Cellulase (beta-1,4-glucan-glucanohydrolase EC 3.2.1.4) activity increased during abscission and was localized in the cell separation layer of Phaseolus vulgaris L. cv. Red Kidney (bean), Gossypium hirsutum L. cv. Acala 4-42 (Cotton) and Coleus blumei Benth. Princeton strain (Coleus) abscission zone explants. Cellulase activity was optimum at pH 7, was reduced by one-half after heating to 55 de...

37 Apple (Malus x domestica) is increasingly being considered an interesting model species for studying 38 early fruit development, during which an extremely relevant phenomenon, i.e. fruitlet abscission, may 39 occur as a response to both endogenous and/or exogenous cues. Several studies were carried out 40 shedding light on the main physiological and molecular events leading to the selective ...

As apples ripen they begin to produce large amounts of the ripening hormone, ethylene. Ethylene stimulates fruit softening and the formation of an abscission zone in the stem. Ethylene stimulates the production of enzymes (cellulase and polyglacturonase) that break down the cell walls and the glue that holds cell walls together in the abscission zone of the stem, leaving the fruit connected to ...

Body temperature is a more pertinent variable to physiological stress than ambient air temperature. Modeling and empirical studies on the impacts of climate change on ectotherms usually assume that body temperature within organisms is uniform. However, many ectotherms show significant within-body temperature heterogeneity. The relationship between regional heterothermy and the response of ectot...

Measurements were made of the transport of 2,4-dichlorophenoxyacetic acid-(14)C (2,4-D) through segments cut from the region of the distal abscission zone in young and old primary leaves of Phaseolus vulgaris L. When old leaves were used basipetal transport of 2,4-D in segments including pulvinar tissue, abscission zone, and petiolar tissue was much less than in wholly petiolar segments. In bot...

Two structurally divergent endo-p-l,Cglucanase (EGase) cDNAs were cloned from tomato. Although both cDNAs (Cell and Ce12) encode potentially glycosylated, basic proteins of 51 to 53 kD and possess multiple amino acid domains conserved in both plant and microbial EGases, Cell and Ce12 exhibit only 50% amino acid identity at the overall sequence level. Amino acid sequence comparisons to other pla...

In Arabidopsis thaliana, the process of abscission, or the shedding of unwanted organs, is mediated by two genes, HAESA (HAE) and HAESA-LIKE 2 (HSL2), encoding receptor-like protein kinases (RLKs). The double loss-of-function mutant hae-3 hsl2-3 is completely deficient in floral abscission, but, interestingly, the hae-3 hsl2-9 mutant displays a less severe defect. This mutant was chosen for an ...

Indoleacetic acid (IAA), a naturally-occurring auxin, prevents or retards abscission of plant parts under many conditions (1). When applied to the cotyledonary petiole stumps of explants of cotton (Gossypium. hirsutum L.) in a commonly used abscission test IAA in moderate physiological coIncentrations retards abscission markedly (2, 6). The disposition within the explant of the auxin applied un...