Progress and perspectives for carotenoid accumulation in selected Triticeae species

Abstract

Plant carotenoids are C40 isoprenoids with multiple biological roles. Breeding for carotenoid content in rice, maize and wheat is a relevant issue, both for their importance in human health and nutrition and for their influence in food colouration in products such as pasta from durum wheat. Regarding human health, vitamin A deficiency (VAD) is one of the major causes of malnutrition in the world. As many as 500 000 children become blind due to VAD each year with many of them dying from VAD-related illness within 1 year. This review presents the main results in the improvement of endosperm carotenoid levels in rice, maize and wheat considering the methodology used, either transgenic or non-transgenic; the breeding target, such as provitamin A or total carotenoid content; the identification of new carotenogenic genes/alleles related to the available variation for this trait; and the development of new functional markers for marker-assisted selection. A comparative overview among these species and key areas for further improvement are also identified. Carotenoid enhancement in grasses would benefit from comparative studies among Triticeae species since they allow the understanding of the diversity basis. Therefore, the comparative overview given in this work will be relevant not only to rice, maize and wheat but also to other Triticeae species.