SummaryPhytoplasmas replicate intracellularly in plants and insects and are dependent on both hosts for dissemination in nature. Phytoplasmas have small genomes lacking genes for major metabolic pathways. Nevertheless, their genomes harbour multicopy gene clusters that were named potential mobile units (PMUs). PMU1 is the largest most complete repeat among the PMUs in the genome of Aster Yellows phytoplasma strain Witches' Broom (AY-WB). PMU1 is c. 20 kb in size and contains 21 genes encoding DNA replication and predicted membrane-targeted proteins. Here we show that AY-WB has a chromosomal linear PMU1 (L-PMU1) and an extrachromosomal circular PMU1 (C-PMU1). The C-PMU1 copy number was consistently higher by in average approximately fivefold in insects compared with plants and PMU1 gene expression levels were also considerably higher in insects indicating that C-PMU1 synthesis and expression are regulated. We found that the majority of AY-WB virulence genes lie on chromosomal PMU regions that have similar gene content and organization as PMU1 providing evidence that PMUs contribute to phytoplasma host adaptation and have integrated into the AY-WB chromosome.

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Background: Mango stones are in general recalcitrant. Moreover, they are available only during April- May months which are the drier parts of the year. So stone germination and plant vigour are very low. Proper seed orientation, age of stones after extraction from fruit and pre-sowing treatments need to be taken into consideration for inducing early germination, boosting growth, enhancing the seedling vigour and reducing the mortality. Methods: The experiment was laid out in factorial completely randomized design with forty two treatment combinations replicated thrice. The treatments were comprised of two sowing positions viz., flat and stalk end up, three age of stones after extraction from fruit, viz., fresh extracted, 10 days and 20 days after extraction and seven pre-sowing treatments viz., 100 ppm GA3, 200 ppm GA3, 1 ppm KNO3, 2 ppm KNO3, cow dung slurry, water, control and their combinations. Result: Stalk end up sowing of freshly extracted stones pre-treated with 200 ppm GA3 for 24 hours recorded better germination and vigour of mango seedlings.

A cell-associated mannose-resistant hemagglutinating factor (HAF) was extracted from enteroinvasive Escherichia coli (EIEC) serotype O124:H by sonication. Ultrastructural analysis of EIEC and immunocytochemical assays with the cell-free HAF and EIEC bacterial cells on HeLa cells, suggested that the HAF is a non-fimbrial putative adhesive factor that mediates in vivo adherence of EIEC to human epithelial cells.