栗疫菌弱毒菌系

本文介绍了果疫菌弱毒菌系的发现过程、弱毒性的概念和本质、弱毒因素的传递以及弱毒因素在自然界盼保持和扩散,对于了解国际上栗疫菌弱毒菌系的研究现状、指导我国的栗疫病研究以及利用弱毒菌系进行生物防治都具有一定的意义。     

栗疫菌营养体亲和型多样性比较及野生栗栗疫菌交配型的分子检测

在北京周边县区、湖北大老岭山区以及陕西安康地区分别调查栗疫病发生情况,采集病原栗疫菌(Cryphonectria parasitica)菌株并进行营养体亲和性试验.结果表明:北京板栗栽培区和陕西安康地区野生栗栗疫病发病率较高,局部地区危害严重;湖北大老岭山区栗疫病发病率低,危害轻微.北京地区菌株群体营养体亲和型多样性指数(Shannon-Wiener's diversity index)极显著低于湖北菌株群体和陕西菌株群体,而陕西与湖北菌株群体营养体亲和型多样性指数差异不显著.随机选取湖北、陕西野生栗栗疫菌部分菌株,利用特异性引物,通过普通PCR和巢氏PCR,对其交配型进行测定,发现陕西与湖北野生栗菌株群体中均存在MAT-1与MAT-2两种交配型的菌株.通过PCR扩增,在两地的野生菌株群体里均发现同时具有两种交配型基因的菌株,其中,陕西群体此类菌株比例较大,湖北菌株比例较小     

用低毒剂防治栗疫病的研究——以病治病

在本世纪前半叶,栗疫病菌(Endothia parasitica 寄生内座壳菌)毁坏了美国栗(Castanea dentata)树林,这种危害遍及美国栗的自然分布区。防治林木病害的一般方法对本病均已无效。本文研究的一种方法是应用病毒状细胞质低毒剂来减弱栗疫病菌的致病力。由于用含有这些低毒剂的菌株处理,溃疡逐一被控制,但无论是低毒剂,还是含有低毒剂的菌株,似乎都不自然传播。或许需要持续的含有低毒剂的溃疡为传播提供长期的种源。     

锥栗对栗疫病的抗性与苯丙氨酸解氨酶的关系

健康的锥栗(Castanea henryi)皮层中,苯丙氨酸解氨酶(PAL)比活力与抗感病性之间不相关.不同抗病性的锥栗品种接种栗疫菌(Cryphonectria parastttca)后,PAL比活力均上升,接种144 h后,PAL比活力抗病性强的品种比抗病性弱的品种高.接种前以及接种后的各个时间内,木质素含量都是抗病品种比感病品种高.绿原酸的含量与品种的抗病性之间不呈规律性的相关,从绿原酸对栗疫菌菌丝生长影响的测定结果可知,锥栗体内的绿原酸浓度不足以影响栗疫菌.可见,接种后的皮层PAL比活力以及接种前、后的皮层木质素含量可作为衡量锥栗抗病性强弱的指标.     

栗疫病致病性研究和栗疫菌混合体系探讨

经过１０余年栗疫病发生特点和致病性的大量调查研究，结果表明栗疫菌在板栗分布区普遍存在，是弱寄生菌，在本地只寄生那些生长十分衰弱，即将死亡的板栗树干，苗木等，但栗疫菌的寄生不是这些部位死亡的主要和直接原因，而且它所寄生的部位局部死亡后对整株栗树的影响不大，因此，栗疫病在一般情况下非毁灭性病害，本文首次提出了栗疫菌混合体系概念，并用此说明中国栗疫病普遍分布，危害很轻的原因。     

我国栗疫病菌体中dsRNA的初步研究

作者在西南、华东、华北的十多个地区共采集140株栗疫菌 Endothiaparasitiica,并对昆明、南京、北京等地的38株栗疫菌进行了dsRNA的提取,发现13株含有1—2组分的dsRNA。根据黑曲霉病毒Aspergillus niger virus dsRNA分子量,推算出栗疫菌核酸分子量为4.0—5.1×10~6道尔顿。对栗疫菌核酸性质进行鉴定,在高离子强度(2×SSC)下核酸抗RNase(20微克/毫升),但经106℃10分钟处理,变性后核酸对RNase敏感,结果表明栗疫菌核酸为dsRNA。     

栗疫病菌弱毒性菌株的筛选及其dsRNA的转化稳定性

为获取栗疫病生物防治的基础信息,本研究根据菌株在PDA培养基上培养7天后的菌丝生长速度、分生孢子形成能力等培养特性,从韩国国立山林科学院树木病理研究室保藏的60个栗疫病菌菌株中筛选了2个弱致病力菌株,进行dsRNA检测、弱致病力菌株和强致病力菌株间的细胞融合试验。结果表明:2个弱致病力菌株(KCP-135和KCP-136)中均检测到了dsRNA,弱毒性菌株KCP-22和其他19个强毒性菌株之间的菌落形成明显的隔离带并沿着隔离带产生分生孢子,没有明显的细胞融合现象,而弱毒性菌株KCP-22和强毒性菌株KCP-9之间的菌落则呈现了显著的细胞融合现象,而且其细胞融合菌株的培养特性和转化dsRNA数量均发生了变异。     

中日美栗疫病菌群体遗传结构比较

采用RFLP技术 ,对中日美 3国的 2 6个子群体共 75 7个栗疫病菌菌株的核DNA进行了群体遗传结构分析。结果表明 ,栗疫病菌的中国子群体间遗传结构有明显的分化 ,日本子群体间的遗传结构差异不明显 ;在美国和亚洲的栗疫病菌群体间没有发现基因流的迹象 ;美国栗疫病菌群体的遗传结构与日本群体的关系比较密切 ,而与中国群体间的差异较大。     

防治板栗疫病室内药物毒力测定

选出６种药剂在室内进行防治栗疫菌的毒力测定，结果多菌灵抑制菌丝生长的效果最好，代森锰锌抑制孢子萌发效果最好，自配农药“ＤＤ”即能抑制菌丝生长，也能抑制孢子萌发。     

栗疫病菌培养性状及毒力的研究

将采自湖南、重庆两省的56个板栗疫病菌(Cryphonectria parasitica (Murr．)Barr．)的培养性状划分为两类：一种为正常培养性状即：菌落桔黄色或黄色、生长快、形成分生孢子器的菌株，其占菌株总数的58．93％；其它为非正常培养性状，菌落颜色表现出黄褐色、深褐色或白色，其生长速率与正常菌株均不同。致病性测定结果表明，各个菌株可分为强毒力菌株、中等毒力菌株、中低毒力菌株、低毒力菌株。     

Virulence and double‐stranded RNA in Sphaeropsis sapinea

Forty wildtype isolates of Sphaeropsis sapinea were grouped into the morphotypes A and B based on previously defined differences in cultural and morphological criteria as well as restriction sites for Dde I and Bst UI endonucleases in nuclear ribosomal DNA amplicons. Thirteen of 20 type A isolates and nine of 20 type B isolates contained detectable dsRNA (55%) of different molecular weight and size. dsRNA was transmitted into conidia at a frequency of 71–100%. By selecting single conidia, dsRNA‐free subcultures were obtained from six of 22 isolates containing dsRNA. Pathogenicity tests on expanding buds of landscape trees of three species of Pinus showed highly significant statistical interactions between isolate virulence, Pinus species, and year. Pine species‐year had a profound impact on virulence. The pattern in the interactions was revealed by principal component analysis of the interaction sums of squares of the anova (Additive Main Effects and Multiplicative Interaction; AMMI). Pinus sylvestris was highly interactive in its susceptibility to S. sapinea with seasonal effects. P. nigra and P. resinosa were more stable. The interactivity analysis was used to apportion interaction to specific isolates to improve the accuracy of the estimates of virulence. Estimates of the relative virulence of isolates were predicted over five different Pinus species‐years. Isolates were ranked in virulence and interactivity using the AMMI model. This model permitted mean separation tests of the relative virulence among isolates over the combined Pinus species‐years. One isolate was identified as potentially having dsRNA‐mediated hypovirulence based on the significantly greater virulence of its isogenic, dsRNA‐free subculture, as expressed over the three Pinus species and 2 years. Type A isolates containing dsRNA ranged from stable to highly interactive and from low to high in virulence. Type B isolates containing dsRNA were similar in interactivity but virulence ranged from avirulent to moderate, seldom exceeding the mean for S. sapinea. dsRNA‐free isogenic subcultures tended not to express higher virulence than their dsRNA‐containing parent strains but often changed in interactivity. Therefore, in one year a dsRNA‐free subculture might be more virulent than its dsRNA‐containing parent. In another year the dsRNA‐free subculture might be less virulent.     

红千层愈伤组织诱导及植株再生

以茎段、芽和叶片为材料,研究了红千层愈伤组织诱导及植株再生的方法。结果表明:红千层的茎段、芽和叶片均可诱导出愈伤组织,通过继代培养愈伤组织可发育成绿色和粉红色2种类型,其中绿色、致密的愈伤组织可以分化出不定芽。培养基1/2M S 6-BA 1.0 m g/L NAA 0.1 m g/L适宜愈伤组织不定芽的诱导,在培养基1/2M S IBA 0.25 m g/L上试管苗的生根率可达95%。     

杜仲愈伤组织培养过程中胶含量的动态变化

培养杜仲愈伤组织并测定其含胶量,结果发现,杜仲胶的合成与愈伤组织的生长周期有一定的相关性。在继代培养中,随着继代次数的增加,含胶量呈增加趋势。外植体上愈伤组织一旦形成就有杜仲胶的积累,杜仲胶含量在S5~S8代出现一个高峰值,S8代愈伤组织的含胶量已经达到原植株的94.38%,S9代后又迅速下降。     

邓恩桉组培中影响继代增殖条件的研究

探讨抗寒树种邓恩桉组培快繁中影响其继代培养的因素。实验表明,继代培养以改良MS为基本培养基,随继代次数的增加逐渐减少细胞分裂素BA和生长素NAA的浓度。最初几次继代,BA的浓度为0.5 mg/L,NAA的浓度为0.2 mg/L。然后BA的浓度逐渐降低到0.1~0.3 mg/L,NAA的浓度逐渐降至0.05~0.1 mg/L,继代5~6次后,BA的浓度保持在0.1~0.3 mg/L,NAA的浓度保持在0.05~0.1 mg/L。继代周期随季节而不同,夏季为15~25 d,春秋季为20~35 d,冬季为40~50 d,芽的月增殖系数为3~5倍,满足工厂化育苗的要求。组培苗的玻璃化和遗传变异等异常现象很少,节间长度适中,有利于生根。     

拟南芥悬浮细胞生长特性及其继代培养条件

研究了拟南芥悬浮细胞的生长特性及其继代培养条件。结果表明:在每个7d一次的继代周期中,拟南芥悬浮细胞的生长表现出明显的S型生长曲线。正常培养条件下,继代后2-4 d出现快速生长,此后生长量迅速下降,但接种量不同,其继代后悬浮细胞生物量及快速增长发生时期不同。维持7 d继代周期的理想接种量为起始悬浮液按10 mL／50 mL稀释。接种量小,生长迟缓,甚至不能增殖。培养基中不同激素及不同蔗糖含量均会对其生长产生极明显的影响,在B5 0．2 mg／L NAA条件下反复继代后的细胞,再加入外源NAA时,反而会抑制其生长。蔗糖含量以30 g／L最好,蔗糖含量低,悬浮生物量及细胞活性明显下降。     

赤桉人工种子的研制 Ⅰ．幼芽繁殖体的高频率诱导及同步性控制

系统地研究了诱导高频、同步可制成“芽珠”的赤桉幼芽（Ｓｈｏｏｔｔｉｐｓ）的方法，为以幼芽为繁殖体制备人工种子奠定基础。试验结果：首先，培养基中适宜的ＢＡ和ＮＡＡ浓度和配比直接控制着制备“芽珠”型幼芽的数量，同时对已分化出的幼芽进一步伸长有很大的影响，ＢＡ为１．０ｍｇ／Ｌ，ＮＡＡ为０．５ｍｇ／Ｌ的培养基中附加４０ｍｇ／Ｌ腺嘌呤和５％的蔗糖能较好地控制幼芽生长及其叶片大小；其次，培养过程中先以１６天光／暗为１０ｈ／１４ｈ培养之后转入４天全黑暗培养可控制幼芽生长的同步性，在半固体培养基上连续继代三次，获得了每次继代（２０天）平均产生２５个／ｃｍ２适宜制备“芽珠”的幼芽。文中就赤桉培养中褐色渗出物问题进行了初步研究，通过预培养的方法克服了褐变物对培养中材料的影响。     

Selection and physiology of cell cultures of Douglas-fir grown under conditions of water stress

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) cell cultures sampled 3, 6, or 9 days after subculture in nutrient medium were able to survive subsequent subculture in a medium containing 15% polyethylene glycol (PEG) (M(r) 6000-8000) (-1.21 MPa), whereas cell sampled 12 or 16 days after subculture in nutrient medium became senescent when transferred to a medium containing 15% PEG. Cells sampled after subculture for 3, 6, or 9 days in nutrient medium had lower fresh weight/dry weight ratios, lower osmotic potentials, smaller cell diameters, and higher turgor pressures than cells sampled after 12 or 16 days subculture in nutrient medium. Cells surviving subculture to a medium containing 15% PEG did not increase in dry weight for 5 weeks even though the medium was exchanged every 7 days. After 5 weeks, however, dry weight growth resumed and reached 75% of the level attained by control cells grown on PEG-free medium. Long-term growth on a medium containing 15% PEG (PEG-selected cells) could only be sustained if the medium was supplemented with 30 mM glutamine. The PEG-selected cells grew in small clusters, were isodiametric, and had chlorophyll contents 50% higher than unselected cells. The PEG-selected cells also showed lowered cellular osmotic potentials, presumably due to osmoregulation. Turgor pressures of PEG-selected cells were greater than or equal to those of unselected cells.     

Light distribution in scattered-trees open woodlands in Western Spain

We have studied the percentage of radiation transmitted through the tree canopy to the underlying pasture and crops in dehesas of Southwest Spain by means of fish-eye photographs taken at different distances from the tree. Thirty-six trees were studied covering all the diametric classes (0.1–14 m canopy width) of two stands, with mean density of 19 mature trees ha⁻¹. Intercepted light decreased with distance following an logistic curve, indicating a rapid increase in the light availability with distance from the tree. For mature trees, radiation was constant beyond 20 m. Applying a multivariable regression light equation, distance, stem diameter and canopy width explained more than 88% of the light variability for each orientation studied. A simple model was built up from light equations, tree growth curves and allometric relationships. From this model, we have estimated that radiation available for crops and pasture decreased up to 21% due to the presence of trees in a standard dehesa with 24 mature trees ha⁻¹ and 13% of canopy cover. In addition, we have generated different radiation maps of virtual dehesas differing in tree age, density and arrangement, which could be useful to determine optimal tree planting schemes and consequent pruning and thinning regimes.     

托里桉组培快繁技术初步研究

以2 a托里桉超级苗不同株系的茎段为外植体进行组培快繁研究,结果表明：适合诱导的培养基为MS改良+6-BA 0.5mg·L-1+NAA 0.1 mg·L-1;适合6号株系增殖培养基为MS改良+6-BA 0.2 mg·L-1+NAA 0.1 mg·L-1,适合7号、10号株系的增殖培养基为MS改良+6-BA 0.3 mg·L-1+NAA 0.2 mg·L-1;适当缩短继代周期是解决桉苗顶稍枯萎、上部叶片脱落等症状简单、有效的方法;适合的生根培养基为1/2MS改良+ IBA 0.2 mg·L-1+ ABT 0.6 mg·L-1,生根苗移栽成活率可达90%。