Sugar and fructosan accumulation in virus‐infected plants: rapid testing by circular‐paper chromatography

The effects of virus infection on the sugar and fructosan contents of plants were studied by circular‐paper chromatography. Fructose and glucose in sugar‐beet leaves were greatly increased, and sucrose slightly, by infection with beet yellows virus (BYV): sugar content was increased more by an avirulent than by a virulent strain. Yellow‐net virus decreased the sugar concentration, whereas yellow‐net mild yellows virus increased it. Sugar accumulated in leaves of magnesium‐deficient plants, which also showed symptoms resembling virus yellows.

Carrot motley dwarf virus increased fructose, glucose and sucrose concentrations in carrot leaves, but in petioles and roots sucrose increased while fructose and glucose decreased: more sugar accumulated in plants infected late than early. Applying menazon to the seed to control aphids increased the sucrose concentration of the roots.

Cereal yellow dwarf virus (CYDV) increased fructose, glucose, sucrose and four fructosans in leaves of oats, an avirulent strain more than a virulent one. Virulent strains of BYV and CYDV apparently decrease photosynthesis more than avirulent ones.