Parental Inbred Lines Research Articles

Combining ability analysis using diallel crosses among seven inbred lines of corn under two sowing dates.

A half diallel cross between 7 inbred lines of maize was evaluated at two different sowing dates for nine quantitative characters. Sowing date and crosses mean squares were significant for all traits under study. Significant crosses x sowing date mean squares were obtained for all studied traits except, No. of rows/ear. General and specific combing ability mean squares were significant for all traits. For days to tasseling and days to silking at early sowing date; ear height, No of rows/ ear at late sowing date; No of kernels/row and 100-kernel weight at early sowing date and combined analysis, high ratios GCA/SCA which largely exceeded the unity were obtained, indicating that a large part of the total genetic variability associated with these traits was a result of additive and additive by additive gene action. For No of rows/ ear at the combined analysis, the ratio equal to one this mean additive and non-additive gene action are similar in controlling this case. For remain cases, showed GCA/SCA ratios less than unity. Therefore, it could be concluded that the large portion of the total genetic variability for these traits was due to non-additive gene action. The parental inbred line No. 6 and 4 seemed to be good combiner for grain yield/plant. Also, the parental inbred line No. 3 exhibited significant desirable ( ) effects for silking date and grain yield/ plant. The crosses P1xP3, P1xP5, P2xP5, P2xP6, P2xP7, P3xP4, P3xP7, P4xP5, P4xP6, and P5xP6 had the highest values for SCA effects. The crosses 2x6 and 3x4 out yielded the check hybrid 168 by 7.1 and 7.9%, respectively in the combined analysis.

Effect of Drought on Morpho-Physiological Traits of Sunflower (Helianthus Annuus L) Hybrids and their Parental Inbred Lines

Effect of Drought on Morpho-Physiological Traits of Sunflower (Helianthus Annuus L) Hybrids and their Parental Inbred Lines

Small RNA-based prediction of hybrid performance in maize

BackgroundSmall RNA (sRNA) sequences are known to have a broad impact on gene regulation by various mechanisms. Their performance for the prediction of hybrid traits has not yet been analyzed. Our objective was to analyze the relation of parental sRNA expression with the performance of their hybrids, to develop a sRNA-based prediction approach, and to compare it to more common SNP and mRNA transcript based predictions using a factorial mating scheme of a maize hybrid breeding program.ResultsCorrelation of genomic differences and messenger RNA (mRNA) or sRNA expression differences between parental lines with hybrid performance of their hybrids revealed that sRNAs showed an inverse relationship in contrast to the other two data types. We associated differences for SNPs, mRNA and sRNA expression between parental inbred lines with the performance of their hybrid combinations and developed two prediction approaches using distance measures based on associated markers. Cross-validations revealed parental differences in sRNA expression to be strong predictors for hybrid performance for grain yield in maize, comparable to genomic and mRNA data. The integration of both positively and negatively associated markers in the prediction approaches enhanced the prediction accurary. The associated sRNAs belong predominantly to the canonical size classes of 22- and 24-nt that show specific genomic mapping characteristics.ConclusionExpression profiles of sRNA are a promising alternative to SNPs or mRNA expression profiles for hybrid prediction, especially for plant species without reference genome or transcriptome information. The characteristics of the sRNAs we identified suggest that association studies based on breeding populations facilitate the identification of sRNAs involved in hybrid performance.

Higher grain yield and higher grain protein deviation underline the potential of hybrid wheat for a sustainable agriculture

AbstractGrain yield and protein content are traits of major importance in wheat breeding, but their combination is challenging due to a tight negative correlation. Protein yield and grain protein deviation have been proposed as selection criteria to simultaneously improve both traits. Sedimentation volume is an indicator of protein quality, which plays an important role for bread‐making quality in wheat. All these traits have been investigated in our study with 135 parental inbred lines, their 1,604 hybrids and 10 commercial check varieties evaluated at five environments. The focus of our study was to investigate the usefulness of the grain protein deviation and to define a bivariate model for calculating the grain protein deviation. Further, we compared line and hybrid wheat for grain yield and quality‐related parameters such as protein content and sedimentation volume. The grain protein deviation determined with a bivariate model delivered robust estimates of variance components and enabled a balanced selection of genotypes with improved protein content and grain yield across different quality classes. Although heterosis for protein content and sedimentation volume was negative, hybrids had a higher grain protein deviation as well as higher grain yield at a given sedimentation volume or a given protein content than line varieties.

Proteomics of Maize Root Development

Maize forms a complex root system with structurally and functionally diverse root types that are formed at different developmental stages to extract water and mineral nutrients from soil. In recent years proteomics has been intensively applied to identify proteins involved in shaping the three-dimensional architecture and regulating the function of the maize root system. With the help of developmental mutants, proteomic changes during the initiation and emergence of shoot-borne, lateral and seminal roots have been examined. Furthermore, root hairs were surveyed to understand the proteomic changes during the elongation of these single cell type structures. In addition, primary roots have been used to study developmental changes of the proteome but also to investigate the proteomes of distinct tissues such as the meristematic zone, the elongation zone as well as stele and cortex of the differentiation zone. Moreover, subcellular fractions of the primary root including cell walls, plasma membranes and secreted mucilage have been analyzed. Finally, the superior vigor of hybrid seedling roots compared to their parental inbred lines was studied on the proteome level. In summary, these studies provide novel insights into the complex proteomic interactions of the elaborate maize root system during development.

Parental Expression Variation of Small RNAs Is Negatively Correlated with Grain Yield Heterosis in a Maize Breeding Population.

Heterosis refers to a quantitative phenomenon in which F1 hybrid trait values exceed the mean of the parental values in a positive direction. Generally, it is dependent on a high degree of heterozygosity, which is maintained in hybrid breeding by developing parental lines in separate, genetically distinct heterotic groups. The mobility of small RNAs (sRNAs) that mediate epigenetic regulation of gene expression renders them promising candidates for modulating the action of combined diverse genomes in trans–and evidence already indicates their contribution to transgressive phenotypes. By sequencing small RNA libraries of a panel of 21 maize parental inbred lines we found a low overlap of 35% between the sRNA populations from both distinct heterotic groups. Surprisingly, in contrast to genetic or gene expression variation, parental sRNA expression variation is negatively correlated with grain yield (GY) heterosis. Among 0.595 million expressed sRNAs, we identified 9,767, predominantly 22- and 24-nt long sRNAs, which showed an association of their differential expression between parental lines and GY heterosis of the respective hybrids. Of these sRNAs, 3,485 or 6,282 showed an association with high or low GY heterosis, respectively, thus the low heterosis associated group prevailing at 64%. The heterosis associated sRNAs map more frequently to genes that show differential expression between parental lines than reference sets. Together these findings suggest that trans-chromosomal actions of sRNAs in hybrids might add up to a negative contribution in heterosis formation, mediated by unfavorable gene expression regulation. We further revealed an exclusive accumulation of 22-nt sRNAs that are associated with low GY heterosis in pericentromeric genomic regions. That recombinational suppression led to this enrichment is indicated by its close correlation with low recombination rates. The existence of this enrichment, which we hypothesize resulted from the separated breeding of inbred lines within heterotic groups, may have implications for hybrid breeding strategies addressing the recombinational constraints characteristic of complex crop genomes.

Recent research on the mechanism of heterosis is important for crop and vegetable breeding systems.

Heterosis or hybrid vigor is a phenomenon where hybrid progeny have superior performance compared to their parental inbred lines. This is important in the use of F1 hybrid cultivars in many crops and vegetables. However, the molecular mechanism of heterosis is not clearly understood. Gene interactions between the two genomes such as dominance, overdominance, and epistasis have been suggested to explain the increased biomass and yield. Genetic analyses of F1 hybrids in maize, rice, and canola have defined a large number of quantitative trait loci, which may contribute to heterosis. Recent molecular analyses of transcriptomes together with reference to the epigenome of the parents and hybrids have begun to uncover new facts about the generation of heterosis. These include the identification of gene expression changes in hybrids, which may be important for heterosis, the role of epigenetic processes in heterosis, and the development of stable high yielding lines.

Physiological and genetic analysis for maize root characters and yield in response to low phosphorus stress.

Root system architecture (RSA) plays an important role in the acquisition of mineral nutrients. Nevertheless, RSA has seldom been selected as an important agricultural trait in conventional breeding programs. Little is known about the response of RSA and phosphorus use efficiency (PUE) in regards to phosphorus (P) availability between parental inbred lines and their F1. In this study, 6 maize inbred lines and their 15 F1 generated by a diallel mating system, were used to analyze the genetic associations between RSA and PUE. Heterosis for PUE-related traits were comparatively greater under high P condition and reduced significantly under low P condition. Relative mid-parent heterosis for root traits were expressed more under the low P condition. Low P supply had a significant effect on heterosis, GCA and SCA of RSA- and PUE- related traits. The hybrid C3 (7922 × 8703-2), which had the highest PUE, showed an average yield with a lower P uptake under the both P conditions. Results from this study suggested breeding for a relatively high grain yield with reducing aboveground P demand and grain P concentration should be sufficient to reduce P fertilizer input and improve P efficiency.

Genome re-sequencing, SNP analysis, and genetic mapping of the parental lines of a commercial F1 hybrid cultivar of Chinese cabbage.

The genome-wide characterization of single nucleotide polymorphism (SNP) between cultivars or between inbred lines contributes to the creation of genetic markers that are important for plant breeding. Functional markers derived from polymorphisms within genes that affect phenotypic variation are especially valuable in plant breeding. Here, we report on the genome re-sequencing and analysis of the two parental inbred lines of the commercial F1 hybrid Chinese cabbage cultivar “W77”. Through the genome-wide identification and classification of the SNPs and indels present in each parental line, we identified about 1,500 putative non-functional genes in each parent. We designed cleaved amplified polymorphic sequence (CAPS) markers using specific mutations found at Eco RI restriction sites in the parental lines and confirmed their Mendelian segregation by constructing a linkage map using 96 F2 plants derived from the F1 hybrid cultivar, “W77”. Our results and data will be a useful genomic resource for future studies of gene function and metagenomic studies in Chinese cabbage.

Parent-progeny imputation from pooled samples for cost-efficient genotyping in plant breeding.

The increased usage of whole-genome selection (WGS) and other molecular evaluation methods in plant breeding relies on the ability to genotype a very large number of untested individuals in each breeding cycle. Many plant breeding programs evaluate large biparental populations of homozygous individuals derived from homozygous parent inbred lines. This structure lends itself to parent-progeny imputation, which transfers the genotype scores of the parents to progeny individuals that are genotyped for a much smaller number of loci. Here we introduce a parent-progeny imputation method that infers individual genotypes from non-barcoded pooled samples of DNA of multiple individuals using a Hidden Markov Model (HMM). We demonstrate the method for pools of simulated maize double haploids (DH) from biparental populations, genotyped using a genotyping by sequencing (GBS) approach for 3,000 loci at 0.125x to 4x coverage. We observed high concordance between true and imputed marker scores and the HMM produced well-calibrated genotype probabilities that correctly reflected the uncertainty of the imputed scores. Genomic estimated breeding values (GEBV) calculated from the imputed scores closely matched GEBV calculated from the true marker scores. The within-population correlation between these sets of GEBV approached 0.95 at 1x and 4x coverage when pooling two or four individuals, respectively. Our approach can reduce the genotyping cost per individual by a factor up to the number of pooled individuals in GBS applications without the need for extra sequencing coverage, thereby enabling cost-effective large scale genotyping for applications such as WGS in plant breeding.

Exploring the genetics of fertility restoration controlled by Rf1 in common wheat (Triticum aestivum L.) using high-density linkage maps.

Hybrid wheat breeding has the potential to significantly increase wheat productivity compared to line breeding. The induction of male sterility by the cytoplasm of Triticum timopheevii Zhuk. is a widely discussed approach to ensure cross-pollination between parental inbred lines in hybrid wheat seed production. As fertility restoration in hybrids with this cytoplasm is often incomplete, understanding the underlying genetics is a prerequisite to apply this technology. A promising component for fertility restoration is the restorer locus Rf1, which was first detected on chromosome 1A of the restorer accession R3. In the present study, we performed quantitative trait locus (QTL) analyses to locate Rf1 and estimate its effect in populations involving the restorer lines R3, R113 and L19. Molecular markers linked to Rf1 in these populations were used to analyse the genomic target region in T. timopheevii accessions and common wheat breeding lines. The QTL analyses revealed that Rf1 interacted with a modifier locus on chromosome 1BS and the restorer locus Rf4 on chromosome 6B. The modifier locus significantly influenced both the penetrance and expressivity of Rf1. Whereas Rf1 exhibited expressivity higher than that of Rf4, the effects of these loci were not additive. Evaluating the marker haplotype for the Rf1 region, we propose that the restoring Rf1 allele may be derived exclusively from T. timopheevii. The present study demonstrates that interactions between restorer and modifier loci play a critical role in fertility restoration of common wheat with the cytoplasm of T. timopheevii.

English

Maize is an important cereal crop in sub-Saharan Africa but production is adversely affected by maize streak virus disease (MSVD). In Ghana, re-occurrence of the disease has been reported in several regions, therefore, necessitating the development of resistant hybrids as the most sustainable and economical option. The objectives of the study were to identify parents and hybrids that combine MSVD resistance with high yield and determine the influence of maternal effect on the inheritance of MSVD resistance. To achieve these, five parental inbred lines namely: TZEI-4, TZEI-7, TZEI-22, TZEI-31 and TZEI-157 were crossed in a full diallel mating design during the major season of 2015. The resulting F1 hybrids were evaluated under natural and artificial infestations during the minor and major seasons of 2015/2016 using 9 x 3 alpha-lattice design with three replications. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant for MSVD severity mean score and only SCA for grain yield. Additive gene effect was preponderant for MSVD severity mean score, whereas grain yield was influenced by non-additive gene effect. Maternal effect had no significant contribution to the inheritance of MSVD resistance. GCA by environment and SCA by environment mean squares were significant for MSVD severity mean score. GCA effects revealed that inbreds TZEI-7 and TZEI-22 were resistant to MSVD. They could be good combiners for grain yield in addition to TZEI-31 and TZEI-157. Hybrids TZEI-4*TZEI-22 and TZEI-4*TZEI-31 showed resistance to MSVD as revealed by their SCA effects and heterotic values. TZEI-7*TZEI-157, TZEI-31*TZEI-157, TZEI-22*TZEI-157 and TZEI-4*TZEI-22 had positive and significant SCA effect, mid-parent heterosis and high parent heterosis for grain yield. Promising hybrids TZEI-4*TZEI-22, TZEI-22*TZEI-157, TZEI-7*TZEI-157 and TZEI-31*TZEI-157 identified in this study should be further tested in multi-locations across Ghana to determine their stability and adaptability. Key words: Maize streak virus disease, grain yield, resistance, full diallel, general combining ability, specific combining ability.

Accumulation Profiles of Embryonic Salt-Soluble Proteins in Maize Hybrids and Parental Lines Indicate Matroclinous Inheritance: A Proteomic Analysis.

Maize is one of the most widely cultivated crops. It accumulates a large quantity of seed storage proteins, which are important for seed development and germination, and contribute to the nutritional quality of seeds. Based on solubility, the storage proteins are divided into albumins (water-soluble), globulins (salt-soluble), prolamins (alcohol-soluble), and glutelins (acid- or alkali-soluble). Maize hybrids are cultivated due to the superior performance of F1 hybrids than that of their parents, a phenomenon known as heterosis. However, the accumulation patterns of seed storage proteins in maize embryos between the hybrids and their parental inbred lines have not been compared. In the present study, two elite inbred lines of China, Zheng 58 and Chang 7-2, and their reciprocal hybrids (Zheng 58 × Chang 7-2 and Chang 7-2 × Zheng 58) were used to explore parental influences on the accumulation patterns of seed storage proteins in maize embryos. For this purpose, we focused on seed salt-soluble proteins (SSPs) in our experiments. The SSPs were selectively extracted from maize mature embryos after extensive removal of water-soluble albumin and separated using two-dimensional gel electrophoresis (2-DE), followed by mass spectrometry analysis. Our results indicated that the 2-DE SSP profiles of hybrids closely resembled those of their maternal parent rather than the paternal parent. In other words, 2-DE SSP profiles of Zheng 58 × Chang 7-2 were more similar those of Zheng 58 whereas such profiles of Chang 7-2 × Zheng 58 were more similar to those of Chang 7-2 although the 2-DE profiles of all four maize types were quite similar. In total, 12 relatively abundant SSPs spots representing five kinds of proteins were identified, of which nine protein spots displayed non-additive accumulation in at least one hybrid. This study provided additional data on dominance and partial dominance effects on maize hybrids embryos. Besides, earlier studies on accumulation profiles of globulin-1 (also known as vicilin), which is one of the most abundant globulins in maize embryos, also support the above results. This study would be helpful in revealing the mechanisms underlying SSPs accumulation patterns in the hybrids.

Hybrid Purity Testing of Brassica rapa Using SSR Marker Technology

Thirteen Chinese cabbage (Brassica rapa) hybrid cultivars and 26 parental inbred lines were used as experimental materials to screen for primers producing hybrid and parental complementary bands and for primers with high polymorphism information contents and low genotype frequencies. A total of 18 pairs of core primers were designed to identify the purity of Chinese cabbage. There was no significant difference in the purity percentage measured between different loci of the same strain. The fingerprint obtained by the amplification of each locus could be used to identify purity to obtain an authentic purity percentage. Curve mapping and significance analyses were conducted using the purity percentage of eight different seed samples and confirmed a sampling seed number of 96. The results of the purity test were verified by comparison with the grow-out test (GOT) using molecular markers. In conclusion, the simple sequence repeat (SSR) detection system could be used for the rapid identification of the purity of the tested Chinese cabbage hybrids.

Daya Gabung Inbrida Jagung Toleran Cekaman Kekeringan dan Nitrogen Rendah pada Pembentukan Varietas Hibrida

<p class="Abstrak">Low maize grain yield due to drought and low N stresses maybe overcome by growing tolerance hybrid maize varieties.<strong> </strong>The objectives of this research were to analyze the combining ability of eight inbred lines possessing those traits and indentify suitable parental inbred lines which can be used to develop single cross hybrid tolerant to drought and low nitrogen. Eight inbred lines were crossed using complete diallel cross design of Griffing’s- I on Februry to June, 2014. Those inbred lines were 1044-30, DTPYC9-F46-3-9-1-1-B (for drought tolerance), MR 14 (medium drought tolerance), G20133077 (tolerant to low N), CY 11, CLRCY039 (medium tolerant to low N), and CY12 and G2013631 (for drought and low N sensitive). Fifty-six experimental hybrids derived from diallel crosses, eight inbred lines and four commercial hybrid varieties as checks were evaluated under managed drought, low dosage of N fertilization and under optimum condition, during the dry season (July to October) of 2014. Randomized complete block design three replications was used in each different stress condition. The results showed that CY 11, G2013631, and MR 14 inbred lines possesed good general combining ability (GCA) for grain yield under drought, low N, and optimum conditions. These inbred lines also showed good GCA for the secondary traits such as large stem, delayed leaf rolling and late leaf senescence to support for high grain yield under drought stress and low N condition. Inbred lines of drought and low N sensitive such as G2013631, but had high GCA, could be used as parent to develop drought and low N tolerance hybrids if crossed with inbred lines having medium-tolerant to drought or tolerant to low N, such as G20133077, which had low DGU, or CY11 which had high GCA. Hybrid maize tolerant to drought and tolerant to low N, such as CY11 x G20133077, G20133077 x G2013631, and CY 11 x G2013631, produced significantly higher grain yield, over 8 t/ha, under drought and under low N, as compared with hybrid varieties Bima 3 and Bisi 2, which yielded 5.91 and 6.59 t/ha under drought, and 6.82 and 7.01 t/ha under low N condition. Grain yields under optimum condition were positively correlated with those under both drought and low N conditions. The result suggests that it is possible for improving grain yield of hybrid maize, simultaneously for optimum, drought stress and low N conditions.</p>

Breeding potential of maize germplasm populations to improve yield and predominant heterotic pattern in Northeast China

Increasing the frequency of favorable alleles in elite germplasm is necessary for germplasm improvement and innovation in maize (Zea mays L.) breeding programs. Jidan27 (Si287 × Si144), an elite commercial single cross hybrid that represents the predominant heterotic pattern Chinese Sipingtou × Stiff Stalk Synthetic, has been widely cultivated in the Northeast China Corn Belt. However, the use of the hybrid Jidan27 has been hampered gradually due to its low yield potential, lack of resistance to lodging, and considerable incidence of head smut disease. Previous studies have evaluated yield potential of exotic populations, but few have considered using these germplasms as donors with favorable alleles to overcome these deficiencies in the hybrid Jidan27. In the present study, 12 exotic populations from CIMMYT and the U.S. and three semi-exotic populations were investigated as sources of favorable alleles to increase yield and lodging resistance, and reducing head smut susceptibility of the hybrid Jidan27. The performance of a set of 30 inbred × populations crosses, the hybrid Jidan27, and the two parental inbred lines Si287 and Si144 was evaluated in three locations for 2 years. Two populations, BS10(FR)C10 and Pop43, were identified as the best donors of favorable alleles lacking in the hybrid for improving the target traits. Further, BS13(S)C7 and Cpop.16 were also found to be better choices for improving grain yield and head smut resistance of the hybrid. These results suggest that the elite exotic germplasms evaluated here could provide useful genetic variability to improve other Chinese Sipingtou × Stiff Stalk Synthetic crosses related to Si287 × Si144 that are widely grown in Northeast China.

Scanning Electron Microscopy study of root tissue of muskmelon: Transferring Fusarium wilt resistance from snapmelon to muskmelon

The overall aim of this study was to investigate the level of Fusarium oxysporum f. sp. Melonis (F.o.m.) infection by studying the Scanning electron micrographs of transverse sections of parent inbred lines and developed F1 hybrid. The current study involved KP4HM-15 (Fusarium wilt resistant inbred line) in a crossing program with well adapted muskmelon cv. Punjab Sunehri (PS) to develop FW resistant hybrid possessing high yield and quality traits. Fom infects melon root and trails through the cortical and endodermal cells to reach xylem vessels by penetrating through pits. This is the first SEM appraisal of the whole tap root of field grown melon accessions, KP4HM-15, PS and PSxKP4HM-15 (MH-41) (F1 hybrid) aimed to discern the role of the root morphometric characters for imparting FW resistance. The trend for root epidermo-cortical thickness was KP4HM-15>PS>MH-41 while for the xylem diameter was MH-41> KP4HM-15>PS. The F1 hybrid exhibited FW resistance intermediate among the two parents i.e. absence or presence of less mycelia as compared to the susceptible parent (PS). However, the extent of infection was higher than the resistant parent KP4HM-15, which shows that partial resistance was transferred from KP4HM-15 to MH-41. This study accentuates the resistance gene mining and use of wild melon accessions to introgress FW resistance in commercial melon cultivars.

Genetic analysis of early-maturing maize (Zea Mays L.) inbred lines under stress and nonstress conditions

ABSTRACTEarly-maturing maize (Zea Mays L.) germplasm developed from diverse sources has the potential for use in developing maize hybrids suitable for increasing maize production in the dry ecologies of eastern Africa. A diallel study was conducted to estimate general combining ability (GCA) of 12 early-maturing maize inbred lines, identify potential single-cross hybrids for use as parents, assess genetic diversity among the inbred lines, and relate genetic distance to specific combining ability (SCA) and hybrid performance. Sixty-six F1 diallel hybrids were evaluated under optimal and drought stress conditions at four locations in Kenya and Uganda. The parental inbred lines were genotyped using 94 single nucleotide polymorphism (SNP) markers. Additive gene action was more important than nonadditive gene action for inheritance of grain yield (GY) under optimal conditions. However, nonadditive gene effects were more important in the inheritance of GY under drought and across all environments. Inbred lines CKL0722, VL058014, and CZL0724 were among the best with positive GCA effects for GY across both optimal and drought stress conditions. The correlation between SCA and both genetic distance and F1 GY was significant under both drought stress and across all environments. Inbred lines with desirable GCA effects for GY and other agronomic traits and hybrids with good performance under both optimal and drought stress conditions are potential parents for development of various types of high-yielding, stress-tolerant, and early-maturing hybrids.

Quantitative trait locus analysis of heterosis for plant height and ear height in an elite maize hybrid zhengdan 958 by design III

BackgroundPlant height (PH) and ear height (EH) are two important agronomic traits in maize selection breeding. F1 hybrid exhibit significant heterosis for PH and EH as compared to their parental inbred lines. To understand the genetic basis of heterosis controlling PH and EH, we conducted quantitative trait locus (QTL) analysis using a recombinant inbreed line (RIL) based design III population derived from the elite maize hybrid Zhengdan 958 in five environments.ResultsA total of 14 environmentally stable QTLs were identified, and the number of QTLs for Z1 and Z2 populations was six and eight, respectively. Notably, all the eight environmentally stable QTLs for Z2 were characterized by overdominance effect (OD), suggesting that overdominant QTLs were the most important contributors to heterosis for PH and EH. Furthermore, 14 environmentally stable QTLs were anchored on six genomic regions, among which four are trait-specific QTLs, suggesting that the genetic basis for PH and EH is partially different. Additionally, qPH.A-1.3, modifying about 10 centimeters of PH, was further validated in backcross populations.ConclusionsThe genetic basis for PH and EH is partially different, and overdominant QTLs are important factors for heterosis of PH and EH. A major QTL qPH.A-1.3 may be a desired target for genetic improvement of maize plant height.

Evaluation of quality protein maize crosses through line X testeranalysis for grain yield and quality traits

A set of eighty one genotypes comprising sixty three newly developed single cross quality protein maize hybrids produced by 9 lines x 7 testers crosses along with sixteen parental inbred lines and two standard checks were evaluated for genetic variability, broad sense heritability and genetic advance at CCS, Haryana Agricultural University, Regional Research Station, Karnal, during kharif 2014. Highly significant values of mean sum of squares due to genotypes for all the 17characters studied could be recorded. Close correspondence between GCV and PCV was observed for all the traits except number of cobs per plant and cob diameter. The characters viz., number of grains per cob, tryptophan content, lysine content and grain yield per plant were recorded high estimates of heritability and genetic advance as per cent of mean indicating them to be controlled by additive genes.