ABSTRACT
Pea (Pisum sativum L.) is an important crop, owing to its symbiotic nitrogen-fixing capability and high nutritive value. Its seeds contain protein up to 40 percent of their dry weight (Monti and Grillo, 1983). Pea storage proteins tend to be rich in arginine, asparagine, glutamine, and lysine, while essential amino acids like methionine and cysteine are underrepresented. The major objectives in pea breeding are resistance against viruses, fungi, and insects as well as environmental stresses. The genetic basis of the present pea varieties is fairly narrow. In vitro cultures of different pea tissues have been routinely used for several years, but the apparent recalcitrance of pea in de novo regeneration of whole plants has prevented the application of genetic engineering in its genetic improvement breeding (Puonti-Kaerlas, 1993). Several promising regeneration systems have been elaborated (Grant et al., 1995; Ochatt et al., 2000; Tzitzikas et al., 2004), indicating the potential for genetic modification. An organogenic/meristematic tissue is formed from nodal tissue, which can be maintained in a cyclic fashion, giving it callus-like properties (Tzitzikas et al., 2004) making it an ideal system for transgenic plant production.
