Identification of quantitative trait loci that affect endoreduplication in maize endosperm
Identification of quantitative trait loci that affect endoreduplication in maize endosperm
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DOI：
10.1007/s00122-007-0640-z
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发表时间：
2007-11-01
影响因子：
5.4
通讯作者：
Larkins, Brian A.
中科院分区：
文献类型：
--
作者：
Coelho, Cintia M.;Wu, Song;Larkins, Brian A.
玉米胚乳中的内复制在淀粉和贮藏蛋白质合成开始之前，通常被认为影响籽粒灌浆。我们通过将SG18和Mo17杂交的F_1代与亲本自交系相互杂交，建立了四个回交群体，它们在内复制方面的两个参数--平均倍性和内重复核百分比--有所不同。这种四回交设计使我们能够估计和检验影响内重复的数量性状座位(QTL)的加性和显性遗传效应。用改进的三倍体作图方法对4个回交群体授粉后16d的胚乳进行分析，发现了3个影响平均倍性的胚乳QTL和2个影响胚乳重复核百分率的QTL。这些QTL中的一些可能通过在胚胎中的表达来显示其对内复制的影响。检测到的QTL表现为强显性或超显性，并与胚胎表达的QTL上位性互作。这有助于解释回交后代超亲分离的遗传基础。虽然增加平均倍性和内重复核比例的有利等位基因可以由双亲贡献，但内重复的Mo17衍生等位基因对Sg18衍生等位基因往往是显性或超显性的。7号染色体上的一个QTL可能同时在胚胎和胚乳中表达，它对内复制的两个不同参数产生多效性效应。本研究结果揭示了玉米胚乳内源复制的调控机制，并为潜在的提高籽粒产量提供了标记辅助选择策略。
Endoreduplication in maize endosperm precedes the onset of starch and storage protein synthesis, and it is generally thought to influence grain filling. We created four backcross populations by reciprocally crossing the F, progeny of a cross between Sg18 and Mo17 to the parental inbreds, which differ in endoreduplication by two parameters-mean ploidy and percentage of endoreduplicated nuclei. This four-backcross design allowed us to estimate and test the additive and dominant genetic effects of quantitative trait loci (QTLs) affecting endoreduplication. An analysis of endosperm from the four backcross populations at 16 days after pollination using a modified triploid mapping approach identified three endosperm QTLs influencing mean ploidy and two endosperm QTLs affecting the percentage of endoreduplicated nuclei. Some of these QTLs may manifest their effects on endoreduplication via expression in the embryo. The QTLs detected display strong dominance or over-dominance and interacted epistatically with an embryo-expressed QTL. This helps to explain the genetic basis for transgressive segregation in the backcross progeny. Although the favorable alleles that increase mean ploidy and percentage of endoreduplicated nuclei can be contributed by both parents, the Mo17-derived alleles for endoreduplication were often dominant or over-dominant to the Sg18-derived allele. One QTL on chromosome 7 that may be expressed in both the embryo and endosperm exerted a pleiotropic effect on two different parameters of endoreduplication. The results from this study shed light on the regulation of endoreduplication in maize endosperm and provide a marker-assisted selection strategy for potentially improving grain yield.