Comparison of maize (Zea mays L.) F1-hybrid and parental inbred line primary root transcriptomes suggests organ-specific patterns of nonadditive gene expression and conserved expression trends
Comparison of maize (Zea mays L.) F1-hybrid and parental inbred line primary root transcriptomes suggests organ-specific patterns of nonadditive gene expression and conserved expression trends
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DOI：
10.1534/genetics.108.088278
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发表时间：
2008-07-01
期刊：
影响因子：
3.3
通讯作者：
Hochholdinger, Frank
中科院分区：
文献类型：
--
作者：
Hoecker, Nadine;Keller, Barbara;Hochholdinger, Frank
杂种优势现象描述了与其纯合亲本近交植物相比，杂合F-I植物的农艺性能增加。玉米杂种优势表现在根系发育的早期阶段。本研究的目的是确定非加性基因的表达在初级根的玉米杂交种相比，其亲本自交系的平均表达水平。为了实现这一目标，采取了两步战略。首先，进行了非加性表达的候选基因的微阵列预选。随后，通过高通量定量实时（qRT）-PCR实验确定基因子集中的基因表达水平。最初的微阵列实验确定了1941个不同的微阵列功能，显示非加性的基因表达，在至少1个分析的12个杂交种相比，他们的亲本自交系的中亲值。大多数非加性表达的基因在亲本值之间表达（>89%）。这些1941个基因与非加性表达的基因在玉米芽顶端分生组织中通过相同的实验程序在相同的基因型比较，发现重叠显着低于预期的纯机会。这一发现表明器官特异性模式的非相加性表达基因。qRT-PCR分析的1941个基因中的64个在4个不同的杂交种揭示了保守模式的非加性表达基因在不同的杂交种。随后，22的64个基因，显示非加性表达在所有4个杂交种进行了分析，在12个杂交种，从4个自交系。在这些基因中，超氧化物歧化酶2在所有12个杂交种中的表达显着高于中亲值，因此可能在玉米杂交种的杂种优势相关的抗氧化防御中发挥保护作用。这项研究的结果是一致的假设，即全球表达趋势和特定基因的一致差异表达有助于杂种优势的器官特异性表现。
The phenomenon of heterosis describes the increased agronomic performance of heterozygous F-1 plants compared to their homozygous parental inbred plants. Heterosis is manifested during the early stages of root development in maize. The goal of this study was to identify nonadditive gene expression in primary roots of maize hybrids compared to the average expression levels of their parental inbred lines. To achieve this goal a two-step strategy was used. First, a microarray preselection of nonadditively expressed candidate genes was performed. Subsequently, gene expression levels in a subset of genes were determined via high-throughput quantitative real-time (qRT)-PCR experiments. Initial microarray experiments identified 1941 distinct microarray features that displayed nonadditive gene expression in at least 1 of the 12 analyzed hybrids compared to the midparent value of their parental inbred lines. Most nonadditively expressed genes were expressed between the parental values (>89%). Comparison of these 1941 genes with nonadditively expressed genes identified in maize shoot apical meristems via the same experimental procedure in the same genotypes revealed significantly less overlap than expected by pure chance. This findings suggests organ-specific patterns of nonadditively expressed genes. qRT-PCR analysis of 64 of the 1941 genes in four different hybrids revealed conserved patterns of nonadditively expressed gene in different hybrids. Subsequently, 22 of the 64 genes that displayed nonadditive expression in all four hybrids were analyzed in 12 hybrids that were generated from four inbred lines. Among those genes a superoxide dismutase 2 was expressed significantly above the midparent value in all 12 hybrids and might thus play a protective role in heterosis-related antioxidative defense in the primary root of maize hybrids. The findings of this study are consistent with the hypothesis that both global expression trends and the consistent differential expression of specific genes contribute to the organ-specific manifestation of heterosis.