RESUMO
The bacteria of the genus Curtobacterium are usually seen as plant pathogen, but some species have been identified as endophytes of different crops and could as such present a potential for disease control and plant growth promotion. We have therefore applied the desorption electrospray ionization mass spectrometry imaging (DESI-MSI) in the direct analysis of living Curtobacterium sp. strain ER1/6 colonies to map the surface metabolites, and electrospray ionization tandem mass spectrometry (ESI-MS/MS) for characterization of these compounds. Several colony-associated metabolites were detected. The ESI-MS/MS showed characteristic fragmentations for phospholipids including the classes of glycerophosphocholine, glycerophosphoglycerol, and glycerophosphoinositol as well as several fatty acids. Although a secure identification was not obtained, many other metabolites were also detected for this bacteria species. Principal component analysis showed that fatty acids were discriminatory for Curtobacterium sp. ER1/6 during inoculation on periwinkle wilt (PW) medium, whereas phospholipids characterize the bacterium when grown on the tryptic soy agar (TSA) medium.
Assuntos
Actinobacteria/isolamento & purificação , Citrus sinensis/microbiologia , Endófitos/química , Cromatografia Líquida de Alta Pressão , Fosfolipídeos/química , Espectrometria de Massas em TandemRESUMO
Arthrobacter agilis UMCV2 is a rhizosphere bacterium that promotes legume growth by solubilization of iron, which is supplied to the plant. A second growth promotion mechanism produces volatile compounds that stimulate iron uptake activities. Additionally, A. agilis UMCV2 is capable of inhibiting the growth of phytopathogens. A combination of quantitative polymerase chain reaction and fluorescence in situ hybridization techniques were used here to detect and quantify the presence of the bacterium in the internal tissues of the legume Medicago truncatula. Our results demonstrate that A. agilis UMCV2 behaves as an endophytic bacterium of M. truncatula, particularly in environments where iron is available.
Assuntos
Arthrobacter/fisiologia , Endófitos/fisiologia , Medicago/microbiologia , Inoculantes Agrícolas , Arthrobacter/genética , Arthrobacter/isolamento & purificação , Meios de Cultura , DNA Bacteriano/análise , Endófitos/genética , Endófitos/isolamento & purificação , Compostos Ferrosos/administração & dosagem , Ferro/metabolismo , Medicago/crescimento & desenvolvimento , Medicago/metabolismo , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Rizosfera , SimbioseRESUMO
Arthrobacter agilis UMCV2 es una bacteria rizosférica que promueve el crecimiento vegetal de plantas leguminosas proveyéndoles hierro soluble. Un segundo mecanismo de promoción se da a través de la producción de compuestos volátiles que estimulan los mecanismos de absorción de hierro. Adicionalmente, A. agilis UMCV2 tiene la capacidad de inhibir el crecimiento de organismos fitopatógenos. En el presente trabajo se emplea una combinación de las técnicas de reacción en cadena de la polimerasa cuantitativa e hibridación in situ con fluorescencia para detectar y cuantificar la presencia de la bacteria en los tejidos internos de la planta leguminosa Medicago truncatula. Nuestros resultados demuestran que A. agilis UMCV2 se comporta como una bacteria endófita de M. truncatula especialmente en medios donde el hierro está disponible.
Arthrobacter agilis UMCV2 is a rhizosphere bacterium that promotes legume growth by solubilization of iron, which is supplied to the plant. A second growth promotion mechanism produces volatile compounds that stimulate iron uptake activities. Additionally, A. agilis UMCV2 is capable of inhibiting the growth of phytopathogens. A combination of quantitative polymerase chain reaction and fluorescence in situ hybridization techniques were used here to detect and quantify the presence of the bacterium in the internal tissues of the legume Medicago truncatula. Our results demonstrate that A. agilis UMCV2 behaves as an endophytic bacterium of M. truncatula, particularly in environments where iron is available.
Assuntos
Arthrobacter/crescimento & desenvolvimento , Medicago truncatula/crescimento & desenvolvimento , Medicago truncatula/microbiologia , Ferro/metabolismo , Reação em Cadeia da Polimerase/métodos , Hibridização In Situ/métodos , Rizosfera , Endófitos/crescimento & desenvolvimentoRESUMO
Abstract A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.