Phosphorus distribution in healthy and potato virus Y-infected tomato plants

ABSTRACT

The influence of Y degree group of the common strain of potato virus Y [PVY] on the amount and distribution of phosphorus in leaves, stems and roots of the susceptible [Lycopersicon esculentum cv. [Money maker]] and resistant [Lycopersicon pimpinellifolium L.] tomato species at 1/2,1, 5,15, 25 and 35 days post infection was studied. During the first days post infection, the infected leaves of the susceptible tomato showed higher organic and total soluble phosphorus content while the inorganic phosphorus remained unchanged. By the end of the experiment, the inorganic and RNA phosphorus contents were lower than in the healthy leaves .PVY infection lowered the DNA-P content during most periods post infection except on the first and fifth day. It also increased the other insoluble and decreased the total insoluble phosphorus contents. During the whole experimental period, the infected stems were low in their soluble phosphorus components and high in the DNA-P whereas the RNA and the other insoluble phosphorus were not affected. Also the virus did not cause any significant change in the soluble fractions of the roots but their RNA and other insoluble phosphorus decreased whereas the DNA and total insoluble phosphorus contents were not affected. In the resistant tomato, the organic and total soluble phosphorus of the inoculated leaves significantly increased but the inorganic phosphorus remained unchanged during the fifth day post inoculation onwards. The RNA-P decreased whereas the DNA, other insoluble and total insoluble phosphorus increased. Infected stems had lower soluble and insoluble phosphorus components except DNA-P that increased. In roots, the soluble phosphorus components increased but the RNA and other insoluble phosphorus components decreased. The distribution of the different phosphorus fractions revealed that PVY infection increased the organic phosphorus and decreased the DNA-P and RNA-P of the leaves of the susceptible tomato plants and also decreased the organic phosphorus and increased the DNA and RNA phosphorus of the stems and roots. In resistant tomato, PVY increased the DNA-P and decreased the organic and RNA phosphorus distribution in leaves while in stems and roots the virus decreased the inorganic and DNA phosphorus and increased die RNA-P