Browsing by Author "Chen, Jie"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Fungi as Architects of the Rimstone Dams in Huanglong, NSD, Sichuan, China(2017-01) Xie, Jie; Strobel, Gary A.; Wu, Wei-Fang; Chen, Jie; An, De-Jun; Geary, BradThe Huanglong park area of the Sichuan Province of China is a unique scenic area of the world. It is known for its thousands of aquamarine-colored pools that are formed behind naturally formed rimstone dams of travertine (calcite) along a cold water stream. The travertine, based on its crystalline structural analysis, is of biological origin. This makes sense since the temperature of the waters of Huanglong varies from 5 to 7 A degrees C and thus geochemical crystallization does not occur as it does in other locations around the world possessing thermal pools whose structures are primarily formed through cooling processes. Fungi and bacteria were discovered associated with both leaves associated with the calcite dams as well as in the older parts of well-established dams. Several species of Phytium, a phycomycete and an endophyte, accounted for over 45 % of all of the fungi successfully isolated from the well-established dam samples and at least 85 % in the floating leaf samples. Saprolegnia spp. (Phycomycetes) along with Phoma spp. (Ascomycetes) were noted along with Mortierella sp. as other dam-associated fungi. The fungal hyphae observed on dead leaf material as well as in the calcite dams directly served as nucleation points for the formation of crystalline CaCO3. Eventually, these crystals grow large enough to fuse to make calcite plates which form the main structural feature of all of the travertine dams in this area. Interestingly, each of the individual crystals associated with the dams has an associated hole in its core where a fungal hypha used to reside as observed by scanning electron microscopy. While diatoms were present in the analysis, they too seem to contribute to the structure of the dams but in a minor way. The only bacteria isolated from the older dam of this aquatic environment were Pseudomonas spp. and their role in dam formation is uncertain. Huanglong is a unique and beautiful place, and the water features present in this area can definitely be attributed to those fungal architects that encourage calcite crystal formation.Item Pantoea agglomerans SWg2 colonizes mulberry tissues, promotes disease protection and seedling growth(2017-10) Xie, Jie; Shu, Ping; Strobel, Gary A.; Chen, Jie; Wei, Junhong; Xiang, Zhonghuai; Zhou, ZeyangMulberry bacterial blight caused by Pseudomonas syringae pv. mori, is one of the most serious diseases on mulberry (Morus alba L.), and threatens sericulture development. An endophytic Pantoea agglomerans SWg2 (referred to as SWg2), originally isolated from roots of healthy mulberry, is extremely inhibitory activity to P. syringae. Greenhouse tests were first conducted to examine the biological control properties of SWg2. A suspension of SWg2, introduced to the host plant, significantly reduced disease symptoms caused by P. syringae. Likewise, when a suspension of SWg2 was sprayed onto plantlets 2 days before inoculation with P. syringae, its disease control efficacy was up to 65.6% even after inoculation with P. syringae 18 days later. Interestingly, the control effect of the traditional agrochemical streptomycin was just 33.2% at 18 days post inoculation (DPI), although it was 55.6% at 9 DPI. Furthermore, SWg2 promoted the growth of mulberry seedlings. The immersion of 107 CFU mL−1 suspension of SWg2 had the most distinctive growth-promoting role since the seed germination rate and radicle length development were enhanced up to 100% and 144.2%, respectively. Based on the green fluorescent protein (GFP) labeling technique and a re-isolation method, it was determined that the SWg2 strain colonized and spread in mulberry seedlings. The bacteria entered seedlings through the areas of emergence of root hairs and cracks in the rhizodermis. Eventually these cells spread to other tissues of the plant with colonization occurring mainly in the intercellular spaces. Furthermore, the GFP-tagged SWg2 strain could be detected in stems and leaves, but the quantity was smaller than that in roots. There appears to be no outward negative effects of SWg2 on treated plants and silkworms feed on them in a normal manner. This work indicates that P. agglomerans SWg2 possesses the biological potential to provide protection of its host against the pathogen of mulberry bacterial blight will at the same time promoting the growth and vigor of the host plant.