what is the genetic basis of wrinkled phenotype of pea seed?

In wrinkled seeds sucrose content is high as compared to round seeds. Higher levels of free sucrose are presumed to result in higher water content and larger cell size in the developing embryo. When the wrinkled seeds mature and dry, a large proportion of seed volume is lost as compared to round seed. The wrinkling results because the outer layer of the seed does not shrink proportionately as much as the cotyledons during maturation and drying.