Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Theor Appl Genet. 2013 Apr;126(4):1011-24. doi: 10.1007/s00122-012-2033-1. Epub 2013 Feb 12.
The Green Revolution (GR-I) included worldwide adoption of semi-dwarf rice cultivars (SRCs) with mutant alleles at GA20ox2 or SD1 encoding gibberellin 20-oxidase. Two series of experiments were conducted to characterize the pleiotropic effects of SD1 and its relationships with large numbers of QTLs affecting rice growth, development and productivity. The pleiotropic effects of SD1 in the IR64 genetic background for increased height, root length/mass and grain weight, and for reduced spikelet fertility and delayed heading were first demonstrated using large populations derived from near isogenic IR64 lines of SD1. In the second set of experiments, QTLs controlling nine growth and yield traits were characterized using a new molecular quantitative genetics model and the phenotypic data of the well-known IR64/Azucena DH population evaluated across 11 environments, which revealed three genetic systems: the SD1-mediated, SD1-repressed and SD1-independent pathways that control rice growth, development and productivity. The SD1-mediated system comprised 43 functional genetic units (FGUs) controlled by GA. The SD1-repressed system was the alternative one comprising 38 FGUs that were only expressed in the mutant sd1 backgrounds. The SD1-independent one comprised 64 FGUs that were independent of SD1. GR-I resulted from the overall differences between the former two systems in the three aspects: (1) trait/environment-specific contributions; (2) distribution of favorable alleles for increased productivity in the parents; and (3) different responses to (fertilizer) inputs. Our results suggest that at 71.4 % of the detected loci, a QTL resulted from the difference between a functional allele and a loss-of-function mutant, whereas at the remaining 28.6 % of loci, from two functional alleles with differentiated effects. Our results suggest two general strategies to achieve GR-II (1) by further exploiting the genetic potential of the SD1-repressed and SD1-independent pathways and (2) by restoring the SD1-mediated pathways, or 'back to the nature' to fully exploit the genetic diversity of those loci in the SD1-mediated pathways which are virtually inaccessible to most rice-breeding programs worldwide that are exclusively based on sd1.
绿色革命（GR-I）包括全球范围内采用半矮秆水稻品种（SRCs），这些品种具有突变等位基因 GA20ox2 或编码赤霉素 20-氧化酶的 SD1。进行了两项实验系列来描述 SD1 的多效性效应及其与影响水稻生长、发育和生产力的大量数量性状基因座（QTLs）的关系。在使用源自 SD1 近等基因系 IR64 的大群体首次证明了 SD1 在 IR64 遗传背景下增加株高、根长/质量和粒重、降低小穗育性和延迟抽穗的多效性效应。在第二组实验中，使用新的分子数量遗传学模型和著名的 IR64/Azucena DH 群体的表型数据，在 11 个环境中评估，以表征控制九个生长和产量性状的 QTLs，结果揭示了三个遗传系统：SD1 介导、SD1 抑制和 SD1 独立途径，它们控制着水稻的生长、发育和生产力。SD1 介导的系统由 43 个受 GA 控制的功能遗传单位（FGUs）组成。SD1 抑制系统是另一种系统，仅在突变 sd1 背景下表达，由 38 个 FGUs 组成。SD1 独立系统由 64 个 FGUs 组成，它们独立于 SD1。GR-I 是前两个系统在三个方面的总体差异造成的：（1）性状/环境特异性贡献；（2）父母中增加生产力的有利等位基因的分布；和（3）对（肥料）投入的不同反应。我们的结果表明，在检测到的 71.4%的位点上，一个 QTL 是由功能等位基因和丧失功能的突变体之间的差异引起的，而在其余的 28.6%的位点上，是由具有不同效应的两个功能等位基因引起的。我们的结果表明了实现 GR-II 的两种一般策略：（1）进一步挖掘 SD1 抑制和 SD1 独立途径的遗传潜力；（2）恢复 SD1 介导的途径，或“回归自然”，以充分利用 SD1 介导途径中那些在全球大多数水稻育种计划中几乎无法获得的遗传多样性，这些计划完全基于 sd1。
