Epiphytic fungi induced pathogen resistance of invasive plant Ipomoea cairica against Colletotrichum gloeosporioides
- Published
- Accepted
- Subject Areas
- Ecology, Microbiology, Plant Science
- Keywords
- Symbiosis, Non-pathogen, NPR1 gene, Hormone, β-1,3-glucanase, Signaling molecules, Hydrogen peroxide
- Copyright
- © 2019 Xu et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2019. Epiphytic fungi induced pathogen resistance of invasive plant Ipomoea cairica against Colletotrichum gloeosporioides. PeerJ Preprints 7:e27956v1 https://doi.org/10.7287/peerj.preprints.27956v1
Abstract
Background. Ipomoea cairica (L.) Sweet is a destructive invasive weed in South China but rarely infected with pathogens in nature. Its pathogen resistance mechanism is largely unknown at present. Some non-pathogenic isolates of Fusarium oxysporum and Fusarium fujikuroi are prevalent on many plant species and function as pathogen resistance inducers of host plants. The objective of the present research is to investigate whether the symbiosis between the both fungi and I. cairica is present, and thereby induce pathogen resistance of I. cairica. Methods. Through field investigation, we explored the occurrence rates of F. oxysporum and F. fujikuroi on leaf surfaces of I. cairica plants in natural habitats and compared their abundance between healthy leaves and leaves infected with Colletotrichum gloeosporioides, a natural pathogen. With artificial inoculation, we assessed their pathogencity to I. cairica and study their contribution of pathogen resistance to I. cairica against C. gloeosporioides. Results. We found that F. oxysporum and F. fujikuroi were widely epiphytic on healthy leaf surfaces of I. cairica in sunny non-saline, shady non-saline and sunny saline habitats. Their occurrence rates reached up to 100%. Moreover, we found that the abundance of F. oxysporum and F. fujikuroi on leaves infected with C. gloeosporioides were significantly lower than that of healthy leaves. With artificial inoculation, we empirically confirmed that F. oxysporum and F. fujikuroi were non-pathogenic to I. cairica. It was interesting that colonization by F. fujikuroi, F. oxysporum alone and a mixture of both fungi resulted in a reduction of C. gloeosporioides infection to I. cairica accompanied by lower lesion area to leaf surface area ratio, increased H2O2 concentration and salicylic acid (SA) level relative to the control. However, NPR1 expression, chitinase and β -1,3-glucanase activities as well as stem length and biomass of I. cairica plant only could be significantly improved by F. oxysporum and a mixture of both fungi but not by F. fujikuroi. In addition, as compared to colonization by F. oxysporum and a mixture of both fungi, F. fujikuroi induced significantly higher jasmonic acid (JA) level but significantly lower β -1,3-glucanase activity in leaves of I. cairica plants. Thus, our findings indicated the symbiosis of epiphytic fungi F. fujikuroi and F. oxysporum facilitated the fitness of I. cairica via the induced systemic resistance of host plant against C. gloeosporioides. F. oxysporum played a dominant role in inducing pathogen resistance of I. cairica. Its presence alleviated the antagonism of the JA signaling on SA-dependent β -1,3-glucanase activity and enabled I. cairica plants to maintain relatively higher level of resistance against C. gloeosporioides.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Raw data of the submission " Epiphytic fungi induced pathogen resistance of invasive plant Ipomoea cairica against Colletotrichum gloeosporioides"
Raw data1: Occurrence rate of F. fujikuroi and F. oxysporum in the field; Raw data2: Comparison of F. oxysporum and F. fujikuroi abundance between infected and healthy leaves of I. cairica in the field; Raw data3: The pathogencity of F. oxysporum and F. fujikuroi to I. cairica ; Raw data4: Effects of pre-inoculation with F. oxysporum, F. fujikuroi alone and a mixture of both on growth parameters (stem length, biomass and lesion area ratio) of I. cairica infected with C. gloeosporioides. Raw data5: Effects of pre-inoculation with F. oxysporum, F. fujikuroi alone and a mixture of both on physiological characteristics (H2O2 concentration, β-1,3-glucanase and chitinase activities) of I. cairica infected with C. gloeosporioides. Raw data6:Effects of pre-inoculation with F. oxysporum, F. fujikuroi alone and a mixture of both on NPR1 expression,salicylic acid and jasmonic acid content of I. cairica infected with C. gloeosporioides.