Burkholderia glumae presumably induces a grain rot symptom of rice that is threatening to rice production in most rice producing states of the USA. The present study was to identify the causal agent of bacteria panicl...Burkholderia glumae presumably induces a grain rot symptom of rice that is threatening to rice production in most rice producing states of the USA. The present study was to identify the causal agent of bacteria panicle blight (BPB), virulence based on hypersensitive reactions and distribution of the pathogen within a plant. 178 rice panicles samples were analyzed with semi-selective media (CCNT), polymerase chain reaction (PCR) with bacterial DNA gyrase (gyrB) specific markers, and hypersensitive reactions on tobacco leaves. A total of 73 samples out of 178 produced a yellow bacterial colony with similar morphology on CCNT medium suggesting they were bacterial panicle diseases. However, with PCR reactions we only determined that 45 of 73 were due to B. glumae, and the causal agent for the remaining samples was undetermined. Within the 45 samples, 31 highly, 6 moderately, and 5 weakly virulent isolates were grouped based on lesion sizes of the hypersensitive reactions. Pathogenicity variability among the 45 B. glumae detected suggests that different degrees of pathogenicity exist. To determine the existence of bacteria in different plant tissues, naturally infected plant parts were examined with CCNT media and PCR analysis. B. glumae was again isolated from seeds followed by stems and sheaths from light yellow pigmented CCNT media. In contrast, roots and leaves show no visible yellow pigment on CCNT. Consistent PCR products were produced from the stem, sheath, and seed, but not from the root and leaves. These findings suggest that B. glumae is distributed in the stem, sheath, and seed, and not in the leaf and root. Together this study demonstrated the usefulness of artificial culture media, tobacco reactions, and DNA test with PCR for characterization of BPB, and distribution of bacteria in plants. These findings will help to understand the mechanism of bacteria translocation in plants.展开更多
Interactions between plants and soil microorganisms can influence the other interactions in which plants participate, including interactions with herbivores. Many fungi, including arbuscular mycorrhizal fungi(AMF), fo...Interactions between plants and soil microorganisms can influence the other interactions in which plants participate, including interactions with herbivores. Many fungi, including arbuscular mycorrhizal fungi(AMF), form symbiotic relationships with the roots they inhabit, and potentially alter defense against pests. The objective of this study was to document the extent of root colonization by AMF on non-flooded rice plants grown under conditions typical of commercial fields. We hypothesized that AMF naturally colonized rice plants in different rice producing field locations. Rice plant samples were collected from areas across the southern United States, including Texas, Mississippi, Arkansas and two research stations in Louisiana. We quantified the amount of AMF colonization in insecticide-free rice plants over three consecutive years(2014–2016). The results revealed natural colonization of AMF in all rice producing areas. In all the three years of survey, rice-AMF associations were the greatest in Arkansas followed by Mississippi and Texas. This research will help draw attention to natural colonization of AMF in rice producing areas that can impact future rice research and production by facilitating agricultural exploitation of the symbiosis.展开更多
文摘Burkholderia glumae presumably induces a grain rot symptom of rice that is threatening to rice production in most rice producing states of the USA. The present study was to identify the causal agent of bacteria panicle blight (BPB), virulence based on hypersensitive reactions and distribution of the pathogen within a plant. 178 rice panicles samples were analyzed with semi-selective media (CCNT), polymerase chain reaction (PCR) with bacterial DNA gyrase (gyrB) specific markers, and hypersensitive reactions on tobacco leaves. A total of 73 samples out of 178 produced a yellow bacterial colony with similar morphology on CCNT medium suggesting they were bacterial panicle diseases. However, with PCR reactions we only determined that 45 of 73 were due to B. glumae, and the causal agent for the remaining samples was undetermined. Within the 45 samples, 31 highly, 6 moderately, and 5 weakly virulent isolates were grouped based on lesion sizes of the hypersensitive reactions. Pathogenicity variability among the 45 B. glumae detected suggests that different degrees of pathogenicity exist. To determine the existence of bacteria in different plant tissues, naturally infected plant parts were examined with CCNT media and PCR analysis. B. glumae was again isolated from seeds followed by stems and sheaths from light yellow pigmented CCNT media. In contrast, roots and leaves show no visible yellow pigment on CCNT. Consistent PCR products were produced from the stem, sheath, and seed, but not from the root and leaves. These findings suggest that B. glumae is distributed in the stem, sheath, and seed, and not in the leaf and root. Together this study demonstrated the usefulness of artificial culture media, tobacco reactions, and DNA test with PCR for characterization of BPB, and distribution of bacteria in plants. These findings will help to understand the mechanism of bacteria translocation in plants.
基金the Louisiana Rice Research Board for funding this work under the Entomology Program
文摘Interactions between plants and soil microorganisms can influence the other interactions in which plants participate, including interactions with herbivores. Many fungi, including arbuscular mycorrhizal fungi(AMF), form symbiotic relationships with the roots they inhabit, and potentially alter defense against pests. The objective of this study was to document the extent of root colonization by AMF on non-flooded rice plants grown under conditions typical of commercial fields. We hypothesized that AMF naturally colonized rice plants in different rice producing field locations. Rice plant samples were collected from areas across the southern United States, including Texas, Mississippi, Arkansas and two research stations in Louisiana. We quantified the amount of AMF colonization in insecticide-free rice plants over three consecutive years(2014–2016). The results revealed natural colonization of AMF in all rice producing areas. In all the three years of survey, rice-AMF associations were the greatest in Arkansas followed by Mississippi and Texas. This research will help draw attention to natural colonization of AMF in rice producing areas that can impact future rice research and production by facilitating agricultural exploitation of the symbiosis.
