Integumentary Mucilage as an Oxygen Barrier During Germination of Blepharis persica (Burm.) Kuntze

Witztum, A.; Gutterman, Yitzchak; Evenari, M.

doi:10.1086/336497

Cited by 67 publications

(51 citation statements)

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“…The mucilage was proposed to influence moisture relations and seed dispersal during seed germination (Young and Evans, 1973). Witztum et al (1969) proposed that mucilage acts as an oxygen barrier during germination of Blepharis persica. If it was the case in Arabidopsis, we would expect the gl2 mutant to germinate earlier than Ler.…”

Section: Discussionmentioning

confidence: 99%

Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis

2000

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The testa of higher plant seeds protects the embryo against adverse environmental conditions. Its role is assumed mainly by controlling germination through dormancy imposition and by limiting the detrimental activity of physical and biological agents during seed storage. To analyze the function of the testa in the model plant Arabidopsis, we compared mutants affected in testa pigmentation and/or structure for dormancy, germination, and storability. The seeds of most mutants exhibited reduced dormancy. Moreover, unlike wild-type testas, mutant testas were permeable to tetrazolium salts. These altered dormancy and tetrazolium uptake properties were related to defects in the pigmentation of the endothelium and its neighboring crushed parenchymatic layers, as determined by vanillin staining and microscopic observations. Structural aberrations such as missing layers or a modified epidermal layer in specific mutants also affected dormancy levels and permeability to tetrazolium. Both structural and pigmentation mutants deteriorated faster than the wild types during natural aging at room temperature, with structural mutants being the most strongly affected.

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Section: Discussionmentioning

confidence: 99%

Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis

2000

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“…The role of the mucilage must also be considered. Germination of seeds of Blepharispersica can be stimulated by removing the mucilage or the seed coat and by increasing the percentage of oxygen to which they are exposed (Witztum et al, 1969). Pricking the seeds or removing the testa also promotes germination of Arabidopsis seeds (Kugler, 1951).…”

Section: Discussionmentioning

confidence: 99%

A Seed Shape Mutant of Arabidopsis That Is Affected in Integument Development.

Léon‐Kloosterziel¹,

Keijzer²,

Koornneef³

1994

Plant Cell

175

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A seed shape mutant of Arabidopsis was isolated from an ethyl methanesulfonate-treated population. Genetic analysis revealed that the heart-shaped phenotype was maternally inherited, showing that this is a testa mutant. This indicated the importance of the testa for the determination of the seed shape. This recessive aberrant testa shape (ats) gene was located at position 59.0 on chromosome 5. A comparison was made between ovules and developing and mature seeds of the wild type and of the mutant using light and scanning electron microscopy. We showed that the mutant seed shape is determined during the first few days after fertilization, when the embryo occupies only a very small part of the seed.The integuments of ats ovules consisted of only three rather than five cell layers. In double mutants, the effect of ats was additive to other testa mutations, such as transparent testa, glabra (ttg), glabrous2 (gl2), and apetala2 (ap2). The ats mutation resulted in a reduced dormancy, which was maternally inherited. This effect of a testa mutation on germination was also seen in ttg seeds, in which the outer layer of the testa was disturbed. This indicated the importance of the testa as a factor in determining dormancy in Arabidopsis.

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“…Mucilage has been proposed to regulate germination by acting as an oxygen barrier (Witztum et al, 1969) or to enable germination under conditions of reduced water potential (Penfield et al, 2001). Other possible functions include seed dispersal (Young and Evans, 1973;Gutterman and ShemTov, 1996) or the protection of the germinating seedling (Western et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

A Naturally Occurring Mutation in an Arabidopsis Accession Affects a β-d-Galactosidase That Increases the Hydrophilic Potential of Rhamnogalacturonan I in Seed Mucilage

et al. 2007

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The Arabidopsis thaliana accession Shahdara was identified as a rare naturally occurring mutant that does not liberate seed mucilage on imbibition. The defective locus was found to be allelic to the mum2-1 and mum2-2 mutants. Map-based cloning showed that MUCILAGE-MODIFIED2 (MUM2) encodes the putative b-D-galactosidase BGAL6. Activity assays demonstrated that one of four major b-D-galactosidase activities present in developing siliques is absent in mum2 mutants. No difference was observed in seed coat epidermal cell structure between wild-type and mutant seed; however, weakening of the outer tangential cell wall by chemical treatment resulted in the release of mucilage from mum2 seed coat epidermal cells, and the mum2 mucilage only increased slightly in volume, relative to the wild type. Consistent with the absence of b-D-galactosidase activity in the mutant, the inner layer of mucilage contained more Gal. The allocation of polysaccharides between the inner and outer mucilage layers was also modified in mum2. Mass spectrometry showed that rhamnogalacturonan I in mutant mucilage had more branching between rhamnose and hexose residues relative to the wild type. We conclude that the MUM2/BGAL6 b-Dgalactosidase is required for maturation of rhamnogalacturonan I in seed mucilage by the removal of galactose/galactan branches, resulting in increased swelling and extrusion of the mucilage on seed hydration.

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Integumentary Mucilage as an Oxygen Barrier During Germination of Blepharis persica (Burm.) Kuntze

Cited by 67 publications

References 0 publications

Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis

Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis

A Seed Shape Mutant of Arabidopsis That Is Affected in Integument Development.

A Naturally Occurring Mutation in an Arabidopsis Accession Affects a β-d-Galactosidase That Increases the Hydrophilic Potential of Rhamnogalacturonan I in Seed Mucilage

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