Abscission of flowers and floral parts

Doorn, Wouter G. van; Stead, Anthony D.

doi:10.1093/jxb/48.4.821

Cited by 174 publications

(100 citation statements)

References 150 publications

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“…They observed that in most dicots, ethylene levels are elevated in response to pollination and abscission subsequently results. However, they also found that many monocots do not show similar ethylene responses (van Doorn and Stead, 1997;van Doorn, 2002).…”

Section: Discussionmentioning

confidence: 98%

Ethylene-Dependent and -Independent Processes Associated with Floral Organ Abscission in Arabidopsis

2004

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Abscission is an important developmental process in the life cycle of the plant, regulating the detachment of organs from the main body of the plant. This mechanism can be initiated in response to environmental cues such as disease or pathogen, or it can be a programmed shedding of organs that no longer provide essential functions to the plant. We have identified five novel dab (delayed floral organ abscission) mutants (dab1-1, dab2-1, dab3-1, dab3-2, and dab3-3) in Arabidopsis. These mutants each display unique anatomical and physiological characteristics and are governed by three independent loci. Scanning electron microscopy shows delayed development of the flattened fracture plane in some mutants and irregular elongation in the cells of the fracture plane in other mutants. The anatomical observations are also supported by breakstrength measurements that show high breakstrength associated with broken cells, moderate levels for the flattened fracture plane, and low levels associated with the initial rounding of cells. In addition, observations on the expression patterns in the abscission zone of cell wall hydrolytic enzymes, chitinase and cellulose, show altered patterns in the mutants. Last, we have compared these mutants with the ethylene-insensitive mutants etr1-1 and ein2-1 to determine if ethylene is an essential component of the abscission process and find that although ethylene can accelerate abscission under many conditions, the perception of ethylene is not essential. The role of the dab genes and the ethylene response genes during the abscission process is discussed.Abscission, the developmental process regulating detachment of organs from the main body of the plant, can be regarded as valuable to the plant in response to disease or pathogen challenge and the shedding of organs that no longer provide essential functions to the plant. Historically, ethylene treatment has been shown to result in early abscission and increases in cell wall hydrolytic enzymes. In their studies on Prunus serrulata senriko and Parthenocissus quinquefolia, Jackson and Osborne (1970) concluded that ethylene was not only responsible for accelerating abscission but an essential regulator of abscission. Alternatively, crops like Citrus sinensis appear to have limited responses to ethylene treatment (Lewis et al., 1968;Palmer et al., 1969). Although the role of ethylene in hastening abscission has been documented repeatedly in many plant species over the last several decades, it has never been shown definitively that ethylene perception in these plants is essential for abscission (Addicott, 1982; Abeles et al., 1992). Previously, we have illustrated that floral organ abscission in Arabidopsis may be used as a model system to study abscission (Bleecker and Patterson, 1997). In this work, we will further elucidate the role of ethylene in floral organ abscission by the identification and characterization of five novel dab (delayed abscission) mutants (dab1-1, dab2-1, dab3-1, dab3-2, and dab3-3), representing three independent loc...

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Section: Discussionmentioning

confidence: 98%

Ethylene-Dependent and -Independent Processes Associated with Floral Organ Abscission in Arabidopsis

2004

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“…Positive biomarkers representing the flowers and stamens included transcripts corresponding to enzymes in the monoterpenoid and sesquiterpenoid biosynthesis pathways (e.g., enzymes that synthesize germacrene, cadinene, terpineol, pinene and myrcene, which are prominent components of floral scents) (Martin et al, 2010). There were also eight pectinesterase and seven polygalacturonase transcripts encoding cell wall-modifying enzymes involved in flower abscission (van Doorn and Stead, 1997) and pollen tube elongation (Bosch and Hepler, 2005). Notably, (A) Correlation matrix of the whole data set.…”

Section: Molecular Biomarkersmentioning

confidence: 99%

The Grapevine Expression Atlas Reveals a Deep Transcriptome Shift Driving the Entire Plant into a Maturation Program

et al. 2012

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We developed a genome-wide transcriptomic atlas of grapevine (Vitis vinifera) based on 54 samples representing green and woody tissues and organs at different developmental stages as well as specialized tissues such as pollen and senescent leaves. Together, these samples expressed ;91% of the predicted grapevine genes. Pollen and senescent leaves had unique transcriptomes reflecting their specialized functions and physiological status. However, microarray and RNA-seq analysis grouped all the other samples into two major classes based on maturity rather than organ identity, namely, the vegetative/ green and mature/woody categories. This division represents a fundamental transcriptomic reprogramming during the maturation process and was highlighted by three statistical approaches identifying the transcriptional relationships among samples (correlation analysis), putative biomarkers (O2PLS-DA approach), and sets of strongly and consistently expressed genes that define groups (topics) of similar samples (biclustering analysis). Gene coexpression analysis indicated that the mature/woody developmental program results from the reiterative coactivation of pathways that are largely inactive in vegetative/green tissues, often involving the coregulation of clusters of neighboring genes and global regulation based on codon preference. This global transcriptomic reprogramming during maturation has not been observed in herbaceous annual species and may be a defining characteristic of perennial woody plants.

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“…Cellulases are able to act on plant cell walls and play a role in loosening and separating cells in the abscission zone in plants [25] [26]. Therefore, cellulases may play a role in endosperm weakening in lettuce seeds.…”

Section: Introductionmentioning

confidence: 99%

Carboxymethylcellulase Activity in Lettuce Seeds Prior to Germination

Pavlišta¹

2017

AJPS

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Does the endosperm pose a mechanical resistance on embryonic axis (radicle) growth for lettuce seed (achene) germination? To aid answering this question, the cell wall degrading enzyme, carboxymethylcellulase (CMCase) was extracted and assayed from lettuce seeds imbibed for 0 to 12 h, prior to germination. Measuring the loss of viscosity of carboxymethylcellulose, CMCase activity was high in dry seeds, low after 6 h of imbibition, high after 9 and 10 h, and then reduced again after 12 h. Fractions from Sephadex columns showed CMCase activity in three peaks labeled E1, E2, E3. The greatest change in CMCase activity during imbibition was with E3 (molecular weight of about 40,000 Daltons) and some reduction in E2 (molecular weight about 280,000). The RNA synthesis inhibitor, 6-methyl purine, eliminated CMCase activity when present from 4.5 to 7 h of imbibition and the protein synthesis inhibitor, cycloheximide, eliminated CMCase activity when present between 5.5 and 9 h. Imbibition in darkness lowered CMCase activity while 15 min of light at 3.5 h restored it and 30 min of far-red light at 3 h eliminated it. Increasing the imbibition temperature to 35˚C under light reduced activity while under darkness, activity was eliminated under 24˚C and 35˚C. CMCase activity was localized in the endosperm surrounding the embryonic axis (micropylar end) of 9 h imbibed seeds. These observations showed that CMCase was active in degrading the cell wall in the endosperm surrounding the radicle, weakening it, prior to radicle protrusion so that the radicle remains undamaged.

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Abscission of flowers and floral parts

Cited by 174 publications

References 150 publications

Ethylene-Dependent and -Independent Processes Associated with Floral Organ Abscission in Arabidopsis

Ethylene-Dependent and -Independent Processes Associated with Floral Organ Abscission in Arabidopsis

The Grapevine Expression Atlas Reveals a Deep Transcriptome Shift Driving the Entire Plant into a Maturation Program

Carboxymethylcellulase Activity in Lettuce Seeds Prior to Germination

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