Some Effects of Yellow Rust (Puccinia striiformis) on14Carbon Assimilation and Translocation in Wheat

Abstract

A well-developed infection of Yellow Rust on a leaf of spring wheat (Jufy I) caused the assimilation of ¹⁴CO₂ by that leaf to decrease to 43.5 per cent of that of an uninfected leaf. Over a period of three hours translocation of ¹⁴C from an infected leaf was only 0.87 per cent of that from a control leaf. When control plants were kept in the light for periods up to 16 hours after assimilating ¹⁴CO₂ translocation continued at a steady rate, whereas there was only negligible translocation from infected leaves after the first few hours. The retention of labelled assimilates in the infected leaf could be partly, but not completely, accounted for by a conversion of assimilates to an alcohol-insoluble form. Rust infection had no effect on the distribution pattern of ¹⁴C to other leaves from one which had assimilated ¹⁴CO₂. In contrast to the marked retention of assimilate by an infected leaf, such a leaf was unable to distort the normal distribution by attracting assimilates from the other leaves.