Yield Of F1 Research Articles

Technological characteristics of tofu from soybean coagulated with cardoon flower extract.

The objective of the present study was to develop tofu with soybean-water soluble extract coagulated with cardoon flower (F1) and magnesium chloride (MgCl2, F2). The produced tofu was characterized in terms of physical, chemical, microbiological, and sensory properties during 14days of storage. The yield of F1 was higher (p < 0.05) (195g/100 soybean seeds) than F2 (162g/100 soybean seeds). F1 presented higher moisture, protein, acidity, syneresis, and lipids when compared with F2, and a reduction of these contents during the storage. F1 presented lower hardness, stickiness, springiness, and cohesiveness compared with F2. The acceptability of F1 showed a score of 6.00 and F2 of 4.68, and the purchase intention was 3.22 for F1 and 2.23 for F2. This study recommended the use of cardoon flower at 35% level as it has great potential as a coagulant for the elaboration of tofu with higher yield, and acceptability and reasonable purchasing intention.

Modeling the influence of phenotypic plasticity on maize hybrid performance

Phenotypic plasticity, the ability of an individual to alter its phenotype in response to changes in the environment, has been proposed as a target for breeding crop varieties with high environmental fitness. Here, we used phenotypic and genotypic data from multiple maize (Zea mays L.) populations to mathematically model phenotypic plasticity in response to the environment (PPRE) in inbred and hybrid lines. PPRE can be simply described by a linear model in which the two main parameters, intercept a and slope b, reflect two classes of genes responsive to endogenous (class A) and exogenous (class B) signals that coordinate plant development. Together, class A and class B genes contribute to the phenotypic plasticity of an individual in response to the environment. We also made connections between phenotypic plasticity and hybrid performance or general combining ability (GCA) of yield using 30 F1 hybrid populations generated by crossing the same maternal line with 30 paternal lines from different maize heterotic groups. We show that the parameters a and b from two given parental lines must be concordant to reach an ideal GCA of F1 yield. We hypothesize that coordinated regulation of the two classes of genes in the F1 hybrid genome is the basis for high GCA. Based on this theory, we built a series of predictive models to evaluate GCA in silico between parental lines of different heterotic groups.

Perbaikan Sudut Daun Populasi Komposit Tanaman Jagung Melalui Hibridisasi Dengan Varietas Hibrida

This study aims to determine the average leaf angle, harvest age and yield of F1 from cross-hybrid composite; heterosis value and knowing the maternal effect of these three traits on maize. The experiment was carried out in technically irrigated rice fields from November 2019 to February 2020. The design used in this experiment was a randomized block design with two replications. The treatment was 28 F1 as a result of crossing P8IS vs NK212 and P8IS vs NK7328 and their respective reciprocal crosses. The experimental data were analyzed by means of analysis of variance and further tested with the LSD test at the 5 percent level. Heterosis values were calculated on the basis of the parents whose scores were higher (High Parent Heterosis). The t test at the 5% level was used to determine whether the maternal effect was significant. The results showed that the mean leaf angles of F1 lines from crosses and reciprocal P8IS vs NK212 were the same as the two parents; whereas the P8IS vs NK7328 cross is different. The reciprocal of cross number 13 (P8IS vs Nk7328 /R13) has smaller leaf angle than P8IS and is the same as the leaf angle of NK7328. The yield of the F1 lines from the two types of crosses was the same as each of the two parents; however, there was a tendency for an increase in yield compared to P8IS for most of the F1 lines. There was a change in leaf angle properties, harvest age and yield of F1 lines compared to one of the best parents with heterosis values are negative and positive with variations from 0.00 to 65.70 percent. Coefficient of correlation between heterosis with the average value of traits was classified as strong for the harvest age; moderate for yield and weak for leaf angle. These three traits in the two types of crosses showed no maternal effects. Smaller leaf angle, super early harvest age and higher yield, are possible to be obtained from the lines of both crosses.

Genome optimization via virtual simulation to accelerate maize hybrid breeding.

The employment of doubled-haploid (DH) technology in maize has vastly accelerated the efficiency of developing inbred lines. The selection of superior lines has to rely on genotypes with genomic selection (GS) model, rather than phenotypes due to the high expense of field phenotyping. In this work, we implemented 'genome optimization via virtual simulation (GOVS)' using the genotype and phenotype data of 1404 maize lines and their F1 progeny. GOVS simulates a virtual genome encompassing the most abundant 'optimal genotypes' or 'advantageous alleles' in a genetic pool. Such a virtually optimized genome, although can never be developed in reality, may help plot the optimal route to direct breeding decisions. GOVS assists in the selection of superior lines based on the genomic fragments that a line contributes to the simulated genome. The assumption is that the more fragments of optimal genotypes a line contributes to the assembly, the higher the likelihood of the line favored in the F1 phenotype, e.g. grain yield. Compared to traditional GS method, GOVS-assisted selection may avoid using an arbitrary threshold for the predicted F1 yield to assist selection. Additionally, the selected lines contributed complementary sets of advantageous alleles to the virtual genome. This feature facilitates plotting the optimal route for DH production, whereby the fewest lines and F1 combinations are needed to pyramid a maximum number of advantageous alleles in the new DH lines. In summary, incorporation of DH production, GS and genome optimization will ultimately improve genomically designed breeding in maize. Short abstract: Doubled-haploid (DH) technology has been widely applied in maize breeding industry, as it greatly shortens the period of developing homozygous inbred lines via bypassing several rounds of self-crossing. The current challenge is how to efficiently screen the large volume of inbred lines based on genotypes. We present the toolbox of genome optimization via virtual simulation (GOVS), which complements the traditional genomic selection model. GOVS simulates a virtual genome encompassing the most abundant 'optimal genotypes' in a breeding population, and then assists in selection of superior lines based on the genomic fragments that a line contributes to the simulated genome. Availability of GOVS (https://govs-pack.github.io/) to the public may ultimately facilitate genomically designed breeding in maize.

The eggplant yield and fruit composition as affected by genetic factor and biostimulant application

Consumer demands regarding eggplant fruits are focused on perfect shape, color, and taste but nutritional and bioactive quality has also become important with rising awareness of food related health. On the other hand, producers value modern cultivars’ earliness, high-yielding, stress-tolerance, and high overall fruit quality. We attempt to link these two standpoints through combining modern hybrids cultivated in the open field of temperate climatic zone with biostimulant application to increase the dynamics of yielding and the quality of fruits. The aim of our research was the determination of the genotypic-dependent response of eggplant (Solanum melongena L.) to Ascophyllum nodosum standardized extract (Göemar BM-86) application in field conditions of Poland, with respect to the most important characteristics linked to yield quality and plant stress status. The early and total yield of investigated hybrids was affected by biostimulant application, and this dependence was confirmed statistically for most of the treatments. The increase of ‘Epic’ F1 and ‘Flavine’ F1 yield potential through Göemar BM-86 application was linked to higher fruit number harvested from the plants, while ‘WA 6020’ F1 led to greater fruit weight. Investigated hybrids responded differently to biostimulant treatment with respect to dietary and pro-health value of fruits. Generally, the content of soluble sugar, anthocyanins, and mineral elements as well as was antioxidant activity of fruits were positively affected by biostimulant application. This tendency was statistically confirmed for several experimental treatments. Presented results give a new perspective on seaweed-based biostimulants as elicitors of crop’s self defense mechanisms as well as modulators of fruit setting, productivity and bioactive compounds accumulation in eggplant.&#x0D; &#x0D; *********&#x0D; In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.&#x0D; *********

Characterizations of male sterility in a glyphosate-tolerant upland cotton (Gossypium hirsutum L.) induced by glyphosate and its assessments on safety utilization

Productivity of hybrid cottonseed by steady male sterile line is considered as an effective strategy in heterosis utilization. The male sterility was obtained by glyphosate application on transgenic glyphosate-tolerant (TGT) cotton line GRR, and its phenotypes were stable and apparent from previous primarily study. Systematic characterizations and safety assessments on the male sterility must accelerate its utilization and release in hybrid cottonseeds productions. In this study, featured characteristics in the male sterility were revealed from morphological phenotype, microsporogenesis, expressing pattern of exogenous G6-EPSPS mRNA, antioxidant enzymes response. Additionally, safety assessments on the male sterility obtained from GRR, based on outcrossing rate test, yield and fiber quality traits, in comparison with conventional manual emasculating, which were conducted for 3 seasons. The results indicated that the male sterile is stable with typical characteristics as following: (1) shorter and fusion filaments, larger distance between androecium and stigma, and anther indehiscence; (2) pre-degradation on tapetum and “cavitation” pollen during microsporogenesis; (3) Higher increasing expression efficiency of G6-EPSPS, as much as approximate 8 times, in pistil versus stamen in GRR-GT (GRR after glyphosate) was revealed, comparing with the control GRR (4) APX activity increased in stamens while decreased in other organs, in GRR-GT versus GRR. GRR-GT is safe as complete abortion and capable in cotton heterosis utilization, since there were no negative effects on F1 yield traits and significance in fiber quality parameters, in comparison with conventional manual emasculation. In details, the all fiber lint yields and Micronaire values ranged from 1536.80 ± 115.64 to 1883.90 ± 18.58 kg/ha and 4.60 ± 0.10 to 5.10 ± 0.79 respectively.

Effects of irrigation and fertilizer levels on the distribution of water and salt in saline field and maize yield

Agriculture development in arid and semi-arid saline areas is seriously affected by water resources scarcity and excessive fertilization. Understanding the effects of different irrigation and fertilization levels on soil water and salt distribution and silage maize yield would provide scientific basis for determining appropriate irrigation and fertilization amount. The experiment was carried out in a saline field of the Datong Basin in 2015 and 2016. There were three irrigation levels, with the upper limit of soil moisture being controlled at 100% (W1), 90% (W2) and 80% (W3) of the field water capacity. Irrigation amount was calculated based on the average actual water content before irrigation of each treatment. There were four fertilization levels in 2015, 900 kg·hm-2 (F1), 750 kg·hm-2 (F2), 600 kg·hm-2(F3), and 450 kg·hm-2(F4), and three levels in 2016 (F1, F2, and F3). The total nutrient content of the slow-release compound fertilizer was 48%, with a 30:12:6 ratio of N:P2O5:K2O. Results showed that the surface conductivity of soil increased with the increases of fertilizer application levels. The effects of fertilization on soil salinity in 0-10 cm was significant. Compared with F1, the average EC of F2 in 0-10 cm was decreased by 25.6%-42.7% in 2015 and by 6.4%-7.7% in 2016, respectively. The water content in 20-80 cm decreased with the increases of fertilizer application levels. Compared with F1, the average soil water content in 20-80 cm soil layer of F2, F3, and F4 increased by 5.9%, 16.7% and 16.7% in 2015, and that of F2 and F3 increased by 13.3% and 16.7% in 2016, respectively. The yield of F1 and F2 was higher than that of F3 and F4, and W3 was lower than W1 and W2 in both years. There was no significant difference in yield between F1 and F2. Compared with W1, decrease in yield of W2 was less than 15%. Therefore, the application of compound fertilizer 600-750 kg·hm-2(nitrogen content 180-270 kg·hm-2), and irrigation levels W1 and W2 were suggested to ensure high yield of forage maize in saline soil in this area, without salt accumulation in root zone.

Study on Atmospheric Distillation of Some Plain and Chemically Dispersed Crude Oils: Comparison of Yields and Fuel Quality of Distillate Fractions

This paper discusses the distillation behavior of the plain (control) and chemically dispersed crude oils. The oils used were paraffinic (denoted as P-RCP-I), naphthenic (denoted as P-RCN-II), and aromatic (denoted as P-RCA-III) crudes. The chemical dispersants used were anionic, cationic, and neutral surfactants including sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and Triton X-100 (a branched p-octylphenol with an average of 9–10 ethylene oxide units). The effect of Dispersant-to-Oil ratio on the yields of distillate fractions (gasoline and diesel) was investigated. Looking at the results, we conclude that using chemically dispersed crudes enabled us to obtain better yields of light distillate fractions (F1 and F2) in comparison with the control. Among the dispersants used, the SDS was more effective in RCA-III crude where the yield of F1 increased significantly to 58% and that of residue decreased to 6%. The CTAB was found to be more effective in RCN-II crude, which gave a sign...

Effects of selenium fertilizer on grain yield, Se uptake and distribution in common buckwheat (Fagopyrum esculentum Moench)

Selenium (Se) is a significant trace element for human and livestock animals because of its physiological functions. Se in plants, especially in the crop plants, is treated as a critical dietary source. The effects of foliar spray together with soil application of Se on Se uptake, distribution in common buckwheat (Fagopyrum esculentum M.) plants were discussed in this study. The results showed that both foliar spray and soil application of Se increased Se uptake in common buckwheat significantly (P < 0.05). The highest Se content was observed in leaves (113.37-690.75 μg/kg), followed by roots (28.98-283.78 μg/kg), grains (26.49-135.89 μg/kg) and stems (23.19-86.80 μg/kg). Se content in grains had the highest correlation coefficient (0.827 and 0.845) with soil Se application treatments. Grain yield of F1 (5 g Se/ha for foliar spray) was 3.65% and 10.25% higher than that of F0 (0 g Se/ha for foliar spray) in two study years, respectively. Under soil Se application conditions, mean grain yields fluctuated from 2890.5-3058.6 kg/ha, 2966.4-3352.8 kg/ha in 2012/2013, respectively. These results indicated a significant interaction effect of foliar spray Se and soil Se application on Se accumulation in common buckwheat. Appropriate Se application might improve common buckwheat grain yield.

Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Heterosis for the improvement of yield in mungbean [Vigna radiata (L.) Wilczek

Heterotic effects of mungbean hybrids from 25 crosses between parents differing in 9 agronomic and physiological traits were evaluated for various selected traits and seed yield. Significant heteroses were observed in most selected traits, except for the number of seeds per plant. When the heterosis of seed yield was evaluated in these hybrids, significant heterosis was found in 9 crosses, which were selected based on the number of pods per plant, number of clusters per plant, pod length, number of seeds per pod, total dry matter, and root length density. These crosses may be exploited for mungbean yield improvement. Nine F8 lines from 2 of these 9 crosses (KPS 1 x V 2106 and SUT 1 x V 4785), a selection based on significant heterosis for seed yield and high seed yield of F1 and F2, which possessed a higher seed yield than their respective certified variety parents, were identified and these may be useful in future breeding programs.

Study of the Gastroprotective Effect of Extracts and Semipurified Fractions of Chresta martii DC. and Identification of Its Principal Compounds.

Chresta martii (Asteraceae) is a species widely used by the population of the Xingu region of Sergipe, Brazil, in the form of a decoction (aerial parts) for the treatment of gastrointestinal diseases. The study aims to assess the gastroprotective activity of organic extracts and semipurified fractions and identify the principal compounds present in C. martii responsible for such activity. The organic extracts (cyclohexane: ECCm, ethyl acetate: EACm, and ethanol: EECm) were obtained from the dried aerial parts (500 g) of C. martii. For evaluation of the gastroprotective activity of extracts (50, 100, or 200 mg/kg; p.o.), male Swiss Webster mice (25–30 g) were used which had gastric ulcers induced by indomethacin (40 mg/kg, s.c.) or ethanol (0.2 mL/animal; p.o.). Among the extracts evaluated, EACm exhibited significant (P < 0.05) gastroprotective activity in the models used. The fractionation of EACm was performed in a silica gel column 60 eluted with the following compounds: [chloroform—F1 yield (10%)], [chloroform/ethyl acetate (1/1)—F2 yield (6%)], [ethyl acetate—F3 yield (8%)], and [ethyl/methanol acetate (1/1)—F4 yield (5%)]. Of the fractions described above, the F1 (25 mg/kg; p.o.) had greater gastroprotective activity (P < 0.05) than that displayed by ranitidine (80 mg/kg; p.o.) in the ethanol-induced ulcer model. The refractionation of F1 produced 23 subfractions and from these two yellow amorphous compounds were obtained by recrystallization, Rf: 0.46 and 0.31 (ethyl acetate : chloroform 5 : 5). The compounds isolated were characterized by nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) and identified as flavones: chrysoeriol (yield: 0.43%) and 3′,4′-dimethoxyluteolin (yield: 0.58%). Conclusion. Flavone 3′,4′-dimethoxyluteolin is the principal compound present in the species C. martii and is probably responsible for gastroprotective activity observed in this species.

A green route towards highly photoluminescent and cytocompatible carbon dot synthesis and its separation using sucrose density gradient centrifugation.

An efficient, fast and green method for synthesis of Carbon dots (C-dots) using natural precursor Citrus limone under ultrasonic condition is demonstrated. Such as-synthesized C-dots were further purified using Sucrose density gradient centrifugation method (SDGC) which resulted in the separation of water-soluble, photo luminescent, monodispersed, highly photostable and chemically stable C-dot fractions (F1 and F2). They possess very small size (5-20 nm) as evidenced by High angle annular dark field-Scanning Transmission electron microscopy (HAADF-STEM) and very strong luminescence as shown by fluorescence spectroscopic studies. Cytocompatibility and bio imaging properties of both the fractions (F1 and F2) were then studied on Hep-2 cells. Quantum yield of F1 and F2 fraction was found to be 12.1 and 15 %, respectively.

DNA divergence as a criterion of a sweet pepper (Capsicum annuum L.) selection for heterosis

The identification of perspective parental lines for the creation of highyield hybrids is the most laborconsuming stage of selection, because it needs exte nsive trials of combining ability. Based on evaluation of the genetic divergence of the parental lines, the prediction accuracy of F1 hybrids performance was inves� tigated. The value of the divergence was calculated using biometric and molecular methods, such as inter sim� ple sequence repeats (ISSR) and random amplified polymorphic DNA (RAPD). Based on estimates of diver� gence, 10 lines were chosen for cyclic cross (scheme I) and testcross (scheme II). In most crosses, the F1 hybrids were significantly superior to the parents in the main economically valuable traits. The level of het� erosis was higher among hybrids of scheme I. Analysis of the relationship between parental divergence and F1 performance showed that the hybrid productivity of scheme I was predetermined by ISSR divergence in 86%, and productivity was caused by RAPD divergence in 69%, whereas the F1 yield of scheme II was not related to the value of genetic distances. Since the values of DNA divergence were closely associated both with mid� parent level and F1 performance, we assumed that part of the polymorphic DNA fragments of the parental lines of scheme I is related to heterotic loci (HTL), which may be considered potential key markers for the heterotic selection of the sweet pepper.

Genetic distance and hybrid value in tropical maize under P stress and non stress conditions in acid soils

An emphasis in maize breeding for areas with acid soils is the development of varieties with tolerance to P-deficiency plus high yield potential in acidic as well as normal soils. This study was carried out to assess the (i) genetic diversity within a set of tropical inbred lines developed from acid soil-tolerant populations; (ii) F1 yield performance, mid-parent heterosis (MPH), high-parent heterosis (HPH), and specific combining ability (SCA) in a diallel set of crosses under P stress (low P) and non-stress (high P) conditions; and (iii) the effect of P stress on the relationship between genetic distance (GD) and hybrid performance. Using field evaluation and molecular marker studies, the results show that these germplasm from the South American maize breeding program of CIMMYT for improving tolerance to acid soils had only a moderate level of genetic diversity. The utility of GD as a predictor of hybrid value is best up to a certain threshold, as correlations with GD became inconsistent when the inbred parents were greatly divergent. There was no correlation between GD and F1 grain yield, MPH, HPH and SCA when the GD was >0.77. The high correlation of GD with F1 grain yield and with SCA in specific subsets of crosses having a narrower range of GD shows that GD can be put to practical use in predicting hybrid performance. The highest correlation between GD and SCA, seen in the subset of crosses between lines within a cluster, was reasonably stable even when the environment had a severe effect on yield.

Genome shuffling amplifies the carbon source spectrum and improves arachidonic acid production in Diasporangium sp.

The aim of this study was to develop a new fungal strain that simultaneously amplifies the carbon source spectrum and increases arachidonic acid (AA) productivity using genome shuffling between Diasporangium sp. and inactive Aspergillus niger. Through three rounds of genome shuffling, one of the stable daughter strains (F1) acquired the ability to produce arachidonic acid and utilize various carbon sources. Compared to the parental Diasporangium sp., which could only use four out of eight carbon sources tested, F1 could utilize all eight carbon sources. During fermentation with CMC-Na as the carbon source, F1 was able to obtain 30.16% of lipid effectively whereas the parental Diasporangium sp. was not able to grow at all. When glucose was used as the carbon source, the CMCase activity of F1 was 879.36 U, 298.23% higher than that of the parental Diasporangium sp. Under optimized fermentation conditions in a 5-L fermentation container, the AA yield of F1 reached 0.81 g/l, 94.78% higher than that of the parental generation. These results indicate that inter-kingdom genome shuffling can be used successfully in eukaryotic microorganisms and that it can effectively improve the production of desired metabolites within a short period of time. The findings of this study may be useful for extending the application of genome shuffling in eukaryotic microbial breeding.

Super Hybrid Rice Breeding in China: Achievements and Prospects

AbstractHybrid rice has contributed greatly to the self‐sufficiency of food supply in China. To meet the future demand for rice production, a national program on super rice breeding was established in China in 1996. The corresponding targets, breeding strategies and most significant advances are reviewed in this paper. New plant type models have been modified to adjust to various rice growing regions. In recognition of the importance of applying parents with intermediate subspecies differentiation in increasing F1 yield, medium type parental lines were selected from populations derived from inter‐subspecies crosses with the assistance of DNA markers for subspecies differentiation. Results also indicate that a substantial increase of biomass is the basis for further enhancement of the grain yield potential, and amelioration of leaf characteristics is helpful in increasing the photosynthetic rate. Thirty‐four super hybrid rice varieties have been released commercially, growing in a total area of 13.5 million hm2 and producing 6.7 thousand million kg more rice in 1998‐2005. Although remarkable progress has been made in super hybrid rice breeding in China, selections on the root system and integration of more biotechnological tools remain a great challenge.

Genetic distances revealed by morphological characters, isozymes, proteins and RAPD markers and their relationships with hybrid performance in oilseed rape (Brassica napus L.)

Genetic distances (GDs) based on morphological characters, isozymes and storage proteins, and random amplified polymorphic DNAs (RAPD) were used to predict the performance and heterosis of crosses in oilseed rape (Brassica napus L.). Six male-sterile lines carrying the widely used Shaan2A cytoplasm were crossed with five restorer lines to produce 30 F1 hybrids. These 30 hybrids and their parents were evaluated for seven agronomically important traits and their mid-parent heterosis (MPH) at Yangling, Shaanxi province in Northwest China for 2 years. Genetic similarity among the parents based on 34 isozyme and seven protein markers was higher than that based on 136 RAPDs and/or 48 morphological markers. No significant correlation was detected among these three sets of data. Associations between the different estimates of GDs and F1 performance for some agronomic traits were significant, but not for seed yield. In order to enhance the predicting efficiency, we selected 114 significant markers and 43 favoring markers following statistical comparison of the mean values of the yield components between the heterozygous group (where the marker is present only in one parent of each hybrid) and the homozygous group (where the marker is either present or absent in both parents of each hybrid) of the 30 hybrids. Parental GD based on total polymorphic markers (GDtotal, indicating general heterozygosity), significant markers (GDsign, indicating specific heterozygosity) and favoring markers (GDfavor, indicating favoring-marker heterozygosity) were calculated. The correlation between GDfavor or GDsign and hybrid performance was higher than the correlation between GDtotal and hybrid performance. GDsign and GDfavor significantly correlated with plant height, seeds per silique and seed yield, but not with the MPH of the other six agronomic traits with the exception of plant height. The information obtained in this study on the genetic diversity of the parental lines does not appear to be reliable for predicting F1 yield and heterosis.

Genetic Diversity for Restriction Fragment Length Polymorphisms: Relation to Estimated Genetic Effects in Maize Inbreds

Restriction fragment length polymorphisms (RFLPs) have been proposed for investigating relationships among inbred lines and predicting heterosis and performance of single‐cross hybrids in maize (Zea mays L.). Such use was evaluated in 20 maize inbreds classified as first‐cycle, second‐cycle, good, and poor lines, and in diallel crosses within types. Eight generations (parents, F1, F2, F3, backcrosses, and backcrosses selfed) from 67 crosses were evaluated for grain yield in five Iowa environments. Genetic effects were estimated from generation means by ordinary diallel analyses and the Eberhart‐Gardner genetic model. Poor inbreds showed significantly greater average heterosis than did good lines. Estimates of additive ✕ additive epistatic effects were negative and highly significant in all except first‐cycle lines. Using two restriction enzymes and 82 genomic) DNA probes distributed throughout the maize genome, all but one probe revealed polymorphisms with at least one enzyme (~4.5 variants per RFLP locus). Genetic distances between lines within types were estimated as Rogers' distances (RD). Within diallel sets, RD values were partitioned into general (GRD)and specific (SRD). All four types of lines showed similar means and substantial variation for RD; GRD explained ~40% of the variation among RD values. Cluster analyses revealed associations among lines generally consistent with expectations based on known pedigrees. Correlations of RD and SRD with F1 yield heterosis, specific heterosis, and specific combining ability were positive but small (r = ≤ 0.50) when combined for all crosses. Results indicated that RFLPs can be used to investigate pedigree relationships among maize inbreds, but also suggest that RFLP‐based genetic distance measures are of limited use in predicting heterotic performance of single crosses between unrelated lines.

Readthrough transcription occurs at the rho dependent signal F1 TIVin suppressor cells

Suppressor cells infected with bacteriophage f1 yield phage encoded gene IV transcripts longer than those present in the supo host and identical to those found in a rho- host. However, such longer transcripts do not appear in the suppressor-infected cell when, by changing the translation frame of gene IV, the ribosome is not allowed to proceed to the end of the gene IV message and thus to reach the rho dependent transcription terminator f1 TIV. This suggests that ribosome movement beyond the natural gene IV stop codon disturbs the activity of that termination signal. In contrast to the rho- behaviour, the suppressor does not accumulate high levels of gene IV messages indicating that the accumulation occurring in the rho- mutant may not be a primary effect of the readthrough per se.