[Endophytic bacterial community analysis of Catharanthus roseus and its association with huanglongbing pathogen].
OBJECTIVE
To analyze the microbial diversity in healthy and HLB-affected Catharanthus roseus under manual-grafting conditions and to find the association between the endophytic bacteria and the HLB pathogen.


METHODS
The endophytic bacterial communities were delineated by using the traditional culturable approach and cultivation-independent techniques based on 16S rRNA gene. The endophytic bacteria were isolated from surface-sterilized C. roseus midribs of leaves and phloem of stems and roots by plating and restriction fragment length polymorphism (RFLP).


RESULTS
By anaerobic culture, we obtained 67 strains that were identified 29 genus by GenBank. Curtobacterium sp. , Erwinia sp., Bacillus cereus and Brevundimonas sp. , Bacillus sp. were the dominant bacterial population in diseased and healthy C. roseus. However, Staphylococcus equorum was the common dominant isolate in both C. roseus. We picked 188 and 182 positive clones in 16S rDNA libraries of diseased and healthy C. roseus that were respectively restricted by the HaeIII, MspI, RsaI restriction endonuclease. Based on the similarity of the RFLP banding profiles in diseased and healthy C. roseus, we obtained 16, 23 OTUs (Operational Taxonomic Units, OTUs) respectively. In addition to Candidatus Liberibacter asiaticus, Candidatus Liberibacter sp. was the dominant bacterial population only in diseased C. roseus.


CONCLUSIONS
With the infection of 'Ca. L. asiaticus', the diversity in diseased C. roseus decreased. The endophytic bacteria isolated from diseased and healthy C. roseus are abundant and have remarkable differences in the composition and function, suggesting that its endophytic bacteria might be inhibited by the HLB pathogen.
Bioengineering College of Chongqing University, Chongqing Engineering Research Center for Fungal Insecticide, Chongqing Key Lab of Genetic Function and Regulation, Chongqing 400030, China. lijia4199@yahoo.cn
Jia
J
Li
Zhongkang
Z
Wang
Pan
P
Xie
Dong
D
Wu
Youping
Y
Yin
D001419:Bacteria / Q000145:classification* / Q000235:genetics; D030008:Catharanthus / Q000382:microbiology*; D002957:Citrus / Q000382:microbiology*; D060026:Endophytes / Q000145:classification* / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D012336:RNA, Ribosomal, 16S