TY - JOUR
T1 - Detection and quantification of ‘Candidatus Phytoplasma asterisʼ and ‘Candidatus Liberibacter asiaticusʼ at early and late stages of Huanglongbing disease development
AU - Arratia-Castro, Alda A.
AU - Santos-Cervantes, María E.
AU - Arce-Leal, Ángela P.
AU - Espinoza-Mancillas, Mariela G.
AU - Rodríguez Negrete, Edgar A.
AU - Méndez-Lozano, Jesús
AU - Arocha-Rosete, Yaima
AU - Leyva-López, Norma E.
N1 - Publisher Copyright:
© 2016 The Canadian Phytopathological Society.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - ʻCandidatus Phytoplasma asterisʼ (CPa) has been identified along with ʻCandidatus Liberibacter asiaticusʼ (CLas) from citrus trees showing Huanglongbing (HLB) symptoms in Mexico. The low titre of CPa and CLas in infected plants is the major constraint to developing an accurate and sensitive method for their detection that would support an effective HLB diagnosis and management programme. This investigation reports the development and validation of a new TaqMan quantitative PCR to detect low titres of CPa in citrus trees with HLB symptoms based on the phytoplasma 16S rRNA gene region. The assay was used to monitor the titre of CPa at early and late stages of disease development in symptomatic and asymptomatic Mexican lime trees in Colima, Mexico. The concentration of CLas was determined by nested-qPCR. Only eight out of 39 sampled branches showed HLB symptoms at the early infection stage. All 39 branches were symptomatic at the late infection stage. The qPCR yielded an increase in the branch incidence and concentration of CLas (49 to 100% and 5 × 103 to 12 × 103 cells/100 ng of total DNA), while CPa showed a decreased incidence and concentration (72to 41% and 199 to 19 cells/100 ng of total DNA) throughout the disease development. Results confirm the occurrence of mixed infection of CLas and CPa in HLB-affected citrus trees, although their epidemiological role in co-infecting remains unknown.
AB - ʻCandidatus Phytoplasma asterisʼ (CPa) has been identified along with ʻCandidatus Liberibacter asiaticusʼ (CLas) from citrus trees showing Huanglongbing (HLB) symptoms in Mexico. The low titre of CPa and CLas in infected plants is the major constraint to developing an accurate and sensitive method for their detection that would support an effective HLB diagnosis and management programme. This investigation reports the development and validation of a new TaqMan quantitative PCR to detect low titres of CPa in citrus trees with HLB symptoms based on the phytoplasma 16S rRNA gene region. The assay was used to monitor the titre of CPa at early and late stages of disease development in symptomatic and asymptomatic Mexican lime trees in Colima, Mexico. The concentration of CLas was determined by nested-qPCR. Only eight out of 39 sampled branches showed HLB symptoms at the early infection stage. All 39 branches were symptomatic at the late infection stage. The qPCR yielded an increase in the branch incidence and concentration of CLas (49 to 100% and 5 × 103 to 12 × 103 cells/100 ng of total DNA), while CPa showed a decreased incidence and concentration (72to 41% and 199 to 19 cells/100 ng of total DNA) throughout the disease development. Results confirm the occurrence of mixed infection of CLas and CPa in HLB-affected citrus trees, although their epidemiological role in co-infecting remains unknown.
KW - Candidatus Liberibacter asiaticus
KW - Candidatus Phytoplasma asteris
KW - Citrus aurantifolia
KW - Huanglongbing
KW - Quantitative PCR
KW - pathogen detection
UR - http://www.scopus.com/inward/record.url?scp=85002145911&partnerID=8YFLogxK
U2 - 10.1080/07060661.2016.1243586
DO - 10.1080/07060661.2016.1243586
M3 - Artículo
SN - 0706-0661
VL - 38
SP - 411
EP - 421
JO - Canadian Journal of Plant Pathology
JF - Canadian Journal of Plant Pathology
IS - 4
ER -