Plant Responses of Maize to Two of Support Recent Fungal Host Jump.

Host jumps are a major factor for the emergence of new fungal pathogens. In the evolution of smut fungi, a putative host jump occurred in that today exists in two host-adapted , the sorghum-pathogenic f. sp.

Molecular Characterization of Indigenous Rhizobia from Kenyan Soils Nodulating with Common Beans.

Kenya is the seventh most prominent producer of common beans globally and the second leading producer in East Africa. However, the annual national productivity is low due to insufficient quantities of vital nutrients and nitrogen in the soils. Rhizobia are symbiotic bacteria that fix nitrogen through their interaction with leguminous plants.

Pea Aphid () Host Races Reduce Heat-Induced Forisome Dispersion in and .

Although phloem-feeding insects such as aphids can cause significant damage to plants, relatively little is known about early plant defenses against these insects. As a first line of defense, legumes can stop the phloem mass flow through a conformational change in phloem proteins known as forisomes in response to Ca influx. However, specialized phloem-feeding insects might be able to suppress the conformational change of forisomes and thereby prevent sieve element occlusion.

Rhizobia Contribute to Salinity Tolerance in Common Beans ( L.).

Rhizobia are soil bacteria that induce nodule formation on leguminous plants. In the nodules, they reduce dinitrogen to ammonium that can be utilized by plants. Besides nitrogen fixation, rhizobia have other symbiotic functions in plants including phosphorus and iron mobilization and protection of the plants against various abiotic stresses including salinity.

CORK1, A LRR-Malectin Receptor Kinase, Is Required for Cellooligomer-Induced Responses in .

Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical and chemical distortions, pH changes, and breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI maintenance to immune responses.

Distribution, Characterization and the Commercialization of Elite Rhizobia Strains in Africa.

Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation and their contribution to soil fertility, much less is known about the distribution and diversity of the bacteria strains in different areas of the world and which of the strains achieve optimal benefits for the host plants under specific soil and environmental conditions.

The Cell Membrane of a Novel Strain Is the Crucial Target for Aluminium Toxicity and Tolerance.

Soils with low pH and high aluminium (Al) contamination restrict common bean production, mainly due to adverse effects on rhizobia. We isolated a novel rhizobium strain, B3, from Kenyan soil which is more tolerant to Al stress than the widely used commercial strain CIAT899. B3 was resistant to 50 µM Al and recovered from 100 µM Al stress, while CIAT899 did not.

So similar yet so different: The distinct contributions of extrafascicular and fascicular phloem to transport and exudation in cucumber plants.

Cucurbits have been used as phloem research models for many decades because their exudates can be accessed with ease. However, cucurbit plants possess two distinct phloem systems known as the fascicular phloem (FP) and extrafascicular phloem (EFP). Therefore, the molecular composition and function of certain exudates can be misinterpreted due to their unclear origin.

Studying the Function of Phytoplasma Effector Proteins Using a Chemical-Inducible Expression System in Transgenic Plants.

Phytoplasmas are bacterial pathogens that live mainly in the phloem of their plant hosts. They dramatically manipulate plant development by secreting effector proteins that target developmental proteins of their hosts. Traditionally, the effects of individual effector proteins have been studied by ectopic overexpression using strong, ubiquitously active promoters in transgenic model plants.

New phytoplasma effector: 50 shades of green.

Phytoplasmas are pathogenic bacteria that manipulate their plant hosts in dramatic ways. In issue 20 Vol. 184 of Cell, Huang and colleagues report on a phytoplasma effector protein that brings about manifold effects by a surprising mechanism.

Isolation and Characterization of High-Efficiency Rhizobia From Western Kenya Nodulating With Common Bean.

Common bean is one of the primary protein sources in third-world countries. They form nodules with nitrogen-fixing rhizobia, which have to be adapted to the local soils. Commercial rhizobial strains such as CIAT899 are often used in agriculture.

Specialized 16SrX phytoplasmas induce diverse morphological and physiological changes in their respective fruit crops.

The host-pathogen combinations-Malus domestica (apple)/`Candidatus Phytoplasma mali´, Prunus persica (peach)/`Ca. P. prunorum´ and Pyrus communis (pear)/`Ca.

An Endophytic Strain Promotes Growth of Its Hosts and Defends Against Pathogen Attack.

Plants host numerous endophytic microbes which promote plant performance, in particular under stress. A new endophytic fungus was isolated from the leaves of a deciduous wood tree Morphological inspection and multilocus phylogeny identified the fungus as a new strain. If applied to and , it mainly colonizes their roots and strongly promotes initial growth of the plants on soil.

Species-Specific and Distance-Dependent Dispersive Behaviour of Forisomes in Different Legume Species.

Forisomes are giant fusiform protein complexes composed of sieve element occlusion (SEO) protein monomers, exclusively found in sieve elements (SEs) of legumes. Forisomes block the phloem mass flow by a Ca-induced conformational change (swelling and rounding). We studied the forisome reactivity in four different legume species-, , and .

The Physiological and Biochemical Effects on Napier Grass Plants Following Napier Grass Stunt Phytoplasma Infection.

Napier grass stunt (NGS) phytoplasma, a phloem-limited bacterium, infects Napier grass leading to severe yield losses in East Africa. The infected plants are strongly inhibited in growth and biomass production. In this study, phytoplasma-induced morphological changes of the vascular system and physiological changes were analyzed and compared with uninfected plants.

Measurement of Electropotential Waves in Intact Sieve Elements Using Aphids as Bioelectrodes.

Electropotential waves (EPWs) are thought to transmit sudden and profound physiological changes between plant organs. The recording of EPWs can be performed via extracellular or intracellular probes. Both approaches have advantages and disadvantages.

Measurement of Electropotential Waves in Intact Phloem Sieve Elements Using Microelectrodes.

Electropotential waves (EPW) are involved in plant responses to both abiotic and biotic stresses. Three different types of EPWs have been identified: action potential, variation potential, and system potential, all of which have been indicated to participate in phloem-based communication between plant organs. In this chapter we describe in detail how to measure EPWs in plants, including how to access the phloem, and how to insert microelectrodes.

Beneficial and Pathogenic Arabidopsis Root-Interacting Fungi Differently Affect Auxin Levels and Responsive Genes During Early Infection.

Auxin (indole-3-acetic acid, IAA) is an important phytohormone involved in root growth and development. Root-interacting beneficial and pathogenic fungi utilize auxin and its target genes to manipulate the performance of their hosts for their own needs. In order to follow and visualize auxin effects in fungi-colonized Arabidopsis roots, we used the dual auxin reporter construct :::: and fluorescence microscopy as well as LC-MS-based phytohormone analyses.

Arabidopsis thaliana responds to colonisation of Piriformospora indica by secretion of symbiosis-specific proteins.

Plants interact with a wide variety of fungi in a mutualistic, parasitic or neutral way. The associations formed depend on the exchange of nutrients and signalling molecules between the partners. This includes a diverse set of protein classes involved in defence, nutrient uptake or establishing a symbiotic relationship.

Collection of Phloem Sap in Phytoplasma-Infected Plants.

Phytoplasmas colonize specifically the phloem sieve elements (SEs) of plants and influence effectively the plant physiology. To study and understand the interaction of phytoplasmas and host plants an access to the cellular, microscale volume of SEs is demanded. Different methods are suitable to collect phloem sap of phytoplasma-infected plants.

The Beneficial Root-Colonizing Fungus Mortierella hyalina Promotes the Aerial Growth of Arabidopsis and Activates Calcium-Dependent Responses That Restrict Alternaria brassicae-Induced Disease Development in Roots.

The endophytic fungus Mortierella hyalina colonizes the roots of Arabidopsis thaliana and stimulates growth and biomass production of the aerial parts but not of roots. An exudate fraction from the fungus induces rapid and transient cytoplasmic Caelevation in the roots. The Ca response does not require the well-characterized (co)receptors BAK1, CERK1, and FLS2 for pathogen-associated molecular patterns, and the Ca channels GLR-2.

Comparison of intracellular location and stimulus reaction times of forisomes in sieve tubes of four legume species.

Forisomes in legumes are responsible for fast sieve-element occlusion in response to injury to the vascular system. This prevents uncontrolled leakage of phloem sap and protects against invasion of pathogens. Here we compared forisomes of four different legumes (Pisum sativum, Vicia faba, Trifolium pratense and Medicago sativa) by their location (basal, central, apical) in the sieve element and reactivity to a distant heat stimulus.

Induces Systemic Jasmonate Responses in Arabidopsis Which Travel to Neighboring Plants via a Hyphal Network and Activate Abscisic Acid Responses.

Stress information received by a particular local plant tissue is transferred to other tissues and neighboring plants, but how the information travels is not well understood. Application of spores to Arabidopsis leaves or roots stimulates local accumulation of jasmonic acid (JA), the expression of JA-responsive genes, as well as of () and (). Infection information is systemically spread over the entire seedling and propagates radially from infected to non-infected leaves, axially from leaves to roots, and .

Infection Leads to Higher Chemical Defense Signals and Lower Electrophysiological Reactions in Susceptible Compared to Tolerant Barley Genotypes.

(BYDV) is a phloem limited virus that is persistently transmitted by aphids. Due to huge yield losses in agriculture, the virus is of high economic relevance. Since the control of the virus itself is not possible, tolerant barley genotypes are considered as the most effective approach to avoid yield losses.