Publications (5)11.32 Total impact
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Article: Synergism between cucumber alpha-expansin, fungal endoglucanase and pectin lyase.
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ABSTRACT: Several recombinant fungal enzymes (endoglucanase and pectinase) were studied for their interactions with alpha-expansin in cell wall extension and polysaccharide degradation. Both Cel12A and Cel5A were able to hydrolyze cellulose CMC-Na and mixed-linkage beta-glucan. In contrast to Cel5A, Cel12A could also hydrolyze xyloglucan and induce wall extension of cucumber hypocotyls in an in vitro assay. Combining alpha-expansin, even at high concentrations, with Cel12A did not enhance the maximum/final wall extension rate induced by Cel12A alone. These results strongly suggest that modification/degradation of the xyloglucan molecule/network is the key for cell wall extension, and alpha-expansin and Cel12A may share the same acting site in the substrate. Pectinase (Pel1, a pectin lyase) enhanced alpha-expansin-induced wall extension in a concentration-dependent manner, suggesting that the pectin network may normally regulate accessibility of expansin to the xyloglucan-cellulose complex. alpha-Expansin enhanced Cel12A's hydrolytic activity on cellulose CMC-Na but not on xyloglucan and beta-glucan. Expansin did not affect Cel5A's hydrolytic activity. Interestingly, expansin also enhanced Pel1's activity on degrading high esterified pectin. A potential explanation for why expansin could synergistically interact with only certain enzymes on specific polysaccharides is discussed. Additional results also suggested that cell wall swelling may not be a significant event during the action of expansin and hydrolases.Journal of plant physiology 09/2010; 167(14):1204-10. · 2.50 Impact Factor -
Article: Development of randomly amplified polymorphic DNA-sequence characterized amplified region marker for identification of Apocynum venetum LINN. from A. pictum SCHRENK.
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ABSTRACT: Apocynum venetum LINN. is an important Chinese crude drug, and its sibling species A. pictum SCHRENK is a confusable herb which is similar to it. The purpose of this study is to develop DNA molecular markers to distinguish A. venetum from A. pictum through the combinative technologies of bulked segregate analysis (BSA) and randomly amplified polymorphic DNA (RAPD). Two putative markers B08-407 and B03-1368 specific for A. venetum were identified and sequenced. Based on the sequence information, two pairs of primers were designed and synthesized for sequence characterized amplified region (SCAR) markers. But only one primer pair, B03-1368, produced a clear SCAR band in all samples of A. venetum and not in A. pictum. This SCAR marker was found useful for rapid identification of A. venetum from A. pictum.Biological & Pharmaceutical Bulletin 01/2010; 33(3):522-6. · 1.66 Impact Factor -
Article: Restoration of mature etiolated cucumber hypocotyl cell wall susceptibility to expansin by pretreatment with fungal pectinases and EGTA in vitro.
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ABSTRACT: Mature plant cell walls lose their ability to expand and become unresponsive to expansin. This phenomenon is believed to be due to cross-linking of hemicellulose, pectin, or phenolic groups in the wall. By screening various hydrolytic enzymes, we found that pretreatment of nongrowing, heat-inactivated, basal cucumber (Cucumis sativus) hypocotyls with pectin lyase (Pel1) from Aspergillus japonicus could restore reconstituted exogenous expansin-induced extension in mature cell walls in vitro. Recombinant pectate lyase A (PelA) and polygalacturonase (PG) from Aspergillus spp. exhibited similar capacity to Pel1. Pel1, PelA, and PG also enhanced the reconstituted expansin-induced extension of the apical (elongating) segments of cucumber hypocotyls. However, the effective concentrations of PelA and PG for enhancing the reconstituted expansin-induced extension were greater in the apical segments than in the basal segments, whereas Pel1 behaved in the opposite manner. These data are consistent with distribution of more methyl-esterified pectin in cell walls of the apical segments and less esterified pectin in the basal segments. Associated with the degree of esterification of pectin, more calcium was found in cell walls of basal segments compared to apical segments. Pretreatment of the calcium chelator EGTA could also restore mature cell walls' susceptibility to expansin by removing calcium from mature cell walls. Because recombinant pectinases do not hydrolyze other wall polysaccharides, and endoglucanase, xylanase, and protease cannot restore the mature wall's extensibility, we can conclude that the pectin network, especially calcium-pectate bridges, may be the primary factor that determines cucumber hypocotyl mature cell walls' unresponsiveness to expansin.Plant physiology 07/2008; 147(4):1874-85. · 6.53 Impact Factor -
Article: Contribution of both cell elongation and cell division to wheat coleoptile elongation
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ABSTRACT: Etiolated wheat coleoptiles (Triticum aestivum L.) elongated slowly (0.29 mm h−1) before their length reached 9 mm, then elongated quickly (1.12 mm h−1) during the next 16 h. Afterwards, their elongation slowed and finally ceased when coleoptiles were about 42.70 mm long and primary leaves protruded from their tips. As coleoptiles grew, cells in the base elongated first (in coleoptiles 3-9 mm in length); gradually the region of fastest cell elongation moved toward the middle region (in 25 mm long coleoptiles), and then the subapical region. Correspondingly, cells in the base first reached the maximum length (282.31 μm) and first ceased elongation (in 25 mm long coleoptiles). Finally, all cells (excluding cells in the tip) reached almost the same length. Despite all cells in coleoptiles having elongated to the maximum had reached their the maximum length, this length was only 9.59 times the length of the original cells, thus far lower than the 42.70-fold increase in coleoptile length (from 1 mm to 42.70 mm maximum length). Therefore, the increase in length of the cells alone cannot explain the increase in length of coleoptiles, and coleoptiles must have produced new cells to realize the increase in length observed. Dividing cells are reported for the first time in this paper and they were scattered throughout every region (excluding the tip) but were most frequent in the middle region of 7mm long coleoptiles, and disappeared when coleoptiles exceeded 9 mm. Therefore, coleoptile elongation was the result of both cell division and cell elongation when coleoptiles were shorter than 9 mm. When over 9 mm it was exclusively dependent on cell elongation. Cell length from the tip increased relatively little, only about 1.58 times that in 1 mm long coleoptiles. The different growth patterns between cells from the tip and cells from other regions may result from their differing functions.Belgian Journal of Botany 11/2006; 139(2):167-172. · 0.63 Impact Factor -
Article: Synergism between cucumber α-expansin, fungal endoglucanase and pectin lyase
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ABSTRACT: Several recombinant fungal enzymes (endoglucanase and pectinase) were studied for their interactions with α-expansin in cell wall extension and polysaccharide degradation. Both Cel12A and Cel5A were able to hydrolyze cellulose CMC-Na and mixed-linkage β-glucan. In contrast to Cel5A, Cel12A could also hydrolyze xyloglucan and induce wall extension of cucumber hypocotyls in an in vitro assay. Combining α-expansin, even at high concentrations, with Cel12A did not enhance the maximum/final wall extension rate induced by Cel12A alone. These results strongly suggest that modification/degradation of the xyloglucan molecule/network is the key for cell wall extension, and α-expansin and Cel12A may share the same acting site in the substrate. Pectinase (Pel1, a pectin lyase) enhanced α-expansin-induced wall extension in a concentration-dependent manner, suggesting that the pectin network may normally regulate accessibility of expansin to the xyloglucan–cellulose complex. α-Expansin enhanced Cel12A's hydrolytic activity on cellulose CMC-Na but not on xyloglucan and β-glucan. Expansin did not affect Cel5A's hydrolytic activity. Interestingly, expansin also enhanced Pel1's activity on degrading high esterified pectin. A potential explanation for why expansin could synergistically interact with only certain enzymes on specific polysaccharides is discussed. Additional results also suggested that cell wall swelling may not be a significant event during the action of expansin and hydrolases.Journal of Plant Physiology.
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Institutions
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2008–2010
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Nanjing Normal University
- College of Life Sciences
Nanjing, Jiangsu Sheng, China
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