Effect of Growth Substances on the Absciss Layer in Leaves of Coleus

Myers, Richard M.

doi:10.1086/334962

Cited by 69 publications

(35 citation statements)

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“…Myers (11,12,13) and Gardner and Cooper (4) by their deblading experiments in Coleus have essentially proved that auxin is responsible for the prevention of leaf drop. They concluded that the leaf blade was the source of the phytohormone naturally serving this function.…”

mentioning

confidence: 99%

The Promotion of Abscission by Auxin

Gaur¹,

Leopold²

1955

Plant Physiol.

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confidence: 99%

The Promotion of Abscission by Auxin

Gaur¹,

Leopold²

1955

Plant Physiol.

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“…Since that time, numerous reports have added substantial support to the idea that auxins control abscission through an inhibitory influence (1,10,19,25). More recently the concept of hormonal control has been extended to include auxin promotion of abscission as well (1,11).…”

mentioning

confidence: 99%

Factors Influencing Abscission.

Biggs¹,

Leopold²

1957

Plant Physiol.

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The hormonal concept of abscission control was spearheaded by the suggestive experiments of Laibach in 1933 (15) and then more specifically established by the experiments of La Rue (17) in which he found that indoleacetic acid, pollen extracts, or urine could delay the abscission of debladed petioles. Since that time, numerous reports have added substantial support to the idea that auxins control abscission through an inhibitory influence (1,10,19, 25). More recently the concept of hormonal control has been extended to include auxin promotion of abscission as well (1,11).A useful tool for studying the effects of various substances on abscission has been the petiole explant test described by Addicott et al (4). This test with modification has been used subsequently by a number of workers: by Livingston (18) to study the effects of ethylene, sucrose, and auxins on abscission; by Carns (6) to study the influence of metabolic inhibitors; by Osborne (21) to seek a natural factor which promotes abscission; and by Gaur and Leopold (11) to study the quantitative effects of auxin on abscission.It has been observed in this laboratory that explant tests performed under similar conditions but at different times showed a considerable degree of variation and in fact in some tests no abscission occurred at all. The following experiments were undertaken to establish a more reliable explant test and to clarify some of the factors influencing abscission. Interactions between leaf age, substrates, light and auxin are described.MATERIAL AND METHODS Seedlings of Phaseolus vulgaris L. var. Red Kidney, were grown in flats in the greenhouse on a 16-hour-day. Daylength was extended with incandescent lamps giving approximately 70 ft-c at plant level.Explants 1 cm in length were taken from the primary leaves to include 5 mm of petiole and 5 mm of pulvinus tissue. These explants were placed in 5-cm Petri dishes, basal end down, to a 4-mm depth in 1 % agar with or without addenda. There were 20 explants per treatment. Each experiment reported here was repeated in its entirety at least 3 times and the results are consistent with 35 other experiments encompassing variations on these reported ones. Napthaleneacetic acid (NAA) was incorporated into the agar as its ammonium salt. No organic solvent was used to dissolve the auxin.Light treatments given to the explants involved a 12-hr day w ith 300 ft-c light intensity supplied by

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“…This was first established by Avery (1) and has since been observed by numerous other workers in a wide range of species (6,9,15,18). A simultaneous decline of auxin content of the leaf and responsiveness of the abscission zone to auxin appears to be a basic part of the aging process.…”

Section: Resultsmentioning

confidence: 75%

“…With aging there are changes in the substances which can regulate abscission, such as a decline in the auxin level (9,15), increases in the amino acids (17,19,11), and increases in extractable abscission-stimulating factors (10,3,4,16). More recently the physiological processes leading to bean leaf abscission have been separated into 2 successive stages (13) and the present study aimis to analyse the increasing tendencies for abscission as they may relate to the completion of the 2 successive stages.…”

mentioning

confidence: 98%