Differences in secondary metabolites in leaves from orange (Citrus sinensis L.) trees affected with greening disease (huanglongbing) (HLB)

John A. Manthey


HPLC analyses of methanol extracts of two sets of orange leaves that were symptomatic of HLB showed differences in concentrations of hydroxycinnamates and flavonoids compared to unaffected, healthy leaves. Other differences were also detected in selected total ion currents (TICs) of HPLC–mass spectral (HPLC–MS) analyses of the leaf extracts. One main difference was the higher levels of limonin glucoside in the HLB-symptomatic leaves compared to the healthy leaves. Another difference was an elevated concentration in HLB symptomatic leaves of a compound, possibly an alkaloid, exhibiting a protonated m/z ion at 188 amu, and a violet-colored Ehrlich Reagent spot on TLC.

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283