几丁质酶在植物抗真菌病害中的作用

几丁质酶对于植物抗真菌病害有重要作用,它可水解真菌细胞壁的重要组成成分———几丁质。正常情况下,植物体内几丁质酶的含量很低,如果将外源几丁质酶基因导入植物,可增强植物抗真菌病害的能力,而将几丁质酶基因与其他防卫蛋白基因一同导入植物,植物抗真菌病害的能力将会大大提高。     

Enzymatic activity of ectendomycorrhizal fungi

 Enzymatic (cellulolytic, pectolytic, proteolytic, chitinolytic and acid phosphatase) activities in the cultures of ten different ectendomycorrhizal strains (mainly Wilcoxina spp.) were studied. Although most of the fungi produced all these enzymes, their activities were low (milliunits per hour), with the exception of those of the pectolytic enzymes, which were detected at considerably higher levels (units per hour). Hebeloma crustuliniforme, an ectomycorrhizal fungus (positive control in our studies) synthesized ca. 2,000 times more exoglucanase than the ectendomycorrhizal fungi. Wilcoxina mikolae (ATCC 52685) had the lowest enzymatic activities of all 11 strains compared. Received: 3 December 1999     

Soil niche effect on species diversity and catabolic activities in an ectomycorrhizal fungal community

The species of an ectomycorrhizal (ECM) community were investigated in a temperate oak forest by morphotyping and ITS rDNA sequencing. Thirty-six ECM morphotypes were found at the site. The niche effect (as organic soil, mineral soil or dead woody debris artificially introduced in the soil) on the ECM community structure and on the potential catabolic activities of the most abundant morphotypes was studied. The morphotypes in each niche were subjected to enzymatic tests developed for hydrolytic and oxidative enzymes involved in the decomposition of organic compounds. The ECM community structure varied widely depending on the soil horizon or habitat patch. The species richness was higher in the A1 horizon than in the other niches. Different ECM species had different activity patterns for the eight enzymatic tests while co-occurring in the same niche. Catabolic activities also changed within species between niches. Dead woody debris were extensively colonized by two saprotrophic fungi (Megacollybia platyphylla and Armillaria sp.) and, in this particular niche, ECM morphotypes predominantly belonged to the genera Lactarius and Tomentella. These morphotypes showed high chitinase activities. This study suggested also that some ECM fungi could obtain nutrients via the chitin degradation of dead or live saprobes.     

向大豆导入几丁质酶基因的初步研究

以根癌农杆菌的Ｔｉ质粒为介导，将抗真菌病的几丁质酶基因，导入默经江省栽培大豆一东农３７号，吉林２８号等１４个品种。从子叶节和下胚轴诱导出丛生芽，并再生植株，经ＰＣＲ和ＤＮＡ分子杂交检测，经ＰＣＲ和ＤＮＡ分子杂交检测的１１３株大豆幼苗中，有７株呈阳性反应，证明几丁质酶基因已导入并整合到大豆的基因组中。     

植物激活蛋白对玉米抗病相关酶活性的影响

以稀释1000倍的植物激活蛋白粗提液处理玉米,以稀释1000倍的pH6.8磷酸缓冲液作对照,分别在处理后1、4、7、10、13和16d测定了玉米中苯丙氨酸解氨酶、过氧化物酶、几丁质酶和多酚氧化酶活性。结果表明:在不同时期处理后4种酶活性比对照有所提高,说明植物激活蛋白能诱导玉米抗病性。     

盾壳霉寄生核盘菌过程中葡聚糖酶、几丁质酶及电导率的变化

为了解盾壳霉寄生核盘菌的生化机理,采用了紫外分光光度法测定了盾壳霉寄生菌核过程中,葡聚糖酶和几丁质酶的变化,并用电导率仪测定了这个过程中电导率的变化。结果表明:从被盾壳霉寄生的活菌核检测到(处理)葡聚糖酶和几丁质酶活性明显高于活菌核和被盾壳霉寄生的死菌核,其中处理的葡聚糖酶活性从15 d以后就明显高于菌核自身也高于盾壳霉本身的酶活性,处理的几丁质酶活性从10 d起就维持在较高水平,处理的电导率从10 d以后明显高于活菌核。在这个过程中这两种酶活性提高,电导率增大,膜透性增强。     

抗逆生防木霉筛选及其相关因子诱导

对供试各木霉菌株经303、5、404、55、0℃保温24 h后,于28℃培养6~7 d,进行耐高温菌株筛选。结果表明,耐高温生防木霉菌株T-30经热激后可产生抗逆蛋白,且表达量较大。对高温抗逆蛋白进行DEAE-32及Sephadex G-100柱层析得到单一蛋白洗脱峰。SDS-PAGE电泳发现该抗逆蛋白含有2个亚基,分子量分别为30和42 kD。酶学检测发现,该高温抗逆蛋白有几丁质酶活力,其最适pH值为5.0,最适温度为50℃,Km值为0.91 mg/ml,对Na+有较强的耐受性。     

微生物几丁质酶及其在植物病害防治中的作用

几丁质酶广泛存在于植物、动物及微生物细胞和组织中,参与多种生理过程。研究发现许多动物、植物、微生物都可以产生几丁质酶。笔者主要对微生物几丁质酶的特性、功能及几丁质酶在植物真茵病害防治中的应用方面进行了综合论述,并对几丁质酶在植物病害生物防治和抗病基因工程中的应用前景进行了展望。     

粘质沙雷氏菌几丁质酶(ChiC)基因克隆及其生物信息学分析

从粘质沙雷氏菌(Serratia marcescensATCC14041)中克隆出几丁质酶基因(ChiC),将回收纯化的PCR产物与载体pMD18-T连接,构建成的重组质粒命名为pMD-Ch iC,将重组质粒转化到受体E.coliDH5α中进行克隆,经BamHI和NheI双酶切验证、核酸序列测定证实,重组质粒pMD-Ch iC含有几丁质酶C基因(ChiC)。利用生物信息学的方法,推测该粘质沙雷氏菌ChiC基因编码的蛋白质由480个氨基酸组成。预测该蛋白的等电点为5.63,分子量约为52kD。针对粘质沙雷氏菌中的几个几丁质酶基因做了进化树,进而验证了粘质沙雷氏菌(Serratia marcescens)几丁质酶(ChiC)在沙雷氏菌几丁质酶中的分类;同时对粘质沙雷氏菌几丁质酶C(ChiC)蛋白的高级结构作出了预测,得到其编码的属于18家族的蛋白质高级结构图谱。     

转几丁质酶和 β-1,3-葡聚糖酶基因提高棉花对枯萎病和黄萎病的抗性

 枯、黄萎病是世界棉花生产中的两大重要病害。传统育种缺乏抗源，几丁质酶和 -1,3-葡聚糖酶是植物防御体系中的两种防卫因子，两者之间存在协同增效作用。据此构建了4个单价和2个双价基因(分别定位于细胞内或细胞外)的植物表达载体，通过花粉管通道法转化棉花，经PCR和Southern杂交检测以及1996 2000年温室及病圃多代筛选鉴定，已培育出对枯、黄萎病抗性提高的转基因棉花株系。将抗病基因导入国产抗虫棉品种GK19中，还获得了兼抗病、虫的转基因优系。