...