Orchid Biotechnology IV presents a series of recent work on both basic and applied researches in biotechnology progress for Phalaenopsis, Oncidium and Erycina pusila orchids. These include breeding of Phalaenopsis orchids of black flower, big-white flower and small and floriferous flowers, physiology for shipping and photosynthesis, SSR markers and mitochondrial DNA markers, virus detection and antiviral immunity, embyogenesis and relationship with mycorrhiza symbiosis, transposon and retrotransposon, orchid genome and evolution, regulation of orchid floral scent, floral color modification, and abiotic stress tolerance.