Segregation Of Traits Research Articles

Rare Variant in MRC2 Associated With Familial Supraventricular Tachycardia and Wolff-Parkinson-White Syndrome.

Accessory pathways are a common cause of supraventricular tachycardia (SVT) and can lead to sudden cardiac death in otherwise healthy children and adults when associated with Wolff-Parkinson-White syndrome. The goal of this study was to identify genetic variants within a large family with structurally normal hearts affected by SVT and Wolff-Parkinson-White syndrome and determine causality of the gene deficit in a corresponding mouse model. Whole exome sequencing performed on 2 distant members of a 3-generation family in which multiple members were affected by SVT or Wolff-Parkinson-White pattern (preexcitation) on ECG identified MRC2 as a candidate gene. Serial electrocardiograms, intracardiac electrophysiology studies, echocardiography, optical mapping studies, and histology were performed on both Mrc2 mutant and WT (wild-type) mice. A rare HET (heterozygous) missense variant c.2969A>G;p.Glu990Gly (E990G) in MRC2 was identified as the leading candidate gene variant segregating with the cardiac phenotype following an autosomal-dominant Mendelian trait segregation pattern with variable expressivity. In vivo electrophysiology studies revealed reentrant SVT in E990G mice. Optical mapping studies in E990G mice demonstrated abnormal retrograde conduction, suggesting the presence of an accessory pathway. Histological analysis of E990G mouse hearts showed a disordered ECM (extracellular matrix) in the annulus fibrosus. Finally, Mrc2 knockdown in human cardiac fibroblasts enhanced accelerated cell migration. This study identified a rare nonsynonymous variant in the MRC2 gene in individuals with familial reentrant SVT, Wolff-Parkinson-White ECG pattern, and structurally normal hearts. Furthermore, Mrc2 knock-in mice revealed an increased incidence of reentrant SVT and bypass tract formation in the setting of preserved cardiac structure and function.

Engineering synthetic apomixis in different hybrid rice varieties using the Fix strategy

Hybrid rice breeding has significantly increased the yield and stability of rice production. However, due to trait segregation in F2 progeny seeds, the F1 hybrid seeds must be renewed annually. Apomixis is a form of reproduction leading to clonal seeds, which has a revolutionary potential in fixing heterosis and realizing selfretention of hybrid rice seeds. Previously, we successfully engineered synthetic apomixis in rice by combining Mitosis instead of Meiosis (MiMe) with haploid induction (mutation of MATRILINEAL), a strategy known as Fix for Fixation of hybrids. However, only one hybrid rice variety has been tested for the Fix synthetic apomixis system. In this study, we expanded the application of the Fix strategy and achieved synthetic apomixis in multiple hybrid rice varieties. We observed significant variations in seed setting rate across diverse genetic backgrounds and witnessed a remarkable tenfold increase in clonal seed efficiency. Our findings will provide valuable insights into the application of the Fix strategy for synthetic apomixis in hybrid rice.

Abstract 16457: Characterization of LTBP2 Mutation in Causing Mitral Valve Prolapse

Introduction: Mitral Valve Prolapse (MVP) is a cardiac valvular disorder often associated with significant morbidity and mortality with a prevalence of 2.4% in the general population. Familial studies of MVP suggest an autosomal dominant model of inheritance with incomplete penetrance. Hypothesis: The aim of the current study was to identify a genetic etiology for MVP through trait segregation in a progeny with MVP. Methods: We used exome sequencing and segregation analysis to identify mutations linked to MVP in a progeny which includes members. We then generated two strains of mice using Crisper-Cas9 technology, a complete knockout and a knock-in mouse of the top candidate mutation. At 6 months of age echocardiography was done, the mice were sacrificed and the valves were examined pathologically as well as histologically by Movat pentachrome staining. The readers of both the echo and histology were blinded to the genotype. Results: Of 11 genes with rare deleterious mutations only LTBP2 Val1506Met variant (minor allele frequency of 0.0001) segregated with the trait with a LOD score of 1.5[-DR1] . Knockout mice were more likely to demonstrate myxomatous changes by histology (7 of 9 vs 2 of 6 animals, p=0.03) and echocardiography (14 of 22 vs 1 of 8, p=0.01). Knock-in mice demonstrated significantly higher phenotype rate by histology (8 of 8 vs 0 of 7, p<0.0005) and higher nominal phenotype by echo (4 of10 vs 1 of 9, p=0.2). Conclusions: LTBP2 Val1506Met variant segregated with MVP in a large pedigree. Animal models that recapitulate the phenotype suggest that the mutation is indeed pathogenic and leads to myxomatous valvular change.

Preliminary study on the anti-CO2 stress and growth ability of hypsizygus marmoreus mutant strain HY68

BackgroundA high concentration of CO2 will stagnate the development of the newly formed primordia of Hypsizygus marmoreus, hinder the development of the mushroom cap, thereby inhibiting the normal differentiation of the fruiting body. Moreover, in the previous experiment, our research group obtained the mutant strain HY68 of H. marmoreus, which can maintain normal fruiting under the condition of high concentration of CO2. Our study aimed to evaluate the CO2 tolerance ability of the mutant strain HY68, in comparison with the starting strain HY61 and the control strain HY62. We analyzed the mycelial growth of these strains under various conditions, including different temperatures, pH levels, carbon sources, and nitrogen sources, and measured the activity of the cellulose enzyme. Additionally, we identified and predicted β-glucosidase-related genes in HY68 and analyzed their gene and protein structures.ResultsOur results indicate that HY68 showed superior CO2 tolerance compared to the other strains tested, with an optimal growth temperature of 25 °C and pH of 7, and maltose and beef paste as the ideal carbon and nitrogen sources, respectively. Enzyme activity assays revealed a positive correlation between β-glucosidase activity and CO2 tolerance, with Gene14147 identified as the most closely related gene to this activity. Inbred strains of HY68 showed trait segregation for CO2 tolerance.ConclusionsBoth HY68 and its self-bred offspring could tolerate CO2 stress. The fruiting period of the strains resistant to CO2 stress was shorter than that of the strains not tolerant to CO2 stress. The activity of β-GC and the ability to tolerate CO2 were more closely related to the growth efficiency of fruiting bodies. This study lays the foundation for understanding how CO2 regulates the growth of edible fungi, which is conducive to the innovation of edible fungus breeding methods. The application of the new strain HY68 is beneficial to the research of energy-saving production in factory cultivation.

Telomere-to-telomere assembly of cassava genome reveals the evolution of cassava and divergence of allelic expression.

Cassava is a crucial crop that makes a significant contribution to ensuring human food security. However, high-quality telomere-to-telomere cassava genomes have not been available up to now, which has restricted the progress of haploid molecular breeding for cassava. In this study, we constructed two nearly complete haploid resolved genomes and an integrated, telomere-to-telomere gap-free reference genome of an excellent cassava variety, 'Xinxuan 048', thereby providing a new high-quality genomic resource. Furthermore, the evolutionary history of several species within the Euphorbiaceae family was revealed. Through comparative analysis of haploid genomes, it was found that two haploid genomes had extensive differences in linear structure, transcriptome features, and epigenetic characteristics. Genes located within the highly divergent regions and differentially expressed alleles are enriched in the functions of auxin response and the starch synthesis pathway. The high heterozygosity of cassava 'Xinxuan 048' leads to rapid trait segregation in the first selfed generation. This study provides a theoretical basis and genomic resource for molecular breeding of cassava haploids.

Heterosis for biomass yield and quality traits in a reciprocal cross population between Miscanthus sinensis and Miscanthus lutarioriparius

Heterosis plays an important role in plant breeding and has been widely used in the production of a variety of food crops. However, cross-breeding is particularly important in the breeding of new varieties of the energy crop miscanthus due to its characteristics of self-incompatibility and lack of interspecific reproductive isolation. Therefore, in the current study, 30 direct cross hybrids and 150 reciprocal cross hybrids were obtained from a cross between M. sinensis and M. lutarioriparius. These hybrids were significantly different in phenotype and were used for a detailed analysis of heterosis. The mid-parent, over-parent and over-standard heterosis of the hybrids for yield-related agronomic traits were analyzed. The results showed that the hybrids from direct and reciprocal crosses exhibited significant trait segregation and acquired dominant agronomic traits from both parents, showing mid-parent, over-parent and over-standard heterosis. Plant height, tiller number, stem node number, and stem diameter showed maternal inheritance. Principal component analysis was used to construct the linear combination relationship of yield-related agronomic traits. Excellent hybrids were screened against the commercial miscanthus variety Miscanthus × giganteus. These hybrids were superior to their two parents and M. × giganteus in terms of phenotypic yield-related agronomic traits, biomass yield, and quality. These results not only confirmed the feasibility of breeding miscanthus by remote crosses, but also provided a reference for the application, cross-breeding and breeding of new miscanthus varieties.

Transgressive segregation in mating traits drives hybrid speciation.

Hybridization can rapidly generate novel genetic variation, which can promote ecological speciation by creating novel adaptive phenotypes. However, it remains unclear how hybridization, creating novel mating phenotypes (e.g., mating season, genitalia shapes, sexual displays, mate preferences), affects speciation especially when the phenotypes do not confer adaptive advantages. Here, based on individual-based evolutionary simulations, we propose that transgressive segregation of mating traits can drive incipient hybrid speciation. Simulations demonstrated that incipient hybrid speciation occurred most frequently when the hybrid population received moderate continued immigration from parental lineages causing recurrent episodes of hybridization. Recurrent hybridization constantly generated genetic variation, which promoted the rapid stochastic evolution of mating phenotypes in a hybrid population. The stochastic evolution continued until a novel mating phenotype came to dominate the hybrid population, which reproductively isolates the hybrid population from parental lineages. However, too frequent hybridization rather hindered the evolution of reproductive isolation by inflating the variation of mating phenotypes to produce phenotypes allowing mating with parental lineages. Simulations also revealed conditions for the long-term persistence of hybrid species after their incipient emergence. Our results suggest that recurrent transgressive segregation of mating phenotypes can offer a plausible explanation for hybrid speciation and radiations that involved little adaptive ecological divergence.

Transgressive segregation of morphological traits in populations derived from cross between Solanum habrochaites and Solanum lycopersicum

Objective: Tomato (Solanum lycopersicum L.) is one of the economically important vegetables due to its worldwide economic in both production and consumption. Due to limited genetic diversity among cultivated tomato genetic resources, wild tomato species are commonly used for unlocking the genetic potential and transferring them to cultivated tomato. Solanum habrochaites is one of those wild tomato species that has great genetic potential for improving fruit quality traits in cultivated tomato. Material and Methods: Analysis of segregating populations derived from the cross between Solanum lycopersicum and Solanum habrochaites is important for the identification and introgression of such genetic potential. Therefore, the present study analyzed transgressive segregation of fruit weight, fruit length, fruit diameter and color parameters in F1, F2 and F3 populations. Results: For fruit weight, transgressive segregation was observed in just F3 population and five lines had higher fruit weight than maternal parent. Although S. habrochaites had smaller fruits than cultivated tomato, there was no significant difference between populations. Although transgressive segregation was observed in F2 and F3 populations for fruit length and diameter, there was no significant difference between mean values of populations. Conclusion: The study showed that F3 population is sufficient to select larger fruits derived from S. habrochaites.

Velvet Family Members Regulate Pigment Synthesis of the Fruiting Bodies of Auricularia cornea.

Color is a crucial feature to consider when breeding and improving strains of Auricularia cornea. To uncover the mechanism of white strain formation in A. cornea, this study selected parental strains that were homozygous for the color trait and analyzed the genetic laws of A. cornea color through genetic population construction, such as test-cross, back-cross, and self-cross populations, and the statistical analysis of color trait segregation. Moreover, the study developed SSR molecular markers to construct a genetic linkage map, perform the fine mapping the color-controlling genetic locus, and verify candidate genes using yeast two-hybrid, transcriptome analysis, and different light treatments. The results of the study indicated that the color trait of A. cornea is controlled by two pairs of alleles. When both pairs of loci are dominant, the fruiting body is purple, while when both pairs of loci are recessive or one pair of loci is recessive, the fruiting body is white. Based on the linkage map, the study finely mapped the color locus within Contig9_29,619bp-53,463bp in the A. cornea genome and successfully predicted the color-controlling locus gene A18078 (AcveA), which belongs to the Velvet factor family protein and has a conserved structure domain of the VeA protein. It can form a dimer with the VelB protein to inhibit pigment synthesis in filamentous fungi. Lastly, the study validated the interaction between AcVeA and VelB (AcVelB) in A. cornea at the gene, protein, and phenotype levels, revealing the mechanism of inhibition of pigment synthesis in A. cornea. Under dark conditions, dimerization occurs, allowing it to enter the nucleus and inhibit pigment synthesis, leading to a lighter fruiting body color. However, under light conditions, the dimer content is low and cannot enter the nucleus to inhibit pigment synthesis. In summary, this study clarified the mechanism of white strain formation in A. cornea, which could aid in improving white strains of A. cornea and studying the genetic basis of color in other fungi.

Genetic Diversity of Red Rice (Oryza Sativa L.) Population M2 Results of G16 Rice Genotype Mutations with 200gy and 300gy Gamma Ray Iradiation

Mutational breeding can be used to obtain superior varieties by improving some of the desired traits, without changing most of the good traits. The purpose of this study was to determine the genetic diversity of brown rice through segregation of traits in rice mutants due to gamma ray irradiation at doses of 200 gy and 300 gy. The method used is an experimental method carried out from May to September 2021 with a single plant. The distribution of the data was tested by the Kolmogorov-Smirnov test using software and the segregation ratio suitability test using the Chi-Square method with a 5% significance level. The results showed that the data distribution was normally distributed, meaning that it was controlled by many genes (polygenic). on the quantitative trait whose data distribution is not normally distributed, it indicates that the trait is controlled by simplegenic. The results of the Mendel's ratio suitability test using Chi-Square for quantitative traits that follow the Mendelian ratio, which shows a segregation ratio of 9: 7 (double recessive epistasis) where the same phenotype is produced by both homozygous recessive genotypes and two recessive genes are epistatic to the dominant allele. For traits that do not follow the Mendelian ratio or their modifications, it is assumed that they are controlled by many genes (minor genes) so that individual effects are difficult to distinguish.

Fine mapping and identification of candidate genes for fruit color in pepper (Capsicum chinense)

The quality of pepper fruits is determined by numerous characteristics such as, flavor, color, and nutritional value. Through little is known about it, fruit color impacts breeding preferences in Capsicum chinense in a substantial way. In the present study, two C. chinense germplasms, HNUCC16 (dark green immature and yellow ripe fruit) and HNUCC22 (light green immature and red ripe fruit) were used to produce an F2 population. Based on genotyping-by-sequencing, we constructed a high-density genetic map of the F2 population with 1,347 bin markers and covered 1,206.37 cM in twelve pepper linkage groups. The trait segregation analysis of the F2 population show that the color of immature and mature fruits is controlled by a single locu . Bin markers 19 (chromosome 1) and 849 (Chromosome 6) were closely associated with the locus that regulates the color of immature and ripe fruits, respectively. The transformation of the two bin markers into dCAPS markers indicate that inactive shikimate kinase-like 2 (BC332_00870) may be a strong candidate gene for regulating immature fruit color, and the premature termination mutation of capsanthin–capsorubin synthase (BC332_17237) gene may possibly cause the yellow color in HNUCC16 pepper fruits. Overall, the findings of this study offer fundamental knowledge concerning the development of color and offer a new resource for pepper fruit color genetic improvement and molecular breeding.

Map-based cloning and transcriptome analysis of the more-tiller and small-grain mutant in rice.

A G to T nucleotide substitution of OsTSG2 led to more tillers and smaller grains in rice by participating in phytohormone signal transduction and starch and sucrose metabolism. Rice is one of the most important food crops worldwide. Grain size and tiller number are the most important factors determining rice yield. The more-tiller and small-grain 2 (tsg2) mutant in rice, developed by ethyl methanesulfonate (EMS) mutagenesis, has smaller grains, more tillers, and a higher yield per plant relative to the wild-type (WT). Based on the genetic analysis, the tsg2 traits were conferred by a single recessive nuclear gene located on the long arm of chromosome 2. After fine-mapping the OsTSG2 locus, a G to T nucleotide substitution was identified, which resulted in an A to S mutation in a highly conserved domain of the growth-regulation factor protein. The single-strand conformation polymorphism (SSCP) marker was developed based on the SNP associated with the phenotypic segregation of traits. The functional complementation of OsTSG2 from the tsg2 mutant to the WT led to an increase in grain size and weight. The differentially expressed genes (DEGs) identified by RNA sequencing were involved in phytohormone signal transduction and starch and sucrose metabolism. Enzyme-linked immunosorbent assay (ELISA) analysis detected variation in the indole acetic acid (IAA) and jasmonic acid (JA) content in the tsg2 inflorescence, while the cellular organization, degree of chalkiness, gel consistency, amylose content, and alkaline spreading value were affected in the tsg2 grains. The findings elucidated the regulatory mechanisms of the tsg2 traits. This mutant could be used in marker-assisted breeding for high-yield and good-quality rice.

Which field of research would Gregor Mendel choose in the 21st century?

Gregor Mendel's work on segregation of traits in plants established the basic methodology and rules of genetics. The interruption of Mendel's research activities in 1870 impeded the immediate recognition of the value of his work until the dawn of the 20th century. Only then were his founding laws of genetics validated, propelling the development of biological research toward the birth of molecular biology in the second half of the 20th century. While molecular plant genetics can be viewed as the spiritual heir of Mendel's research, one might wonder whether in the 21st century Gregor Mendel would prefer to practice scientific approaches other than molecular genetics such as population genetics, comparative genomics, or the emerging field of evo-chromo. In this perspective, I review aspects of these fields that might have attracted or perplexed a 21st century Mendel.

Could the Dilatata group of Paspalum be bred as sexual species? A preliminary assessment

AbstractPaspalum dilatatum Poir. is a perennial apomictic and pentaploid South American grass and a very valued forage crop. The species has been available commercially in several parts of the world; however, its low seed production, apomictic reproduction and ergot susceptibility are important limitations for its adoption and breeding. The Dilatata complex includes five sexual tetraploid mostly selfing species, very closely related to P. dilatatum, which can be hybridized in different combinations. To explore the productive potential of breeding this species group as a sexual selfing tetraploid by combining germplasm from different tetraploid sources, a cross was made between Paspalum flavescens and Paspalum plurinerve which showed high productivity and resistance to ergot. The F1 was compared to the parents and 20 F3 families to evaluate the presence of heterosis, and estimate the additive genetic variance and the degree of transgressive segregation for morphological and productive traits. The F1 showed heterosis for dry matter and the number of fertile tillers, while the F3 showed transgressive segregation in more than 30% of the families for most traits. These results show that hybridization at the tetraploid level can generate vigorous and productive recombinants with a high potential to produce promising transgressive segregants. This breeding strategy appears highly promising, supporting further research on the potential of interspecific hybridization in this group.

Loss of chromatin remodeler DDM1 causes segregation distortion in Arabidopsis thaliana.

In ddm1 mutants, the DNA methylation is primarily affected in the heterochromatic region of the chromosomes, which is associated with the segregation distortion of SNPs in the F2 progenies. Segregation distortion (SD) is common in most genetic mapping experiments and a valuable resource to determine how gene loci induce deviation. Meiotic DNA crossing over and SD are under the control of several types of epigenetic modifications. DNA methylation is an important regulatory epigenetic modification that is inherited across generations. In the present study, we investigated the relationship between SD and DNA methylation. The ecotypes Col-0/C24 and chromatin remodeler mutants ddm1-10/Col and ddm1-15/C24 were reciprocally crossed to obtain F2 generations. A total of 300 plants for each reciprocally crossed plant in the F2 generations were subjected to next-generation sequencing to detect the single-nucleotide polymorphisms (SNPs) as DNA markers. All SNPs were analyzed using the Chi-square test method to determine their segregation ratio in F2 generations. Through the segregation ratio, whole-genome SNPs were classified into 16 classes. In class 10, the SNPs in the reciprocal crosses of wild type showed the expected Mendelian ratio of 1:2:1, while those in the reciprocal crosses of ddm1 mutants showed distortion. In contrast, all SNPs in class 16 displayed a normal 1:2:1 ratio, and class 1 showed SD, regardless of wild type or mutants, as assessed using CAPS (cleaved amplified polymorphic sequences) marker analysis to confirm the next-generation sequencing. In ddm1 mutants, the DNA methylation is highly reduced throughout the whole genome and more significantly in the heterochromatic regions of chromosomes. Our results showed that the ddm1 mutants exhibit low levels of DNA methylation, which facilitates the SD of SNPs primarily located in the heterochromatic region of chromosomes by reducing the heterozygous ratio. The present study will provide a strong base for future research focusing on the impact of DNA methylation on trait segregation and plant evolution.

Familial Temperature-Sensitive Auditory Neuropathy: Distinctive Clinical Courses Caused by Variants of the OTOF Gene.

Objective: To investigate the clinical course and genetic etiology of familial temperature-sensitive auditory neuropathy (TSAN), which is a very rare subtype of auditory neuropathy (AN) that involves an elevation of hearing thresholds due to an increase in the core body temperature, and to evaluate the genotype–phenotype correlations in a family with TSAN.Methods: Six members of a non-consanguineous Chinese family, including four siblings complaining of communication difficulties when febrile, were enrolled in this study. The clinical and audiological profiles of the four siblings were fully evaluated during both febrile and afebrile episodes, and the genetic etiology of hearing loss (HL) was explored using next-generation sequencing (NGS) technology. Their parents, who had no complaints of fluctuating HL due to body temperature variation, were enrolled for the genetics portion only.Results: Audiological tests during the patients’ febrile episodes met the classical diagnostic criteria for AN, including mild HL, poor speech discrimination, preserved cochlear microphonics (CMs), and absent auditory brainstem responses (ABRs). Importantly, unlike the pattern observed in previously reported cases of TSAN, the ABRs and electrocochleography (ECochG) signals of our patients improved to normal during afebrile periods. Genetic analysis identified a compound heterozygous variant of the OTOF gene (which encodes the otoferlin protein), including one previously reported pathogenic variant, c.5098G > C (p.Glu1700Gln), and one novel variant, c.4882C > A (p.Pro1628Thr). Neither of the identified variants affected the C2 domains related to the main function of otoferlin. Both variants faithfully cosegregated with TSAN within the pedigree, suggesting that OTOF is the causative gene of the autosomal recessive trait segregation in this family.Conclusion: The presence of CMs with absent (or markedly abnormal) ABRs is a reliable criterion for diagnosing AN. The severity of the phenotype caused by dysfunctional neurotransmitter release in TSAN may reflect variants that alter the C2 domains of otoferlin. The observations from this study enrich the current understanding of the phenotype and genotype of TSAN and may lay a foundation for further research on its pathogenesis.

De novo super-early progeny in interspecific crosses Pisum sativum L.\u2009\xd7\u2009P. fulvum Sibth. et Sm

Earliness in crop plants has a crucial role in avoiding the stress of drought and heat, which are the most important challenging stressors in crop production and are predicted to increase in the near future due to global warming. Furthermore, it provides a guarantee of vegetable production in the short growing season of agricultural lands in the northern hemisphere and at high altitudes. The growing human population needs super early plant cultivars for these agricultural lands to meet future global demands. This study examined de novo super-early progeny, referred to as much earlier than that of the earlier parent, which flowered in 13–17 days and pod setting in 18–29 days after germination, discovered in F2 and studied up to F5 derived from interspecific crosses between garden pea (P. sativum L.) and the most distant relative of pea (P. fulvum Sibth. et Sm.). De novo super-early progeny were found to be earlier by about one month than P. sativum and two months than P. fulvum under short day conditions in the F5 population. In respect of days to flowering and pod setting, de novo super-early progeny had a relatively high level of narrow sense heritability (h2 = 82% and 80%, respectively), indicating that the selections for earliness in segregating populations was effective for improvement of extreme early maturing varieties. De novo super-early progeny could be grown under heat stress conditions due to the escape ability. Vegetable types were not only high yielding but also free of any known undesirable traits from the wild species, such as pod dehiscence and non-uniform maturity. It could be considered complementary to “speed breeding”, possibly obtaining more than six generations per year in a suitable climate chamber. Not only de novo super-early progeny but also transgressive segregation for agro-morphological traits can be created via interspecific crosses between P. sativum and P. fulvum, a precious unopened treasure in the second gene pool. Useful progeny obtained from crossing wild species with cultivated species reveal the importance of wild species.

Morphometric relationships and their contribution to biomass and cannabinoid yield in hybrids of hemp (Cannabis sativa).

The breeding of hybrid cultivars of hemp (Cannabis sativa L.) is not well described, especially the segregation and inheritance of traits that are important for yield. A total of 23 families were produced from genetically diverse parents to investigate the inheritance of morphological traits and their association with biomass accumulation and cannabinoid yield. In addition, a novel classification method for canopy architecture was developed. The strong linear relationship between wet and dry biomass provided an accurate estimate of final dry stripped floral biomass. Of all field and aerial measurements, basal stem diameter was determined to be the single best selection criterion for final dry stripped floral biomass yield. Along with stem diameter, canopy architecture and stem growth predictors described the majority of the explainable variation of biomass yield. Within-family variance for morphological and cannabinoid measurements reflected the heterozygosity of the parents. While selfed populations suffered from inbreeding depression, hybrid development in hemp will require at least one inbred parent to achieve uniform growth and biomass yield. Nevertheless, floral phenology remains a confounding factor in selection because of its underlying influence on biomass production, highlighting the need to understand the genetic basis for flowering time in the breeding of uniform cultivars.

Single-Cell RNA Sequencing Elucidates the Structure and Organization of Microbial Communities.

Clonal bacterial populations exhibit various forms of heterogeneity, including co-occurrence of cells with different morphological traits, biochemical properties, and gene expression profiles. This heterogeneity is prevalent in a variety of environments. For example, the productivity of large-scale industrial fermentations and virulence of infectious diseases are shaped by cell population heterogeneity and have a direct impact on human life. Due to the need and importance to better understand this heterogeneity, multiple methods of examining single-cell heterogeneity have been developed. Traditionally, fluorescent reporters or probes are used to examine a specific gene of interest, providing a useful but inherently biased approach. In contrast, single-cell RNA sequencing (scRNA-seq) is an agnostic approach to examine heterogeneity and has been successfully applied to eukaryotic cells. Unfortunately, current extensively utilized methods of eukaryotic scRNA-seq present difficulties when applied to bacteria. Specifically, bacteria have a cell wall which makes eukaryotic lysis methods incompatible, bacterial mRNA has a shorter half-life and lower copy numbers, and isolating an individual bacterial species from a mixed community is difficult. Recent work has demonstrated that these technical hurdles can be overcome, providing valuable insight into factors influencing microbial heterogeneity. This perspective describes the emerging microbial scRNA-seq toolkit. We outline the benefit of these new tools in elucidating numerous scientific questions in microbiological studies and offer insight about the possible rules that govern the segregation of traits in individual microbial cells.

Comparative study on the growth, survival, gonad development and trait segregation of F2 hybrids and their grandparent species (Crassostrea ariakensis and C. hongkongensis)

In previous studies, we showed that F1 hybrids of Crassostrea ariakensis and C. hongkongensis had faster growth and higher survival rates than the parent species. Further intraspecific crossing of F1 hybrids allowed us to further understand the law of trait segregation and indicated a potential direction for breeding of a new strain with high salinity tolerance and fast growth. In this study, we systematically analyzed the growth, survival, fertility and trait segregation of F2 hybrids and their grandparent species (C. ariakensis and C. hongkongensis) at two sites. Our results confirmed that there were no significant differences in fertilization, cleavage, D larval and survival rates among the three groups of larvae, but the shell heights of F2 hybrids and C. ariakensis were significantly higher than those of C. hongkongensis on the 12th and 16th days. At the high salinity site (Zhulin Pond), the shell heights and survival rates of the F2 hybrids were significantly higher than those of C. hongkongensis from the 90th to the 360th day. However, at the low salinity site (Dafeng River), the F2 hybrids consistently had higher shell heights than C. ariakensis, but there was no significant difference in the survival rates among the three groups. F2 hybrids were classified into three types based on size and number of holes on the gill water tubes, and only F2-A (like C. ariakensis) and F2-H/A (intermediate form) were confirmed to survive at the high salinity site. Moreover, three number of ITS-2 gene fragment were identified in the F2 hybrids, and only A (like C. ariakensis) and HA (like F1 hybrids) existed at the high salinity site. Paraffin sections of gonad tissue confirmed that all three types of F2 hybrids were fertile and could produce mature gametes. In summary, through this comprehensive comparative analysis, we confirmed that F2-A and F2-H/A hybrids had clear advantages in terms of high salinity tolerance and fast growth over their grandparent species, and had potential to be used as the foundations of a new strain.