乙烯对匍匐翦股颖ISR抗病反应中AsA-GSH循环及胼胝质沉积的影响

以匍匐翦股颖品种“Penn-A4”为试验材料,侵染立枯丝核菌后,经丁二醇(BDO)诱导产生系统抗性(ISR),喷施不同浓度的乙烯合成抑制剂氯化钴(CoCl₂)和促进剂1-氨基环丙烷羧酸(ACC)后,检测抗坏血酸-谷胱甘肽(AsA-GSH)循环中抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量及相关酶活性的变化,并观察匍匐翦股颖ISR反应中胼胝质沉积的变化。结果表明,乙烯抑制剂处理下,匍匐翦股颖幼苗中AsA含量较低,抗坏血酸过氧化物酶(APX)活性下降,大量GSH被催化还原为氧化型谷胱甘肽(GSSG),GSSG大量积累,同时谷胱甘肽还原酶(GR)活性较低,GSSG经GR少量还原为GSH。乙烯促进剂处理下,AsA含量较高,APX活性升高,GSSG在高活性GR作用下催化还原为GSH,使得GSH大量积累。因此在匍匐翦股颖ISR抗病反应中,高浓度乙烯促进AsA和GSH的大量积累,它们不仅参与了活性氧的代谢平衡,同时也作为信号分子在ISR抗病反应中起着重要作用。匍匐翦股颖感染褐斑病后,胼胝质主要沉积在厚壁细胞、韧皮部、木质部和表皮组织,其中厚壁细胞胼胝质沉积最多,表皮组织沉积最少。此外,胼胝质沉积面积在不同乙烯信号分子处理间存在差异,但随着处理时间的延长差异不显著。一定浓度的乙烯对ISR反应中胼胝质的沉积具有一定的影响,随着处理时间的延长显著增加,在100 μmol·L^-1ACC处理5 d后,胼胝质沉积总面积仅为9.916 mm²,处理10 d后升至最高,为38.396 mm²,但在病害侵染后期,胼胝质数量减少,在100 μmol·L^-1ACC处理15 d后,胼胝质沉积总面积降至20.052 mm²,反映了乙烯信号分子对胼胝质沉积的影响是一种短期效应,短期内可提高匍匐翦股颖植株抗病性,具有信号分子的短时效特点。研究结果为探清匍匐翦股颖ISR抗病响应中ET信号分子如何调控抗病生理特性提供了理论基础。     

粤选1号匍匐翦股颖新品系果岭草坪 夏季性状及高温胁迫效应

粤选1号匍匐翦股颖新品系是丛Penncross建坪的老果岭中分离出的无性系。在广州地区夏季果岭草坪密度、绿叶盖度、叶片老化指数、抗坏血酸含量显著高于原品种Penncross，叶片质膜相对透性低。持续高温(36℃)胁迫下，新品系叶片中游离脯氨酸含量显著增加，而原品种在高温胁迫第3d才开始显著增加，新品系游离脯氨酸含量明显高于原品种；高温胁迫下新品系叶片可溶性蛋白含量增加并高于Penncross，而Penncross在高温胁迫2d后显著下降；新品系匍匐茎可溶性糖含量增加，高温胁迫5d后，Penncross显著高于新品系；新品系匍匐茎淀粉含量显著高于Penncross；高温胁迫对叶片相对含水量和叶绿素含量无明显影响。     

Growth and competitiveness of the New Zealand tree species Podocarpus cunninghamii is reduced by ex-agricultural AMF but enhanced by forest AMF

The composition of arbuscular mycorrhizal fungi (AMF) communities found in agricultural systems has been found to be very different to that of forest. The implications of this, if any, for the restoration of indigenous forest on ex-agricultural land is poorly understood. This study investigated the effect that AMF communities isolated from ex-agricultural and forest soils have on the growth of an indigenous New Zealand tree species (Podocarpus cunninghamii). The forest AMF community was isolated from a remnant stand of P. cunninghamii forest and the ex-agricultural AMF from a retired grazing grassland. In addition, the study examined how the two AMF communities affected the competitiveness of P. cunninghamii when grown in competition with an invasive grass species (Agrostis capillaris), which is frequently dominant on ex-agricultural land in New Zealand. P. cunninghamii growth was significantly decreased by inoculation with ex-agricultural AMF compared to forest AMF. Furthermore, the forest AMF community was able to significantly increase P. cunninghamii root production when in competition with A. capillaris. The findings suggest that when attempting to restore indigenous forest on ex-agricultural land, inoculation of tree seedlings with appropriate forest AMF may improve their growth and survival.     

野生匍匐翦股颖与引进品种光合日变化比较

利用Li-6400光合仪研究了田间自然条件下3种野生匍匐翦股颖(Agrostis stolonifera L.)05GA5、05GA8、05GA11居群和对照品种普特(Putter)的光合作用日变化特征.结果表明,①4个材料净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)的日变化曲线均呈"双峰"型,都存在明显的光合"午休"现象;且05GA5的Pn、Tr、Gs值都高于其他材料,表明其具有很强的光合能力和对极端高温环境的适应能力.②根据Pn、Ci、气孔限制值(k)的变化方向,推测05GA5、CK的光合"午休"主要受气孔因素限制,05GA8、05GA11主要受气孔和非气孔因素限制.③相关分析结果表明,夏季的光照对05GA5、05GA8、CK都有很大影响,相关系数分别为0.750,0.876,0.756,而对05GA11的影响不大.从总的相关系数大小来看,对Pn影响最大的因子是PAR,其次是Ta、Ca、RH.     

剪股颖属植物遗传分化及系统关系的分子标记研究

剪股颖属植物形态变异大、倍性复杂、种间易于杂交,导致异名多、分类混乱。本研究采用4种分子标记技术,对包括匍茎剪股颖、巨序剪股颖及红顶草在内的7种剪股颖,共58个个体的遗传分化和系统关系进行研究。根据谱带清晰程度及多态性,筛选出9个RAPD引物、2个SSR引物、5个ISSR引物及1个SCAR标记,并建立了最适的PCR反应条件。采用最大简约法和距离法对7种剪股颖植物进行系统树分析,并用靴带检验法计算内部分支的支持率。启发式搜索得到的简约树和由UPGMA方法得到的表征树近乎相同,其中,匍茎剪股颖和红顶草构成单系类群并得到100%的置信支持。红顶草显示了匍茎剪股颖特异性特征谱带,但同时具有不同于匍茎剪股颖的遗传分化,支持将红顶草视为匍茎剪股颖一个变种的观点。对匍茎剪股颖与巨序剪股颖间的遗传分化进行了探讨。     

Sodium Alginate as an Adjuvant of an Antagonistic Bacterium, Pseudomonas fluorescens Strain A11RN, to Enhance Biocontrol of Turfgrass Snow Mold Caused by Typhula ishikariensis

Pretreatment with sodium alginate (20 g/m²) prior to application of a biocontrol agent, Pseudomonas fluorescens strain A11RN, enhanced the control turfgrass snow mold caused by Typhula ishikariensis biotype B. Disease severities in two fields relative to untreated control plots were 53% and 61% in plots treated with both the strain and sodium alginate, which were significantly lower than 69% and 77% in plots treated only with the strain. The antagonist population remained above the threshold for effective control (ca. 1×10⁷ cfu/cm³) at least for the first month under snow in pretreatment with sodium alginate. The population of the biocontrol agent after snowmelt on turfgrass was five times higher in sodium alginate-amended plots than in unamended plots. Sodium alginate alone did not reduce disease severity. Sodium alginate might have supported the survival of the applied strain. Received 7 June 1999/ Accepted in revised form 20 December 1999     

Resistance to Rhizoctonia solani AG‐2‐2 (IIIB) in creeping bentgrass plants transformed with pepper esterase gene PepEST

A pepper esterase (PepEST) gene was introduced into creeping bentgrass (Agrostis stolonifera) by Agrobacterium‐mediated transformation. Purified recombinant PepEST proteins were sufficient to inhibit the growth of the fungal pathogens Rhizoctonia solani AG2‐2 (IIIB) (causing brown patch) and Sclerotinia homoeocarpa (dollar spot), but not the oomycete responsible for pythium blight, Pythium aphanidermatum. PepEST proteins were most effective against R. solani. After genetic transformation of creeping bentgrass with PepEST, the genomic integration of transgenes bar and PepEST was confirmed by Southern blot analysis, and their expression was also validated by northern blot and western blot analyses. Disease severity on R. solani‐inoculated leaves of transgenic plants was <10% compared to ca. 50% in non‐transgenic plants. Microscopic observation of infected leaves indicated that PepEST inhibited the growth of hyphae upon fungal infection.     

几种匍匐翦股颖品种植株再生的研究

以匍匐翦股颖Agrostis stolonifera潘娜1号、海滨和普特的成熟种子为外植体,进行愈伤组织诱导、分化及生根研究。结果表明：在MS培养基上,以不同浓度2,4 D诱导潘娜1号、海滨和普特的愈伤组织时,普特的愈伤组织诱导率均高于潘娜1号和海滨。2 mg/L 2,4 D+0.1 mg/L 6 BA为潘娜1号和海滨诱导愈伤组织的最适激素组合,3 mg/L 2,4 D+0.1 mg/L 6 BA为普特愈伤组织诱导的最适激素组合。诱导率分别为45.2%、76.5%和87.0%;MSO(MS培养基的大量、微量元素和铁盐+B5培养基的有机元素)为最适合的分化培养基,分化率分别为50.0%、59.0%和57.6%。1/2 MS +1.0 mg/L IBA为生根培养基。     

匍匐翦股颖果岭草坪草的坪用性状及关联度分析

采用灰色系统关联度分析法,综合评价了匍匐翦股颖品种Penncross、粤选1号匍匐翦股颖和匍匐翦股颖新品系粤选2号、粤选3号、35号、38号6个品种(系)在广州地区夏季的草坪质量,分析了6个草坪质量评价指标之间的关联度大小。结果表明:草坪质量评价指标间的关联度大小顺序是抗热性>质地>密度>绿期>颜色>均一性,草坪草品种(系)间的关联度大小依次为粤选3号>38号>粤选1号>35号>粤选2号>Penncross。这表明,在广州地区选择匍匐翦股颖作为果岭草坪草考虑的首要因素是抗热性,其次是质地和密度。供试的6个匍匐翦股颖品种(系)的草坪综合质量以新品系粤选3号最优,适宜该地区建植高质量的常绿果岭草坪。     

早熟禾族3种基因型草坪草的染色体核型分析

通过对禾本科早熟禾族(Poeae)匍匐翦股颖(帕特putter)和多年生黑麦草(首相premier、焦点focus)3种草坪草染色体核型进行分析,结果显示,3种基因型材料的染色体均以中部着丝点和近中部着丝点染色体为主,都具有随体。匍匐翦股颖帕特体细胞染色体数目为30条,核型公式是2n=30=22m(2SAT)+2sm,核型不对称系数(AS.K%)55.2%,分类标准属于“2C”型;多年生黑麦草2个品种草坪草体细胞染色体数目均为14条,其中首相核型公式是2n=14=12m(2SAT)+2st,核型不对称系数58.0%,核型分类标准属于“2C”型;焦点核型公式是2n=14=6m(2SAT)+8sm,核型不对称系数63.05%,属于“2B”型。