Xlr1 is involved in the transcriptional control of the pentose catabolic pathway, but not hemi-cellulolytic enzymes in Magnaporthe oryzae
Xlr1 is involved in the transcriptional control of the pentose catabolic pathway, but not hemi-cellulolytic enzymes in Magnaporthe oryzae
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DOI：
10.1016/j.fgb.2013.06.005
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发表时间：
2013-08-01
影响因子：
3
通讯作者：
de Vries, Ronald P.
中科院分区：
文献类型：
--
作者：
Battaglia, Evy;Klaubauf, Sylvia;de Vries, Ronald P.
稻瘟病菌是包括水稻在内的许多禾本科植物的真菌病原体。由于阿拉伯木聚糖是禾本科植物细胞壁的主要成分之一，M.真菌可能降解这种多糖以支持其在受感染叶片中的生长。D-木糖通过真菌解聚酶从阿拉伯木聚糖释放，并通过戊糖途径分解代谢。参与这些途径的基因的表达受到转录激活因子XlnR/Xlr 1的控制，该因子在丝状子囊菌中是保守的。在这项研究中，我们确定了M。通过对靶向无效突变体的表型分析，研究了参与戊糖分解代谢途径（PCP）的XlnR基因及其在感染过程中的功能，包括XlnR同源物XLR 1。Delta xlr 1菌株的生长在D-木糖和木聚糖上减少，但在L-阿拉伯糖和阿拉伯聚糖上不受影响。在Delta xlr 1菌株中观察到PCP基因表达在D-木糖和L-阿拉伯糖上的强烈降低。然而，有木聚糖和纤维素分解酶活性之间的Delta xlr 1突变体和参考菌株没有显着差异。这些数据表明，XLR 1编码M中PCP的转录激活因子。的，但似乎没有发挥作用，在这种真菌的（半）纤维素分解系统的调节。这表明Xlr 1和A之间的功能仅部分相似。尼日尔XlnR. D-木酮糖激酶编码基因（XKI 1）的缺失突变体显然不能在D-木糖或L-阿拉伯糖上生长，并且在木糖醇、L-阿拉伯糖醇和木聚糖上显示出降低的生长。Delta xki 1表现出一种有趣的分子表型，因为它过表达其他PCP基因以及编码（半）纤维素分解酶的基因。然而，Delta xlr 1和Delta xki 1在水稻和大麦上的致病性与野生型相比都没有表现出显着差异，这表明p-木糖催化剂对于受感染叶片中的真菌生长是不需要的。(C)2013 Elsevier Inc. All rights reserved.
Magnaporthe oryzae is a fungal plant pathogen of many grasses including rice. Since arabinoxylan is one of the major components of the plant cell wall of grasses, M. oryzae is likely to degrade this polysaccharide for supporting its growth in infected leaves. D-Xylose is released from arabinoxylan by fungal depolymerising enzymes and catabolized through the pentose pathway. The expression of genes involved in these pathways is under control of the transcriptional activator XlnR/Xlr1, conserved among filamentous ascomycetes. In this study, we identified M. oryzae genes involved in the pentose catabolic pathway (PCP) and their function during infection, including the XlnR homolog, XLR1, through the phenotypic analysis of targeted null mutants. Growth of the Delta xlr1 strain was reduced on D-xylose and xylan, but unaffected on L-arabinose and arabinan. A strong reduction of PCP gene expression was observed in the Delta xlr1 strain on D-xylose and L-arabinose. However, there was no significant difference in xylanolytic and cellulolytic enzyme activities between the Delta xlr1 mutant and the reference strain. These data demonstrate that XLR1 encodes the transcriptional activator of the PCP in M. oryzae, but does not appear to play a role in the regulation of the (hemi-) cellulolytic system in this fungus. This indicates only partial similarity in function between Xlr1 and A. niger XlnR. The deletion mutant of D-xylulose kinase encoding gene (XKI1) is clearly unable to grow on either D-xylose or L-arabinose and showed reduced growth on xylitol, L-arabitol and xylan. Delta xki1 displayed an interesting molecular phenotype as it over-expressed other PCP genes as well as genes encoding (hemi-) cellulolytic enzymes. However, neither Delta xlr1 nor Delta xki1 showed significant differences in their pathogeny on rice and barley compared to the wild type, suggesting that p-xylose catabolism is not required for fungal growth in infected leaves. (C) 2013 Elsevier Inc. All rights reserved.