Differential characteristics of salicylic acid-mediated signaling in potato

Abstract

Potato ( Solanum tuberosum) has key differences in salicylic acid (SA) metabolism and signaling from tobacco and Arabidopsis such as high basal salicylic acid concentrations in all tissues examined, including roots and tubers. Potato has high levels of basal PR-1 expression and this appears to be a consequence of the high SA levels, because the expression is reduced in nahG plants. Despite the high basal SA levels, potato was nevertheless responsive to exogenous SA and as little as 250 μM SA-induced PR-1 when sprayed on plants. However, plants grown in field conditions appeared less responsive to BTH at certain times. In spite of the high total SA concentrations, some potato varieties are able to maintain free SA levels as low as 0.5% of the total SA. Potato is also unusual in that PR-1 is strongly induced in leaf discs in the absence of any additional treatment. Furthermore, potato leaf discs are hypersensitive to BTH, with concentrations as low as 1 μM causing extensive cell death, whereas concentrations as high as 500 μM had no such effect on tobacco.