TITLE:
Chemical composition of acid lime leaves infected with Candidatus Phytoplasma aurantifolia
AUTHORS:
Rashid Al-Yahyai, Ali Al-Subhi, Jamal Al-Sabahi, Fahad Al-Said, Khadija Al-Wahaibi, Abdullah M. Al-Sadi
KEYWORDS:
Citrus aurantifolia; Phytoplasma; Essential Oils; Volatile Compounds; Phytochemistry; Oman
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.1,
January
14,
2014
ABSTRACT: The
production of acid lime (Citrus
aurantifolia) has declined in many parts of the world due to phytoplasmal
infection by “Candidatus Phytoplasma aurantifolia”. The resulting Witches’ Broom Disease of Lime (WBDL) causes stem and leaf proliferation and clustering that
starts on a few branches and continues to spread until trees are killed within
5-7 years. Recent studies have shown that Phytoplasma alters the chemical
composition of leaves. Leaves from WBDL-symptomatic lime trees were collected
to determine their volatile compound composition. Phytoplasmal infection was
confirmed by a polymerase chain reaction (PCR) assay using primers P1/P7
and R16F2n/R16R2 in direct and nested PCR, respectively. Restriction fragment
length polymorphism (RFLP) profiles of acid lime Phytoplasma were identical
with those of WBDL Phytoplasma. The phytochemical composition of symptomatic
(infected) and asymptomatic (healthy) leaves of acid lime were determined
using GC-MS analysis of steam distilled extract. The WBDL-symptomatic leaves
had higher concentration in ?-limonene, β-ocimene and trans-caryophyllene and a reduction in other compounds (i.e. citral, citronellal, cisverbenol,
neryl acetate, and linalool). Variations in the leaf phytochemical
concentration indicate a possible role in the development of the WBDL disease
symptoms.