Although much effort has been made to uncover the mechanism underlying double fertilization, little knowledge has been acquired for understanding the molecular base of gamete recognition, mainly because of technical limitations. Still, progress has been made in terms of the mechanism, including the identification of candidate molecules that are involved in gamete recognition in angiosperms. New cues for gamete recognition have been found by the successful separation of the gametes and construction of gamete-specific cDNA libraries in several species, and the application of molecular approaches for studying this process by mutations. Thus, the topic is considered an abstruse but charming mystery.
Double fertilization is one of the predominant features of sexual reproduction in flowering plants but, because of the physical inaccessibility of gametes, the essential molecular mechanisms in these processes are largely unknown. Based on the techniques for isolating highly purified gametes from several species and well-developed methods for manipulating RNA from limited quantities of gametes, genome-wide investigations of gamete transcription profiles were recently conducted in flowering plants. In this review, we survey the accumulated knowledge on gamete collection and purification, cDNA library construction, and transcript profile analysis to assess our understanding of the molecular mechanisms of gamete specialization and fertilization.
XIN HaiPing & SUN MengXiang Key Laboratory of the Ministry of Education for Plant Developmental Biology, College of Life Science, Wuhan University, Wuhan 430072, China
