近些年的研究表明，二氧化碳水平的上升可能会提高产量，但会以营养损失为代价。伊利诺伊大学、美国农业部农业研究局（USDA-ARS）和唐纳德丹福斯植物科学中心发表在《植物杂志》的一项新的研究成果提出，这种对未来影响作物的复杂环境相互作用的理解并不完整，气温上升实际上可能有利于营养，但代价是产量降低。 两年的田间试验表明，将温度升高约3℃可能有助于保持种子质量，抵消二氧化碳降低食物营养的影响。在大豆中，二氧化碳水平升高使种子中铁和锌的含量减少了约8%至9%，但温度升高则产生了相反的效果。 研究人员介绍说，铁和锌对植物和人类健康至关重要，植物有多个过程影响种子中这些元素的积累，环境因素会以不同的方式影响这些过程，因此很难预测不断变化的气候将如何影响人类的食物。 但这项研究表明，可能存在优化全球作物产量和作物营养质量之间的权衡。 该团队在开放式浓度试验（SoyFACE）的大田条件下测试了大豆的产量与营养，该试验可以人为地将二氧化碳和温度提高到未来水平。这种方式能够实现对农作物种植环境的控制，作物的种植和管理与美国中西部的其他田地则完全一样。接下来，研究人员计划设计实验以找出造成这种影响的机制。
[学术文献] Exploring the Diversity of Mechanisms Associated With Plant Tolerance to Virus Infection 进入全文
Frontiers in Plant Science
Tolerance is defined as an interaction in which viruses accumulate to some degree without causing significant loss of vigor or fitness to their hosts. Tolerance can be described as a stable equilibrium between the virus and its host, an interaction in which each partner not only accommodate trade-offs for survival but also receive some benefits (e.g., protection of the plant against super-infection by virulent viruses; virus invasion of meristem tissues allowing vertical transmission). This equilibrium, which would be associated with little selective pressure for the emergence of severe viral strains, is common in wild ecosystems and has important implications for the management of viral diseases in the field. Plant viruses are obligatory intracellular parasites that divert the host cellular machinery to complete their infection cycle. Highjacking/modification of plant factors can affect plant vigor and fitness. In addition, the toxic effects of viral proteins and the deployment of plant defense responses contribute to the induction of symptoms ranging in severity from tissue discoloration to malformation or tissue necrosis. The impact of viral infection is also influenced by the virulence of the specific virus strain (or strains for mixed infections), the host genotype and environmental conditions. Although plant resistance mechanisms that restrict virus accumulation or movement have received much attention, molecular mechanisms associated with tolerance are less well-understood. We review the experimental evidence that supports the concept that tolerance can be achieved by reaching the proper balance between plant defense responses and virus counter-defenses. We also discuss plant translation repression mechanisms, plant protein degradation or modification pathways and viral self-attenuation strategies that regulate the accumulation or activity of viral proteins to mitigate their impact on the host. Finally, we discuss current progress and future opportunities toward the application of various tolerance mechanisms in the field.
Plant Soil Environ
The aim of this work was to compare the dynamics of the degradation of herbicides commonly used in brassica vegetables. Series of plot field experiments were carried out in planting cauliflower in 2012–2014. The amount of herbicide residues with the maximum residue level (MRL) determined by the Regulation (EC) No. 396/2005 and with requirements of non-residue production (up to 10 µg/kg of active ingredient in harvested product) was compared. Napropamide, clomazone and dimethachlor were applied before planting and pendimethalin, S-metolachlor, pyridate, ethametsulfuron, dimethenamid, metazachlor, quinmerac, picloram, clopyralid, cycloxydim, fluazifop, propaquizafop and quizalofop were applied after planting the cauliflower. Besides fluazifop and quizalofop, all tested herbicides showed a fast degradation and can be recommended for non-residue production. The amount of fluazifop residues did not fall below the MRL even 6 weeks after application. Residues of post-emergently applied quizalofop were detected in cauliflower 10–44 days after application in most of the samples at concentration 9–73 µg/kg (below the MRL).
[学术文献] Brassica oleracea resistance-related proteins identified at an early stage of black rot disease 进入全文
Physiological and Molecular Plant Pathology
Previously, we analyzed the protein profile of pooled samples (5, 10 and 15 days after inoculation) of Brassica oleracea inoculated with Xanthomonas campestris pv. campestris (Xcc). To search for proteins that may trigger resistance/defense response, here we analyzed B. oleracea plants at an early stage of infection (24 h after Xcc inoculation - hai). Photosynthesis-related proteins showed pronounced reduction in the susceptible plants. Epithiospecifier protein was detected only in resistant inoculated plants, and may influence Xcc colonization. We show that regulation of photosynthesis is crucial for a resistance response against Xcc, even at an early stage of infection.
[学术文献] Differential cobalt-induced effects on plant growth, ultrastructural modifications, and antioxidative response among four Brassica napus (L.) cultivars 进入全文
International Journal of Environmental Science and Technology
Despite the increasing environmental threat of cobalt in the modern era, less is known as its phytotoxicity behavior. Therefore, the present study was undertaken to assess the toxicity effects of cobalt and to understand the associated physio-biochemical response in Brassica napus, an economically important plant crop species. Five-day-old seedlings of four cultivars (Zheda 619, Zheda 622, ZS 758, and ZY 50) were exposed to five different levels of cobalt under hydroponic conditions. Results showed a concentration-dependent inhibition of plant growth, accompanied by notable chlorophyll loss, protein degradation, and accumulation of reactive oxygen species and malondialdehyde. Further, Co contents in different plants parts were found to be higher in Zheda 622 than all other cultivars. In all cultivars, the contents of enzymatic activities (SOD, POD, GR, and GSH) were markedly increased following cobalt exposure; by contrast, catalase and ascorbate peroxidase activities declined with increased cobalt concentration in medium, which was also, echoed by the pattern of enzymes-related mRNA levels. Morphological observations, supported by ultrastructural analysis revealed clear differences in cobalt sensitivity among cultivars, with ZS 758 identified as less sensitive cultivar, and Zheda 622 the most sensitive one. In addition to revealing genotypic differences in cobalt sensitivity in B. napus, findings suggest the mechanisms of cobalt tolerance in this specie could, at least partially, in relation with the ability of plant to sustain the activity of superoxide dismutase and guaicol peroxidase and to maintain glutathione reduced pool through the action of glutathione reductase.
植物通过光合作用将日光转变成能量，但是，一种称作光呼吸的耗费能量的过程极大地抑制了作物产量。美国农业部农业研究局和伊利诺伊大学的研究人员在《科学》杂志上发文称，在现实农业条件下，设计有光呼吸捷径的作物生长量可提高40%。 这一成果来自于一项国际研究项目——增进光合作用效率方法的计划（RIPE）的一部分，该项目希望通过改造作物进行更为有效的光合作用，以可持续地提高全球粮食生产率。 光合作用利用核酮糖-1,5-二磷酸羧化酶／加氧酶（Rubisco）和太阳能将二氧化碳与水转变成糖分，促进作物生长。由于无法准确区分氧气和二氧化碳分子，Rubisco在大约五分之一的时间里抓取的是氧气分子而不是二氧化碳分子，生成了一种对作物有毒的化合物，必须通过光呼吸进行再循环。 一般来说，光呼吸需要穿过植物细胞中三个区室的复杂路径。科学家们设计了三条替代路径改变了原有进程，极大地缩短了距离，节约了大量资源从而使植物产量增加了40%。这是首次经改造的光呼吸补救作物在现实农业环境中进行测试。 为了优化新路径，研究人员利用多套不同启动子和基因设计了基因结构，基本上创建了一套独特的路线图。他们将这些路线图在1,700种植物中进行了测试，筛选出表现最佳的几种。经过两年不断重复的实地研究，研究人员发现这些经过改造的作物长得更快更高，并且生物质提高了约40%，主要表现为茎秆粗壮了一半。 研究团队在烟草上也测试了这一假设，因为作为理想的模式植物，烟草比粮食作物更易改造和测试，而和其他模式植物不同的是，烟草还能长出枝叶冠盖，并能在田野里进行测试。现在，研究团队正在将研究成果转移应用到大豆、豇豆、稻米、马铃薯、番茄、茄子上，以提升产量。