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Open Access Research article

Transcriptomic profiling of mature embryo from an elite super-hybrid rice LYP9 and its parental lines

Xiaomeng Ge12, Weihua Chen1, Shuhui Song12, Weiwei Wang12, Songnian Hu1* and Jun Yu1*

Author Affiliations

1 CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100029, PR China

2 Graduate University of Chinese Academy of Sciences, Beijing, 100049, PR China

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BMC Plant Biology 2008, 8:114  doi:10.1186/1471-2229-8-114

Published: 11 November 2008

Abstract

Background

The mature embryo of rice (Oryza sativa, L.) is a synchronized and integrated tissue mass laying the foundation at molecular level for its growth, development, and differentiation toward a developing and ultimately a mature plant. We carried out an EST (expressed-sequence-tags)-based transcriptomic study, aiming at gaining molecular insights into embryonic development of a rice hybrid triad–an elite hybrid rice LYP9 and its parental lines (93-11 and PA64s)–and possible relatedness to heterosis.

Results

We generated 27,566 high-quality ESTs from cDNA libraries made from mature rice embryos. We classified these ESTs into 7,557 unigenes (2,511 contigs and 5,046 singletons) and 7,250 (95.9%) of them were annotated. We noticed that the high-abundance genes in mature rice embryos belong to two major functional categories, stress-tolerance and preparation-for-development, and we also identified 191 differentially-expressed genes (General Chi-squared test, P-value <= 0.05) between LYP9 and its parental lines, representing typical expression patterns including over-dominance, high- and low-parent dominance, additivity, and under-dominance. In LYP9, the majority of embryo-associated genes were found not only abundantly and specifically enriched but also significantly up-regulated.

Conclusion

Our results suggested that massively strengthening tissue-(or stage-) characteristic functions may contribute to heterosis rather than a few simple mechanistic explanations at the individual gene level. In addition, the large collection of rice embryonic ESTs provides significant amount of data for future comparative analyses on plant development, especially for the important crops of the grass family.