From plant immunity to crop disease resistance

Plant diseases caused by diverse pathogens lead to a serious reduction in crop yield and threaten food security worldwide. Genetic improvement of plant immunity is considered as the most effective and sustainable approach to control crop diseases. In the last decade, our understanding of plant immunity at both molecular and genomic levels has improved greatly. Combined with advances in biotechnologies, particularly clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-based genome editing, we can now rapidly identify new resistance genes and engineer disease-resistance crop plants like never before. In this review, we summarize the current knowledge of plant immunity and outline existing and new strategies for disease resistance improvement in crop plants. We also discuss existing challenges in this field and suggest directions for future studies.     

N、P供给对作物排放N2O的影响研究初报

The preliminary results with detached leaves and seedlings of corn, soybean and sorghumfrom pot and field experiments indicate that inorganic nitrogen supply can significantly enhance the N₂O emission and NO₃^- concentration in plants in the case of phosphorus deficiency and of less light, but phosphorus Supply and sunlight condition can markedly reduce the N₂O emission and NO₃^- concentration in the plants.It's concluded seemed thatthe N₂O emission is a kind of physiological protection to avoid NO₃^- accumulation in plantswhen nitrogen metabolism in plants is in disorder and mineral nitrogen is in over supply.     

Biogeographic bases for a shift in crop C : N : P stoichiometries during domestication

We lack both a theoretical framework and solid empirical data to understand domestication impacts on plant chemistry. We hypothesised that domestication increased leaf N and P to support high plant production rates, but biogeographic and climate patterns further influenced the magnitude and direction of changes in specific aspects of chemistry and stoichiometry. To test these hypotheses, we used a data set of leaf C, N and P from 21 herbaceous crops and their wild progenitors. Domestication increased leaf N and/or P for 57% of the crops. Moreover, the latitude of the domestication sites (negatively related to temperature) modulated the domestication effects on P (+), C (?), N : P (?) and C : P (?) ratios. Further results from a litter decomposition assay showed that domestication effects on litter chemistry affected the availability of soil N and P. Our findings draw attention to evolutionary effects of domestication legacies on plant and soil stoichiometry and related ecosystem services (e.g. plant yield and soil fertility).     

芒萁对几种杂草和农作物的生化他感作用

本文研究了芒萁植株地上部分和地下部分水提液对几种杂草和农作物的生化他感作用。证明：（１） 芒萁水提液对供试杂草及白菜、萝卜的种子萌发有显著或极显著抑制作用,对全部供试幼苗的根生长和多数供试幼苗的苗高有显著抑制作用;（２） 地上部分的生化他感作用强于地下部分;（３） 芒萁对供试植物幼苗根生长的抑制作用强于对茎、叶的作用     

Do farmers perceive a deficiency of soil organic matter? A European and farm level analysis

Agricultural soils with too little soil organic matter (SOM) content are characterized by fertility problems. A number of authors have tried to specify threshold values for SOM content to indicate what is ‘too little’, ranging from 1 to 5%, below which yields may be affected. How much SOM content is sufficient, however, depends on a number of environmental factors. In addition, up to date farmers’ perceptions were not included when developing thresholds. Therefore, this study focuses on the following three objectives: (1) to identify a risk indicator on SOM deficiency based on environmental factors and agricultural land use; (2) to test the risk indicator using farmers’ perceptions and (3) to establish threshold values for SOM content based on farmers’ perceptions.For objective 1, literature was reviewed on effects of environmental factors and land use on SOM deficiency. Findings were combined into nine options for a risk indicator on SOM deficiency, mapped at European scale. For objective 2, a farm survey was done among 1452 arable farmers in five European countries (Belgium, Germany, Austria, Spain and Italy). Associations between perceived deficiency of SOM by farmers and environmental factors, land use and the risk indicator were investigated. For objective 3, farmers’ perceptions on SOM deficiency were related to the average SOM content of their fields.Mapping the risk indicator at European scale gives a high to very high risk of SOM deficiency for 7 to 37% of European agricultural land, mainly located in Southern and Eastern Europe. Of the farmers in our survey, 18% perceived a high to very high SOM deficiency. A weak correlation was found between the risk indicator and farmers’ perceptions of SOM deficiency (0.15-0.18, Spearman’s rank correlation). Stronger relations were found between separate environmental factors and perceived SOM deficiency. Apparently, having a more extreme environmental condition for one factor gives a higher chance of perceiving a deficiency of SOM than a combination of moderate environmental conditions. Based on farmers’ perceptions threshold intervals for SOM content were established (sand: 1.2–4.7%, loam: 0.6–2.6% and clay: 1.0–2.4%).If policies on SOM management want to include benefits for productive capacity, targeting areas with a relatively high risk of SOM deficiency, more extreme environmental conditions or with very low SOM contents (below the given threshold intervals) seems most promising.     

Food security in 2044: How do we control the fungal threat?

Plant fungal pathogens place considerable strain on agricultural productivity and threaten global food security. In recent decades, advances in crop breeding, farming practice and the agrochemical industry have allowed crop yields to keep pace with food demand. In this opinion article, we speculate on which recent technological advances will allow us to maintain this situation into the future. We take inspiration that it is 25 y since the first plant disease resistance genes were cloned, and imagine if and how agricultural control of pathogens will be achieved by the year 2044. We examine which technologies are best poised to make the jump from lab bench to field application, and propose that future control measures will likely depend on effective integrated disease management.     

荧光假单胞杆菌化感作用的初步研究

The study on the allelopathy of Pseudomonas fluorescens showed that 200 times dilution of its cultured solution could restrain the growth of all test crops,400 times dilution showed a weak restraining effect on most crops,while 600 times dilution had some stimulating effect.The effects differed with crop varieties.     

The plant remains from Gouda-Oostpolder, a twelfth century farm in the peatlands of Holland

An excavation in the near surroundings of the town of Gouda revealed the remains of a wooden farmhouse. Radiocarbon dates and pottery indicate that the farm was built around A.D. 1120–1135. It belongs to the initial phase of land reclamation in the wetlands of the part of the Netherlands called Holland. Pollen and wood analysis show that the original vegetation consisted of ash and alder woodland on a subsoil of eutrophic peat. People used local wood very economically for the construction of the house. A triangular figure of splitPinus sp. andAbies alba branches near the entrance provides an exotic and probably ritual element. The farmers practised mixed farming based on the raising of cattle, pigs and crops comprisingTriticum dicoccum (emmer wheat),Hordeum sp. (barley).Avena sativa (oats),Linum usitatissimum (flax) andCannabis sativa (hemp). Conspicuously absent isSecale cereale (rye). There are no indications of an orchard.     

Suitability of crops,fruit trees/plants to plant parasitic nematodes

Fifteen economically important plant species were tested for their suitability to commonly occurring plant parasitic nematodes viz, Hoplolaimus indicus, Helicotylenchus indicus, Tylenchus filiformis, Rotylenchulus reniformis, Tylenchorhynchus brassicae, Pratylenchus zeae and Meloidogyne incognita. The plants reacted differently to different nematodes. Moreover, eight fruit trees/plants were also tested for their suitability to nematodes.