ABSTRACT
Pea (Pisum sativum L.) has several favorable biological features that determine its agricultural importance. Its climate and soil requirements are modest enough to enable it to adapt to cultivation in a wide range of environments. Pea is predominantly grown in Europe, China, India, and North America. Like the other legume species, it has the ability to fix atmospheric nitrogen and enrich soil with nitrogen, and it has seeds with high protein content and of good quality. Green peas contain 5 to 8 percent protein, 0.5 percent fat, and 10 to 15 percent carbohydrate, and the mature seeds contain 20 to 25 percent protein, 1 to 3 percent fat, and 60 percent carbohydrate. Peas are limited in their contents of the sulfur-containing amino acids methionine and cysteine, but are rich in lysine and other essential amino acids. As a crop, they are used as a vegetable for human consumption, fodder and as a green manure, while the dry seeds are used for feeds. Besides the pea’s high nutritional value, its other main attributes are high net yield in a relatively short growth period (short-term crop) and its good intake characteristics. In terms of worldwide production levels, it ranked fourth among the grain legumes after soybean, peanut, and the beans (FAO, 1994). The chromosome number of the whole genus Pisum is low (2n = 14); however, the genome is very large, estimated for 1C as 4.4 × 109 bp (Dolezel et al., 1998). Only about 10 to 25 percent of the DNA comprises large, gene-rich regions, called the gene space, separated by repetitive sequences that are gene-empty (Barakat et al., 2000). This genome organization might influ-
ence the distribution and expression of transgenes introduced by direct (biolistic) and indirect (Agrobacterium-mediated) methods (Kohli et al., 2003).
