Ethylene-Induced Leaf Abscission in Cotton Seedlings

Suttle, Jeffrey C.; Hultstrand, Julie F.

doi:10.1104/pp.95.1.29

Cited by 29 publications

(11 citation statements)

References 14 publications

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“…However, it is likely that the rise in ethylene production noted here increased the concentration of the gas in the abscission zone because of previous data showing close correlations of ethylene production and concentrations in both leaf blades and petioles (11). The relevance of a peak in ethylene production by the leaf blade to initiation of abscission is supported by the observed inhibition of auxin transport capacity in petioles (3,6,23) and leaf blade midribs (19) by ethylene.…”

Section: Resultsmentioning

confidence: 94%

“…(18). In cotton leaves and flowers, as well as in leaves of bean and Prunus serrulata, auxin levels decline with age (8,20,21,23). In addition, auxin transport in cotton leaves decreases with age, and sensitivity to ethylene-induced abscission increases with age (3,6,23).…”

Section: Resultsmentioning

confidence: 99%

“…In cotton leaves and flowers, as well as in leaves of bean and Prunus serrulata, auxin levels decline with age (8,20,21,23). In addition, auxin transport in cotton leaves decreases with age, and sensitivity to ethylene-induced abscission increases with age (3,6,23). The combination of declining auxin transport to the abscission zone and elevated ethylene levels has been proposed as a signal for abscission (3,6).…”

Section: Resultsmentioning

confidence: 99%

“…For cotton, it has been reported that young leaves are more sensitive to ethylene-induced abscission than older leaves (13,23). Although this is true, that fact needs to be considered carefully because the pattern is more complicated in older plants with 10 or 11 leaves.…”

Section: Resultsmentioning

confidence: 99%

“…A more important reason arises from the fact that leaf age often alters sensitivity to ethylene (13,23); thus, it is possible that increased sensitivity to ethylene, rather than increased concentrations of ethylene, signals the abscission process. This possibility suggests that there would be no need for a peak in ethylene production to occur for ethylene to mediate abscission.…”

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confidence: 99%

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Intact Leaves Exhibit a Climacteric-Like Rise in Ethylene Production before Abscission

Morgan¹,

He²,

Drew³

1992

Plant Physiol.

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The rate of ethylene production by intact, attached leaves of cotton plants (Gossypium hirsutum L.) during aging and senescence was studied using a continuous flow system that allowed air around enclosed leaves to be scrubbed to collect and assay ethylene. Senescence of lower leaves began around 150 d after planting in a controlled environment room. A progressive decline in the ethylene production rate was observed when comparing the 3rd, 6th, and 10th leaves from the base with each other. Ethylene production rates of individual leaves also declined over a 50-d period. However, as leaves began to appear chlorotic, a peak of ethylene production occurred that lasted for about 4 d followed by abscission. This peak involved a 3-fold or greater increase in the rate of ethylene production. The data indicate that intact leaves experience a climacteric-like surge in ethylene production after visible symptoms of senescence appear. This "ethylene climacteric" is apparently the signal that initiates hydrolysis of cell walls in the abscission zone. A more important reason arises from the fact that leaf age often alters sensitivity to ethylene (13, 23); thus, it is possible that increased sensitivity to ethylene, rather than increased concentrations of ethylene, signals the abscission process. This possibility suggests that there would be no need for a peak in ethylene production to occur for ethylene to mediate abscission. Finally, young leaves or other organs generally produce ethylene at higher rates than older leaves (7,11,14), a fact attributed to the well-known ability of auxin to promote ethylene synthesis (1,15). This correlation raises the question of what cue might initiate ethylene production in an aging leaf in which auxin levels are presumed to be declining. Although auxin levels have been shown to decrease in leaves with age (20,22,24), the analyses have not been frequent enough to eliminate the possibility of a transient rise in auxin levels. Logically, before solution to the question of what cues the presumed rise in ethylene production should be sought, it would be desirable to determine with certainty that ethylene production rates increase in intact leaves on intact plants before abscission.Availability of an apparatus to collect ethylene from intact plants via a flowing air stream (16) allowed us to enclose individual leaves on intact plants and determine their ethylene production rates with age. Plants were grown under conditions in which older leaves abscised at around 150 d after planting. We measured ethylene production of several leaves from 90 d after planting until abscission and detected a consistent burst in ethylene production just before abscission. MATERIALS AND METHODSCotton plants (Gossypzum hirsutum L. v. Stoneville 213) were grown in 7.6-L pots in growth rooms (Environmental Growth Chambers, Chagrin Falls, OH) using a 12-h photoperiod as described (16). Fluorescent and incandescent lamps provided 800 to 1000 gtmol photons.m-2 s-l at the upper canopy level with height-adjustable ...

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