Interactions between iron nutrition and Verticillium wilt resistance in tomato

Abstract

The relationship between Fe nutritional status and Verticillium wilt disease in tomatoes possessing single gene resistance to Race 1 of Verticillium dahliae was investigated using hydroponic culture media. Iron limiting conditions increased the sensitivity of resistant tomatoes to the pathogen as expressed by wilting and chlorosis. Distance of fungal vascular invasion was approximately the same in both Fe replete and Fe limited treatments. Comparison of near-isolines revealed that the magnitude of disease expressed in Fe deficient Pixie II (resistant) was considerably less than that expressed by the susceptible Pixie variety. Infection of tomato did not enhance the severity of low-Fe stress as quantified by root peroxidase activity and chlorophyll content of young leaves.

An adequate Fe nutritional status of maize suppresses infection and biotrophic growth of Colletotrichum graminicola

“…The tendency of plants supplied with 250 µ M Fe to be more susceptible to C. graminicola fully agrees with a promotive function of surplus plant Fe for ROS production and fungal infection (Deak et al , Liu et al ). At first glance, an increasing susceptibility of Fe‐deficient maize to C. graminicola may also not be unexpected with regard to previous reports showing that bean or tomato plants grown under low Fe supplies were more susceptible to F. solani or V. dahliae , respectively (Guerra and Anderson , Macur et al ). However, these results are in contradiction to those reported by Kieu et al (), who showed that Fe‐deficient Arabidopsis plants exhibit increased tolerance to bacterial and fungal pathogens.…”

“…Treatment of Salmonella‐infected mice with the Fe chelator DFO dramatically exacerbated the infection by inhibiting the host NADPH oxidase‐dependent respiratory burst due to a decreased availability of reactive Fe (Collins et al ). A similar role of Fe may hold true for plants, where the sensitivity of bean to Fusarium solani (Guerra and Anderson ) or of tomato to Verticillium dahliae (Macur et al ) was enhanced when plants were Fe deficient, indicating a requirement for Fe in plant defense responses. A direct involvement of Fe in the defense response was observed in Arabidopsis (Segond et al ) and wheat (Liu et al ) by a cellular relocalization of Fe to infection sites which coincided with local ROS production.…”

Iron deficiency affects plant defence responses and confers resistance to Dickeya dadantii and Botrytis cinerea

“…In plants, as in humans and other animals, the availability of iron is one of the factors which may limit the growth of pathogenic microorganisms within the host. Although the role of high‐affinity iron uptake systems in the virulence of plant pathogens is beginning to be well documented, the role of the plant iron status per se on the susceptibility to disease has only been investigated in a few cases (Anderson and Guerra, 1985; Macur et al ., 1991). In this work, we explored this question on the model plant A. thaliana .…”

“…For instance, Anderson and Guerra (1985) observed an increase in severity of Fusarium solani ‐initiated disease on iron‐restricted bean seedlings. Similarly, infection levels by Verticillium dahliae of tomato resistant genotypes increased when the plants were grown under iron‐deficient conditions (Macur et al ., 1991). In these reports, the authors studied plant pathogens that invaded the root vascular system.…”

Iron and Immunity

“…In other cases, iron starvation promotes susceptibility to certain pathogens. For example, the soil-borne fungal pathogen Verticillium dahliae caused more disease in peanut, eggplant, and a resistant tomato line when the plants were grown in iron-deficient soils (6,68,85). Likewise, the maize pathogen C. graminicola was better able to infect iron-starved than iron-sufficient plants, likely because iron-deprived plants developed a weaker oxidative burst at the site of pathogen infection (149) (Figure 4b).…”