Departamento de Produção Vegetal-Setor Defesa Fitossanitária, Faculdade de Ciências Agronômicas, CP 237, 18603-970 Botucatu, SP, Brazil.
Mol Plant Pathol. 2002 Jul 1;3(4):251-9. doi: 10.1046/j.1364-3703.2002.00119.x.
Summary Adopting the sequencing of expressed sequence tags (ESTs) of a sugarcane database derived from libraries induced and not induced by pathogens, we identified EST clusters homologous to genes corresponding to enzymes involved in the detoxification of reactive oxygen species. The predicted amino acids of these enzymes are superoxide dismutases (SODs), glutathione-S-transferase (GST), glutathione peroxidase (GPX), and catalases. Three MnSOD mitochondrial precursors and 10 CuZnSOD were identified in sugarcane: the MnSOD mitochondrial precursor is 96% similar to the maize MnSOD mitochondrial precursor and, of the 10 CuZnSOD identified, seven were 98% identical to maize cytosolic CuZnSOD4 and one was 67% identical to putative peroxisomal CuZnSOD from Arabidopsis. Three homologues to class Phi GST were 87-88% identical to GST III from maize. Five GPX homologues were identified: three were homologous to cytosolic GPX from barley, one was 88% identical to phospholipid hydroperoxide glutathione peroxidase (PHGPX) from rice, and the last was 71% identical to GPX from A. thaliana. Three enzymes similar to maize catalase were identified in sugarcane: two were similar to catalase isozyme 3 and catalase chain 3 from maize, which are mitochondrial, and one was similar to catalase isozyme 1 from maize, whose location is peroxisomal subcellular. All enzymes were induced in all sugarcane libraries (flower, seed, root, callus, leaves) and also in the pathogen-induced libraries, except for CuZnSOD whose cDNA was detected in none of the libraries induced by pathogens (Acetobacter diazotroficans and Herbaspirillum rubrisubalbicans). The expression of the enzymes SOD, GST, GPX, and catalases involved in the detoxification was examined using reverse transcriptase-polymerase chain reaction in cDNA from leaves of sugarcane under biotic stress conditions, inoculated with Puccinia melanocephala, the causal agent of sugarcane rust disease.
采用从受病原体诱导和未诱导的文库衍生的甘蔗数据库的表达序列标签 (EST) 进行测序，我们鉴定了与参与解毒活性氧物种的酶同源的 EST 簇。这些酶的预测氨基酸是超氧化物歧化酶 (SOD)、谷胱甘肽-S-转移酶 (GST)、谷胱甘肽过氧化物酶 (GPX) 和过氧化氢酶。在甘蔗中鉴定出 3 种 MnSOD 线粒体前体和 10 种 CuZnSOD：MnSOD 线粒体前体与玉米 MnSOD 线粒体前体的相似性为 96%，鉴定出的 10 种 CuZnSOD 中有 7 种与玉米胞质 CuZnSOD4 的相似性为 98%，有一种与拟南芥过氧化物体 CuZnSOD 的相似性为 67%。3 种类 Phi GST 同源物与玉米 GST III 的相似性为 87-88%。鉴定出 5 种 GPX 同源物：3 种与大麦胞质 GPX 同源，1 种与水稻磷脂氢过氧化物谷胱甘肽过氧化物酶 (PHGPX) 的相似性为 88%，最后一种与拟南芥 GPX 的相似性为 71%。在甘蔗中鉴定出 3 种与玉米过氧化氢酶相似的酶：2 种与玉米过氧化氢酶同工酶 3 和过氧化氢酶链 3 相似，这两种酶都是线粒体的，1 种与玉米过氧化氢酶同工酶 1 相似，其位置是过氧化物体亚细胞。除了 CuZnSOD 外，所有的酶在所有的甘蔗文库（花、种子、根、愈伤组织、叶片）和病原体诱导的文库中都被诱导，而 CuZnSOD 的 cDNA 在所有受病原体（固氮醋杆菌和中华根瘤菌）诱导的文库中都未被检测到。在生物胁迫条件下，用接种甘蔗锈病病原菌 Melanocarpus melanocephalus 的叶片 cDNA 进行逆转录-聚合酶链反应，检测参与解毒的 SOD、GST、GPX 和过氧化氢酶等酶的表达。
