The acceleration of yellow lupine flower abscission by jasmonates is accompanied by lipid-related events in abscission zone cells

The lifetime of many plant organs does not exceed a few weeks or a few months. These organs separate from the plant at the level of specialized abscission zones. The observation of xylem vasculature in abscission zones, a largely neglected subject, revealed original features when a vessel casting method was used. In all species of dicotyledons examined so far, flower and leaf abscission zones possessed heterogenous metaxylem vessels adjoining protoxylem and secondary xylem vessels with homogenous patterns of lignified thickenings. Heterogenous metaxylem vessel thickenings were helical, reticulate, or scalariform elements when in the abscission zone and pitted elements on the proximal and the distal sides. The origin and possible role of these vessels are considered. Data obtained on the flower abscission zone of tomato (Lycopersicon esculentum Mill.) suggest that formation of heterogenous vessels results from localized changes in the rhythm of cell differentiation and cell maturation inside the procambium-cambium continuum.Key words: abscission zone, cambium, differentiation, heterogenous vessels, procambium, vessel cast.

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EPIP-Evoked Modifications of Redox, Lipid, and Pectin Homeostasis in the Abscission Zone of Lupine Flowers

International Journal of Molecular Sciences ◽

10.3390/ijms22063001 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3001

Author(s):

Emilia Wilmowicz ◽

Agata Kućko ◽

Wojciech Pokora ◽

Małgorzata Kapusta ◽

Katarzyna Jasieniecka-Gazarkiewicz ◽

...

Keyword(s):

Fatty Acids ◽

Cell Wall ◽

Redox Homeostasis ◽

Abscission Zone ◽

Wall Structure ◽

Related Research ◽

Flower Abortion ◽

Mitogen Activated Protein ◽

Acyl Lipids ◽

Flower Abscission

Yellow lupine is a great model for abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN ABSCISSION) amino-acid sequence, is a sufficient molecule to induce flower abortion, however, the question remains: What are the exact changes evoked by this peptide locally in abscission zone (AZ) cells? Therefore, we used EPIP peptide to monitor specific modifications accompanied by early steps of flower abscission directly in the AZ. EPIP stimulates the downstream elements of the pathway—HAESA and MITOGEN-ACTIVATED PROTEIN KINASE6 and induces cellular symptoms indicating AZ activation. The EPIP treatment disrupts redox homeostasis, involving the accumulation of H2O2 and upregulation of the enzymatic antioxidant system including superoxide dismutase, catalase, and ascorbate peroxidase. A weakening of the cell wall structure in response to EPIP is reflected by pectin demethylation, while a changing pattern of fatty acids and acyl lipids composition suggests a modification of lipid metabolism. Notably, the formation of a signaling molecule—phosphatidic acid is induced locally in EPIP-treated AZ. Collectively, all these changes indicate the switching of several metabolic and signaling pathways directly in the AZ in response to EPIP, which inevitably leads to flower abscission.

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The influence of abscisic acid on the ethylene biosynthesis pathway in the functioning of the flower abscission zone in Lupinus luteus

Journal of Plant Physiology ◽

10.1016/j.jplph.2016.08.018 ◽

2016 ◽

Vol 206 ◽

pp. 49-58 ◽

Cited By ~ 19

Author(s):

Emilia Wilmowicz ◽

Kamil Frankowski ◽

Agata Kućko ◽

Michał Świdziński ◽

Juan de Dios Alché ◽

...

Keyword(s):

Abscisic Acid ◽

Ethylene Biosynthesis ◽

Abscission Zone ◽

Lupinus Luteus ◽

Biosynthesis Pathway ◽

Flower Abscission

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High floral bud abscission and lack of open flower abscission in Dendrobium cv. Miss Teen: rapid reduction of ethylene sensitivity in the abscission zone

Functional Plant Biology ◽

10.1071/fp05200 ◽

2006 ◽

Vol 33 (6) ◽

pp. 539 ◽

Cited By ~ 9

Author(s):

Kanokpon Bunya-atichart ◽

Saichol Ketsa ◽

Wouter G. van Doorn

Keyword(s):

Abscission Zone ◽

Flower Opening ◽

Open Flower ◽

Rapid Reduction ◽

Ethylene Sensitivity ◽

Floral Buds ◽

Endogenous Ethylene ◽

Ethylene Insensitivity ◽

Floral Bud ◽

Flower Abscission

We studied the abscission of floral buds and open flowers in cut Dendrobium inflorescences. Abscission of floral buds was high and sensitive to ethylene in all cultivars studied. Many open flowers abscised in most cultivars, but cv. Willie exhibited only small amount of floral fall and cv. Miss Teen none. Applied ethylene (0.4 μL L–1 for 24 h at 27°C) greatly hastened abscission of open flowers in most cultivars, but had only a small effect in cv. Willie and no effect in cv. Miss Teen. Flower fall, if it occurred, was completely inhibited by 1-methylcyclopropene (1-MCP), showing that it was regulated by endogenous ethylene. Ethylene production from the abscission zones was low in all cultivars studied. In cv. Miss Teen the abscission zone changed from highly ethylene sensitive to completely insensitive in ~30 h, coinciding with floral opening. Removal of the floral buds somewhat reduced abscission in open flowers, but the lack of open flower abscission in cv. Miss Teen could not be explained by higher bud fall. The ovary did not grow in the (unpollinated) flowers, showing that lack of abscission in cvv. Willie and Miss Teen was not due to parthenocarpy. Flower removal in cv. Miss Teen had no effect on ethylene sensitivity of the abscission of the remaining pedicel. However, removal of the distal 2 cm of the 3-cm-long pedicels dramatically increased ethylene sensitivity. This suggests that the pedicel is important for the low ethylene insensitivity of abscission, in this cultivar. It is concluded that the abscission zones in the cvv. Willie and Miss Teen, in contrast with the other cultivars investigated, became rapidly insensitive to ethylene at the time of flower opening. At least part of the ethylene sensitivity in Miss Teen seems to be due to a factor in the pedicel.

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Drought Disrupts Auxin Localization in Abscission Zone and Modifies Cell Wall Structure Leading to Flower Separation in Yellow Lupine

International Journal of Molecular Sciences ◽

10.3390/ijms21186848 ◽

2020 ◽

Vol 21 (18) ◽

pp. 6848

Author(s):

Aleksandra Bogumiła Florkiewicz ◽

Agata Kućko ◽

Małgorzata Kapusta ◽

Sebastian Burchardt ◽

Tomasz Przywieczerski ◽

...

Keyword(s):

Cell Wall ◽

Control Plant ◽

Pectin Methylesterase ◽

Economic Consequences ◽

Abscission Zone ◽

Cell Wall Structure ◽

Plant Production ◽

Wall Structure ◽

Flower Abortion ◽

Yellow Lupine

Drought causes the excessive abscission of flowers in yellow lupine, leading to yield loss and serious economic consequences in agriculture. The structure that determines the time of flower shedding is the abscission zone (AZ). Its functioning depends on the undisturbed auxin movement from the flower to the stem. However, little is known about the mechanism guiding cell–cell adhesion directly in an AZ under water deficit. Therefore, here, we seek a fuller understanding of drought-dependent reactions and check the hypothesis that water limitation in soil disturbs the natural auxin balance within the AZ and, in this way, modifies the cell wall structure, leading to flower separation. Our strategy combined microscopic, biochemical, and chromatography approaches. We show that drought affects indole-3-acetic acid (IAA) distribution and evokes cellular changes, indicating AZ activation and flower abortion. Drought action was manifested by the accumulation of proline in the AZ. Moreover, cell wall-related modifications in response to drought are associated with reorganization of methylated homogalacturonans (HG) in the AZ, and upregulation of pectin methylesterase (PME) and polygalacturonase (PG)—enzymes responsible for pectin remodeling. Another symptom of stress action is the accumulation of hemicelluloses. Our data provide new insights into cell wall remodeling events during drought-induced flower abscission, which is relevant to control plant production.

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Gibberellic acid affects the functioning of the flower abscission zone in Lupinus luteus via cooperation with the ethylene precursor independently of abscisic acid

Journal of Plant Physiology ◽

10.1016/j.jplph.2018.07.014 ◽

2018 ◽

Vol 229 ◽

pp. 170-174 ◽

Cited By ~ 4

Author(s):

Katarzyna Marciniak ◽

Agata Kućko ◽

Emilia Wilmowicz ◽

Michał Świdziński ◽

Krzysztof Przedniczek ◽

...

Keyword(s):

Abscisic Acid ◽

Gibberellic Acid ◽

Abscission Zone ◽

Lupinus Luteus ◽

Ethylene Precursor ◽

Flower Abscission

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Disruption of the Auxin Gradient in the Abscission Zone Area Evokes Asymmetrical Changes Leading to Flower Separation in Yellow Lupine

International Journal of Molecular Sciences ◽

10.3390/ijms21113815 ◽

2020 ◽

Vol 21 (11) ◽

pp. 3815

Author(s):

Agata Kućko ◽

Emilia Wilmowicz ◽

Wojciech Pokora ◽

Juan De Dios Alché

Keyword(s):

Auxin Transport ◽

Proximal Part ◽

Polar Auxin Transport ◽

Abscission Zone ◽

Marker Genes ◽

Transcriptional Level ◽

Local Concentration ◽

Strong Response ◽

Molecular Events ◽

Yellow Lupine

How auxin transport regulates organ abscission is a long-standing and intriguing question. Polar auxin transport across the abscission zone (AZ) plays a more important role in the regulation of abscission than a local concentration of this hormone. We recently reported the existence of a spatiotemporal sequential pattern of the indole-3-acetic acid (IAA) localization in the area of the yellow lupine AZ, which is a place of flower detachment. In this study, we performed analyses of AZ following treatment with an inhibitor of polar auxin transport (2,3,5-triiodobenzoic acid (TIBA)). Once we applied TIBA directly onto the AZ, we observed a strong response as demonstrated by enhanced flower abscission. To elucidate the molecular events caused by the inhibition of auxin movement, we divided the AZ into the distal and proximal part. TIBA triggered the formation of the IAA gradient between these two parts. The AZ-marker genes, which encode the downstream molecular components of the inflorescence deficient in abscission (IDA)-signaling system executing the abscission, were expressed in the distal part. The accumulation of IAA in the proximal area accelerated the biosynthesis of abscisic acid and ethylene (stimulators of flower separation), which was also reflected at the transcriptional level. Accumulated IAA up-regulated reactive oxygen species (ROS) detoxification mechanisms. Collectively, we provide new information regarding auxin-regulated processes operating in specific areas of the AZ.

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Endogenous auxin regulates the sensitivity of Dendrobium (cv. Miss Teen) flower pedicel abscission to ethylene

Functional Plant Biology ◽

10.1071/fp07146 ◽

2007 ◽

Vol 34 (10) ◽

pp. 885 ◽

Cited By ~ 7

Author(s):

Karnchana Rungruchkanont ◽

Saichol Ketsa ◽

Orawan Chatchawankanphanich ◽

Wouter G. van Doorn

Keyword(s):

Abscission Zone ◽

Flower Buds ◽

Flower Stalk ◽

Gene Encoding ◽

Ethylene Sensitivity ◽

Floral Buds ◽

Ethylene Removal ◽

Highly Correlated ◽

Floral Bud ◽

Flower Abscission

Dendrobium flower buds and flowers have an abscission zone at the base of the pedicel (flower stalk). Ethylene treatment of cv. Miss Teen inflorescences induced high rates of abscission in flower buds but did not affect abscission once the flowers had opened. It is not known if auxin is a regulator of the abscission of floral buds and open flowers. The hypotheses that auxin is such a regulator and is responsible for the decrease in ethylene sensitivity were tested. Severed inflorescences bearing 4–8 floral buds and 4–6 open flowers were used in all tests. The auxin antagonists 2,3,5-triiodobenzoic acid (TIBA, an inhibitor of auxin transport) or 2-(4-chlorophenoxy)-2-methyl propionic acid (CMPA, an inhibitor of auxin action) were applied to the stigma of open flowers. Both chemicals induced high flower abscission rates, even if the inflorescences were not treated with ethylene. The effects of these auxin antagonists virtually disappeared when the inflorescences were treated with 1-methylcyclopropene (1-MCP), indicating that the abscission induced by the auxin antagonists was due to ethylene. Removal of the open flowers at the distal end of the pedicel hastened the time to abscission of the remaining pedicel, and also resulted in an increase in ethylene sensitivity. Indole-3-acetic acid (IAA) in lanolin, placed on the cut surface of the pedicel, replaced the effect of the removed flower. Treatments that promoted abscission of open flowers up-regulated a gene encoding a β-1,4-glucanase (Den-Cel1) in the abscission zone (AZ). The abundance of Den-Cel1 mRNA was highly correlated with β-1,4-glucanase activity in the AZ. The results show that auxin is an endogenous regulator of floral bud and flower abscission and suggest that auxin might explain, at least partially, why pedicel abscission of Dendrobium cv. Miss Teen changes from very ethylene-sensitive to ethylene-insensitive.

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