The expression and analysis of a lysine-rich wound-response protein in tomato plants.

Understanding the genetic regulation of the response to wounding and wound
healing in fruiting plants is imperative to maintaining agricultural sustainability,
preserving the quality of food supplies, and ensuring the economic viability of
agriculture. Many genes are known to be induced by wounding, providing both structural
repair and defense. The KED gene in tobacco (Nicotiana tabacum) has been shown to be
induced by wounding. We have identified its homologue gene in tomato (Solanum
lycopersicum) that we named SlKED. We have analyzed gene expression pattern of
SlKED through tomato growth and development and in response to wounding as well as
hormonal and inhibitor treatments. We found that the plant hormone ethylene played a
major role in the expression of SlKED. To further identify evidence for physiological and
transductional functions of KED and SlKED, the tobacco KED gene was introduced to
tomato and overexpressed by the fruit tissue-active PUN1 promoter from pepper
(Capsicum annuum,). The expression of this gene was compared to the expression of the native SlKED gene and other known wound response genes in both the wild-type and
transgenic tomato plants. The upregulation of the native SlKED gene by wounding was
significantly muted in the tobacco KED-expressing transgenic plants. The expression of
other genes known to be associated with wound response transduction pathways was also
altered. Our studies implicate the KED gene in defense mechanisms for mechanical stress
in tomato plants.