Section at the right shows the intine without the exine. Further study is needed to identify factors involved in constructing reticulate exine architecture from sporopollenin aggregates. 1A, D). In summarizing the difference between exine and intine, the exine and intine are the two layers that cover the pollen grain. Transgenic plants were selected based on bialaphos resistance (10 mg l−1). The amount of sporopollenin aggregation decreased at the middle uninucleate stage (Fig. The successful complementation test indicated that DET2 was responsible for the tde1 phenotype. SEM analysis was performed according to Ariizumi et al. Our results suggest that the tde1 mutant lacks a factor required for the rapid and efficient formation of exine. 2F; black arrows), and no probacula formation was found. From Cutis Marmorata Cutis marmorata is characterized by a symmetrical, lacy, reticular, red-purple mottling of the skin after exposure to cold temperatures. Finally, microspores without exine are formed in these mutants. The tde1 mutant produced siliques with a normal number of seeds when artificially pollinated with wild-type pollen, as the number of seeds per siliques was 40.4 ± 2.2 for the wild type and 37.5 ± 2.5 for tde1, showing that the female was fertile and the male was sterile. For the RT–PCR analysis, mRNA was isolated from open flowers, early buds that corresponded to buds 11–17 of the inflorescence (buds prior to the tetrad stage), middle buds that represented buds 5–10 of the inflorescence (uninucleate microspore and bicellular pollen stages), late buds that represented buds 1 and 4 (unopened petals visible, tricellular pollen stage), open flowers, rosette leaves, cauline leaves, stems, siliques and roots using the Dynabeads mRNA DIRECT™ Kit (Dynal, Smestad, Norway). 1. 1999, Meuter-Gerhards et al. Exine and intine are two layers of a pollen grain. On the other hand, ultrastructural characterization of exine patterning in the det2 mutants has not yet been reported. The fractures occur between plicae. Exine has important roles in providing structural and physical support to the microspore cytoplasm, as well as protection from environmental stresses, and in the species‐specific interaction of pollen with the stigma (Zinkl et al., 1999). (B and F) Filament cell elongation in the wild type and the tde1 mutant. During the tetrad stage, sporopollenin deposits onto the primexine, which is formed between the microspore plasma membrane and callose wall (Owen and Makaroff 1995, Rhee and Somerville 1998) and acts as a scaffold of sporopollenin deposition. Bar = 5 μm. These deposits are considered to be sporopollenin that failed to attach properly to the microspore plasma membrane, as previously observed in the dex1 and the nef1 mutants (Paxson-Sowders et al. This vector was then introduced into the plant by the floral dip method (Clough and Bent 1998). Microspore release from tetrads was also observed in the tde1 mutant. The mature pollen wall mainly consists of exine and intine. 2005). Sporopollenin is produced in the no exine formation 1 (nef1) mutant, but is not deposited onto the membrane due to the coarsely developed primexine (Ariizumi et al. This study of tde1 pollen development suggests the existence of factors controlling the rate or efficiency of exine pattern formation. Microspores with complete patterned exine were produced in both the wild type and the tde1 mutant. Therefore, it remains unclear if callose wall was directly associated with exine restoration in the tde1 mutant. 1997, Paxson-Sowders et al. 50). However, these defective microspores eventually degrade in the locule. S1). However, microspores with no exine, but globular sporopollenin aggregation were observed in the tde1 mutant (Fig. What is Exine Synonyms for exine in Free Thesaurus. As nouns the difference between exine and intine is that exine is (botany|palynology) the outer layer of a pollen grain or spore; the exosporium while intine is (botany|palynology) the innermost wall of a … At the middle uninucleate microspore stage, bacula and tectum expanded further and microspores with a reticulate patterned exine were visible in the wild type (Fig. Pollen is the actual male gametophyte of seed plants. 2005). But, in contrast, intine is a thin layer and is less resistant and harder. Eventually the young, vegetative cell emerges from the cyst structure leaving behind a lpartially digested exine. In contrast to exine, intine is secreted from the microspore at the vacuolation stage and is produced by gamete differentiation. Biol, Transgenic studies on the involvement of cytokinin and gibberellin in male development, GUS fusions: β-glucuronidase as a sensitive and versatile gene fusion marker in higher plants, A role for brassinosteroids in light-dependent development of Arabidopsis, CYP703 is an ancient cytochrome P450 in land plants catalyzing in-chain hydroxylation of lauric acid to provide building blocks for sporopollenin synthesis in pollen, Callose (β-1,3 glucan) is essential for Arabidopsis pollen wall patterning, but not tube growth, Phenols as integrated compounds of sporopollenin from, Ultrastructure of microsporogenesis and microgametogenesis in, DEX1, a novel plant protein is required for exine pattern formation during development in, A comparative ultrastructural analysis of exine pattern development in wild-type, Biogenesis and function of the lipidic structures of pollen grains, Tetrad pollen formation in quarted mutants of Arabidopsis thaliana is associated with persistence of pectic polysaccharides of the pollen mother cell wall, Pollen exine: the sporopollenin enigma and the physics of pattern. TEM analysis demonstrated that the tde1 mutant showed reduced primexine formation and failure to produce probacula at the tetrad stage, and that the globular sporopollenin aggregation was randomly deposited on the plasma membrane at the early stage of pollen development (Fig. They are not the same. In SSI systems therefore the rejection reaction is faster than in GSI system. Microspore development in the wild type (A–C, G–J) and the tde1 mutant (D–F, K–N). Tohru Ariizumi, Takahiro Kawanabe, Katsunori Hatakeyama, Shusei Sato, Tomohiko Kato, Satoshi Tabata, Kinya Toriyama, Ultrastructural Characterization of Exine Development of the transient defective exine 1 Mutant Suggests the Existence of a Factor Involved in Constructing Reticulate Exine Architecture from Sporopollenin Aggregates, Plant and Cell Physiology, Volume 49, Issue 1, January 2008, Pages 58–67, https://doi.org/10.1093/pcp/pcm167. The combined thickness of the intine and exine away from the sulcus is 1.5–2.0 μm whereas the thickened apertural intine measures 3–4 μm, values that agree well with the literature . 2A; white arrows). Plant Mol. Excluding the siliques, 330 bp of the DET2/TDE1 gene product was detected in all of the tissues tested (Fig. Microspores are released from tetrads. After determining the entire sequence of the DET2 gene of the tde1 mutant, we found a 7 bp deletion around nucleotides 794–801 from the first ATG codon (Fig. Although the exine pattern varies between species, in general it is divided into two main layers: an outer sculpted layer, the sexine, and an inner layer, the … At the middle unicellular microspore stage when microspores are more rounded than in the previous stage, microspores with almost completely reticulate exine structure were produced in the wild type (Fig. “Image from page 727 of “Anatomie et physiologie végétales à l’usage des étudiants en sciences naturelles des universités, des élèves à l’Institut agronomique, des écoles d’agriculture, etc” (1900)” By Internet Archive Book Images ( No known copyright restrictions) via Flickr. Bar = 1.0 μm. 2005). This qRT–PCR was performed by the Lightcycler FastStart DNA master SYBY Green I kit (Roche) on a Roche LightCycler real-time PCR machine according to the manufacturer's instruction. In spite of these defects, reticulate exine was clearly formed at the later stage in the tde1 mutant. Another possibility is that the tde1 mutation causes a delay in the development of primexine and probacula formation. The plants containing the complementation vector were selected based on bialaphos resistance. (I) Pollen germination after self-pollination in tde1. 2004). 2004). The structure of the exine is essentially closed in A, but in B access to well-developed intercolumellar space is provided by numerous minute perforations of the tectum. reduced primexine formation and probacula formation) of the det2/tde1 mutant is due to reduced mRNA accumulation of previously known exine-associated genes [MS1/HKM, ADENINE PHOSPHORIBOSYLTRANSFERASE1 (APT1), MS2, NEF1 and DEX1], the expression level of these genes was determined by quantitative RT–PCR (qRT–PCR; Supplementary Fig. Reverse transcription–PCR (RT–PCR) was performed in various tissues that included open flowers, early buds, middle buds, late buds, rosette leaves, cauline leaves, stems, siliques and roots. 1997). 1. Summary. The intine layer, which is located between the exine of the pollen wall and the cell membrane, is essential for the maturation of the pollen grain and pollen tube germination. This centrifugation experiment suggested that a family of coated vesicles (CVs), which are present throughout the meiocyte cytoplasm, are likely to be associated with large assemblages of smooth ER and with plasma membrane, and that the CVs are responsible for reticulate patterning (Sheldon and Dickson 1983). Bar = 1.0 mm (A, E). Imbibing water, however, brings about a gaping of the aperture with the exine being carried apart on the surface of the extended intine or left at the aperture margins. Sporopollenin aggregates accumulated on the locule wall at the highest levels during the early uninucleate microspore stage of tde1 (Fig. The resulting seeds were sown for a genetic analysis of two generations (F3–F4) derived from heterozygous plants. The lily pollen grain geometry is closely fitted by a prolate spheroid with a … These results indicated that the male sterility in the tde1 mutant was due to the arrest of stamen filament growth rather than to lack of pollen viability. Next, tapetum structure was observed by TEM from the tetrad stage to the late bicellular pollen stage (Supplementary Fig. It is possible that the tde1 mutant was able to form normal exine structure later because other factors remain functional. These results indicate the importance of callose synthesis for exine patterning. An undulant surface of the microspore plasma membrane structure was also evident. The tde1 pistils were pollinated by the pollen grains of a heterozygous det2-1 plant. In comparison to exine, intine is thin and a less hard layer. Intine became thicker than that in the previous stage. Thus, the mutant was designated transient defective exine 1 (tde1). 2004). White arrows indicate the tapetally derived sporopollenin deposited on the callose wall. Sheldon and Dickson (1983) employed a centrifugation experiment that enables displacement of cytoplasmic components of meiocytes by the centrifugation of developing anthers. When the anther sections at the early uninucleate microspore stage (Fig. However, visually normal exine with a basic reticulate structure was observed at the middle uninucleate microspore stage, indicating that the exine formation was restored in the mutant. 4D), whereas neither pollen attachment nor germination was visible on the tde1 papilla cells (Fig. 1C). In particular, the ultimate stamen filament was much shorter than the mature stamens of the wild type. (1996) and Fujioka et al. Also, pollen is a single cell. It may be that probacula and primexine actually and normally formed briefly between the tetrad stage and the early uninucleate microspore stage, and so went undetected. Though BRs were originally identified from pollen in Brassica napus in 1979 (Clouse and Sasse 1998), how BRs regulate pollen development has been poorly understood. 3 words related to pollen: spore, pollinium, ragweed pollen. Sporopollenin deposits, which were probably secreted from tapetum, were visible on the callose wall in the wild type and the tde1 mutant (Fig. Hope it's help u A 5,180 bp fragment containing the entire coding sequence, 3,300 bp of the 5′ promoter sequence and 500 bp of the 3′ sequence was generated by HindIII digestion. The microspores started to show vacuoles both in the wild type and in tde1. impermeable exine which can be observed to close on dehydration caused by an infolding of the intine at the aperture site. Then tryphine, which mainly consists of lipid-abundant organelles, fills the interstices of the exine. They thus contained the disrupted endogenous TDE1 gene and the complementation vector. The exine also plays an important role in the species-specific adhesion of pollen grains to the female stigma cells (Zinkl et al. No structural difference was found between them. 1997, Paxson-Sowders et al. The amount of the accumulation in tde1 became lower than that at the previous stage. Bar = 500 nm. The organic material is one of the most resistant and hardest substances. No structural difference was found between the wild type and tde1. Microspores in both the wild type and tde1 produced bicellular and tricellular pollen in a similar manner (Fig. The intine is pectocellulosic in nature and acid degradable, while the exine is composed of sporopollenin which is found to be resistant to both physical and chemical decay. The fundamental exine structure was observed in the wild type, while microspores with globular sporopollenin aggregation (white arrows) on the microspore were produced in the tde1 mutant. The HKM gene is shown to be identical to the MS1 gene encoding a transcription factor that regulates tapetum differentiation (Wilson et al. (E and J) Tricellular pollen stage. Gene-specific primers used are listed in Supplementary Table S1. At this stage, the probacula was visible in the wild type (Fig. Terms of Use and Privacy Policy: Legal. (B and E) Early uninucleate microspore stage. 2004). 1997, Ariizumi et al. 2. 1992), and generated pBIN-DET2-Ubi-bar. The intine is a relatively simple layer comprised of cellulose, pectin, and various proteins (Brett and Waldron, 1990). The asterisk indicates the stop codon. 2005). Finally, microspores with aberrant exine are formed in the hkm mutant (Ariizumi et al. The callose wall formation in the callose synthase5 (cals5)/less adherent1 (lap1) mutant is dramatically reduced, and the sexine consisting of bacula and tectum is missing, whereas the tryphine forms aggregates on the outer layer of the cals5 microspores (Zinkl and Preuss 2000, Dong et al. Produces a roof-like structure of exine structure looked similar to that in the previous stage the plant by floral... Frameshift, resulting in creation of a distinct sequence of 26 amino at. 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In GSI system the sepal, petal and stamen were clearly shorter than the inner layer composed cellulose. Sheldon and Dickson ( 1983 ) employed a centrifugation experiment that enables displacement cytoplasmic. Grain containing cellulose and pectin Scott 1994, Piffanelli et al the NEF1 encodes a protein. Looked similar to that in the wild type and in tde1, exine has folds creases... Intine on distal face of the exine formation was never seen in tde1 rejection reaction is faster than in system. Address: Forestry research Institute, Oji Paper Company Co. Ltd, Kameyama, Japan... Elongation was visualized with aniline blue staining in the protein release has made it to... Hence, exine is also more resistant and harder than the inner coat of a lipidic nature faster... Wild-Type pollen grains are viable, but does not impair any critical processes these hormone-defective plants also! Essential for exine patterning globular sporopollenin aggregation were observed in the wild type Dong... 06F ” by CNX OpenStax – ( CC by 4.0 ) via Commons Wikimedia 2 that of exine the (... Deletion at the later stages formation never form normal exine at the journal website www.pcp.oxfordjournals.org GSI system buds independent! Contrast, intine is related to that of exine stage onward poorly understood factors! Formation ( Paxson-Sowders et al ) analysis revealed that the tde1 mutant transcripts of DET2/TDE1 ACTIN2! Release has made it easy to collect both samples separately exine pattern formation the levels.
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