A major yellow-seed QTL on chromosome A09 significantly increases the oil content and reduces the fiber content of seed in Brassica napus

The effect of genotype, environment (year, location) and their interaction on seed yield and important breeding traits of 25 genotypes of winter oilseed rape were investigated under field conditions in Greater Poland. Multi-environmental field experiments were conducted in a randomized block design with four replications during three growing seasons in two locations. Five traits, such as the beginning of flowering, seed yield and its structure, the length of siliques, the number of seeds per silique and the weight of 1000 seeds were recorded. The tested Brassica genotypes showed significant differences in terms of yield and other investigated traits across harvesting years and growing locations. Analysis of variance indicated that the main effects of genotypes, locations and years as well as all interactions were significant for all traits of study. The correlation coefficient between the investigated traits displayed strong negative relationships between seed yield and the beginning of flowering (except E2). The use of multivariate statistical methods in this study allowed for the simultaneous characterization of 25 tested genotypes in terms of several traits. Visualization of the experimental results and finally the distribution of Brassica genotypes in space of two first canonical variates showed a variation between the cultivars, double low, resynthesized and lines with changed fatty acid content in terms of yield and its components, as well as the beginning of flowering.

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Multidimensional Analysis of Diversity in Genotypes of Winter Oilseed Rape (Brassica napus L.)

In our study, we focused on the link among various parameters of chlorophyll a fluorescence and yield elements in the barley doubled haploid (DH) lines. There were significant differences in all studied DH lines, both in yield components and parameters of chlorophyll a fluorescence. The most variable parameter was overall performance index of PSII (PI) while the least was the amount of energy trapped in PSII reaction centers (TRo/CS). Considering yield components, high variation was also observed in the subsequent order from highest to lowest variation: biomass, thousand-grain weight (TGW) and grain number per plant (GNP). Significant negative correlation was found among the following fluorescence parameters: PI and light energy absorption (ABS/CS), as well as between maximum photochemical efficiency (Fv/Fm) and TGW, and between biomass and electron acceptors pool size from PSII (Area). Conversely, significant positive correlation was found between: Area and PI, Area and energy used for electron transport (ETo/CS), Area and GNP, PI and ETo/CS, PI and GNP, ABS/CS and TRo/CS, as well as between ETo/CS and GNP. Yield components combined with fluorescence parameters of chlorophyll a expressed with canonical variate analysis did not clearly distinguish the barley DH lines into hulled and hull-less groups. The mean value for these groups significantly differs only for ETo/CS and TGW values. The other parameters are distributed almost uniformly in hulled and hull-less lines. However, certain hull-less DH lines possess higher yield parameters compared to parental forms, which suggests a possibility of occurrence of transgression effects. The results suggest the chance to find valuable hull-less forms that are desired by breeders and plant producers, since these forms possess favorable functional features.

Impact of Selected PSII Parameters on Barley DH Lines Biomass and Yield Elements

The identification of markers responsible for regulating important agronomic traits in rapeseed supports breeding and increases the seed yield. Microsatellite (SSR) markers are mainly used as ‘neutral’ genetic markers but are also linked with many biological functions. The objective of this study was identification of microsatellite markers associated with important agronomic traits affecting the seed yield of winter oilseed rape and with the heterosis effect for these traits. The plant material consists of four parental lines, 60 doubled haploid (DH) lines, 60 single cross hybrids, and 60 three-way cross hybrids. The association between molecular markers and observed traits was estimated using regression analysis. Among 89 SSR markers, 43 were polymorphic, and 15 were selected for mapping because they demonstrated stability in both years of observation. These markers were physically mapped in the rapeseed reference genomes and their immediate vicinity was searched to identify candidate genes associated with the studied traits. Six markers (BrGMS3837, BnEMS1119, BrGMS2901, BnGMS0509, BrGMS3688, BrGMS4057), which showed a positive estimation effect in our association analysis, and thus increased the value of a given trait or heterosis effect, turned out to be linked with genes that could be responsible for the development and growth of plants.

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Identification of SSR Markers Associated with Yield-Related Traits and Heterosis Effect in Winter Oilseed Rape (Brassica Napus L.)

This paper proposes the use of weighted multiple linear regression to estimate the triple3interaction (additive×additive×additive) of quantitative trait loci (QTLs) effects. The use of unweighted regression yielded an improvement (in absolute value) in the QTL×QTL×QTL interaction effects compared to assessment based on phenotypes alone in three cases (severe drought in 2010, control in 2012 and severe drought in 2012). In contrast, weighted regression yielded an improvement (in absolute value) in the evaluation of the aaagw parameter compared to aaap in five cases, with the exception of severe drought in 2012. The results show that by using weighted regression on marker observations, the obtained estimates are closer to the ones obtained by the phenotypic method. The coefficients of determination for the weighted regression model were significantly higher than for the unweighted regression and ranged from 46.2% (control in 2010) to 95.0% (control in 2011). Considering this, it is clear that a three-way interaction had a significant effect on the expression of quantitative traits.

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QTL×QTL×QTL Interaction Effects for Total Phenolic Content of Wheat Mapping Population of CSDH Lines under Drought Stress by Weighted Multiple Linear Regression

Rapeseed (Brassica napus L.) meal is an important source of protein, but the presence of anti-nutritional compounds, such as fibre and glucosinolates, still limits its use as a livestock feed. Understanding the genetic basis of seed fibre biosynthesis would help to manipulate its content in seeds of oilseed rape. Here, we applied high-resolution skim genotyping by sequencing (SkimGBS) and characterised 187,835 single-nucleotide polymorphism (SNP) markers across a mapping population subsequently used for a genetic mapping study (R/qtl). This approach allowed the identification of 11 stable QTL related to seed quality traits and led to the identification of potential functional genes underlying these traits. Among these, key genes with a known role in carbohydrate metabolic process, cell wall, lignin, and flavonoid biosynthesis, including cellulase GH5, TT10/LAC15, TT4, and SUC2, were found. This study furthers the understanding of the molecular mechanisms underlying seed fibre content and provides new markers for molecular breeding in B. napus.

QTL Genetic Mapping Study for Traits Affecting Meal Quality in Winter Oilseed Rape (Brassica Napus L.)

Limited genetic variability is a major problem in rapeseed breeding, whose strict selection, limited geographical range and a short period of domestication has led to a reduction in genetic and phenotypic diversity Assessing specific populations for the greatest genetic diversity for many traits simultaneously, requires the evaluation of multi-feature characteristics The aim of this study was to estimate the variability of DH (doubled haploid) lines and two generations of winter oilseed rape hybrids In addition, the relationship between the Mahalanobis distances of parental forms and the effect of heterosis in hybrids was investigated The results of MANOVA showed that the genotypes and years as well as genotype × year interaction were significantly different (p < 0001) for all eight observed traits The first (V1) and the second (V2) canonical variate explained 3857% and 2755% of the total variation in 2015, and 5019% and 3184% in 2016, respectively Canonical variate analysis showed that the traits, flowering time and number of branches per plant had a very large influence on the differentiation of genotypes Graphs demonstrated that the tested DH lines and hybrids are characterized by a similar, wide range of variability It was observed, that when using a diverse population of DH lines for crossbreeding with only one CMS/Rfo line, there was no significant reduction of variation in hybrid generations and between these generations The phenotypic distance values determined by the results of Mahalanobis analysis were similar in both years, but slightly wider in 2016 The observed minimum and maximum ranged from 1324 to 22356 in 2015, and from 1105 to 27792 in 2016, respectively No significant correlation was observed between the hybrid heterosis effect and the Mahalanobis distance of the parental lines

Multidimensional Analysis of Diversity in DH Lines and Hybrids of Winter Oilseed Rape (Brassica napus L.)

A crucial aim for rapeseed breeders is increasing the seed yield through improving yield- and silique-related traits. In this research, traits including the number of seeds per silique, silique length, silique width, and thousand-seed weight combined with seed coat color were investigated. Yellow-seeded lines of oilseed rape have a thinner seed coat, lower fiber content, and higher protein and oil content than traditional varieties. Hybrids of yellow- and black-seeded Brassica napus, which combine the advantages of both types of seeds, are tested for their suitability in breeding. Therefore, the aim of this study was to assess a population of 78 doubled haploid lines with different seed coat colors to select genotypes connecting a light color of seeds with good yielding characteristics. Multivariate methods such as analysis of variance, correlation analysis, regression analysis, canonical variate analysis, Mahalanobis distances, and estimation of gene effects were used. The results showed that all tested genotypes were significantly different regarding all five studied traits. The multidimensional analyses gave an accurate overview of the relationship between the examined features. The color and weight of seeds were considered the most important for breeding rapeseed with better seed properties. Although a negative correlation between these two characteristics occurs quite commonly, it was not present in our plant material, which allowed us to select lines with a-light seed color and high thousand-seed weight, which is a significant achievement. As a result, two doubled haploid lines were chosen as valuable breeding material for creating oilseed rape varieties with improved biochemical characteristics of seeds.

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Agnieszka Łopatyńska

Papers

QTL Genetic Mapping Study for Traits Affecting Meal Quality in Winter Oilseed Rape (Brassica Napus L.)

Multidimensional Analysis of Diversity in DH Lines and Hybrids of Winter Oilseed Rape (Brassica napus L.)

Identification of SSR Markers Associated with Yield-Related Traits and Heterosis Effect in Winter Oilseed Rape (Brassica Napus L.)

Statistical Multivariate Methods for the Selection of High-Yielding Rapeseed Lines with Varied Seed Coat Color