Superior Phenotypes Research Articles

Transcriptome analysis of hybrid abalone (Haliotis discus hannai ♀ × H. fulgens ♂) reveals non-additive effects contributing to growth heterosis at early summer water temperature in Fujian

Heterosis refers to the superior phenotypes observed in hybrid offsprings relative to their parents with respect to traits such as growth rate and stress resistance. Superior hybrids are widely utilized in aquaculture with large benefits. As a typical example, interspecific hybrid “Lvpan” abalone (Haliotis discus hannai ♀ × H. fulgens ♂) also has excellent growth performance, as well as advantaged thermal tolerance. Nevertheless, the mechanisms responsible for this growth heterosis in “Lvpan” hybrid abalone have remained elusive. In this study, a two-month thermostatic acclimation experiment was conducted for “Lvpan” abalone and its parental species at three temperatures (14, 18, and 24 °C). The results showed that the interspecific hybrid ‘Lvpan’ abalone exhibited significant growth heterosis when compared to its parental species, especially at high temperatures. Transcriptome dynamics in the foot muscles of abalones also unveiled that most genes expression patterns represented to be maternal-biased, which are involved in growth-related process. It indicated that maternal effects on gene expression in hybrid abalones play can play an important role in growth heterosis. Moreover, we observed that most genes expressed non-additively in the hybrid abalone are involved in the regulation of growth and cell differentiation during development, which play pivotal roles in the formation of growth heterosis. Consequently, we have provided new insights into abalone interspecific heterosis, emphasizing the pivotal role that non-additive gene expression plays in generating heterosis through cross-breeding.

The interaction between abiotic and biotic soil factors drive heterosis expression in maize.

Heterosis or hybrid vigor refers to the superior phenotypes of hybrids relative to their parental inbred lines. Recently, soil microbes were identified as an environmental driver of maize heterosis. While manipulation of the soil microbial community consistently altered heterosis, the direction of the effect appeared to be dependent on the microbiome composition, environment, or both. Abiotic factors are well-known modifiers of heterosis expression, however, how the interactive effects between the soil microbial community and abiotic factors contribute to heterosis are poorly understood. To disentangle the proposed mechanisms by which microbes influence heterosis, we characterize the variation in heterosis expression when maize was grown in soil inocula derived from active maize farms or prairies. While we did not observe consistent differences in heterosis among plants grown in these inocula, our observations reaffirm that microbial effects on heterosis are likely specific to the local microbial community. The introduction of a nutrient amendment resulted in greater heterosis expression in the presence of an agricultural inoculum but not a prairie inoculum. We also observed an effect of soil inocula and nutrient treatment on the composition of bacterial and fungal communities in the root endosphere. In addition, the interaction between soil and nutrient treatment significantly affected bacterial community composition, whereas fungal community composition was only marginally affected by this interaction. These results further suggest that the soil microbial community plays a role in maize heterosis expression but that the abiotic environment is likely a larger driver.

Fenotipos sobresalientes de Pinus chiapensis y Pinus douglasiana en rodales bajo manejo forestal en Oaxaca

In some areas of Oaxaca, Mexico, it is necessary to implement plantations that use seeds of genetic quality, to increase productivity and phenotypic quality. The objective was to select outstanding phenotypes of Pinus chiapensis (Martínez) Andresen and P. douglasiana Martínez, evaluating quantitative and qualitative characteristics. In 2021, 15 superior phenotypes per species were selected to evaluate inventory variables (height, diameter), density (trees ha-1), age and chip increments, recording climate and site data. Crown area (m2), basal area (m2) and total volume with bark (VTcc, m3) were determined for each tree; site index (SI) was determined based on anamorphic curves, density guides and average VTcc. Data were analyzed with Student's t tests, Pearson's correlation (a = 0.05), cluster analysis, and principal component analysis. The species showed significant differences (p ≤ 0.01) in dasometric characteristics. Using the average volume as a selection criterion, six P. chiapensis trees presented volumes above average (≥ 9.76 m3) and seven P. douglasiana trees presented volume above average (> 4.14 m3) and clear stem height (18.7 m), in places with high precipitation; while comparing morphological, of site and climatic characteristics, 10 individuals of P. chiapensis and six of P. douglasiana with excellent quality IS were selected. The selected trees have outstanding characteristics of wood quality and volume, so it is convenient to use them to collect seeds in the study area.

DNA hydroxymethylation differences underlie phenotypic divergence of somatic growth in Nile tilapia reared in common garden

ABSTRACTPhenotypic plasticity of metabolism and growth are essential for adaptation to new environmental conditions, such as those experienced during domestication. Epigenetic regulation plays a key role in this process but the underlying mechanisms are poorly understood, especially in the case of hydroxymethylation. Using reduced representation 5-hydroxymethylcytosine profiling, we compared the liver hydroxymethylomes in full-sib Nile tilapia with distinct growth rates (3.8-fold difference) and demonstrated that DNA hydroxymethylation is strongly associated with phenotypic divergence of somatic growth during the early stages of domestication. The 2677 differentially hydroxymethylated cytosines between fast- and slow-growing fish were enriched within gene bodies (79%), indicating a pertinent role in transcriptional regulation. Moreover, they were found in genes involved in biological processes related to skeletal system and muscle structure development, and there was a positive association between somatic growth and 5hmC levels in genes coding for growth factors, kinases and receptors linked to myogenesis. Single nucleotide polymorphism analysis revealed no genetic differentiation between fast- and slow-growing fish. In addition to unveiling a new link between DNA hydroxymethylation and epigenetic regulation of growth in fish during the initial stages of domestication, this study suggests that epimarkers may be applied in selective breeding programmes for superior phenotypes.

Novel evolved Yarrowia lipolytica strains for enhanced growth and lipid content under high concentrations of crude glycerol

BackgroundYarrowia lipolytica is a well-studied oleaginous yeast known for its ability to accumulate and store intracellular lipids, while growing on diverse, non-conventional substrates. Amongst them, crude glycerol, a low-cost by-product of the biodiesel industry, appears to be an interesting option for scaling up a sustainable single-cell oil production process. Adaptive laboratory evolution (ALE) is a powerful tool to force metabolic adaptations endowing tolerance to stressful environmental conditions, generating superior phenotypes with industrial relevance.ResultsY. lipolytica MUCL 28849 underwent ALE in a synthetic medium with increasing concentration of pure or crude glycerol as a stressing factor (9–20% v/v) for 520 generations. In one case of pure glycerol, chemical mutagenesis with ethyl methanesulfonate (EMS) was applied prior to ALE. Growth profile, biomass production and lipid content of 660 evolved strains (EVS), revealed 5 superior isolates; exhibiting from 1.9 to 3.6-fold increase of dry biomass and from 1.1 to 1.6-fold increase of lipid concentration compared to the parental strain, when grown in 15% v/v crude glycerol. NGS for differential gene expression analysis, showed induced expression in all EVS affecting nucleosomal structure and regulation of transcription. As strains differentiated, further changes accumulated in membrane transport and protein transport processes. Genes involved in glycerol catabolism and triacylglycerol biosynthesis were overexpressed in two EVS. Mismatches and gaps in the expressed sequences identified altered splicing and mutations in the EVS, with most of them, affecting different components of septin ring formation in the budding process. The selected YLE155 EVS, used for scale-up cultivation in a 3L benchtop bioreactor with 20% v/v crude glycerol, achieved extended exponential phase, twofold increase of dry biomass and lipid yields at 48 h, while citric acid secretion and glycerol consumption rates were 40% and 50% lower, respectively, compared to the parental strain, after 24 h of cultivation.ConclusionALE and EMS-ALE under increasing concentrations of pure or crude glycerol generated novel Y. lipolytica strains with enhanced biomass and lipid content. Differential gene expression analysis and scale-up of YLE155, illustrated the potential of the evolved strains to serve as suitable “chassis” for rational engineering approaches towards both increased lipid accumulation, and production of high-added value compounds, through efficient utilization of crude glycerol.

Breeding strategy and contract farming model to promote Boer Cross population continuity: A case study at Sadhana Arif Nusa Company Lombok Island West Nusa Tenggara Province, Indonesia)

<p><strong>Objective</strong>: This study aims to analyze population development strategies and contract farming models with East Lombok regency West Nusa Tenggara province farmers. This research was focused on SAN-C which is very concerned with the development of Boer goats and employing the people of East Lombok.</p><p><strong>Methods</strong>: The study employed action research. Boer cross-goats data was obtained from the log book of SAN-C. Supporting data were obtained from in-depth interviews and FGDs with representatives of farmers, livestock traders, representatives of the East Lombok district government, and management representatives of SAN-C.</p><p><strong>Results</strong>: This study found that the previous contract farming model with the credit system was changed to a profit-sharing system based on the weight of the goat. That is the difference in the final weight minus the initial weight multiplied by the price per kilogram divided by two. One part is for partners, and the other part is for SAN-C. Thus, the income for farmers is close to the minimum standard wage for the district of East Lombok.</p><p><strong>Conclusion</strong>: By applying a new breeding strategy and contract farming models, the population of Boer cross increased sustainably. Similarly, the income of farmers will also increase. It is recommended that the new contract farming model can be applied to other farmers all over WNT. It was also recommended that both SAN-C and must make a selection, especially for F2 and F3 with the most superior phenotypes as stock breeders. Finally, excess feed production in the rainy season should be stored in the form of hay or silage to overcome the shortage of feed in the dry season.</p>

Morphoagronomic characterization and production gain after two mass selection cycles in Nawa Sheki landraces maize originated from the Western Brazilian Amazon

Intensive breeding and artificial selection of the desired traits in maize landraces through domestication have created modern maize, which needs a great technological contribution for optimal productive development. However, the narrowing of the genetic bases of maize made it difficult for traditional farmers to access productive genetic material that maintains the genotypic and phenotypic diversity capable of ensuring productive sustainability. Thus, objective of the study was to evaluate the variability and production gain in morphoagronomic characters of Nawa Sheki landraces maize after two mass selection cycles. The work was carried out in the experimental area of the Federal University of Acre, where two cycles of mass selection were applied on variety Nawa Sheki, in periods 2018/2019 and 2019/2020. The characteristics evaluated were: plant height, ear insertion height, ear length, ear diameter, number of rows of grains, number of grains per row, ear mass and grain mass. Data were submitted to descriptive analysis, with presentation of the histogram of frequency, asymmetry, kurtosis and Shapiro-Wilk test for the general population in both cycles. For the selected population, the following were obtained: mean, coefficient of variation, amplitude, minimum and maximum values and population variance in each cycle. The genetic parameters were selection differential for both cycles, production gain with selection and realized heritability of the first cycle. The choice of individuals in both cycles of mass selection was based on the ranking of the best values of the evaluated characteristics. The two cycles of mass selection provided high variability in the traits with the presence of superior phenotypes. Still, mass selection stabilized values for plant height, ear insertion height, followed by production gains for number of grains per row and ear mass.

Mining microbial resources from water

In the past two decades, the concept of microbial resources evolved from the conserved strains in culture collection centers and microbial genome data in databases to functional microbial consortia, strains with superior phenotypes, novel biochemical and signaling systems, highly efficient enzymes, secondary metabolites, and unique genetic traits. Natural and engineered water environments provide diverse ecological niches for microorganisms to evolve and thrive, serving as treasure troves of microbial resources. Compared with that of chemical and energy resources from water, mining of microbial resources is severely underexplored. In this review, we first summarize various approaches (e.g., cultivation, functional metagenomics, and single-cell genomics) that have been employed to mine microbial resources from water, and then discuss their distinctive advantages and limitations. Lastly, we explore future directions on the mining of microbial resources from water.

HEAT AND DROUGHT FORBEARING, UPLAND COTTON (GOSSYPIUM HIRSUTUM L.) VARIETY; RH-668 FOR CULTIVATION IN SEMI-ARID REGION

Cotton variety: RH-668, produced by Cotton Research Institute, Khanpur, holds excessive tolerance against dry climatic stipulations and maintains superior fiber personae.Parental combination;VH-259 × RH-620 was used in hybridization followed by Pedigree method of selection to extract uniform genotypes with superior phenotypes. These superior plantswere then tested for yield under drought stress at station level before competing atseries of adaptability trials in Punjab followed by provincialand national coordinated varietal trials in the course of 2013-2018. Due to governance incorporated by tolerance against heat & drought it outperformed others at various climatic conditions countrywide for yield and fiber linked characters in opposition to the Standards varieties FH-142 &CIM-602. In Provincial (PCCT) and National level(NCVT) it gave 29.0% & 8.8%, respectively more yield when compared to check variety; FH-142. Hence, Accredited by seed Council, Punjab in 2018 for generic cultivation with 39.4 Ginning outturn percentage, 4.5 micronaire value, staple length of 28.78 (mm) and seed-cotton yield prospectiveper acre ofsixty twomounds.Due to fruiting from lower nodes; erect root development, Brittle leaf surface, lesser shedding of fruiting structures and protracted sympods with bead like bolls arrangement, it deliberately tolerates heat stress.

Mapping QTLs for anaerobic tolerance at germination and bud stages using new high density genetic map of rice.

Due to its low cost and convenience, direct seeding is an efficient technique for the production of rice in different rice growing areas. However, anaerobic conditions are a major obstacle to the direct seeding of rice and result in poor seedling establishment, which leads to yield losses. We constructed a collection of recombinant inbred lines (RIL) comprising 275 lines derived from the H335 and CHA-1 cross by the method of single seed descent. Via a genotyping-by-sequencing (GBS) strategy, a high-density genetic map containing 2498 recombination bin markers was constructed, the average physical distance between the markers was only 149.38 Kb. After anaerobic treatment, 12 phenotypes related to both the coleoptile at germination and seedling quality at budding were evaluated. There were no significant correlations between seedling and bud traits. Genetic mapping of quantitative traits was performed for these traits across two cropping seasons. A total of 20 loci were detected, named locus 1~20. Three of them were repeatedly detected across both seasons. Six loci overlapped with those in previous reports, and nine loci were associated with multiple traits at both stages. Notably, locus 3, which is located on chromosome 2 (26,713,837 to 27,333,897 bp), was detected for both the germination and bud traits. By focusing on the locus 3 interval and by combining gene annotation and expression analyses, we identified a promising candidate gene, trehalose-6-phosphate phosphatase (OsTPP1, LOC_Os02g44230). Furthermore, RILs (G289, G379, G403, G430 and G454) that have superior phenotypes and that pyramid elite alleles were recognized. The findings of present study provide new genetic resources for direct-seeding rice (DSR) varieties for molecular breeding strategies and expand our knowledge of genetic regulation of seedling establishment under anaerobic conditions.

Are Copy Number Variations within the FecB Gene Significantly Associated with Morphometric Traits in Goats?

Simple SummaryThe Booroola fecundity (FecB) gene, as a major fertility-related gene in sheep, is currently attracting considerable attention. While first discovered in sheep, determining whether FecB is a vital gene in goats has recently become a major research interest. Contemporary research has addressed this issue and discovered that several FecB variations in goats are significantly associated with litter size in goats. Given that growth development is positively associated with litter size, FecB may also exert a significant effect on goat morphometric traits. Five copy number variations (CNVs) of the FecB gene were tested in Shaanbei white cashmere (SBWC, n = 318), Guizhou Heima (GZHM, n = 203), and Nubian (n = 120) goats, all of which were significantly associated with body morphometric traits in the Shaanbei white cashmere goats (p < 0.05). Notably, individuals with the normal type of CNV3 consistently displayed a superior phenotype in litter size and morphometric traits, which allows its use as an effective marker for goat breeding.The Booroola fecundity (FecB) gene is a major fertility-related gene first identified in Booroola sheep. Numerous studies have investigated whether the FecB gene is a major fecundity gene in goats or whether there are other genes that play a critical role in goat fertility. Nevertheless, little attention has been paid to the role of the FecB gene in the body morphometric traits of goats, despite the positive relationship discerned between litter size and growth. We identified five copy number variations (CNVs) within the FecB gene in 641 goats, including 318 Shaanbei white cashmere (SBWC) goats, 203 Guizhou Heima (GZHM) goats, and 120 Nubian goats, which exhibited different distributions among these populations. Our results revealed that these five CNVs were significantly associated with goat morphometric traits (p < 0.05). The normal type of CNV3 was the dominant type and displayed superior phenotypes in both litter size and morphometric traits, making it an effective marker for goat breeding. Consequently, LD blocks in the region of 10 Mb upstream and downstream from FecB and potential transcription factors (TFs) that could bind with the CNVs were analyzed via bioinformatics. Although no significant LD block was detected, our results illustrated that these CNVs could bind to growth-related TFs and indirectly affect the growth development of the goats. We identified potential markers to promote litter size and growth, and we offer a theoretical foundation for further breeding work.

The Exploitation of Orphan Legumes for Food, Income, and Nutrition Security in Sub-Saharan Africa

Poverty, food, and nutrition insecurity in sub-Saharan Africa (SSA) have become major concerns in recent times. The effects of climate change, drought, and unpredictable rainfall patterns threaten food production and sustainable agriculture. More so, insurgency, youth restiveness, and politico-economic instability amidst a burgeoning population requiring a sufficient and healthy diet remain front-burner issues in the region. Overdependence on only a few major staple crops is increasingly promoting the near extinction of many crops, especially orphan legumes, which possess immense potentials as protein and nutritional security crops. The major staple crops are declining in yield partly to their inability to adapt to the continuously changing climatic conditions. Remarkably, the orphan legumes are climate-smart crops with enormous agronomic features which foster sustainable livelihood. Research efforts on these crops have not attained a reasonable comparative status with most commercial crops. Though many research organizations and scientists have made efforts to promote the improvement and utilization of these orphan legumes, there is still more to be done. These legumes’ vast genetic resources and economic utility are grossly under-exploited, but their values and promising impacts are immeasurable. Given the United Nations sustainable development goals (SDGs) of zero hunger, improved nutrition, health, and sustainable agriculture, the need to introduce these crops into food systems in SSA and other poverty-prone regions of the world is now more compelling than ever. This review unveils inherent values in orphan legumes needing focus for exploitation viz-a-viz cultivation, commercialization, and social acceptance. More so, this article discusses some of the nutraceutical potentials of the orphan legumes, their global adaptability, and modern plant breeding strategies that could be deployed to develop superior phenotypes to enrich the landraces. Advanced omics technologies, speed breeding, as well as the application of genome editing techniques, could significantly enhance the genetic improvement of these useful but underutilized legumes. Efforts made in this regard and the challenges of these approaches were also discussed.

Single-molecule real-time transcript sequencing of developing cotton anthers facilitates genome annotation and fertility restoration candidate gene discovery

Heterosis refers to the superior phenotypes observed in hybrids. Cytoplasmic male sterility (CMS) system plays an important role in cotton heterosis utilization. However, the global gene expression patterns of CMS-D2 and its interaction with the restorer gene Rf1 remain unclear. Here, the full-length transcript sequencing was performed in anthers of the CMS-D2 restorer line using PacBio single-molecule real-time sequencing technology. Combining PacBio SMRT long-read isoforms and Illumina RNA-seq data, 107,066 isoforms from 44,338 loci were obtained, including 10,086 novel isoforms of novel genes and 66,419 new isoforms of known genes. Totally 56,572 alternative splicing (AS) events, 1146 lncRNAs, 61 fusion transcripts and 10,466 genes exhibited alternative polyadenylation (APA), and 60,995 novel isoforms with predicted open reading frames (ORFs) were further identified. Furthermore, the specifically expressed genes in restorer line were selected and confirmed by qRT-PCR. These findings provide a basis for upland cotton genome annotation and transcriptome research, and will help to reveal the molecular mechanism of interaction between Rf1 and CMS-D2 cytoplasm.

Two strongly linked blocks within the KIF16B gene significantly influence wool length and greasy yield in fine wool sheep (Ovis aries)

A previous genome-wide association study (GWAS) identified the kinesin family member 16B (KIF16B) as a candidate gene related to sheep wool production. In this work, DNA pool sequencing and SNPscanTM high-throughput genotyping methods were used to detect single-nucleotide polymorphisms (SNPs) in the sheep KIF16B gene. The correlations between the SNPs and wool length and greasy wool yield were systematically assessed. Forty-five SNPs were identified and 37 of them were genotyped, including 10 exon mutations, 26 intron mutations, and 1 promoter region mutation. Most of the SNPs were of medium genetic diversity and at Hardy-Weinberg equilibrium (HWE). Among them, 10 SNPs were associated with greasy wool yield and 28 SNPs impact the wool length. Five specific SNPs were found to exert significant effects on the wool length in all body parts analyzed in this study. Furthermore, linkage disequilibrium (LD) analysis was conducted among SNP loci and they were found to be significantly associated with economically important traits. Two strongly linked SNP blocks were identified within these SNPs and they might exert significant impacts on the greasy wool yield and wool length. The identified SNPs exert significant effects on wool production and could be considered as potential DNA markers for selecting the individuals with superior phenotypes. How to cite: Zhao H, Hu R, Li F, et al. Two strongly linked blocks within the KIF16B gene significantly influence wool length and greasy yield in fine wool sheep (Ovis aries). Electron J Biotechnol 2021:53. https://doi.org/10.1016/j.ejbt.2021.05.003

Microbe-dependent heterosis in maize.

Hybrids account for nearly all commercially planted varieties of maize and many other crop plants because crosses between inbred lines of these species produce first-generation [F1] offspring that greatly outperform their parents. The mechanisms underlying this phenomenon, called heterosis or hybrid vigor, are not well understood despite over a century of intensive research. The leading hypotheses-which focus on quantitative genetic mechanisms (dominance, overdominance, and epistasis) and molecular mechanisms (gene dosage and transcriptional regulation)-have been able to explain some but not all of the observed patterns of heterosis. Abiotic stressors are known to impact the expression of heterosis; however, the potential role of microbes in heterosis has largely been ignored. Here, we show that heterosis of root biomass and other traits in maize is strongly dependent on the belowground microbial environment. We found that, in some cases, inbred lines perform as well by these criteria as their F1 offspring under sterile conditions but that heterosis can be restored by inoculation with a simple community of seven bacterial strains. We observed the same pattern for seedlings inoculated with autoclaved versus live soil slurries in a growth chamber and for plants grown in steamed or fumigated versus untreated soil in the field. In a different field site, however, soil steaming increased rather than decreased heterosis, indicating that the direction of the effect depends on community composition, environment, or both. Together, our results demonstrate an ecological phenomenon whereby soil microbes differentially impact the early growth of inbred and hybrid maize.

A standardised approach for determining heat tolerance in cotton using triphenyl tetrazolium chloride

Improving the heat tolerance of cotton is a major concern for breeding programs. To address this need, a fast and effect way of quantifying thermotolerant phenotypes is required. Triphenyl tetrazolium chloride (TTC) based enzyme viability testing following high-temperature stress can be used as a vegetative heat tolerance phenotype. This is because when live cells encounter a TTC solution, TTC undergoes a chemical reduction producing a visible, insoluble red product called triphenyl formazan, that can be quantified spectrophotometrically. However, existing TTC based cell viability assays cannot easily be deployed at the scale required in a crop improvement program. In this study, a heat stress assay (HSA) based on the use of TTC enzyme viability testing has been refined and improved for efficiency, reliability, and ease of use through four experiments. Sampling factors that may influence assay results, such as leaf age, plant water status, and short-term cold storage, were also investigated. Experiments conducted in this study have successfully downscaled the assay and identified an optimal sampling regime, enabling measurement of large segregating populations for application in breeding programs. The improved HSA methodology is important as it is proposed that long-term improvements in cotton thermotolerance can be achieved through the concurrent selection of superior phenotypes based on the HSA and yield performance in hot environments. Additionally, a new way of interpreting both heat tolerance and heat resistance was developed, differentiating genotypes that perform well at the time of a heat stress event and those that maintain a similar performance level to a non-stressed control.

Establishment of genomic library technology mediated by non-homologous end joining mechanism in Yarrowia lipolytica.

Genomic variants libraries are conducive to obtain dominant strains with desirable phenotypic traits. The non-homologous end joining (NHEJ), which enables foreign DNA fragments to be randomly integrated into different chromosomal sites, shows prominent capability in genomic libraries construction. In this study, we established an efficient NHEJ-mediated genomic library technology in Yarrowia lipolytica through regulation of NHEJ repair process, employment of defective Ura marker and optimization of iterative transformations, which enhanced genes integration efficiency by 4.67, 22.74 and 1.87 times, respectively. We further applied this technology to create high lycopene producing strains by multi-integration of heterologous genes of CrtE, CrtB and CrtI, with 23.8 times higher production than rDNA integration through homologous recombination (HR). The NHEJ-mediated genomic library technology also achieved random and scattered integration of loxP and vox sites, with the copy number up to 65 and 53, respectively, creating potential for further application of recombinase mediated genome rearrangement in Y. lipolytica. This work provides a high-efficient NHEJ-mediated genomic library technology, which enables random and scattered genomic integration of multiple heterologous fragments and rapid generation of diverse strains with superior phenotypes within 96 h. This novel technology also lays an excellent foundation for the development of other genetic technologies in Y. lipolytica.

Recurrent selection method for improvement of lutein and zeaxanthin in orange waxy corn populations

The information on the responses to simple recurrent selection for yield and total carotenoid content in orange waxy corn is lacking. The objectives were to evaluate the responses to simple recurrent selection for two cycles for yield and carotenoids of orange waxy corn population and to investigate the correlations between color parameter with carotenoids in waxy corn kernels. Parental sources of germplasm with differences in kernel colors and levels of disease resistance were used for generation of a base population of orange waxy corn. A simple recurrent selection for superior phenotypes was practiced on this population for two selection cycles. Cycle 0 (C0), C1 and C2 were evaluated for two locations in 2016. The cycles showed significant differences for most traits except for plant height. The locations contributed to large portions of total variation in total yield, whereas selection cycle contributed to large portions of total variations in lutein, zeaxanthin, β-carotene and total carotenoid content and color parameter (ho), indicating that selection for carotenoids would be possible. Simple recurrent selection for two cycles increased total yield and husked ear weight of 23.2% and 15.0%, respectively. Simple recurrent selection for two cycles also increased lutein, zeaxanthin, β-carotene and total carotenoid content with increasing percentages ranging from 18.5 to 196.6%. The results indicated that population improvement by simple recurrent selection could be useful in increasing these traits. Color parameter at immature stage and dry stage was negatively and significantly correlated with lutein, zeaxanthin, β-carotene and total carotenoid content, indicating that color parameter can be used as an indirect selection criterion for these traits.

Clostridium acetobutylicum grows vegetatively in a biofilm rich in heteropolysaccharides and cytoplasmic proteins

BackgroundBiofilms are cell communities wherein cells are embedded in a self-produced extracellular polymeric substances (EPS). The biofilm of Clostridium acetobutylicum confers the cells superior phenotypes and has been extensively exploited to produce a variety of liquid biofuels and bulk chemicals. However, little has been known about the physiology of C. acetobutylicum in biofilm as well as the composition and biosynthesis of the EPS. Thus, this study is focused on revealing the cell physiology and EPS composition of C. acetobutylicum biofilm.ResultsHere, we revealed a novel lifestyle of C. acetobutylicum in biofilm: elimination of sporulation and vegetative growth. Extracellular polymeric substances and wire-like structures were also observed in the biofilm. Furthermore, for the first time, the biofilm polysaccharides and proteins were isolated and characterized. The biofilm contained three heteropolysaccharides. The major fraction consisted of predominantly glucose, mannose and aminoglucose. Also, a great variety of proteins including many non-classically secreted proteins moonlighting as adhesins were found considerably present in the biofilm, with GroEL, a S-layer protein and rubrerythrin being the most abundant ones.ConclusionsThis study evidenced that vegetative C. acetobutylicum cells rather than commonly assumed spore-forming cells were essentially the solvent-forming cells. The abundant non-classically secreted moonlighting proteins might be important for the biofilm formation. This study provides the first physiological and molecular insights into C. acetobutylicum biofilm which should be valuable for understanding and development of the biofilm-based processes.

DIFERENCIAS ENTRE EL MEJORAMIENTO GENÉTICO CLÁSICO DEL MAÍZ Y EL MEJORAMIENTO POR INGENIERÍA GENÉTICA

&#x0D; &#x0D; &#x0D; En este ensayo se analizan dos aseveraciones: a) no hay diferencias fundamentales entre el mejoramiento genético clásico (MGC) o fitomejoramiento, y el mejoramiento por ingeniería genética (MIG); este último es una extensión del primero pero es más preciso, por lo que da mayor seguridad al consumidor; y b) la transformación por ingeniería genética es equivalente a una mutación natural. Se concurre con la afirmación de que el MGC y el MIG persiguen objetivos que pueden ser complementarios; sin embargo, sus fundamentos, métodos e implicaciones biológicas son fundamentalmente distintos: el MGC funciona dentro de los límites de la compatibilidad sexual, usando a la diversidad genética de la especie como fuente de ADN favorable, lo que le confiere la precisión y mecanismos de recombinación de la reproducción sexual. El MIG recurre al ADN foráneo integrado en una quimera transgénica, que se inserta con imprecisión conocida en el espacio cromosómico del transformando, y genera un diferente locus en cada evento transgénico independiente. Tal dispersión puede conducir a la acumulación de quimeras transgénicas en sus progenies, y posibles efectos deletéreos. Al excluir a los caracteres fenotípicos de tipo cuantitativo como el rendimiento, el MIG depende de los avances logrados por el MGC para desarrollar fenotipos superiores. También se concurre con la aseveración de que la inserción transgénica es una mutación con diferentes implicaciones para el genoma del maíz. La expresión de cada alelo es regulada por el genoma y epigenoma para activarse o desactivarse de acuerdo con un plan de crecimiento de desarrollo del genotipo. En cambio, el mutante transgénico se expresa somáticamente (en todas las células de la planta, sin pausa).&#x0D; &#x0D; &#x0D;