Characteristics of the rhizosphere and phyllosphere microbial community of three submerged plants in the dragon-shaped water system of Beijing / 生物工程学报

Aquatic plants and the epiphytic microorganisms are important contributors to the purification of constructed wetlands. Taking the dragon-shaped water system of Beijing Olympic Park as a model, this study analyzed the structure and function of the microbial communities reside the sediment, the water body and the rhizosphere and phyllosphere of three submerged plants-Vallisneria natans, Myriophyllum verticillatum, and Potamogeton pectinatus using high-throughput sequencing technology. The results showed that the microbial diversity from the highest to the lowest were samples from sediment, plant rhizosphere, plant phyllosphere and water. The microbial diversity of plant phyllosphere samples were significantly higher than those of the water body. LEfSe analysis showed that different habitats enriched different microbial groups. The sediments mainly enriched anaerobic microbes, while the water body and the phyllosphere of plants mainly enriched aerobic microbes, and the rhizosphere of plants had the both. Functional prediction analysis showed that the abundance of denitrification marker genes in phyllosphere samples was higher than that in samples from rhizosphere, sediment and water body, and the abundance of denitrification marker genes in phyllosphere samples of M. verticillatum and P. pectinatus was higher than that of V. natans. This study could serve as a guidance for the selection of submerged plants and functional microorganisms for constructed wetlands.

Colonization of Serratia fonticola on phylloplane of tomato and its impact on leaf cytoplasmic protein profile

Aim: The aim of the present study was to understand the impact of human enteric pathogen (Serratia fonticola) colonization on cytoplasmic protein profile of tomato leaves. Methodology: Aseptically grown plants were inoculated with S. fonticola and sampled at different interval of time. Colonization pattern was studied by leaf impression technique. Changes in cytoplasmic protein profile were studied by protein-protein crosslinking method followed by separation through SDS PAGE. Results: The colonization pattern study revealed that maximum colonies were found at 24 hr post inoculation which gradually decreased with time, showing the survival of the pathogen on phylloplane. Electrophoretic separation of cytoplasmic proteins showed crosslinking of some proteins in treated samples at 48, 72 and 96 hr post inoculation. Interpretation: This study will help in understanding the molecular changes in cytoplasmic protein profile and survival of pathogen on phylloplane, thus limiting the growth of bacteria, Serratia fonticola on phyllosphere.

UV-B Resistant Yeast Inhabit the Phyllosphere of Strawberry.

The increase on the worldwide influx of solar ultraviolet radiation (UV-B) has inflicted a considerable challenge, due to its deleterious effects to live beings and pose a special threat to phyllosphere communities. However, UV-B influence on epiphytic yeasts associated with agricultural crops remains limited. Main aim of the present study was to determine the effect of ultraviolet-B radiation on the epiphytic yeast populations associated with strawberry under field conditions. Thus, strawberries (Fragaria x ananassa Duchesne cv. Oso Grande) were grown under three different treatments: a) environmental UV-B, b) enhanced UV-B and c) decreased UV-B; thereafter, their yeast epiphytic populations were analyzed by T-RFLP prior to yeast isolation, identification and in vitro test for the sensitivity against UV-B. Our results demonstrated that UV-B radiation did not significantly affect the strawberry epiphytic yeast populations. However, isolates directly exposed to radiation, generally revealed morphological abnormalities and a diminishing value in the percentage of survival, although they remained constant after 240 min of exposure. The increase in UV-B radiation was not sufficient to affect the dynamics and composition of epiphytic yeast communities from strawberry, there was a clear morphotype shift towards the selection of pigmented isolates.

RESPUESTA FISIOLÓGICA Y CAPACIDAD ANTAGONISTA DE AISLAMIENTOS FILOSFÉRICOS DE LEVADURAS OBTENIDOS EN CULTIVOS DE MORA (Rubus glaucus) / Physiological Responses And Antagonistic Capacity Of Yeast Phyllospheric Isolates Obtained In Blackberry Crops (Rubus glaucus)

La filósfera es un ecosistema complejo que a pesar de contar con un gran número de microorganismos asociados, presenta pocos estudios diseñados para entender las características ecofisiológicas de los microorganismos que lo habitan. Las levaduras, como elemento importante de este hábitat, están expuestas a un ambiente variable afectado por la planta hospedera, edad y posición de la hoja, disponibilidad y calidad de nutrientes, temperatura, pH, radiación y actividad del agua. Estos factores producen una presión de selección para el establecimiento de poblaciones naturales o introducidas de levaduras que puedan desplazar otras poblaciones de hongos fitopatógenos. En este estudio se obtuvieron 80 aislamientos de levaduras filosféricas de dos cultivos de mora (Rubus glaucus), a las que se les determinó su nicho potencial en términos de su capacidad para crecer a diferentes condiciones de temperatura, pH, estrés osmótico y tolerancia a radiación UV. El estrés osmótico fue la condición evaluada más restrictiva para las levaduras obtenidas, ya que únicamente seis aislamientos presentaron un crecimiento superior a 0,3 unidades de DO a 405 nm, cuando fueron crecidas a 50% y 60% de glucosa. Este estudio permitió seleccionar diez aislamientos filosféricos de levaduras, destacados por su capacidad para crecer en un amplio rango de condiciones. De estos, cuatro aislamientos LvF 34, LvF 43, LvF 44 y LvF 50 se destacaron por su capacidad de antagonismo contra el hongo fitopatógeno Botritys cinérea. Su determinación taxonómica permitió reportar por primera vez las especies Candida kunwinensis y Rhodotorula colostri con potencial biocontrolador.

The phyllosphere is a complex ecosystem in which despite of having a great number of associated microorganisms, few studies have been designed to understand the ecophysiological characteristics of the microorganism’s inhabitant. Yeasts, as an important element of this habitat, are exposed to a variable environment, affected by the host plant, age and leaf position, availability and nutrient quality, temperature, pH, radiation and water activity. All these factors produce an important selection pressure for the establishment of natural or introduced populations of yeast which may displace other phytopathogenic fungi. In this study 80 isolates of phyllospheric yeast were obtained from two blackberry crops (Rubus glaucus). Its potential niche was determined in terms of its capacity to growth at different conditions of temperature, pH, osmotic stress and UV radiation. The osmotic stress was the most restrictive evaluated condition for the obtained yeast. Only six isolates presented a growth higher to 0.3 OD units at 405 nm, when grown at 50% or 60% of glucose. This study identified the ecological niche of ten yeast phyllospheric isolates, selected for their capacity to growth at a wide range of conditions. Four of these isolates LvF 34, LvF 43, LvF 44 and LvF 50 were selected for their antagonistic capacity against the phytopathogenic fungi Botritys cinérea. Its taxonomic determination allowed us to report for the first time isolates of Candida kunwinensis and Rhodotorula colostri with biocontrol capacity.

Genetic and metabolic diversity of pink-pigmented facultative methylotrophs in phyllosphere of tropical plants

Diversity of Pink-Pigmented Facultative Methylotrophs (PPFMs) in phyllosphere of cotton, maize and sunflower was determined based on differential carbon-substrate utilization profile and Random Amplified Polymorphic DNA data. Results indicate that six diversified groups of PPFMs are found in these crops. Sunflower and maize phyllosphere harbor four different groups of methylobacteria while cotton has only two groups.

A diversidade de microrganismos metilotróficos facultativos pigmentados (PPFMs) na filosfera de algodão, milho e girassol foi determinada baseada no perfil diferencial de utilização de substratos de carbono e em dados de RAPD. Os resultados indicaram a existência de seis grupos diferentes de PPFMs nessas plantas. As filosferas de girassol e milho apresentaram quatro grupos diferentes de metilobactérias enquanto a de algodão apresentou apenas dois grupos.

Leaf Exudates of Vicia faba and their Effects on Botrytis fabae and Some Associated Fungi

Analysis of leaf exudates of Vicia faba using paper chromatography to identify individual amino acids and sugars qualitatively was investigated. The results revealed that the number of identified amino acids detected in the leaf exudates of the susceptible plants was more than those of resistant plants. The results also showed an increase in the number of amino acids exuded by infected leaves, but no marked difference in sugars of infected and non infected plants. Lithium chloride application led to decrease in amino acid and sugar contents. The number of amino acids and sugars was also decreased with leaf age. Botrytis fabae and the selected fungal species (Alternaria alternata, Fusarium oxysporum and Aspergillus niger) were used to show the effect of individual amino acid and sugar on their spore germination. It was observed that all amino acids stimulated the fungal spore germination except serine which inhibited its spore germination. In case of A. alternata, spore germination was stimulated by all amino acids except serine, alanine, glutamic acid, arginine and methionine which caused the inhibition. In case of F. oxysporum, aspartic and glutamic acids inhibited spore germination but the other amino acids stimulated its spore germination. Aspartic acid and phenyl alanine inhibited the spore germination of A. niger. All the identified sugars (galactose, glucose, fructose and rhamnose) stimulated spore germination of all tested fungi.

Characteristics of Phyllosphere and Epiphytes / 微生物学通报

Phyllosphere and epiphytes have attracted significant interest of more and more researchers by their unique biological characteristics. Progress of research on phyllosphere and epiphytes was summarized in this paper, and the special emphasis was put on the characteristic of phyllosphere, microbial communities, invasion and the location of bacteria on leaf surfaces. Some ideas for further studies on phyllosphere microbes were also proposed.