These authors contributed equally to this work.
NUCLEAR MONOPLOIDY AND ASEXUAL PROPAGATION OF NANNOCHLOROPSIS OCEANICA (EUSTIGMATOPHYCEAE) AS REVEALED BY ITS GENOME SEQUENCE1
Article first published online: 23 SEP 2011
© 2011 Phycological Society of America
Journal of Phycology
Volume 47, Issue 6, pages 1425–1432, December 2011
How to Cite
Pan, K., Qin, J., Li, S., Dai, W., Zhu, B., Jin, Y., Yu, W., Yang, G. and Li, D. (2011), NUCLEAR MONOPLOIDY AND ASEXUAL PROPAGATION OF NANNOCHLOROPSIS OCEANICA (EUSTIGMATOPHYCEAE) AS REVEALED BY ITS GENOME SEQUENCE. Journal of Phycology, 47: 1425–1432. doi: 10.1111/j.1529-8817.2011.01057.x
Received 13 January 2011. Accepted 11 May 2011.
This article was published online on September 23, 2011. A spelling error in the title was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected September 29, 2011.
- Issue published online: 1 DEC 2011
- Article first published online: 23 SEP 2011
- asexual reproduction;
- genome sequencing;
- Nannochloropsis oceanica;
- polyunsaturated fatty acid
Species in genus Nannochloropsis are promising candidates for both biofuel and biomass production due to their ability to accumulate rich fatty acids and grow fast; however, their sexual reproduction has not been studied. It is clear that the construction of their metabolic pathways, such as that of polyunsaturated fatty acid (PUFA) biosynthesis, and understanding of their biological characteristics, such as nuclear ploidy and reproductive strategy, will certainly facilitate their genetic improvement through gene engineering and mutation and clonal expansion. In this study, the genome of N. oceanica S. Suda et Miyashita was sequenced with the next-generation Illumina GA sequencing technologies. The genome was ∼30 Mb in size, which contained 11,129 protein-encoding genes. Of them, 59.65% were annotated by aligning with those in diverse protein databases, and 29.68% were assigned at least one function described in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Less frequent polymorphic nucleotides (one in 22.06 kb) and the obvious deviation from 1:1 (major:minor, minor ≥10) expectation indicated the nuclear monoploidy of N. oceanica. The lack of the majority of meiosis-specific proteins implied the asexual reproduction of this alga. In combination, the nuclear monoploidy and asexual propagation led us to favor the hypothesis that N. oceanica was a premeiotic or ameiotic alga. In addition, sequence similarity-based searching identified the elongase- and desaturase-encoding genes involved in the biosynthesis of long-chain PUFAs, which provided the genetic basis of its rich content of eicosapentaenoic acid (EPA). The functional genes and their metabolic pathways profiled against its genome sequence will facilitate its integrative investigations.