Cf-2/Rcr3pim番茄品系对南方根结线虫的抗性测定

Cf-2/Rcr3~(pim)基因型番茄不仅能够抵御番茄叶霉菌的侵染,而且对马铃薯金线虫的寄生也有一定的抑制效果。为挖掘根结线虫的新抗性资源,本研究采用室内人工接种法测定了Cf-0/Rcr3~(pim)、Cf-2/Rcr3-3和Cf-2/Rcr3~(pim)基因型番茄品系对南方根结线虫的抗感性。抗性评价结果显示,Cf-0/Rcr3~(pim)品系对南方根结线虫表现高感,Cf-2/Rcr3-3品系为中感,而Cf-2/Rcr3~(pim)品系则为感病。与Cf-0/Rcr3~(pim)和Cf-2/Rcr3-3基因型相比,Cf-2/Rcr3~(pim)基因型番茄品系虽然对南方根结线虫侵染的敏感性略低,但是不能阻止线虫在根系上的大量繁殖,不适于根结线虫的防控应用。     

外植体不同长度及接种方式对马尾松愈伤组织诱导的影响

为研究外植体不同长度及接种方式对马尾松愈伤组织诱导率的影响,将马尾松的外植体按照长度与接种方式的不同分别将其分组,比较组间差异。结果表明:外植体最佳接种长度为0.1~0.2 cm,愈伤组织细胞在切口处大量增殖和生长,外植体全部分化成愈伤组织,愈伤组织诱导率高达84.00%,几乎没有褐化和污染现象发生;外植体最佳接种方式为竖直接种,竖直接种的外植体愈伤组织形成较早,且褐化和污染程度较低。     

非亲和性稻瘟病菌对水稻的诱导抗性

为研究稻瘟病菌Magnaporthe oryzae不同菌株间的相互作用,选择与单抗性基因系水稻IRBL5-M （携带抗性基因Pi5）表现为亲和性的菌株HN52与非亲和性的菌株HN119为研究对象,将其单独或混合接种到单抗性基因系水稻IRBL5-M中,并通过荧光显微镜观察接种后水稻叶鞘的发病情况及病斑面积,测定接种后水稻内相关抗性基因OsWRKY45、OsNPR1、OsPR10、OsMAPK2的表达量以及活性氧的变化。结果显示,相较于单独接种亲和性菌株,混合接种后单抗性基因系水稻IRBL5-M病斑发病面积减少;混合接种中亲和性菌株HN52菌丝侵染能力降低,侵染菌丝细胞间扩展率显著降低73.13%;同时单抗性基因系水稻IRBL5-M中OsWRKY45、OsNPR1、OsPR10和OsMAPK2抗性基因表达量显著增加,水稻叶片中活性氧含量增加,表明在菌株混合侵染过程中,非亲和性菌株可通过激发水稻的抗性反应来降低亲和性菌株对水稻的侵染程度。     

The combined effects of cover crops and symbiotic microbes on phosphatase gene and organic phosphorus hydrolysis in subtropical orchard soils

P deficiency is a major obstacle for crop production in subtropical red soils in South China, and the hydrolysis of organic P (Po) is of great significance in these soils due to the immobilization of P by Fe and Al. Cover cropping in orchards and symbiotic microbial inoculation are considered to improve soil quality, including P status, however, their effects on the hydrolysis of Po is little known. In this study, five soil managements were established in a guava orchard in South China for two and a half years, including clean culture (CC), cover cropping with Paspalum natatu (PN), PN with arbuscular mycorrhizal fungal inoculation (PNA), cover cropping with Stylosanthes guianensis (SG), SG with rhizobial inoculation (SGR). Soil chemical, biochemical and microbial properties were analyzed. Results indicate that soil pH and SOM content tended to increase following cover cropping alone or with microbial inoculation. Po content was significantly elevated in PNA. Po fractionation revealed that cover cropping alone or with microbial inoculation significantly affected the contents of moderately labile Po (MLPo) and moderately resistant Po (FAPo). Enzyme assay indicated that cover cropping with microbial inoculation increased the activities of acidic phosphomonoesterase (ACP), neutral phosphomonoesterase (NP) and alkaline phosphomonoesterase (ALP), with ALP the most sensitive, although ACP activity dominated in red soils. Correlation analysis suggested a significantly positive relationship between ALP activity and MLPo or FAPo. PCR-DGGE profile of the alp-harboring bacterial community showed that cover cropping with S. guianensis and mycorrhizal inoculation to P. natatu promoted the bacterial diversity and/or species richness. For almost all the measured parameters, PN and SG were comparable, however, PNA was superior to SGR, indicating the stronger additive effect of arbuscular mycorrhizal fungus than that of rhizobia. Cat-PCA indicated that MLPo was the most influential factor on phosphomonoesterase. In general, this study suggests that, in subtropical orchards with red soil, cover cropping with microbial inoculation can improve the Po hydrolysis via the promoted alp-harboring bacterial community and then ALP activity. Our results also suggest that the combination of P. natatu and arbuscular mycorrhizal fungus is better than S. guianensis and rhizobia, which possesses practical significance for sustainable production in these orchards.     

Effect of Induced Autotetraploidy on Response to Sclerotinia Clover Rot in Trifolium pratense L.

The effect of induced autotetraploidy on the response of red clover to Sclerotinia clover rot (SCR) was studied under laboratory, glasshouse and field conditions. To assess the response in the laboratory, the detached leaf technique was employed, whereas in the glasshouse and in the field, 6—14 weeks old seedlings and adult plants, respectively, were artificially inoculated with the pathogen grain inoculum. The results of the studies showed that great genotypic variability occurs within diploid (2×)and tetraploid (4×)red clover in response to that disease. Generally, tetraploid red clover, in comparison to diploid, is more resistant to SCR. The laboratory, glasshouse and field experiments showed that the effect of induced autotetraploidy on SCR resistance is positive. The hardening of plant with light and temperature enlarged the differences in reponse to SCR between ploidy levels, family pairs and individual strains with every testing method. Other factors, like plant age and flowering time, influencing red clover response to SCR are also discussed.     

Artificial inoculation and susceptibility of Pinus armandii to Dothistroma septosporum

Dothistroma needle blight (DNB) is a serious needle disease of conifers that primarily affects pine species (Pinus spp.). Dothistroma septosporum is one of the DNB pathogens that has a diverse range of host species excluding Pinus armandii. In 15 inoculated P. armandii seedlings, D. septosporum acervuli were observed in 43 infected needles of ten seedlings with a mean disease severity of 1.11% at 25 weeks after inoculations, demonstrating the potential of D. septosporum to cause symptoms on the needles of P. armandii via artificial inoculation. The disease severity of P. armandii was similar to the positive control, Pinus nigra (median 0.75 for P. armandii to 0.70 for P. nigra), thus, P. armandii acts under artificial conditions as a susceptible host species.     

枸橼种质对柑橘溃疡病的抗性鉴定

柑橘溃疡病(Xanthomonas citri subsp. citri,Xcc)是严重阻碍柑橘产业发展的世界性检疫病害,防控困难,选育抗病品种为防治溃疡病的唯一有效办法。枸橼C-05是柑橘属独特的抗溃疡病种质,为抗性机理和抗病育种提供了种质基础。为了进一步评价枸橼C-05的抗性,另外收集了13份枸橼种质,对其进行溃疡病的离体和活体抗性评价。叶片形态学观察表明,14份枸橼种质存在较大的形态学差异。采用离体与活体注射接种不同浓度的柑橘溃疡病菌,根据叶片的感病症状、病斑周围黄色晕圈大小等典型溃疡病症状,综合评价枸橼类种质的抗病性。结果表明:枸橼种质之间对溃疡病的抗性存在极大差异,溃疡病的抗性评价综合病情指数显示枸橼C-05、园香橼、矮果香橼、美国枸橼、普通枸橼和印度大果综合病情指数较小,表现为极抗病或抗病,其他枸橼种质表现不同程度的感病性;枸橼种质的抗病或感病性与其叶片形态特征无关。枸橼C-05和5个抗病枸橼种质对柑橘溃疡病具有针对性的抗性,这对进一步研究抗病机理和抗病育种具有重要意义。     

大蒜白腐病抗性鉴定方法研究

 以汉中红皮蒜（抗病）和改良蒜（感病）为鉴别品种,对大蒜抗白腐病鉴定中的接种叶龄、接种部位、接种后培养温度及调查时期等进行研究。结果表明,苗期白腐病菌通过伤口和自然孔口均可浸染大蒜植株,而花芽鳞芽分化期通过伤口侵入。抗病性鉴定最适接种叶龄为6叶期,离体接种法较活体接种法更简便快捷。离体接种鉴定时叶面接种和叶背接种鉴定结果无显著性差异;接种后最适培养温度为18 ℃,最适调查时期为接种后7 ~ 8 d。以G005（抗病）、G023（感病）和G025（感病）大蒜为验证品种,离体接种鉴定结果显示,建立的大蒜白腐病抗病性鉴定方法可行,能反映品种的真实抗性。     

Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei‐induced responses in the potato periderm

Using hydroponics and novel non‐destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole‐tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first‐formed internodes were most susceptible to infection, whilst later‐forming and slower‐expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen‐induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common‐scab‐tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).     

在人工接种和自然感虫情况下美洲黑杨后代对桑天牛抗性的研究

杨树 (Ｐｏｐｕｌｕｓｓｐｐ .)是我国主要造林和工业用材树种之一 ,据统计我国杨树人工林面积达 666×1 0 4ｈｍ2 (王世绩 ,1 995 )。但杨树天牛危害十分猖獗 ,其中光肩星天牛 (Ａｎｏｐｌｏｐｈｏｒａｇｌａｂｒｉｐｅｎｎｉｓ)和黄斑星天牛 (Ａｎｏｐｌｏｐｈｏｒａｎｏｂｉ