Frontiers in Plant Science (Nov 2014)
Comparative transcriptomic analysis of male and female flowers of monoecious Quercus suber
Abstract
Monoecious species provide a comprehensive system to study the developmental programs underlying the establishment of female and male organs in unisexual flowers. However, molecular resources for most monoecious non-model species are limited, hampering our ability to study the molecular mechanisms involved in flower development of these species. The objective of this study was to identify differentially expressed genes during the development of male and female flowers of the monoecious species Quercus suber, an economically important Mediterranean tree. Total RNA was extracted from different developmental stages of Q. suber flowers. Non-normalised cDNA libraries of male and female flowers were generated using 454 pyrosequencing technology producing a total of 962,172 high-quality reads with an average length of 264 nucleotides. The assembly of the reads resulted in 14,488 contigs for female libraries and 10,438 contigs for male libraries. Comparative analysis of the transcriptomes revealed genes differentially expressed in early and late stages of development of female and male flowers, some of which have been shown to be involved in pollen development, in ovule formation and in flower development of other species with a monoecious, dioecious or hermaphroditic sexual system. Moreover, we found differentially expressed genes that have not yet been characterised and others that have not been previously shown to be implicated in flower development. This transcriptomic analysis constitutes a major step towards the characterisation of the molecular mechanisms involved in flower development in a monoecious tree with a potential contribution towards the knowledge of conserved developmental mechanisms in other species.
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