PHYL1 and SAP54 are orthologs of pathogenic effectors of Aster yellow witches'-broom (AYWB) phytoplasma and Peanut witches'-broom (PnWB) phytoplasma, respectively. These effectors cause virescence and phyllody symptoms (hereafter leafy flower) in phytoplasma-infected plants. T0 lines of transgenic Arabidopsis expressing the PHYL1 or SAP54 genes (PHYL1 or SAP54 plants) show a leafy flower phenot...

Phytoplasmas are a group mollicute plant pathogens transmitted by insect vectors in the Hemiptera. Although vector species have been identified for many of plant diseases associated with phytoplasmas, little is known about the specificity of vector transmission. Some phytoplasma strains seem to be specifically transmitted, for example phytoplasmas in the Elm yellow group seem to be transmitted ...

Association of phytoplasma with quick decline of macadamia trees in Hawaii was reevaluated. Twenty samples were collected from symptomatic and symptomless trees of the two susceptible cultivars cv. 333, and cv. 344 grown at Keaau and Kaiwiki on the island of Hawaii. Ultrasensitive nested-PCR assays using two universal primer pairs failed to detect phytoplasmas in all samples tested, contradicti...

Phytoplasmas such as "Candidatus Phytoplasma pruni," the causal agent of X-disease of stone fruits, lack detailed biological analysis. This has limited the understanding of plant resistance mechanisms. Chokecherry (Prunus virginiana L.) is a promising model to be used for the plant-phytoplasma interaction due to its documented ability to resist X-disease infection. A consensus chokecherry genet...

The grapevine cultivar Grk, a close relative of Crljenak ka{telanski/Zinfandel, is grown exclusively in southern Croatia. Grapevine yellows-like symptoms were observed on vines in the vineyards in Lumbarda (southern Croatia) and in propagated grapevines near Zadar and Zagreb. The majority of the detected phytoplasma isolates belonged to the 16SrI group. However, RFLP pattern and R16F2n/R2 fragm...

The two acknowledged vectors of ‘Candidatus Phytoplasma mali’ in north-western Italy, the psyllid Cacopsylla melanoneura and the leafhopper Fieberiella florii, have been compared to highlight their role in the apple proliferation epidemiology in relation to their infectivity, transmission efficiency and permanence in apple orchards and in wild vegetation, predominantly hawthorn formations. The ...

Abstract “Huanglongbing” (HLB) is one of the most devastating diseases citrus orchards worldwide. Samples from 183 plants different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, Guadeloupe-France), were collected to verify possible co-infection ‘ Candidatus Phytoplasma’ Liberibacter’ species. The 64% samples resulted positive Ca...

Introduetion Apple proliferation (AP) is one of the most economically important phytoplasmal diseases in Europe. It seriously impairs fruit size, yield, and vigor of the trees. AP was first reported in northern Italy (Rui et al., 1950). In the following decades, the occurrence of AP was reported from most European countries. Due to its transmissibility by grafting, the disease was initially tho...

The present paper describes a new approach for diagnosis of apple proliferation (AP) phytoplasma in plant material using a multiplex real-time PCR assay simultaneously amplifying a fragment of the pathogen 16S rRNA gene and the host, Malus domestica, chloroplast gene coding for tRNA leucine. For the first time, such an approach, with an internal analytical control, is described in a diagnostic ...