木质素合成酶基因F5H的RT-PCR引物筛选

据EMBL核酸序列库中发表的白杨杂种F5H的cDNA序列,利用Primer 5.0软件设计3组扩增引物。通过PCR及RT-PCR扩增反应,筛选出一组比较合适的引物,确定该引物对的最适反应体系和程序参数。利用该引物对,从正在分化的2年生欧美杨107茎的次生木质部提取的mRNA中RT-PCR扩增出一个867bp的木质素合成特异表达的f5h基因片段。将其克隆到pGM-T载体上,构建了f5h在大肠杆菌中的表达载体,并对引物筛选进行讨论。     

新西兰辐射松根朽病与温度、湿度关系的数量模型*

新西兰辐射松根朽病与温度、湿度关系的数量模型束庆龙，宋淑梅，赵卫中，Ｎ．Ｍ．Ｓｅｌｆ关键词辐射松根朽病，温度，降雨量，土壤湿度，数量模型早在１９３０年，新西兰就有关于４年生辐射松ＰｉｎｕｓｒａｄｉａｔａＤ．Ｄｏｎ幼树受根朽病危害致死的报道［１］。６０...     

Evaluation of the level of threat and protective classification of the vegetation of Makehe Forest in Sanjiangyuan Nature Reserve, west China

After investigating and studying the vegetation, we have established that Makehe Forest, in Sanjiangyuan Nature Reserve, Qinghai Province, is host to a total of 364 different species, representing 173 “genera” in 55 different vegetative families. We propose five quantifiable indices for evaluating the level of threat to these plants: 1) the distribution frequency of the “line transect”; 2) the distribution frequency of sample plots; 3) the distribution density inside sample plots; 4) the existing abundance in the forest region; and 5) plant fidelity. The results show that there are two endangered species, six vulnerable species, 12 nearly threatened species and 344 safe species. The study tried to evaluate the urgency for conserving these plants, according to coefficients of closeness to disappearance, of genetic loss and of usefulness. Results also showed that the number of species of primary concern is two; of secondary concern, nine; of the third level, 23; and of least concern, 330 species. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 20–25 [译自: 北京林业大学学报]     

Comparison of image and rapid field assessments of riparian zone condition in Australian tropical savannas

Suitable methods for measuring and monitoring the condition of riparian environments are being investigated by government agencies responsible for maintaining these environments in Australia. The objective of this work was to compare two riparian condition assessment approaches, the Tropical Rapid Appraisal of Riparian Condition (TRARC) method developed for rapid on-ground assessment of the environmental condition of savanna riparian zones and an image based riparian condition monitoring scheme. Measurements derived from these two approaches were compared and correlated. The sample representativeness of the TRARC method was evaluated and the cost-effectiveness and suitability for multi-temporal analysis of the two approaches were assessed. Two high spatial resolution multi-spectral QuickBird satellite images captured in 2004 and 2005 and coincident field data covering sections of the Daly River in the Northern Territory, Australia were used in this work. Both field and image data were processed to map indicators of riparian zone condition including percentage canopy cover, organic litter on the ground, canopy continuity, tree clearing, bank stability, and flood damage. Spectral vegetation indices, image segmentation, and supervised classification were used to produce riparian health indicator maps. QuickBird image data were used to examine if the spatial distribution of TRARC transects provided a representative sample of ground based estimates of riparian health indicators. Covering approximately 3% of the study area, the sample mean of the TRARC estimates of individual indicators of riparian zone condition were in most cases within 20% of the global mean derived from the whole imaged riparian area. The cost-effectiveness of the image based approach was compared to that of the ground based TRARC method. Results showed that the TRARC method was more cost-effective at spatial scales from 1 km to 200 km of river in relatively homogeneous riparian zones along rivers with only one channel, while image based assessment becomes more feasible at regional scales (200–2000 km of river). A change detection analysis demonstrated that image data can provide detailed information on gradual change, while the TRARC method is less suited for multi-temporal analysis due to the ranked data format, which inhibits precise detection of change. However, results from both methods were considered to complement each other for single date assessment of riparian zones if used at appropriate spatial scales.     

森林生态效益计量评价的理论方法概述

森林生态效益计量评价是对一定时期森林所提供的生态效益大小的计量。文章论述了森林生态效益计量评价的理论和方法。为了使评价结果更真实客观,从而能为社会承认和接受,提出应从森林生态效益划分标准问题、综合效益定量问题、林龄动态分析等方面进行深入的研究。     

湖北宜昌公益林可持续经营能力的数量化评价

论述了宜昌公益林可持续经营数量化评价的指导思想和基本原则,并以公益林可持续经营的基本要素为依据,建立了综合评价指标变量集;通过主成分分析和层次分析,提取了累计贡献率大于81%的11个指标因子,确定了各指标因子的权重;从发展规模总量和结构协调度两方面对公益林可持续经营能力进行了评价,认为宜昌公益林的发展规模不断扩大,但其结构协调度DHT=0.722,协调能力较差,仍处于弱可持续发展阶段.     

广东西瓜上检测到甜瓜黄斑病毒

在广东发现了可能被番茄斑萎病毒属(Tospovirus)病毒侵染的西瓜,采用ELISA和RT-PCR法对该西瓜病样进行了检测,西瓜病叶粗汁液不与番茄斑萎病毒(Tomato spotted wilt virus,TSWV)和西瓜银斑驳病毒(Watermelon silver mottle virus,WSMoV)的血清发生反应;利用引物J13/UHP通过RT-PCR可以扩增出约1400 bp的基因片段,该片段包括一个840 bp的核衣壳蛋白ORF,其推导的氨基酸序列与已报道的Melon yellow spot virus(MYSV)NP基因氨基酸序列的同源率都为99%,进化树分析表明侵染广东西瓜的病毒(命名为MYSV-GZ)属于Tospovirus的MYSV血清组。     

Direct evidence of surface infestation of seeds and tubers by Plasmodiophora brassicae and quantification of spore loads

Using quantitative PCR, DNA of Plasmodiophora brassicae, the causal agent of clubroot, was detected and quantified on canola, pea and wheat seeds, as well as on potato tubers, all harvested from clubroot‐infested fields in Alberta, Canada. Quantifiable levels of infestation were found on seven of the 46 samples analysed, and ranged from <1·0 × 10³ to 3·4 × 10⁴ resting spores per 10 g seeds; the vast majority (80–100%) of resting spores on these samples were viable, as determined by Evan’s blue vital staining. However, the levels of infestation found were generally lower than that required to cause consistent clubroot symptoms in greenhouse plant bioassays. While the occurrence of P. brassicae resting spores on seeds and tubers harvested from clubroot‐infested fields suggests that seedborne dissemination of this pathogen is possible, practices such as commercial seed cleaning may be sufficient to effectively mitigate this risk.     

The threat of wild habitat to scab resistant apple cultivars

Evaluations of plant resistance to pathogens are rarely made using isolates from wild habitats, although the heterogeneity of such habitats may generate pathogen diversity which could be a source of new virulence in cultivated habitats. The aim of this study was to investigate whether scab resistance factors, identified and characterized in apples using isolates of Venturia inaequalis from a cultivated habitat, remained effective against isolates from a wild habitat. Three V. inaequalis core collections originating from the cultivated apple Malus × domestica and from two wild species, M. sieversii and M. sylvestris, were established to maximize pathogen diversity. For each core collection, 10 isolates were inoculated in mixtures onto 51 genotypes from an apple progeny segregating for two qualitative resistance genes and six quantitative resistance loci (QRL). On each apple genotype, isolates that contributed to the scab symptoms were identified within the mixture using microsatellite markers. The most frequently detected isolates were inoculated singly to compare their aggressiveness according to their host origin. The results showed that isolates from a wild habitat were able to infect the susceptible apple genotypes. However, these isolates were never more aggressive than isolates from the cultivated habitat on the resistance factors tested. It can therefore be concluded that the resistance factors used in this study, identified with V. inaequalis isolates from a cultivated habitat, remained effective against isolates from M. sylvestris and M. sieversii.     

Effects of temperature,inoculum concentration,leaf age,and continuous and interrupted wetness on infection of olive plants by Spilocaea oleagina

Experiments were conducted on olive plants in controlled environments to determine the effect of conidial concentration, leaf age, temperature, continuous and interrupted leaf wetness periods, and relative humidity (RH) during the drier periods that interrupted wet periods, on olive leaf spot (OLS) severity. As inoculum concentration increased from 1·0 × 10² to 2·5 × 10⁵ conidia mL^?1, the severity of OLS increased at all five temperatures (5, 10, 15, 20 and 25°C). A simple polynomial model satisfactorily described the relationship between the inoculum concentration at the upper asymptote (maximum number of lesions) and temperature. The results showed that for the three leaf age groups tested (2–4, 6–8 and 10–12 weeks old) OLS severity decreased significantly (P < 0·001) with increasing leaf age at the time of inoculation. Overall, temperature also affected (P < 0·001) OLS severity, with the lesion numbers increasing gradually from 5°C to a maximum at 15°C, and then declining to a minimum at 25°C. When nine leaf wetness periods (0, 6, 12, 18, 24, 36, 48, 72 and 96 h) were tested at the same temperatures, the numbers of lesions increased with increasing leaf wetness period at all temperatures tested. The minimum leaf wetness periods for infection at 5, 10, 15, 20 and 25°C were 18, 12, 12, 12 and 24 h, respectively. The wet periods during early infection processes were interrupted with drying periods (0, 3, 6, 12, 18 and 24 h) at two levels of RH (70 and 100%). The length of drying period had a significant (P < 0·001) effect on disease severity, the effect depending on the RH during the interruption. High RH (100%) resulted in greater disease severity than low RH (70%). A polynomial equation with linear and quadratic terms of temperature, wetness and leaf age was developed to describe the effects of temperature, wetness and leaf age on OLS infection, which could be incorporated as a forecasting component of an integrated system for the control of OLS.