Der mit der Versuchsdauer anwachsende Resistenzfaktor

Abstract

Pseudomonas spp. strains capable of inducing systemic resistance were applied to sugarcane by sett treatment followed by soil applications in the field. Later the fungal pathogen Colletotrichum falcatum causing red rot disease of sugarcane was inoculated in the treated canes and its colonization was assessed by ELISA at different nodal positions above the point of inoculation. Studies with three cvs showed a significant variation in pathogen colonization only in disease susceptible cv CoC 671 and not with cvs Co 8021 and BO 91, moderately susceptible and moderately resistant to the disease, respectively. In further studies when pathogen colonization was assessed on the entire stalks of cv CoC 671, the pathogen titre was significantly reduced from three nodes upwards in the treated canes. In the upper nodes no pathogen colonization was noticed in bacteria-treated canes, whereas in the control all the nodes recorded higher titre for pathogen infection. Incorporation of chitin in the talc formulation caused further reduction in fungal colonization in the stalks.     

Saccharum species as horticultural classes

 Sugarcane, commonly referred to as Saccharum officinarum, is currently divided into six species, two of them are wild and four exist only in cultivation. The two wild species and three of the cultivated ones are interfertile and have produced the interspecific hybrids that constitute the sugarcane of commerce. All species are represented by wide ranges of intergrades preserved as clones through vegetative propagation. Species are separated by variable floral characters, sugar content, chromosome numbers and epidermal hair groups. Floral characteristics are sometimes useful with clones that flower, sugar is present in widely overlapping ranges and is highly influenced by environment, chromosome numbers range from 36 to 170 in the genus and range widely within species, and some epidermal hair groups are more quantitative than qualitative. Molecular techniques show that Saccharum spontaneum is distinctly different from the other species in cytoplasmic DNA, and cluster analyses of nuclear DNA support the difference. Not only are the species interfertile but chromosomal pairing and recombination have been demonstrated, as has the possibility that some Saccharum species are hybrids of others. Taken together, these observations suggest that there is little basis for the present separation and that the six species should more properly consist of two: one being S. spontaneum, based on molecular data, and the other S. officinarum including the other four species and all interspecific hybrids. Received: 20 December 1997 / Accepted: 5 June 1998     

Identification and Validation of Molecular Markers Associated with Pachymetra Root Rot and Brown Rust Resistance in Sugarcane Using Map- and Association-based Approaches

Marker-assisted selection for traits that are difficult to screen for, such as resistance to many sugarcane diseases, has the potential to facilitate the development of improved cultivars in sugarcane. Pachymetra root rot (PRR) and brown rust resistance ratings were obtained over two years for 192 I1 progeny (progeny produced by two heterozygous, non-inbred parental lines) of a sugarcane (Saccharum spp. hybrid) cross between two elite sugarcane clones, Q117 and 74C42. Approximately 1000 single-dose markers, including microsatellite (SSR), amplified fragment length polymorphism (AFLP) and restriction fragment length polymorphism (RFLP) markers, were scored across the population and maps containing approximately 400 markers were constructed for each parent. At p ≤ 0.01, two genomic regions, one from the female Q117 map and a different region from the 74C42 male map, plus an unlinked bi-parental simplex marker (single-dose marker present in both parents) were identified as associated with PRR over both years of data collection. These regions explained between 6 and 16% of the phenotypic variation. An additional region was identified in the female map as associated with PRR at p ≤ 0.01 in one year and p ≤ 0.05 in the second year. This region explained between 4 and 8% of the phenotypic variation. For brown rust, two genomic regions, one from the female map and one from the male map, plus an unlinked marker from both maps, were identified as associated with brown rust resistance at p ≤ 0.01 over two years of phenotypic data. Each region explained between 7 and 18% of the phenotypic variation. Several additional regions were identified in both maps as associated with brown rust at p ≤ 0.01 in one year and p ≤ 0.05 in the second year. These regions also explained between 5 and 11% of the phenotypic variation. To validate these markers and determine whether they would be useful in alternative germplasm, markers from each genomic region associated with PRR or brown rust were screened across a set of 154 elite sugarcane clones; PRR and brown rust ratings were available for 131 and 72 of the clones, respectively. For PRR, three of the 6 markers tested remained significantly associated (p ≤ 0.01) with resistance ratings in the elite clone set. For brown rust, only one of the seven markers tested remained significantly associated (p ≤ 0.01) with resistance in the elite clone set, with one other marker associated at p ≤ 0.05. These results suggest that these markers could be broadly effective in selecting for PRR and/or brown rust resistance in sugarcane breeding programs.     

甘蔗蔗汁品质性状的回归分析及模型

本文对47份不同甘蔗基因型的蔗汁品质性状进行简单回归和逐步回归分析.结果表明,蔗汁蔗糖分(Suc)与锤度(BX)、温度校正后锤度(BX′)、蔗汁旋光读数(0Z)以及转光度(pol)之间均呈线性回归,简单回归模型均达极显著水平(P＜0.01),决定系数(R2)分别为0.9393、0.9199、0.9861及0.9839.通过逐步回归分析和残差分析建立多重线性回归方程为Suc=0.05706 0.21488BX 0.181030Z,方差分析表明多重线性回归模型达极显著水平(P＜0.01),决定系数为0.9931.t测验表明,蔗汁蔗糖分的模型预测值与实测值间的差异不显著,相对误差平均为0.49%.     

Interaction between Colletotrichum falcatum pathotypes and biocontrol agents

Abstract

To select efficient antagonistic strain(s) of biocontrol agents against most of the existing pathotypes of Colletotrichum falcatum, an in vitro interaction study was carried out with 13 pathotypes, 12 isolates of Pseudomonas spp. and 6 isolates of Trichoderma spp. Antagonistic pseudomonad strains exhibited greater variation in their activity depending on the virulence of the pathotype. The lower the pathogen virulence, the higher was the antagonistic activity noticed. In general, sub-tropical pathotypes were suppressed at a comparatively higher level than the tropical pathotypes. Among the four efficient P. fluorescens strains selected based on their inhibitory effect against various pathotypes, ARR1G and VPT4 were effective against tropical pathotypes and FP7 showed moderate effect against all the pathotypes. The strain KKM2 was effective against sub-tropical and weaker tropical pathotypes. Strains of Trichoderma spp. did not show much variation in antagonism, but varied in their mode of action in suppressing the pathogen growth. However, based on higher rate of hyperparasitism, T. harzianum strains T5 and T62 were selected against all the pathotypes.     

12个HoCP系列甘蔗种质资源初步鉴定和评价

为了解甘蔗(Saccharum spp.)亲本特性,以ROC22为对照,对12个重要Ho CP系列亲本种质进行了初步鉴定与评价。结果表明,Ho CP系列品系具有出苗率高、分蘖性好、有效茎数多、早熟高糖等特性。Ho CP01-564含糖量最高,Ho CP00-1142产量最高,Ho CP02-610发芽率和有效茎数最高,Ho CP07-613蔗糖分最高。聚类分析表明,12个Ho CP系列品系(种)可分为4类。因此,根据这些品系(种)特性可以合理配制杂交组合。     

CL系列甘蔗亲本的遗传力及配合力分析

为探讨CL系列甘蔗品种作杂交亲本的遗传特点,采用3×3不完全双列杂交(NCⅡ)遗传设计,估算了7个产量和品质性状的遗传方差、一般配合力(GCA)和特殊配合力(SCA)。结果表明:锤度的遗传主要受母本加性基因效应控制,株高的遗传主要受父母本加性基因控制,而锤重的遗传主要受非加性基因效应所制约;CL83-1163作为母本,糖分配合力高,且能把高糖特性传递给后代,CL88-4730为父本,产量和品质性状的配合力大,其杂交后代表现高产高糖;根据配合力总效应(TCA),综合表现好的组合有CL83-1364×CL88-4730、CL83-1900×CL84-3152、CL83-1163×CL88-4730,可用于今后的甘蔗有性育种计划。     

Application of Lake-model based indices from chlorophyll fluorescence on sugarcane seedling Application of Lake-model based indices from chlorophyll fluorescence on sugarcane seedling

 为从能量平衡及分配的角度研究干旱胁迫下甘蔗(Saccharum officinarum)苗期光系统的运转状况, 进而为丰富不同甘蔗品种的抗旱性评价指标及实现对季节性干旱胁迫的快速诊断提供理论依据, 该研究通过对基于Lake模型的叶绿素荧光参数在不同入射光强下变化的动态分析, 研究光合电子传递链中能量平衡状态对不同水分梯度(40%、25%、10%、8%)的响应。结果表明: 两个供试品种(耐旱品种‘ROC22’和非耐旱品种‘ROC16’)的最大光能利用效率(F_v/F_m)、相对电子传递速率(rETR)、光系统II(PSII)量子效率(Φ_II)和光化学猝灭(q_L)均随着干旱胁迫程度的增加而下降, 可调节性能量耗散(Φ_NPQ)和非调节性能量耗散(Φ_NO)则随着干旱胁迫程度的增加而上升。除Φ_NO之外的叶绿素荧光参数的变化幅度均随着光合有效辐射(PAR)的增加而增大。在干旱胁迫的前中期, 相对于‘ROC22’, ‘ROC16’的PSII反应中心能够维持较高的开放程度; 但‘ROC22’调节能量耗散的能力和对干旱胁迫的敏感程度均高于‘ROC16’, 说明较强的光保护能力是‘ROC22’的抗旱性高于‘ROC16’的主要原因之一。对干旱胁迫敏感且在不同PAR下较为稳定的Φ_NO可作为甘蔗苗期抗旱性的快速诊断和评价指标。rETR对递增的PAR的响应表现为随着干旱胁迫程度的增加而提前出现峰值或下降趋势, 但是不同水分梯度下的rETR在PAR较低时并无显著差异, 表明干旱胁迫下光抑制现象的提早出现是造成光系统损伤的首要因素, 高光强对干旱胁迫信号起放大作用。     

一种改良的转基因甘蔗基因组DNA提取方法

用改良的转基因甘蔗基因组DNA提取方法可从少量的转基因甘蔗叶片中简便快速地提取高质量的DNA,有效地去除甘蔗叶片中的多糖、多酚类和RNA等物质。经核酸蛋白测定仪及凝胶电泳分析表明,该改良方法提取的DNA具有典型的DNA分子标准紫外吸收光谱特点,其A260/A280为1．7-1．9,A260/A230为1．8-2．0,叶片的DNA产量为45-60μg(100mg)^-1,适用于对转基因甘蔗进行PCR、酶切和Southern杂交检测分析。