Photodynamic herbicides: 1. Concept and phenomenology

A new approach to the design of conceptually and phenomenologically new herbicides is described. It involves the joint utilization of tetrapyrrole precursors, such as δ-aminolaevulinic acid (a biodegradable amino acid) and activators of the chlorophyll biosynthetic pathway, such as 2,2′-dipyridyl, in order to induce treated plants to biosynthesize and accumulate massive amounts of tetrapyrrole intermediates of the chlorophyll biosynthetic pathway in the dark (i.e. at night). During the subsequent light period (daylight) the accumulated tetrapyrroles act as potent photodynamic sensitiziers, which in turn result in the death of susceptible plants in a matter of hours. We have therefore proposed to name herbicides that act via this mechanism as photodynamic herbicides, or more pictorially as laser herbicides. From a limited survey of agricultural plant and weed species it appears that photodynamic herbicides exhibit a very pronounced organ, age and species-dependent selectivity. For example, dicotyledonous weeds such as mustard, red-root pigweed, common purslane and lambsquarter are very susceptible while monocotyledonous plants such as corn, wheat, barley and oats are not. The biochemical basis of this selectivity seems to lie, among other things, in the rates of tetrapyrrole turnover and in a differential enhancement by the applied chemicals of the monovinyl and divinyl tetrapyrrole biosynthetic pathways in the various species. A survey of various groups of chemicals (herbicides and other selected biochemicals) that are likely to exhibit photodynamic herbicidal properties is currently under investigation.     

黑木耳‘高原云耳2号’的选育

‘高原云耳2号’由采自云南省普洱市景东县哀牢山的一株野生黑木耳多次分离和反复驯化,通过连续6年的系统选育、评价筛选而育成。该品种为中早熟、广温广适型新品种。子实体多单生,小口出耳单片率高,耳片厚、大小适中、边缘圆整、质地硬脆,背面青灰至灰黑色、腹面黑色、有光泽,耳脉少,平均产量55-65g/袋,商品性佳,抗性强。适于1 500-2 200m高海拔地区立体袋栽。     

Morphological and molecular identification to secure cultivar maintenance and management of self-sterile Rubus arcticus

Background and Aims

Preservation of cultivar purity creates a particular challenge for plants that are self-incompatible, require insects for cross-pollination, and have easily germinating seeds and vigorously spreading rhizomes. As the fields must be planted with mixed populations, and a balance must be maintained between the cultivars to achieve effective pollination, methods for field monitoring of the relative density of different cultivars must be practical. Furthermore, a DNA-based method is needed for cultivar verification in the collections and outside of the growing season. The aim of this study was to develop both types of methods for Rubus arcticus (arctic bramble).

Methods

Morphological parameters were measured from six cultivars grown on three farms. Observations from the flowers and fruits included: petal and sepal number, flower diameter, arrangement of petals, size of calyx in relation to corolla, fruit weight, yield and soluble sugars. Observations from the leaves included: width and height of middle leaflet, shape of the base of terminal leaflet, shape of terminal leaflet, leaf margin serration and fingertip touch. The applicability of simple sequence repeat (SSR) or microsatellite DNA markers developed for red raspberry was tested on eight arctic bramble cultivars.

Key Results and Conclusions

Morphological and molecular identification methods were developed for R. arcticus. The best morphological characteristics were the length-to-width ratio of the middle leaflet and leaf margin serration. A particular characteristic, fingertip touch, was shown by electron microscopy to be related to the density and quality of the leaf hairs. Red raspberry SSR marker no. 126 proved to be applicable for differentiation of the eight arctic bramble cultivars tested. These identification methods are critical to secure the maintenance and management of R. arcticus. However, the challenges faced and approaches taken are equally applicable to other species with similar biology.     

Biology and fertility life table of the greenbug,Schizaphis graminum (Hemiptera: Aphididae) on the resistant winter wheat cultivar (Pishgam) in Iran

The greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) has been known as a major pest of small grains, particularly wheat, worldwide. In this study, the effect of new wheat cultivar (Pishgam) for cold regions on biological characteristics of greenbug was investigated in a greenhouse at 25 ± 2 °C, 55 ± 10% relative humidity and a photoperiod of 16:8 h (L:D). The raw data were analysed based on the age-stage, two-sex life table. The intrinsic rate of increase (r), the finite rate of increase (λ), the net reproduction rate (R₀) and the mean generation time (T) of greenbug were 0.313 ± 0.0019, 1.36 ± 0.0027 females/female/day, 83.33 ± 0.331 females/female and 14.11 ± 0.09 days, respectively. The life expectancy of a nymph is 43.57 days. The maximum reproductive value of females is on the 16th day which coincides with the total pre-reproduction period counted from birth. Hence, the present results may provide helpful information for comprehensive IPM programme of greenbug on this variety in cold regions of Iran. Result revealed that nymphal survival rate of the aphid was 100% on studied cultivar like that on sensitive host plant cultivar.     

Screening of oilseed rape cultivars relation to diamondback moth,Plutella xylostella (Lep.: Plutellidae) in fields of Tehran

The diamondback moth (DBM), Plutella xylostella (L.) (Lep., Plutellidae), is one of the most important pests of oilseed rape, Brassica napus L., in the world. In this study, resistance of oilseed rape cultivars to DBM was evaluated in fields of Tehran based on injury rate of the cultivars. To evaluate cultivar resistance, 19 cultivars of oilseed rape were planted in randomised complete-block design with three replications. Total experiments were conducted in experimental field of Shahed University. Results showed that DBM had activity on the plants during season and peak of the injury occurred on 27 May. Results indicated that the total of oilseed rape cultivar was spotty. Statistical analysis showed that there was significant difference among determined characteristics in all cultivars. The highest and lowest numbers of holes in the leaf were observed in Midas, Karaj3, Zarfam and Hyola420, Hyola308 cultivars, respectively, in sampling of the end growth. Opera and Midas cultivars have the highest percentage of leaf infestation and the lowest percentage of leaf infestation was observed in Hyola420 and Hyola308. Also, Karaj3 and Zarfam cultivars have the highest percentage of meristem infestation and the lowest percentage of meristem infestation was observed in Licard and Hyola420 cultivars. Based on peak of the injury rate and importance of meristem injury, Hyola420 and Hyola308 cultivars were relatively resistant to DBM, and Karaj3 and Zarfam were relatively sensitive to DBM.     

Feeding behaviour and performance of different populations of the black currant‐lettuce aphid,Nasonovia ribisnigri,on resistant and susceptible lettuce

When crops are bred for resistance to herbivores, these herbivores are under strong selection pressure to overcome this resistance, which may result in the emergence of virulent biotypes. This is a growing problem for crop species attacked by aphids. The Nr‐gene in lettuce confers near‐complete resistance against the black currant‐lettuce aphid, Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae). Since 2007, populations of N. ribisnigri have been reported in several locations in Europe to infest resistant lettuce varieties that possess the Nr‐gene. The objective of this study was to analyse the behaviour and level of virulence of several N. ribisnigri populations observed to have colonized Nr‐locus‐containing lettuce lines. We analysed the stylet penetration and feeding behaviour, and the performance of these N. ribisnigri populations on resistant and susceptible lettuce lines. Large variation in the degree of virulence to the Nr‐locus‐containing lettuce lines was found among populations of the Nr:1 biotype. The German population was highly virulent on the Nr‐containing resistant lettuce lines, and showed similar feeding behaviour and performance on both the susceptible and resistant lettuces. The French population from Paris was the second most virulent, though reproduction on the resistant lines was reduced. The French population from Perpignan and a population from Belgium, however, showed reduced performance and feeding rate on the resistant compared to the susceptible lettuces. The lettuce background in which the Nr‐gene is expressed influences the level of resistance to the various Nr:1 aphid populations, because the performance and feeding behaviour differed between the aphids on the cultivars (romaine lettuce) compared to the near‐isogenic lines (butterhead/iceberg lettuce). This study also shows that being able to feed on a plant not automatically implies that a population can successfully develop on that plant, because aphids showed phloem ingestion during the 8‐h recording period on resistant lettuce, but were not able to survive and reproduce on the same lettuce line.     

Biosynthesis of Cercosporin

¹³C NMR spectra were measured for 19 pyrethroids and their related compounds including allethrin, tetramethrin, resmethrin, furamethrin, phenothrin and permethrin. Complete assignment of chemical shifts was accomplished by relative spectral pattern, single-frequency off-resonance decoupling, benzene substituent effects, proton selective decoupling and use of shift reagents. The use of shift reagent was found to be especially efficient for assignment of ¹³C resonances. In the case of allethrin, the splittings of some resonance peaks were observed originating from diastereomerism.     

Recent Advances in Structural Research on Ether Lipids from Archaea Including Comparative and Physiological Aspects

A great number of novel and unique chemical structures of archaeal polar lipids have been reported. Since 1993, when those lipids were reviewed in several review articles, a variety of core lipids and lipids with unique polar groups have been reported successively. We summarize new lipid structures from archaea elucidated after 1993. In addition to lipids from intact archaeal cells, more diverse structures of archaea-related lipids found in environmental samples are also reviewed. These lipids are assumed to be lipids from unidentified or ancient archaea or related organisms. In the second part of this paper, taxonomic and ecological aspects are discussed. Another aspect of archaeal lipid study has to do with its physiological significance, particularly the phase behavior and permeability of archaeal lipid membranes in relation to the thermophily of many archaea. In the last part of this review we discuss this problem.     

Establishment of a New Cross of the Rice Blast Fungus Derived from Japanese Differential Strain Ina168 and Hermaphroditic Rice Pathogen Guy11

Mating experiments between Magnaporthe grisea Japanese rice pathogens and Guy11, a hermaphroditic fertile rice pathogen, were done aimed at identification of avirulence genes. A cross named cross 2107 with thirty-six random progenies was obtained. Segregation analyses of genetic markers found that the cross was less suitable for genetic analysis. Backcrosses with cross 2107 progenies and Guy11 were done and another cross named cross 5307 with sixty-five progenies was obtained. A locus controlling kasugamycin resistance named Ksg1R was identified and used for a model case of genetic mapping. Bulked segregant analysis was done to find adjacent RAPD markers for mapping of the gene. Three adjacent markers to Ksg1R were obtained and a genetic map around the Ksg1R was made, but these markers were not located on a single chromosome. These results suggest that genetic analysis to identify a gene locus is available in cross 5307. Infection assay of parental strains of cross 5307 to Japanese differential rice cultivars suggested the possibility of genetic analysis of cultivar specificity toward four rice cultivars: Aichiasahi, Kusabue, Tsuyuake, and K59.     

Modelling shifts in agroclimate and crop cultivar response under climate change

This paper aims: (i) to identify at national scale areas where crop yield formation is currently most prone to climate‐induced stresses, (ii) to evaluate how the severity of these stresses is likely to develop in time and space, and (iii) to appraise and quantify the performance of two strategies for adapting crop cultivation to a wide range of (uncertain) climate change projections. To this end we made use of extensive climate, crop, and soil data, and of two modelling tools: N‐AgriCLIM and the WOFOST crop simulation model. N‐AgriCLIM was developed for the automatic generation of indicators describing basic agroclimatic conditions and was applied over the whole of Finland. WOFOST was used to simulate detailed crop responses at four representative locations. N‐AgriCLIM calculations have been performed nationally for 3829 grid boxes at a 10 × 10 km resolution and for 32 climate scenarios. Ranges of projected shifts in indicator values for heat, drought and other crop‐relevant stresses across the scenarios vary widely – so do the spatial patterns of change. Overall, under reference climate the most risk‐prone areas for spring cereals are found in south‐west Finland, shifting to south‐east Finland towards the end of this century. Conditions for grass are likely to improve. WOFOST simulation results suggest that CO₂ fertilization and adjusted sowing combined can lead to small yield increases of current barley cultivars under most climate scenarios on favourable soils, but not under extreme climate scenarios and poor soils. This information can be valuable for appraising alternative adaptation strategies. It facilitates the identification of regions in which climatic changes might be rapid or otherwise notable for crop production, requiring a more detailed evaluation of adaptation measures. The results also suggest that utilizing the diversity of cultivar responses seems beneficial given the high uncertainty in climate change projections.