Analysis of nonadditive protein accumulation in young primary roots of a maize (Zea mays L.) F₁‐hybrid compared to its parental inbred lines

Abstract

Heterosis describes the superior performance of heterozygous F(1)-hybrids compared to their homozygous parental inbred lines. Heterosis is already manifested during early maize (Zea mays L.) primary root development. In this study, the most abundant soluble proteins have been investigated before the phenotypic manifestation of heterosis in 3.5-day-old primary roots in the flint inbred line UH002, the dent inbred line UH301 and the corresponding hybrid UH301 x UH002. In CBB-stained 2-DE gels, 150 of 304 detected proteins (49%) were accumulated in a nonadditive fashion in the hybrid compared to the average of their parental inbred lines (Student's t-test: p < 0.05). Remarkably, expression of 51% (76/150) of the nonadditively accumulated proteins exceeded the high parent or was below the low parent. ESI-MS/MS identified 75 of the 76 proteins that belonged to these expression classes. The most abundant functional classes among the 75 proteins that were encoded by 60 different genes were metabolism (58%) and disease and defense (19%). Nonadditive protein accumulation in primary roots of maize hybrids might be associated with heterosis manifestation. Identification of these proteins could therefore contribute to the better understanding of the molecular basis of heterosis.

Specification of Cortical Parenchyma and Stele of Maize Primary Roots by Asymmetric Levels of Auxin, Cytokinin, and Cytokinin-Regulated Proteins

“…In contrast to RNA, proteins cannot be amplified. Therefore, most proteome analyses have been confined to whole roots (Hochholdinger et al, 2004aWen et al, 2005;Liu et al, 2006;Hoecker et al, 2008) or longitudinal segments of roots (Chang et al, 2000;Zhu et al, 2006Zhu et al, , 2007. In this study, therefore, we developed an approach that allowed separating and subsequently analyzing the functionally diverse internal stele tissue and the surrounding cortical parenchyma tissues (endodermis, cortex, and epidermis) in the differentiation zone of the primary root without damaging pericycle or endodermis cells.…”

“…J01238; forward primer, 5#-AGGCCACGTACAACTCCATC-3#; reverse primer, 5#-CCACC-GATCCAGACACTGTA-3#). Relative expression of the b-glucosidase gene compared with the actin gene was calculated as mean normalized expression compared with actin, using threshold cycle values and averaged primer efficiencies calculated from three biological replications as described previously (Hoecker et al, 2008). Semiquantitative reverse transcription (RT)-PCR was performed to determine the relative expression of BGAF (GenBank accession no.…”

“…Proteomic technology provides an approach that allows us to dissect and quantify components such as biochemical pathways in a tissue-specific way by combining the resolution of two-dimensional gel electrophoresis (2-DE) with the sensitivity of mass spectrometry and database searching . In recent years, maize root proteomes were analyzed in order to better understand development , genotypic variation (Hochholdinger et al, 2004a;Wen et al, 2005;Liu et al, 2006;Sauer et al, 2006;Hoecker et al, 2008), environmental interactions (Chang et al, 2000;Zhu et al, 2006Zhu et al, , 2007Li et al, 2007), or subcellular processes (Zhu et al, 2006(Zhu et al, , 2007 of different root types. Most of these surveys investigated whole roots (Hochholdinger et al, 2004a;Wen et al, 2005;Liu et al, 2006;Li et al, 2007;Hoecker et al, 2008), while a few specifically analyzed the primary root tip (Chang et al, 2000) and the elongation zone (Zhu et al, 2006(Zhu et al, , 2007.…”

Heterosis: Many Genes, Many Mechanisms—End the Search for an Undiscovered Unifying Theory

“…Proteomic analysis of seedling roots of maize [83][84][85][86] and rice [87] indicates that non-additive expression of proteins in hybrids versus inbreds is more frequent than non-additive transcriptional variation. Dahal et al [88] compared two heterotic maize hybrids to a non-heterotic hybrid.…”

Nonsyntenic genes drive tissue-specific dynamics of differential, nonadditive and allelic expression patterns in maize hybrids

“…nonadditive expression, widely varied between different species, tissues, and genotypes (Guo et al, 2006;Stupar and Springer, 2006;Swanson-Wagner et al, 2006;Uzarowska et al, 2007;Stupar et al, 2008;Hoecker et al, 2008b;Paschold et al, 2012). Nonadditive gene expression is the result of allelic interactions that modify regulatory networks that lead to gene activity patterns different from average parental values (Stupar and Springer, 2006).…”