Proceedings of the National Academy of Sciences
2016-08 | journal-article
Significance
Indica rice accounts for >70% of total rice production worldwide, is genetically highly diverse, and can be divided into two major varietal groups independently bred and widely cultivated in China and Southeast Asia. Here, we generated high-quality genome sequences for two elite rice varieties, Zhenshan 97 and Minghui 63, representing the two groups of indica rice and the parents of a leading rice hybrid. Comparative analyses uncovered extensive structural differences between the two genomes and complementarity in their hybrid transcriptome. These findings have general implications for understanding intraspecific variations of organisms with complex genomes. The availability of the two genomes will serve as a foundation for future genome-based explorations in rice toward both basic and applied goals.
Abstract
Asian cultivated rice consists of two subspecies: Oryza sativa subsp. indica and O. sativasubsp. japonica. Despite the fact that indica rice accounts for over 70% of total rice production worldwide and is genetically much more diverse, a high-quality reference genome for indica rice has yet to be published. We conducted map-based sequencing of two indica rice lines, Zhenshan 97 (ZS97) and Minghui 63 (MH63), which represent the two major varietal groups of the indica subspecies and are the parents of an elite Chinese hybrid. The genome sequences were assembled into 237 (ZS97) and 181 (MH63) contigs, with an accuracy >99.99%, and covered 90.6% and 93.2% of their estimated genome sizes. Comparative analyses of these two indica genomes uncovered surprising structural differences, especially with respect to inversions, translocations, presence/absence variations, and segmental duplications. Approximately 42% of nontransposable element related genes were identical between the two genomes. Transcriptome analysis of three tissues showed that 1,059–2,217 more genes were expressed in the hybrid than in the parents and that the expressed genes in the hybrid were much more diverse due to their divergence between the parental genomes. The public availability of two high-quality reference genomes for the indica subspecies of rice will have large-ranging implications for plant biology and crop genetic improvement.
Cite this article
Zhang J#, Chen L#, Xing F# (#co-first authors), Kudrna D, Yao W, Copetti D, Mu T, Li W, Song J, Xie W, Lee S, Talag J, Shao L, An Y, Zhang C, Ouyang Y, Sun S, Jiao W, Lv F, Du B, Luo M, Maldonado C, Goicoechea J, Xiong L, Wu C, Xing Y, Zhou D, Yu S, Zhao Y, Wang G, Yu Y, Luo Y, Zhou Z, Hurtado B, Danowitz A, Wing R* and Zhang Q* (*corresponding authors). Extensive sequence divergence between the reference genomes of two elite indica rice varieties Zhenshan 97 and Minghui 63. Proceedings of the National Academy of Sciences of the United States of America, 2016, 113(35):E5163-E5171. DOI: 10.1073/pnas.1611012113