Identification and expression analysis of a new glycoside hydrolase family 55 exo-¦Â-1,3-glucanase-encoding gene in Volvariella volvacea suggests a role in fruiting body development

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• 作者：Yongxin Tao ; Baogui Xie ; Zhiyun Yang ; Zhihong Chen ; Bingzhi Chen ; Youjin Deng ; Yuji Jiang ; Arend F. van Peer
• 关键词：GH55 ; glycoside hydrolase family 55 ; CTAB ; Hexadecyl trimethyl ammonium Bromide ; PR ; primordia ; BU ; button stage ; EG ; egg stage ; EL ; elongation stage ; MA ; maturation stage ; DGE ; digital gene expression ; Q-PCR ; real time quantitative PCR ; iTRAQ ; isobaric t
• 刊名：Gene
• 出版年：2013
• 出版时间：15 September, 2013
• 年：2013
• 卷：527
• 期：1
• 页码：154-160
• 全文大小：1400 K

文摘

The edible straw mushroom Volvariella volvacea is an important crop in South East Asia and is predominantly harvested in the egg stage. Rapid stipe elongation and cap expansion result in a swift transition from the egg to elongation and maturation stage, which are subjected to fast senescence and deterioration. In other mushrooms, ¦Â-1,3-glucanases have been associated with degradation (softening) of the cell wall during stipe elongation and senescence. We present a new glycoside hydrolase family 55 (GH55) exo-¦Â-1,3-glucanase gene, exg2, and highly conserved deduced EXG2 protein. The 3D model and presumed catalytic residues of V. volvacea EXG2 are identical to Lentinula edodes EXG2 and Phanerochaete chrysosporium Lam55A, supporting similar enzymatic functions. In addition to previous association to stipe elongation and senescence, our data clearly indicates a role for cap (pileus) expansion. Digital gene expression, quantitative PCR and isobaric tags for relative and absolute quantification analysis showed low exg2 and EXG2 levels in primordia, button, egg and elongation stages and significantly increased levels in the maturation stage. Subsequent relative quantitative PCR analysis designated expression of exg2 to the stipe in the elongation stage and to the pileus and stipe in the maturation stage. EXG2 cell wall softening activity, close correlation of exg2 expression with the principal expanding mushroom tissues and a strong conservation of expression patterns and protein sequences in other mushrooms, make V. volvacea exg2 an important candidate for future studies on mechanisms of fruiting body expansion and senescence causing commodity value loss.