Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
J Integr Plant Biol. 2010 Nov;52(11):971-80. doi: 10.1111/j.1744-7909.2010.00985.x.
Heterosis, or hybrid vigor, is the phenomenon whereby progeny of two inbred lines exhibit superior agronomic performance compared with either parent. We analyzed the expression of miRNAs and highly expressed small RNAs (defined according to Solexa sequencing results) in two rice (Oryza sativa) subspecies (japonica cv. Nipponbare and indica cv. 93-11) and their reciprocal hybrids using microarrays. We found that of all the 1141 small RNAs tested, 140 (12%, 140 of 1141) and 157 (13%, 157 of 1141) were identified being significantly differentially expressed in two reciprocal hybrids, respectively. All possible modes of action, including additive, high- and low- parent, above high- and below low-parent modes were exhibited. Both F1 hybrids showed non-additive expression patterns, with downregulation predominating. Interestingly, 15 miRNAs displayed stark opposite expression trends relative to mid-parent in reciprocal hybrids. Computational prediction of targets of differentially expressed miRNAs showed that they participated in multifaceted developmental pathways, and were not distinguishable from the targets of non-differentially expressed miRNAs. Together, our findings reveal that small RNAs play roles in heterosis and add a new layer in the understanding and exploitation of molecular mechanisms of heterosis.
杂种优势，或杂种优势，是指两个近交系的后代表现出优于双亲的农艺表现的现象。我们使用微阵列分析了两个水稻亚种（粳稻 cv. 日本晴和籼稻 cv. 93-11）及其正反交杂种中 miRNA 和高表达小 RNA（根据 Solexa 测序结果定义）的表达。我们发现，在所有测试的 1141 个小 RNA 中，有 140 个（12%，1141 个中的 140 个）和 157 个（13%，1141 个中的 157 个）在两个正反交杂种中差异表达显著。所有可能的作用模式，包括加性、高亲和低亲、高于高亲和低于低亲模式都有表现。两个 F1 杂种均表现出非加性表达模式，下调为主。有趣的是，15 个 miRNA 在正反交杂种中相对于中亲表现出截然相反的表达趋势。差异表达 miRNA 的靶基因的计算预测表明，它们参与了多方面的发育途径，与非差异表达 miRNA 的靶基因没有区别。总之，我们的研究结果表明，小 RNA 在杂种优势中发挥作用，并为杂种优势的分子机制的理解和利用增添了新的层面。
