Separation of abscission zone cells in detached Azolla roots depends on apoplastic pH

The anatomical development of the abscission zone in grains of Zizania aquatica L. was correlated with development of the embryo. The abscission zone is well developed when the embryo sac is mature. Soon after pollination, the first anatomical evidence of abscission appears as plasmolysis of the separation layer parenchyma cells. This is followed by separation of the layers by dissolution of the middle lamella and fragmentation of cell walls. Persistence of intact vascular tissue and presence of a surrounding cone-shaped mass of lignified cells may be involved in abscission of wild rice grains.

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Identification and Characterization of an Ionically-Bound Cell Wall Glycoprotein Expressed Preferentially in the Leaf Rachis Abscission Zone of Sambucus nigra L.

Journal of Plant Physiology ◽

10.1016/s0176-1617(11)80731-5 ◽

1991 ◽

Vol 138 (1) ◽

pp. 63-67 ◽

Cited By ~ 6

Author(s):

Michael T. Mcmanus ◽

Daphne J. Osborne

Keyword(s):

Cell Wall ◽

Abscission Zone ◽

Sambucus Nigra ◽

Identification And Characterization

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Physiological and ultrastructural analysis reveal the absence of a defined abscission zone in coffee fruits

Bragantia ◽

10.1590/1678-4499.575 ◽

2016 ◽

Vol 75 (4) ◽

pp. 386-395

Author(s):

Isabel Rodrigues Brandão ◽

Dayane Meireles da Silva ◽

Kamila Rezende Dázio de Souza ◽

Lissa Vasconcellos Vilas Boas ◽

Meline de Oliveira Santos ◽

...

Keyword(s):

Ultrastructural Analysis ◽

Abscission Zone

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Transcriptomics of Improved Fruit Retention by Hexanal in ‘Honeycrisp’ Reveals Hormonal Crosstalk and Reduced Cell Wall Degradation in the Fruit Abscission Zone

International Journal of Molecular Sciences ◽

10.3390/ijms22168830 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8830

Author(s):

Karthika Sriskantharajah ◽

Walid El Kayal ◽

Davoud Torkamaneh ◽

Murali M. Ayyanath ◽

Praveen K. Saxena ◽

...

Keyword(s):

Cell Wall ◽

Ethylene Biosynthesis ◽

Abscission Zone ◽

Cell Wall Degrading Enzymes ◽

Fruit Abscission ◽

Fruit Drop ◽

Expression Of Genes ◽

Hormonal Crosstalk ◽

Honeycrisp Apples ◽

And Control

Apples (Malus domestica Borkh) are prone to preharvest fruit drop, which is more pronounced in ‘Honeycrisp’. Hexanal is known to improve fruit retention in several economically important crops. The effects of hexanal on the fruit retention of ‘Honeycrisp’ apples were assessed using physiological, biochemical, and transcriptomic approaches. Fruit retention and fruit firmness were significantly improved by hexanal, while sugars and fresh weight did not show a significant change in response to hexanal treatment. At commercial maturity, abscisic acid and melatonin levels were significantly lower in the treated fruit abscission zone (FAZ) compared to control. At this stage, a total of 726 differentially expressed genes (DEGs) were identified between treated and control FAZ. Functional classification of the DEGs showed that hexanal downregulated ethylene biosynthesis genes, such as S-adenosylmethionine synthase (SAM2) and 1-aminocyclopropane-1-carboxylic acid oxidases (ACO3, ACO4, and ACO4-like), while it upregulated the receptor genes ETR2 and ERS1. Genes related to ABA biosynthesis (FDPS and CLE25) were also downregulated. On the contrary, key genes involved in gibberellic acid biosynthesis (GA20OX-like and KO) were upregulated. Further, hexanal downregulated the expression of genes related to cell wall degrading enzymes, such as polygalacturonase (PG1), glucanases (endo-β-1,4-glucanase), and expansins (EXPA1-like, EXPA6, EXPA8, EXPA10-like, EXPA16-like). Our findings reveal that hexanal reduced the sensitivity of FAZ cells to ethylene and ABA. Simultaneously, hexanal maintained the cell wall integrity of FAZ cells by regulating genes involved in cell wall modifications. Thus, delayed fruit abscission by hexanal is most likely achieved by minimizing ABA through an ethylene-dependent mechanism.

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Analysis of Boron and B-pectin Complex Content in the Abscission Zone during Floral and Fruit Abscission in Tobacco (Nicotiana tabacum)

Journal of the Japanese Society for Horticultural Science ◽

10.2503/jjshs1.82.83 ◽

2013 ◽

Vol 82 (1) ◽

pp. 83-90 ◽

Cited By ~ 2

Author(s):

Keita Tsukahara ◽

Hiroaki Iwai ◽

Eri Hamaoka ◽

Jun Furukawa ◽

Toshiro Matsunaga ◽

...

Keyword(s):

Nicotiana Tabacum ◽

Abscission Zone ◽

Fruit Abscission

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The North American ginseng inflorescence: development, floret abscission zone, and the effect of ethylene

Canadian Journal of Botany ◽

10.1139/b01-074 ◽

2001 ◽

Vol 79 (9) ◽

pp. 1048-1056 ◽

Cited By ~ 3

Author(s):

Andrea E Fiebig ◽

John TA Proctor ◽

Usher Posluszny ◽

Dennis P Murr

Keyword(s):

North American ◽

American Ginseng ◽

Abscission Zone ◽

Panax Quinquefolius ◽

Inflorescence Development ◽

Zone Formation ◽

Zone Length ◽

The North ◽

Seed Head ◽

Industry Practice

Characterization of the North American ginseng (Panax quinquefolius L.) inflorescence, the floret abscission zone, and its stimulation by ethylene were undertaken to gain insights into the potential for floret abscission induction as a replacement for the industry practice of expensive manual removal of the inflorescence. In each of 3 years, peduncle length of 3-year-old cultivated ginseng inflorescences increased rapidly in June, reaching maximal values of 140180 mm. During this period, seed head diameter also increased to about 35 mm, while seed head fresh mass increased in July and August to 6.58.0 g. Flowering in 1996 and 1997 began in the last 2 weeks of June and lasted through July, with open flowers never exceeding 35%. Anatomical studies and manual dissection of 1- and 3-year-old perennating buds revealed development of the floral primordia first at their periphery and progressing centripetally. Stamen initials were seen as a pentamerous whorl just under the petal primordia, and the characteristic inferior ovary initiated as a slight depression at the centre of the floral meristem. Sections through 3-year-old inflorescences harvested on May 23, 1996, showed that distal floral apices had already formed constriction zones between the flower and the pedicel, indicating the position of the abscission zone. Length of time to ethylene-induced abscission zone formation was less than 24 h in 3-year-old ginseng harvested on July 23, 1997. The abscission threshold for ginseng berry drop was in the range of 10-100 µL·L1 ethylene.Key words: anatomy, flowering, Panax quinquefolius, perennating bud.

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Influence of Temperature Differential between Tomatoes and Postharvest Water on Salmonella Internalization

Journal of Food Protection ◽

10.4315/0362-028x.jfp-15-525 ◽

2016 ◽

Vol 79 (6) ◽

pp. 922-928 ◽

Cited By ~ 3

Author(s):

ASHLEY N. TURNER ◽

LORETTA M. FRIEDRICH ◽

MICHELLE D. DANYLUK

Keyword(s):

Abscission Zone ◽

Most Probable Number ◽

P Value ◽

Temperature Differential ◽

Time Intervals ◽

Probable Number ◽

Treatment Conditions ◽

Pulp Temperature ◽

Tomato Pulp ◽

Effects Of Temperature

ABSTRACT Salmonella bacteria may internalize into tomato pulp when warm tomatoes from the field are submerged into colder water. Several washing steps may follow the initial washing and packing of tomatoes at the packinghouses; the potential for internalization into tomatoes in subsequent washing steps when tomatoes have a cooler pulp temperature is unknown. Our objective was to evaluate Salmonella internalization into mature green and red tomatoes with ambient (21°C) and refrigeration (4°C) pulp temperatures when they were submerged into water at various temperature differentials, simulating repacking and fresh-cut operations. Red (4°C and 21°C) and mature green (21°C) tomatoes were submerged (6 cm) into a six-strain Salmonella cocktail (6 log CFU/ml) and maintained at ±5 and 0°C temperature differentials for varying time intervals, ranging from 30 s to 5 min. Following submersion, tomatoes were surface sterilized using 70% ethanol, the stem abscission zone and blossom end epidermis were removed, and cores were recovered, separated into three segments, and analyzed. Salmonella populations in the segments were enumerated by most probable number (MPN). The effects of temperature differential and maturity on Salmonella populations were analyzed; results were considered significant at a P value of ≥0.5. Internalized populations were not significantly different (P ≥ 0.5) across temperature differentials. Salmonella internalization was seen in tomatoes under all treatment conditions and was highest in the segment immediately below the stem abscission zone. However, populations were low (typically >1 log MPN per segment) and varied greatly across temperature differentials. This suggests that the temperature differential between tomatoes and water beyond the initial packinghouse may be less important than submersion time in Salmonella internalization.

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