稻鸭共生绿色农业生产技术

2010～2011年在广东省梅州市五华县水寨镇进行稻鸭共生技术示范试验,探索稻鸭共生绿色农业生产技术模式,取得了显著的成效。该文介绍了稻鸭共生技术的基本要求、主要做法及存在问题。     

Buried in the sand: Uncovering the ecological roles and importance of rays

Rays (superorder Batoidea) are the most diverse group of elasmobranchs, and many are threatened with extinction. However, there remain areas where research on the ecology of this group is lacking, from trophic interactions to their importance to ecosystem structure and function. Such ecological insights are critical for predicting the potential consequences of changes in their population sizes. Our aim was to synthesize the existing ray ecology literature and identify key knowledge gaps in order to provide a framework for future research. Numerous studies describe ray diets, and the number of studies using biochemical methods to address ray trophic interactions is increasing. The implications of ray predator–prey interactions on population dynamics of prey and how ray foraging might influence ecosystem dynamics through bioturbation remain relatively unexplored, despite claims that rays are ecologically important because they are bioturbators and because of their potential to deplete stocks of commercially important bivalves. Therefore, to better integrate rays in our understanding of marine community dynamics, there is a need to: (i) combine behavioural data with dietary information to describe predator–prey interactions; (ii) understand how ray bioturbation affects biogeochemical cycles and infaunal communities; (iii) elucidate conditions under which rays might initiate or transmit trophic cascades through consumptive and non‐consumptive pathways; and (iv) consider anthropogenic influences on the ecological roles and importance of rays.     

Manganese modulates the responses of nitrogen-supplied and Rhizobium-nodulated Phaseolus vulgaris L. to inoculation with arbuscular mycorrhizal fungi

In Venezuela, low yields of black bean crops are attributed, in part, to the low manganese (Mn) and phosphorus (P) contents in the Quartzipsamment soils where this crop is usually sown. To test this hypothesis, black bean plants were grown in sterilized sand to simulate soil physical properties, were fertilized with increasing Mn concentrations (0.1-20 μM) and inoculated with a commercial mixture of Rhizobium leguminosarum bv phaseoli strains 127K44, 127K89, 127K105 (+Rh), in combination with arbuscular mycorrhizal fungi Scutellospora heterogama and Entrophospora colombiana (+AMF). Non-inoculated plants fertilized with 6 mM NO₃ and 2 mM P served as controls. Plants were harvested at 18, 25, 33, and 40 days after emergence. At all harvests, the greatest growth and highest P and iron (Fe) leaf concentrations occurred in control plants grown in 5 μM Mn. The growth of +AMF plants was promoted at 0.1 μM Mn and inhibited at higher than 1 μM Mn. Whereas, concentrations of 5-10 μM Mn enhanced the growth and the Mn concentrations in leaves of +Rh plants 40 days after emergence. The tripartite symbiosis (+Rh+AMF) decreased growth, nodulation and leaf ureide and chlorophyll concentrations in plants grown in less than 20 μM Mn, imputed to severe ultrastructural alterations in the leaf and nodule tissues. Only +Rh+AMF plants grown in 20 μM Mn were effectively nodulated, AMF colonized and reached the flowering stage, although with diminished growth and low chlorophyll concentrations. Results confirm the high Mn requirement of +Rh plants for growth and nodulation and question the implementation of the tripartite symbiosis to improve yields in early flowering black bean varieties planted in soils deficient in Mn and P.     

植物内生真菌多样性及其共生作用

植物内生真菌是生活在健康的植物体内不引起寄主植物任何病害的一类微生物。内生真菌具有丰富的多样性,在与寄主植物协同进化的过程中,通过不同方式为寄主提供有利保护。人们在对内生真菌的研究利用中,可根据研究的需要寻找特殊的内生真菌来源,为生产和研究提供最具研究价值和使用价值的资源。     

Regulation of biosynthesis,perception, and functions of strigolactones for promoting arbuscular mycorrhizal symbiosis and managing root parasitic weeds

Strigolactones (SLs) are carotenoid‐derived plant secondary metabolites that play important roles in various aspects of plant growth and development as plant hormones, and in rhizosphere communications with symbiotic microbes and also root parasitic weeds. Therefore, sophisticated regulation of the biosynthesis, perception and functions of SLs is expected to promote symbiosis of beneficial microbes including arbuscular mycorrhizal (AM) fungi and also to retard parasitism by devastating root parasitic weeds. We have developed SL mimics with different skeletons, SL biosynthesis inhibitors acting at different biosynthetic steps, SL perception inhibitors that covalently bind to the SL receptor D14, and SL function inhibitors that bind to the serine residue at the catalytic site. In greenhouse pot tests, TIS108, an azole‐type SL biosynthesis inhibitor effectively reduced numbers of attached root parasites Orobanche minor and Striga hermonthica without affecting their host plants; tomato and rice, respectively. AM colonization resulted in weak but distinctly enhanced plant resistance to pathogens. SL mimics can be used to promote AM symbiosis and to reduce the application rate of systemic‐acquired resistance inducers which are generally phytotoxic to horticultural crops. © 2019 Society of Chemical Industry     

丛枝菌根真菌对砷胁迫下水稻砷酸盐还原酶基因表达的影响

试验以水稻(Oryza sativa L.)金优64为宿主,以4种丛枝菌根真菌Glonus mosseae、Glomus intraradices、Gigaspora margarita、Gigaspora rosea为接种剂,通过盆栽试验研究在砷胁迫下4种丛枝菌根真菌分别与水稻金优64共生后对水稻的促生效应.结果表明,丛枝菌根真菌与宿主之间具有选择偏好性,水稻接种Glomus mosseae与接种其他3种丛枝菌根真菌相比,长势较明显,地上部砷的积累也较低.砷胁迫下接种不同种属的丛枝菌根真菌对水稻体内砷酸盐还原酶基因的表达影响也不同,推测砷胁迫下接种不同的丛枝菌根真菌对水稻砷代谢途径的调控机制是不同的.     

基于共生理论的城乡统筹机理研究

本文基于城乡统筹发展的内涵及目标，引入种群生态学中的共生理论，将城市和农村作为两个具有复杂相关关系的生态有机种群，通过分析二者的共生单元、共生模式、共生环境和共生界面，从一个全新的角度，提出了城乡统筹的运作机理及可行对策。     

非豆科木本植物与放线菌共生固氮相关基因研究进展

氮素固定是地球上维持生产力的一个重要生态反应,是继CO2固定之后最重要的生化反应.非豆科木本双子叶植物与固氮放线菌Frankia共生形成根瘤固氮,这些植物对绿化荒山、防止水土流失和保护生态环境等具有重要的作用,它们是陆地生态系统中的重要供氮者.Frankia菌具有对宿主的侵染范围广、固氮活性比较强和对氧气不敏感等特性,在Frankia菌与农作物之间建立起新的共生固氮体系的可能性很大.利用生物工程技术和方法构建高效的Frankia工程菌和新的固氮共生体系将成为今后生物固氮研究领域中的发展方向和追求目标.重点介绍了弗氏放线菌中共生固氮相关的固氮基因和谷氨酰胺合成酶基因、根瘤中结瘤固氮相关的nod基因、血红蛋白cDNA克隆及其他根瘤特异蛋白cDNA克隆等方面的研究进展.参33     

菌根真菌对铁皮石斛生长和矿质元素的影响

铁皮石斛组培苗接种6个真菌菌株,培养60 d后,接菌苗的平均鲜重增长率均高于对照,其中接种GS222、GDB162、GDB254、MLX102菌株的苗平均鲜重增长率均达到极显著差异(α=0.01),接种CLN103、CLX104的苗达到显著差异(α=0.05);接菌苗的各矿质元素(除Zn外)含量也均高于对照。接菌苗的营养根重分离获得原接种菌株。显微观察到在皮层和中柱组织形成菌丝结等典型的共生结构,表明接种菌株已与铁皮石斛根共生形成了菌根,对铁皮石斛的生长和矿质元素的吸收有较明显促进作用。由此可认为GS222、GDB162、GDB254、MLX102、CLN103、CLX104是铁皮石斛优良的菌根菌株。     

A single dominant gene in McCall soybean prevents effective nodulation with Rhizobium fredii USDA257

Summary Rhizobium fredii USDA257 will effectively nodulate Asiatic and unimproved soybean cultivars, such as Peking, but most of the highly selected North American cultivars, such as McCall, produce at most rudimentary, ineffective nodules. In R. fredii USDA 257, a locus containing 6 open reading frames is responsible for this cultivar specific incompatibility. To examine the genetic control of incompatability on the part of the host, the soybean cultivars Peking and McCall were crossed to produce five F₁ progeny. These plants and their selfed progeny were tested for nodulation with USDA257. Resistance to nodulation was found to be conditioned by a single dominant gene. These results indicate that, in soybean, strain specific resistance to nodulation can result from gene(s)-for-gene interactions.