Abstract
During infection with the phanerogamic parasite Cuscuta reflexa the incompatible host plant Lycopersicon esculentum shows characteristic anatomical tissue modifications at the infection sites that
are exclusively provoked following contact with Cuscuta - striking cell elongation is observed in the hypodermis and collenchyma of the host
plant. Due to the influence of auxins on the process of cell elongation in plants,
the role of indole-3-acetic acid (IAA) in the interaction of Cuscuta and Lycopersicon was studied using a highly specific enzyme-linked immunosorbent assay for hormone
measurement. It was shown that the tissue modifications in the host plant as well
as cell elongation in the parasite tissue leading to the formation of an adhesive-secretory
epithelium are correlated with increasing IAA levels in the respective tissues. Both
anatomical modifications can also be induced artificially by injection of IAA into
control tissue. Based on the obtained data, it can be hypothesized that during the
parasitic attack IAA is accumulated in the haustoria-bearing regions of Cuscuta and exuded from the epithelial cells. Due to the close contact between host and parasite,
the hormone probably enters the host plant tissue causing the observed anatomical
reactions.
Key words
Lycopersicon esculentum
-
Cuscuta reflexa
- host-parasite relationship - indole-3-acetic acid
