F3 Families Research Articles

Inheritance of resistance to the peach root‐knot nematode (Meloidogyne floridensis) in interspecific crosses between peach (Prunus persica) and its wild relative (Prunus kansuensis)

AbstractThe peach root‐knot nematode, Meloidogyne floridensis (MF), infects majority of available nematode‐resistant peach rootstocks which are mostly derived from peach (Prunus persica) and Chinese wild peach (P. davidiana). Interspecific hybridization of peach with its wild relative, Kansu peach (P. kansuensis), offers potential for broadening the resistance spectrum in standard peach rootstocks. We investigated the inheritance of resistance to MF in segregating populations of peach (‘Okinawa’ or ‘Flordaguard’) × P. kansuensis. A total of 379 individuals from 13 F2 and BC1F1 families were challenged with a pathogenic MF isolate “MFGnv14” and were classified as resistant (R) or susceptible (S) based on root galling intensity. Segregation analyses in F2 progeny revealed the involvement of a major locus with a dominant or recessive allele determining resistance in progeny segregating 3R:1S and 1R:3S, respectively. Testcrosses with a homozygous‐susceptible peach genotype (‘Flordaguard’ or ‘UFSharp’) confirmed P. kansuensis as a source of new resistance and the heterozygous allelic status of P. kansuensis at the locus conferring resistance to MF. We propose a single‐locus dominant/recessive model for the inheritance of resistance.

Genomic Prediction in Tetraploid Ryegrass Using Allele Frequencies Based on Genotyping by Sequencing.

Perennial ryegrass is an outbreeding forage species and is one of the most widely used forage grasses in temperate regions. The aim of this study was to investigate the possibility of implementing genomic prediction in tetraploid perennial ryegrass, to study the effects of different sequencing depth when using genotyping-by-sequencing (GBS), and to determine optimal number of single-nucleotide polymorphism (SNP) markers and sequencing depth for GBS data when applied in tetraploids. A total of 1,515 F2 tetraploid ryegrass families were included in the study and phenotypes and genotypes were scored on family-pools. The traits considered were dry matter yield (DM), rust resistance (RUST), and heading date (HD). The genomic information was obtained in the form of allele frequencies of pooled family samples using GBS. Different SNP filtering strategies were designed. The strategies included filtering out SNPs having low average depth (FILTLOW), having high average depth (FILTHIGH), and having both low average and high average depth (FILTBOTH). In addition, SNPs were kept randomly with different data sizes (RAN). The accuracy of genomic prediction was evaluated by using a “leave single F2 family out” cross validation scheme, and the predictive ability and bias were assessed by correlating phenotypes corrected for fixed effects with predicted additive breeding values. Among all the filtering scenarios, the highest estimates for genomic heritability of family means were 0.45, 0.74, and 0.73 for DM, HD and RUST, respectively. The predictive ability generally increased as the number of SNPs included in the analysis increased. The highest predictive ability for DM was 0.34 (137,191 SNPs having average depth higher than 10), for HD was 0.77 (185,297 SNPs having average depth lower than 60), and for RUST was 0.55 (188,832 SNPs having average depth higher than 1). Genomic prediction can help to optimize the breeding of tetraploid ryegrass. GBS data including about 80–100 K SNPs are needed for accurate prediction of additive breeding values in tetraploid ryegrass. Using only SNPs with sequencing depth between 10 and 20 gave highest predictive ability, and showed the potential to obtain accurate prediction from medium-low coverage GBS in tetraploids.

Designing Deep-UV Birefringent Crystals by Cation Regulation.

Two new alkaline earth metal fluorooxoborates, CaB4 O6 F2 and SrB4 O6 F2 , have been synthesized and characterized. The title compounds are isostructural and crystallize in centrosymmetric space group P1‾ (No. 2). Structurally, the fundamental building blocks, B4 O8 F2 groups, are connected by B-O bonds to form [B4 O6 F2 ]∞ layers, which stack parallelly along the c axis. In addition, BaB4 O6 F2 , a known fluorooxoborate with different crystal structure, was also synthesized and characterized for comparison. The cation size influence on the structure of this MB4 O6 F2 (M=Ca, Sr, Ba) family is discussed in detail. The diffuse-reflectance spectroscopy measurements indicate that the cutoff edges of title compounds are below 190 nm. Moreover, first-principle calculation results demonstrate that MB4 O6 F2 (M=Ca, Sr, Ba) have large birefringence of 0.091, 0.089, and 0.085 at 1064 nm. Both experimental and theoretical studies suggest that MB4 O6 F2 (M=Ca, Sr, Ba) are promising birefringent materials for deep-UV applications.

Genetic parameters and selection gains in early clonal evaluation trials: implications for cassava breeding

The objective of this study was to estimate and compare genetic parameters in early cassava breeding phases (clonal evaluation trials—CET and preliminary yield trials—PYT) in full-sib (F1) and self-pollinated (S1) families, besides estimating the genetic gains. Twenty-three F1 and six S1 families were evaluated using the augmented block design in CET and the randomized complete block design in PYT for fresh root yield (FRY), root dry matter content (DMC) and starch yield (STY). In CET, most of the variance was due to environmental ( $$\sigma_{e}^{2}$$ ) followed by variance within F1 and S1 ( $$\sigma_{Clone/Fam}^{2}$$ ) families, with the exception of DMC in S1 families. PYT presented the opposite behavior. In contrast, specifically for S1 families, the variance between families ( $$\sigma_{ Fam}^{2}$$ ) was more important than $$\sigma_{e}^{2}$$ and $$\sigma_{Clone/Fam}^{2}$$ in PYT. The heritability of families ( $$h_{Fam}^{2}$$ ) was lower than individual broad-sense heritability ( $$h_{g}^{2}$$ ) in all trials and families. Regardless of the family type and trial, family accuracy ( $$r_{ggFam}$$ ) was lower than the clone accuracies ( $$r_{ggCl}$$ ). Predicted gains using the selection index (SI) applied to best linear unbiased prediction (BLUP) were higher in PYT compared with CET and higher in F1 families in comparison with S1. There was also low coincidence in clone selection in both trials (30 and 45% for F1 and S1 families, respectively). For cassava breeding, it is recommended to obtain a higher number of clones per family and to use the SI with moderate intensity, particularly in CET.

Combining ability analysis of earliness and yield of potato (Solanum tuberosum L.) genotypes in Uganda

Potato (Solanum tuberosum L.) is a major food and cash crop mainly grown by small-scale farmers in the highland regions of Uganda. Changing global weather patterns require varieties that are able to grow within the short rainfall cycles and yield optimally under the prevailing conditions. The objectives of this study were to estimate the combining ability effects for early maturity, yield and yield related traits in potato. Eighteen F1 families generated from two sets of 12 parents using a North Carolina Design II were evaluated for days to 50% flowering, leaf senescence, yield and yield related traits in two different locations. Both additive and non-additive genetic effects influenced the expression of traits. However, additive genetic effects were predominant over the non-additive for most of the traits. The GCA/SCA ratios were 0.68 and 0.78 for days to 50% flowering and average tuber weight. Broad sense heritability estimates were 0.70 for total tuber weight and 0.78 for days to 50% flowering. The predominance of additive genetic effects imply that, genetic gains can be achieved through different selection methods and traits transferred to the respective progenies. Parents Rwangume, 396,038.107, 395,011.2, NKRK19.17, 393,077.54, Kimuri, and 392,657.8 had desirable GCA effects for the number of days to flowering and yield related traits. Families of Rwangume × NKRK19.17, 393,077.54 × 395,011.2, 396,038.107 × Rwangume and 396,038.107 × 395,011.2 had desirable SCA effects for yield and number of days to 50% flowering. The selected parents and families will be subjected to further clonal evaluation and selection.

Relative potential of seed yield component traits as selection criteria in the segregating generations of a desi × kabuli cross of chickpea

To assess the response to early generation selection in chickpea, a total of 150 F4 progenies derived from selection for total branches per plant, pods per plant, seeds per pod, seed yield per plant and 100-seed weight as independent selection criteria in F2 population of Pusa 362 (desi) × PG 0515 (kabuli) cross were evaluated along with their parents and unselected F2 bulk. The F2 population revealed high variability for all the yield components and transgressive segregation for all traits except 100-seed weight. Mean of the F4 families relative to the corresponding F2 plants was high, indicating effectiveness of early generation selection for all characters studied except branch number per plant. Significant correlated response for seed yield was also observed in F4. Based on realized response to selection as percentage of mean, realized heritability and realized generalized response values, we suggest utilization of pods per plant, seed yield per se and 100-seed weight as selection criteria in desi-kabuli introgression breeding for higher genetic gains.

Inheritance of 4-hydroxyphenylpyruvate dioxygenase inhibitor herbicide resistance in an Amaranthus tuberculatus population from Iowa, USA

Waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer) is a weed prevalent in the Midwest United States and can cause yield losses up to 74% in maize (Zea mays L.) and 56% in soybean (Glycine max (L.) Merr.). An important adaptive trait commonly found in waterhemp is the ability to evolve herbicide resistance and waterhemp populations have evolved resistance to six herbicide sites of action. In 2011, two waterhemp populations were discovered resistant to p-hydroxyphenylpyruvate-dioxygenase (HPPD, EC 1.13.11.27) inhibitor herbicides. We reciprocally crossed a known HPPD-resistant waterhemp population with a known HPPD-susceptible waterhemp population and then intermated the F1 families to established a pseudo-F2 generation. We challenged the parent, F1 and pseudo-F2 generations against four HPPD-inhibiting herbicide rates (mesotrione). Our results suggest the HPPD-resistance trait is polygenic. Furthermore, the number of genes involved with the herbicide resistance increase at higher herbicide rates. These data indicated at least one dominant allele at each major locus is required to confer HPPD herbicide resistance in waterhemp. Using different waterhemp populations and methodologies, this study confirms the reported “complex” HPPD resistance inheritance while providing new information in the response of HPPD-resistant waterhemp to HPPD herbicides.

TRANSGRESSIVE SEGREGATION, HETEROSIS AND HERITABILITY FOR YIELD-RELATED TRAITS IN A SEGREGATING POPULATION OF PISUM SATIVUM L.

SUMMARYPea is a self-pollinated, diploid (2n = 14), annual crop produced worldwide for human consumption and animal feed. The exploitation of maximum genetic potential from available pea resources implies the knowledge of genetic parameters of yield components. Hence, the present study was conducted in a cross between two pea varieties, namely DDR14 and Explorer, its F2 progeny and F3 families to find out transgressive segregants and to determine the magnitude of narrow sense heritability and heterosis. The high narrow sense heritability values obtained indicated that rapid gain could be achieved through selection for the different traits; however, the presence of genotype x environment interaction could limit the correspondence of these estimated values with the observed ones. The selection of lines through their phenotypic values is influenced by environmental and error effects. Best linear unbiased prediction (BLUP) was used for the prediction of genotypic values using morphological data from different years, allowing the correction for environmental effects. These estimates were used for genetic analysis of the traits. Heterosis was observed for number of pods (27.1%) and number of seeds (23.3%), characters that have a direct effect on yield. The cross also showed high frequency of transgressive segregation for these characters in F3 generation (15.5% and 13.6%, respectively). There were 12.73% families transgressive for two or more characters, with genotypic values of 49.82–64.41 for number of pods and 153.75–189.59 for seed number. The crossing between Explorer and DDR14 provided a base for the selection of superior progeny.

The Foc gene governs resistance to race 3 of Fusarium oxysporum f. sp. cucumerinum in the cucumber cv. SMR-18

The genetics of resistance to race 3 of Fusarium oxysporum f. sp. cucumerinum (FOC race 3) in the cucumber cv. SMR-18 (P1) was investigated by crossing it with the susceptible cucumber cv. Ashley (P2) and evaluating the disease reaction in the parents, F1, F1 reciprocal, F2 and backcross (BC1P1 and BC1P2) populations. Resistance of cv. SMR-18 to FOC race 3 was consistent with that of a single dominant, nuclear gene. To study the linkage relationship between this gene and the Foc gene, which expresses resistance to both FOC races 1 and 2, 73 plants that were backcrossed to the susceptible parent (BC1P2) were self-crossed. Each resulting F2 family was evaluated for resistance or susceptibility to race 1 and race 3 by inoculating different groups of 15–20 plants with each race of the pathogen. Segregation data exhibited an absolute linkage between the Foc gene and the gene controlling resistance to race 3 of the pathogen, since no recombinants were observed and only the two parental classes at a frequency of 50% each were observed. Our data support the concept that the Foc gene, which controls resistance to races 1 and 2, also confers resistance to race 3.

The FTO Gene Is Associated with Growth and Omega-3/-6 Ratio in Asian Seabass.

Polymorphisms in the FTO gene are associated with obesity and body mass index in humans and livestock. Little information of whether FTO plays an important role in aquaculture fish species is available. We cloned and characterized the FTO gene in an economically important food fish species: Asian seabass (Lates calcarifer). The full-length cDNA of the gene is 3679bp, containing an ORF of 1935bp encoding 644 amino acids, a 216bp 5' UTR and a 1538bp 3' UTR. The gene consisted of nine exons and eight introns and was 117,679bp in length. Phylogenetic analysis revealed that the gene in Asian seabass was closely related to those of Japanese flounder and Nile tilapia. Analysis of its expressions using qRT-PCR showed that it was expressed ubiquitously, but was higher in the liver, stomach and intestine. Comparative analysis of the genomic sequences of part of intron 1 of the gene among 10 unrelated individuals identified two SNPs. Analysis of associations between SNPs and traits (i.e. growth, oil content, omega-3 and -6 contents) in an F2 family demonstrated that the two SNPs were significantly associated with growth, oil content, omega-3 content and omega-3/-6 ratio. Altogether, our data suggest that the gene or/and its linked genes play an important role in growth and fatty acid synthesis, and that the SNPs associated with traits may be used as markers for selecting quicker growth and higher omega-3/-6 ratio at the fingerling stage.

Speed breeding for multiple quantitative traits in durum wheat

BackgroundPlant breeding requires numerous generations to be cycled and evaluated before an improved cultivar is released. This lengthy process is required to introduce and test multiple traits of interest. However, a technology for rapid generation advance named ‘speed breeding’ was successfully deployed in bread wheat (Triticum aestivum L.) to achieve six generations per year while imposing phenotypic selection for foliar disease resistance and grain dormancy. Here, for the first time the deployment of this methodology is presented in durum wheat (Triticum durum Desf.) by integrating selection for key traits, including above and below ground traits on the same set of plants. This involved phenotyping for seminal root angle (RA), seminal root number (RN), tolerance to crown rot (CR), resistance to leaf rust (LR) and plant height (PH). In durum wheat, these traits are desirable in environments where yield is limited by in-season rainfall with the occurrence of CR and epidemics of LR. To evaluate this multi-trait screening approach, we applied selection to a large segregating F2 population (n = 1000) derived from a bi-parental cross (Outrob4/Caparoi). A weighted selection index (SI) was developed and applied. The gain for each trait was determined by evaluating F3 progeny derived from 100 ‘selected’ and 100 ‘unselected’ F2 individuals.ResultsTransgressive segregation was observed for all assayed traits in the Outrob4/Caparoi F2 population. Application of the SI successfully shifted the population mean for four traits, as determined by a significant mean difference between ‘selected’ and ‘unselected’ F3 families for CR tolerance, LR resistance, RA and RN. No significant shift for PH was observed.ConclusionsThe novel multi-trait phenotyping method presents a useful tool for rapid selection of early filial generations or for the characterization of fixed lines out-of-season. Further, it offers efficient use of resources by assaying multiple traits on the same set of plants. Results suggest that when performed in parallel with speed breeding in early generations, selection will enrich recombinant inbred lines with desirable alleles and will reduce the length and number of years required to combine these traits in elite breeding populations and therefore cultivars.

Plant Resistance to Colorado Potato Beetle (Coleoptera: Chrysomelidae) in Diploid F2 Families Derived From Crosses Between Cultivated and Wild Potato.

Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), is a serious global pest of potato, Solanum tuberosum L. Management of L. decemlineata has relied heavily on insecticides, but repeated evolution of insecticide resistance has motivated the exploration and development of alternative strategies, such as plant resistance. The recent development of two diploid potato families derived from crosses between cultivated and wild potato species (S. chacoense and S. berthaultii) has provided a unique opportunity to reexamine plant traits for resistance breeding. In this 2-yr study, we surveyed select F2 clones for the induction of L. decemlineata mortality and a reduction in defoliation in no-choice feeding assays when challenged with adults and larvae from three sites in Wisconsin. We tested for an association with glandular trichome density and foliar levels of the glycoalkaloids chaconine and solanine. Several potato clones demonstrated resistance in specific feeding assays, but none excelled consistently across experiments. Mortality and defoliation generally differed significantly among L. decemlineata populations, which could be indicative of heritable variation in beetle responses to plant defenses or variation in the physiological status of the beetle populations tested. Contrary to expectations, higher trichome density increased mortality or decreased defoliation in only a few cases, and levels of mortality and defoliation were unrelated to foliar glycoalkaloid content, warranting further investigation of the defense mechanisms of resistant clones. In addition to identifying several potential L. decemlineata resistance sources, this study underscores the need to include multiple insect populations in surveys of plant resistance to this diverse pest.

The gene conferring susceptibility to spot blotch caused by Cochliobolus sativus is located at the Mla locus in barley cultivar Bowman

We identified, fine mapped, and physically anchored a dominant spot blotch susceptibility gene Scs6 to a 125kb genomic region containing the Mla locus on barley chromosome 1H. Spot blotch caused by Cochliobolus sativus is an important disease of barley, but the molecular mechanisms underlying resistance and susceptibility to the disease are not well understood. In this study, we identified and mapped a gene conferring susceptibility to spot blotch caused by the pathotype 2 isolate (ND90Pr) of C. sativus in barley cultivar Bowman. Genetic analysis of F1 and F2 progeny as well as F3 families from a cross between Bowman and ND 5883 indicated that a single dominant gene (designated as Scs6) conferred spot blotch susceptibility in Bowman. Using a doubled haploid (DH) population derived from a cross between Calicuchima-sib (resistant) and Bowman-BC (susceptible), we confirmed that Scs6, contributed by Bowman-BC, was localized at the same locus as the previously identified spot blotch resistance allele Rcs6, which was contributed by Calicuchima-sib and mapped on the short arm of chromosome 1H. Using a genome-wide putative linear gene index of barley (Genome Zipper), 13 cleaved amplified polymorphism markers were developed from 11 flcDNA and two EST sequences and mapped to the Scs6/Rcs6 region on a linkage map constructed with the DH population. Further fine mapping with markers developed from barley genome sequences and F2 recombinants derived from Bowman × ND 5883 and Bowman × ND B112 crosses delimited Scs6 in a 125kb genomic interval harboring the Mla locus on the reference genome of barley cv. Morex. This study provides a foundational step for further cloning of Scs6 using a map-based approach.

A high-resolution genetic linkage map and QTL fine mapping for growth-related traits and sex in the Yangtze River common carp (Cyprinus carpio haematopterus)

BackgroundA high-density genetic linkage map is essential for QTL fine mapping, comparative genome analysis, identification of candidate genes and marker-assisted selection for economic traits in aquaculture species. The Yangtze River common carp (Cyprinus carpio haematopterus) is one of the most important aquacultured strains in China. However, quite limited genetics and genomics resources have been developed for genetic improvement of economic traits in such strain.ResultsA high-resolution genetic linkage map was constructed by using 7820 2b-RAD (2b-restriction site-associated DNA) and 295 microsatellite markers in a F2 family of the Yangtze River common carp (C. c. haematopterus). The length of the map was 4586.56 cM with an average marker interval of 0.57 cM. Comparative genome mapping revealed that a high proportion (70%) of markers with disagreed chromosome location was observed between C. c. haematopterus and another common carp strain (subspecies) C. c. carpio. A clear 2:1 relationship was observed between C. c. haematopterus linkage groups (LGs) and zebrafish (Danio rerio) chromosomes. Based on the genetic map, 21 QTLs for growth-related traits were detected on 12 LGs, and contributed values of phenotypic variance explained (PVE) ranging from 16.3 to 38.6%, with LOD scores ranging from 4.02 to 11.13. A genome-wide significant QTL (LOD = 10.83) and three chromosome-wide significant QTLs (mean LOD = 4.84) for sex were mapped on LG50 and LG24, respectively. A 1.4 cM confidence interval of QTL for all growth-related traits showed conserved synteny with a 2.06 M segment on chromosome 14 of D. rerio. Five potential candidate genes were identified by blast search in this genomic region, including a well-studied multi-functional growth related gene, Apelin.ConclusionsWe mapped a set of suggestive and significant QTLs for growth-related traits and sex based on a high-density genetic linkage map using SNP and microsatellite markers for Yangtze River common carp. Several candidate growth genes were also identified from the QTL regions by comparative mapping. This genetic map would provide a basis for genome assembly and comparative genomics studies, and those QTL-derived candidate genes and genetic markers are useful genomic resources for marker-assisted selection (MAS) of growth-related traits in the Yangtze River common carp.

Response to Selection for Grain Filling Capacity in Wheat (Triticum aestivum L.) under Heat Stress

Improving tolerance to heat stress of bread wheat has been achieved through enhancing grain filling capacity by two cycles of selection imposed on five F2 populations derived from crosses among long spike–equally tall inbred lines quite variable in 1000 kernel weight (1000 KW). The first cycle was a divergent selection for 1000 KW conducted under the high temperature of a late rowing date at an intensity of 5% and the responses were measured in favorable and heat stress environments. Significant positive responses were obtained in the five populations in the two contrasting environments. Selection for higher 1000 KW resulted in greater response under heat stress (averaged 6.9% of population mean) than under favorable conditions (averaged 4.92%). The F3 families selected for higher 1000 KW were less sensitive to high temperature as they displayed less reductions due to heat stress (averaged 5.55%) than the unselected bulks (7.14% average reduction) relative to the performance under favorable conditions. The responses to selection for lower 1000 KW were greater under the favorable conditions (averaged 5.6%) than under heat stress (averaged 4.12%). Significant concurrent positive responses were obtained in stem diameter with selection for higher 1000 KW which was greater under heat stress (averaged 8.82%) than under favorable conditions (averaged 4.51%). Directional selection for stem diameter imposed on the plants of the F3 families in the second cycle resulted in significant positive responses in the five populations which averaged 16.24% of population mean as well as concurrent responses in 1000 KW (averaged 16.01%) and in grain yield /spike (averaged 19.5%). Selection for 1000 KW under heat stress produced concurrent response in stem diameter and vice versa which implies that the two characters are closely related. Increasing stem diameter by selection was more efficient than selection for 1000 KW in enhancing grain filling capacity through providing greater storage of stem reserves of water soluble carbohydrates to be remobilized into the developing grains under high temperature.

Molecular markers reliably predict post-harvest deterioration of fresh-cut lettuce in modified atmosphere packaging

Fresh-cut lettuce is popular, but highly perishable product. Genetic studies of two bi-parental populations derived from crossing parents with rapid and slow rates of deterioration showed that the deterioration rate is a heritable trait (broad spectrum heritability, H2 of 0.56–0.87). The major genetic determinant of the deterioration rate in both populations was the quantitative trait locus (QTL), qSL4, located on linkage group 4. This QTL explained 40–74% of the total phenotypic variation of the trait in the two populations. Saturating the qSL4 region with single-nucleotide (SNP) markers allowed detection of six haplotypes in a set of 16 lettuce accessions with different rates of deterioration. Three of the haplotypes were always associated with very rapid rates of deterioration, while the other three haplotypes were associated with slow rates of deterioration. Two SNPs located 53 bp apart were sufficient to separate the 16 accessions into two groups with different rates of deterioration. The accuracy of markers-trait association was subsequently tested on 350 plants from seven F2 families that originated from crossing parents with different rates of deterioration. The H2 of deterioration rate in these seven families ranged from 0.64 to 0.90. The SNP-based analysis accurately identified individuals with rapid, intermediate, and slow rates of deterioration in each family. Intermediate rate of deterioration was found in individuals having heterozygous alleles at qSL4, indicating an additive effect of the alleles. The assay can be used for fast, accurate, and reliable identification of deterioration rate after processing for salad.

Pb2 BO3 I: A Borate Iodide with the Largest Second-Harmonic Generation (SHG) Response in the KBe2 BO3 F2 (KBBF) Family of Nonlinear Optical (NLO) Materials.

Borate halides are an ideal materials class from which to design high-performance nonlinear optical (NLO) materials. Currently, borate fluorides, chlorides, and bromides are extensively investigated while borate iodide materials discovery remains rare because of the perceived synthetic challenges. We report a new borate iodide, Pb2 BO3 I, synthesized by a straightforward hydrothermal method. The Pb2 BO3 I chemical formula conceals that the compound exhibits a structure similar to the well-established KBe2 BO3 F2 (KBBF), which we show supports the highest second-harmonic generation (SHG) at 1064 nm in the KBBF family, 10 × KH2 PO4 (KDP), arising from the inclusion of Pb2+ and I- and the crystal chemistry. Our work shows that KBBF-related compounds can be synthesized incorporating iodide and exhibit superior NLO responses.

Optimized Use of Low-Depth Genotyping-by-Sequencing for Genomic Prediction Among Multi-Parental Family Pools and Single Plants in Perennial Ryegrass (Lolium perenne L.)

Ryegrass single plants, bi-parental family pools, and multi-parental family pools are often genotyped, based on allele-frequencies using genotyping-by-sequencing (GBS) assays. GBS assays can be performed at low-coverage depth to reduce costs. However, reducing the coverage depth leads to a higher proportion of missing data, and leads to a reduction in accuracy when identifying the allele-frequency at each locus. As a consequence of the latter, genomic relationship matrices (GRMs) will be biased. This bias in GRMs affects variance estimates and the accuracy of GBLUP for genomic prediction (GBLUP-GP). We derived equations that describe the bias from low-coverage sequencing as an effect of binomial sampling of sequence reads, and allowed for any ploidy level of the sample considered. This allowed us to combine individual and pool genotypes in one GRM, treating pool-genotypes as a polyploid genotype, equal to the total ploidy-level of the parents of the pool. Using simulated data, we verified the magnitude of the GRM bias at different coverage depths for three different kinds of ryegrass breeding material: individual genotypes from single plants, pool-genotypes from F2 families, and pool-genotypes from synthetic varieties. To better handle missing data, we also tested imputation procedures, which are suited for analyzing allele-frequency genomic data. The relative advantages of the bias-correction and the imputation of missing data were evaluated using real data. We examined a large dataset, including single plants, F2 families, and synthetic varieties genotyped in three GBS assays, each with a different coverage depth, and evaluated them for heading date, crown rust resistance, and seed yield. Cross validations were used to test the accuracy using GBLUP approaches, demonstrating the feasibility of predicting among different breeding material. Bias-corrected GRMs proved to increase predictive accuracies when compared with standard approaches to construct GRMs. Among the imputation methods we tested, the random forest method yielded the highest predictive accuracy. The combinations of these two methods resulted in a meaningful increase of predictive ability (up to 0.09). The possibility of predicting across individuals and pools provides new opportunities for improving ryegrass breeding schemes.

Restricted glyphosate translocation in Lolium multiflorum is controlled by a single incomplete dominant nuclear gene

ABSTRACTThe mode of inheritance for herbicide resistance was investigated in a population of Lolium multiflorum (Italian ryegrass) with restricted glyphosate translocation mechanism of resistance. The degree of dominance for glyphosate resistance in Italian ryegrass was evaluated in the progenies of F1 families which were created by reciprocal-crossing between resistant (R) and susceptible (S) parental individuals. The results showed an intermediate level of glyphosate resistance for F1 families compared to that of the parental types. The phenotypic resistance segregation was also investigated using backcross families which were created by pair-crossing the F1 individuals to the susceptible population, and the observed segregation values fitted a one-gene model very well. Thus it appears that glyphosate resistance in the Italian ryegrass obtained from a New Zealand vineyard with restricted herbicide translocation is controlled by a single incompletely dominant nuclear gene.

The mechanism of diflufenican resistance and its inheritance in oriental mustard (Sisymbrium orientale L.) from Australia.

An oriental mustard population (P3) collected near Quambatook, Victoria was identified as being resistant to diflufenican by screening with the field rate (200 g a.i. ha-1 ) of the herbicide. The mechanism(s) of diflufenican resistance and its inheritance in this population were therefore investigated. Dose-response experiments confirmed that population P3 was 140-fold more resistant to diflufenican than susceptible populations, as determined by the comparison of 50% lethal (LD50 ) values. The phytoene desaturase (PDS) gene from five individuals each of the S1 [susceptible (S)] and P3 [resistant (R)] populations was sequenced, and a substitution of valine for leucine at position 526 (Leu-526-Val) was detected in all five individuals of P3, but not in the S1 population. Inheritance studies showed that diflufenican resistance is encoded in the nuclear genome and is dominant, as the response to diflufenican at 200 g a.i. ha-1 of F1 families was equivalent to that of the resistant biotype. The segregation of F2 phenotypes fitted a 3:1 inheritance model. Segregation of 42 F2 individuals by genotype sequencing fitted a 1:2:1 (ss:Rs:RR) ratio. Resistance to diflufenican in oriental mustard is conferred by the Leu-526-Val mutation in the PDS gene. Inheritance of resistance is managed by a single gene with high levels of dominance. © 2018 Society of Chemical Industry.