Genomics of Papaya a Common Source of Vitamins in the Tropics

Papaya is amajor fruit crop of the tropics and is grown to a lesser extent in the subtropics. The genome is small (372 Mbp) and has evolutionarily primitive sex chromosomes. These characters justify papaya genomics programs. In addition to whole genome sequencing, a second major goal is to completely sequence the male specific region of the Y chromosome (MSY) and its corresponding region of the X chromosome.Genomic resources such as high density genetic maps, a physical map, and an expressed sequence tag database have been generated to support genome sequencing and as tools for papaya improvement. The papaya genome is currently being sequenced by the Hawaii Papaya Genome Consortium. Physical mapping of the MSY is near completion. Sequencing the papaya genome and the MSY will enhance our capacity to explore the origin and evolution of dioecy in the family of Caricaceae, to expand our knowledge on genome evolution by serving as an outgroup for the intensively studied family Brassicaceae, identify candidate genes for target traits, and provide genome-wide DNA markers for papaya improvement.