دامنه ميزباني فيتوپلاسماي عامل جاروك بادام در درختان ميوه هسته دار

Host range of almond witchesʹ broom Phytoplasma among stone fruits.

Almond witchesʹ broom (AlmWB) is an economically important disease in Iran and Lebanon. Graft inoculation was used to study the reaction of stone fruits other than almond to AlmWB phytoplasma. Two-year old seedlings of bitter almond (Primus scoparia), peach (P. per sic a), (Cultivars Elberta, zaferani and Shaftalou) nectarine (P. persica var. nusipersica), apricot (P. armeniaca,), cherry (P. avium), plum (P. salicina ), prune {P. domestica) and soure cherry (P. cerasus) were obtained from a local nursery in an AlmWB disease free area in Isfahan. The absence of phytoplasma in provided seedlings was confirmed by nested- PCR using P1/P7 followed by R16F2n/R16R2 primer pairs. Seedlings of each cultivar were graft inoculated (3 scions per seedling) with Candidatus Phytoplasma phoenicium infected shoots of an infected almond tree. Five seedlings of each cultivar were grafted and one remained as control. The grafted almond shoots used as inoculum developed into witchcsʹ broom and were positive for the presence of Ca. Phytoplasma phoenicium by nested PCR. Two years po.stinoculation, among inoculated stone fruits, bitter almond, peach all cultivar, nectarine (cultivar Red), plum (cultivars Santa Rosa, Shiro), prune (Cultivars Saadi, Barghan and Holandi), apricot (cultivars Asefi and Talkh) and sour cherry (cultivar Schattenmorelle) showed little leaf, internode shortening, yellowing and stunting. Peach, cultivars and nectartine, in addition to these symptoms, showed witchesʹ broom as well. Nested-PCR confirmed phytoplasmal infection of symptomatic graft inoculated varieties. Nested-PCR assay showed that Meshki cultivar of sweet cherry and Holandi cultivar of prune are asymptomatic hosts of AlmWB phytoplasma. RFLP analysis of nested-PCR product (1.2 kbp) using Rial, AM and Hinfl enzymes showed that phytoplasmas detected in almond and other stone fruits are identical. This is the first report of apricot, sweet cherry, sour cherry, nectartine, prune and plum as experimental hosts of Ca. Phytoplasma phoenicium. Transmission of this phytoplasma to peach and nectarine was previously reported from Lebanon.