Natural Infection of Murraya paniculata and Murraya sumatrana with 'Candidatus Liberibacter asiaticus' in Java
Ayu Lestiyani1,2, Tri Joko3, Paul Holford4
1Study Program of Biotechnology, Graduate School, Universitas Gadjah Mada, Barek, Yogyakarta 55281, Indonesia.
Abstract:
The phloem-limited bacterium 'Candidatus Liberibacter asiaticus' (CLas) is the putative causal pathogen of the severe Asiatic form of huanglongbing (citrus greening) and is most commonly transmitted by the Asiatic citrus psyllid Diaphorina citri. CLas severely affects many Citrus species and hybrids and has been recorded in the Citrus relative, orange jasmine, Murraya paniculata (L.) Jack (syn. M. exotica L.). In this study, 13 accessions of three Murraya species (M. paniculata, M. sumatrana Roxb., and M. lucida [G.Forst.] Mabb.) and the Papuan form of a putative hybrid (M. omphalocarpa Hayata) were identified morphologically and molecularly based on sequence identity of the matK-5'trnK region of the chloroplast genome, and infection on these plants under field conditions was determined by PCR and quantitative real-time PCR (qPCR) on two to four occasions over 14 months. CLas was repeatedly detected in leaflet midribs by PCR and qPCR on four and three accessions of M. paniculata and M. sumatrana, respectively. It was not detected in leaflet midribs of single accessions of M. lucida and M. omphalocarpa. The species identification of the CLas-positive accessions was further confirmed using all the molecular taxonomic markers consisting of the six fragments of the maternally inherited chloroplast genome and part of the nuclear-encoded internal transcribed spacer (ITS) region. The results indicated that natural infection of M. paniculata and M. sumatrana with CLas can occur in Java. To our knowledge, this is the first demonstration of the natural infection of M. sumatrana with CLas. Further studies are required to determine whether infections persist in the absence of D. citri.
Insights
The bacterium causing citrus greening, Candidatus Liberibacter asiaticus (CLas), naturally infects Murraya paniculata and Murraya sumatrana in Java. This study is the first to demonstrate CLas infection in Murraya sumatrana.
Area of Science:
- Plant Pathology
- Bacteriology
- Genetics
Background:
- Huanglongbing (citrus greening) is a severe disease affecting citrus species.
- The phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) is the causal agent of citrus greening.
- CLas is primarily transmitted by the Asiatic citrus psyllid, Diaphorina citri, and has been found in Murraya paniculata.
Purpose of the Study:
- To investigate the natural infection of CLas in various Murraya species.
- To identify and confirm the presence of CLas in different accessions of Murraya species under field conditions.
Main Methods:
- Morphological and molecular identification of 13 accessions from three Murraya species (M. paniculata, M. sumatrana, M. lucida) and M. omphalocarpa.
- Detection of CLas infection using PCR and quantitative real-time PCR (qPCR) on leaflet midribs over 14 months.
- Confirmation of CLas-positive accessions using chloroplast and nuclear DNA markers.
Main Results:
- CLas was repeatedly detected in four accessions of M. paniculata and three accessions of M. sumatrana.
- CLas was not detected in M. lucida or M. omphalocarpa accessions.
- This study provides the first evidence of natural CLas infection in M. sumatrana.
Conclusions:
- Natural infection of Murraya paniculata and Murraya sumatrana with CLas occurs in Java.
- Further research is needed to determine if CLas infections persist in Murraya species without the presence of Diaphorina citri.
