Overexpression of OsSPL9 enhances accumulation of Cu in rice grain and improves its digestibility and metabolism

Copper （Cu） is an essential trace mineral element for all forms of life, and is an important structural component and co-factor for a variety of metalloenzymes （Pefia et al., 1999; Bertinato and L＇Abbe, 2004）. In humans, Cu deficiency is not common because of the ubiquitous occurrence of Cu and ease of gastrointestinal absorption （Zidar et al., 1977; Uauy et al., 1998）.