S1 Progenies Research Articles

Analysis of inbreeding depression in five S1 Cassava families of elite varieties at the seedling nursery and clonal evaluation trial stages.

Background Cassava is an outcrossing, highly heterozygous plant that is reported to suffer from inbreeding depression. However, unraveling recessive traits and exploring additive genes would require a limited level of inbreeding for the genetic improvement of cassava. Method The impact of inbreeding depression (ID) on agronomic and biotic tolerance of cassava was evaluated using the S1 progenies of five African cassava varieties (TMS 30572, TME 419, TMS 98/0505, TMS 01/1371, and TMS 98/0002) at the seedling and clonal evaluation stages. Results At both trial stages, the effects of ID were severe on average performance of fresh root yield and fresh foliage yield; moderate on harvest index, dry matter content, vigor, and tolerance to cassava mosaic disease, cassava bacterial blight, and cassava anthracnose diseases; and less severe on plant height. Further examination of S1 families using molecular markers showed varying levels of heterozygosity at several loci across the genome. In addition, the degree of heterozygosity and ID varied by the S1 family. The TMS 01/1371 family showed the lowest degree of heterozygosity and ID on the average performance of different agronomic attributes, indicating that inbreeding may be strategically explored in this family to increase genetic gain and identify useful recessive traits. Lastly, the observed depression from inbreeding was higher in seedling evaluation than in clonal evaluation trials for fresh root yield, fresh foliage yield, harvest index, and dry matter content. Conclusion S1 individuals showing relatively low heterozygosity based on SNP data were selected as parents to advance genetic gain in cassava. Generally, reduced heterozygosity was prominent in traits with severe ID impacts on average phenotypic performance. Our results highlight the relative importance of exploring non-additive genetic effects and transgressive segregations for favorable allele combinations in cassava improvement.

Avaliação e caracterização morfoagronômica de acessos de abóbora provenientes do semiárido do nordeste brasileiro

ABSTRACT The objective of this study was to evaluate morphoagronomic characteristics of different Cucurbita moschata (Duch) accessions from the Semiarid region of the Northeast of Brazil. Two experiments were conducted at the experimental field of the Bahia State University (Department of Technology and Social Sciences), Juazeiro, BA, Brazil, one from May to October 2021 and another from February to July 2022. Eighteen C. moschata accessions were evaluated in the first experiment, and 11 S1 progenies were evaluated in the second. Quantitative descriptors were analyzed in both experiments: fruit weight (FW; kg); fruit diameter (FD; cm); fruit length (FL; cm); fruit internal cavity diameter (FICD; cm); fruit internal cavity length (FICL cm); average of fruit skin thickness (AFST; mm); average of fruit flesh thickness (AFFT; mm); soluble solids content (SS; °Brix); 100-seed fresh weight (100SFW; g); 100seed dry weight (100SDW; g). Qualitative descriptors evaluated included fruit shape, fruit ribbing, skin color, flesh color, flesh texture, and skin texture. Significant differences were found for FW, FD, FL, FICD, FICL, AFST, AFFT, and SS in the first experiment, and or FD, FL, FICD, FICL, AFST, SS, and 100SDW in the second experiment. The results indicate genetic variability among accessions for quantitative and qualitative morphological fruit characteristics.

Study the Nutritional Performance of Original and S1 Progeny of Local Maize Germplasm of North East India

Local maize landraces are generally less yielders. Farmers have been cultivating and consuming local maize available in their areas due to specific color and taste of the grains. Only a few attempts were made by the researchers to study the nutritional status in north eastern maize, there was a lot of scope to study the local maize germplasm of the north eastern region for various nutritional compositions further. Considering the above, the following research study was undertaken. The six germplasm and their corresponding S1 progenies along with check were analyzed for estimation of the nutritional traits viz., crude protein, crude fat, carbohydrate, crude fiber, ash, iron and zinc. The mean value for a replicate for each entry in respect of a trait was used for analysis of data in Completely Randomized Design (CRD) with two replications. Analysis of variance reveals that the estimates of mean square due to germplasm were significant to highly significant for the traits viz., iron (mg /100 g), zinc (mg /100 g), moisture content (%), crude protein (%), crude fat (%), carbohydrate plus crude fiber (%) and ash (%) indicating sufficient variation among the thirteen entries tested. The result showed ARY2 exhibited high carbohydrate content, crude protein and zinc content.

Diversidade morfoagronômica e identificação botânica de acessos de melão do nordeste brasileiro

ABSTRACT Melon (Cucumis melo L.) crops are grown in the Semiarid region of Brazil by small, medium, and large farmers, focused on domestic and international markets. However, melon is also grown by family farmers using their own seeds, which are important germplasm for melon breeding programs. Samples of these seeds were collected and stored in the Active Germplasm Bank of Cucurbitaceae from the Northeast Region at the Brazilian Agricultural Research Corporation (Embrapa Semiarid), and require more thorough studies for a better understanding of the existing variability. Thus, the objective of this work was to characterize sub-accessions and their respective endogamic progenies to assess the genetic variability between and among these accessions. Two experiments were conducted in a randomized complete block design, with three replications, using 11 quantitative and 8 qualitative descriptors: the first using seeds from 17 accessions from natural pollination, and the second using seeds from S1 progenies. Morphological data were used for comparisons between generations. The 17 accessions evaluated originated 24 sub-accessions, denoting variability between and among accessions and sub-accessions. A dendrogram developed based on the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) showed the existing variability and, according to the newest melon classification, the groups identified were: makuwa, subgroup nashi-uri; and momordica and cantalupensis, subgroup prescott. The results showed a probable existence of introgression of alleles between different botanical groups, and some sub-accessions were not identified regarding their group by presenting variations in morphological characteristics, indicating the presence of new botanical groups.

Effect of different concentrations and combinations of some plant growth regulators on Punica granatum anther culture

Plant growth regulators (PGR), also known as plant hormones, are a variety of chemical compounds that have a significant impact on the development and differentiation of plant cells. This work aimed to study the effect of various combinations of Plant Growth Regulators (PGRs) for example [6-Benzyladenine (BA), 2,4-dichlorophenoxyaceticg acid (2,4-D), Naphthalene acetic acid (NAA) and indol-3-ylbutyric acid (IBA)] on callus induction and shoot regeneration from anther culture of S1 progenies resulted from Manfalouty cultivar open pollinated. The results showed that highest value of percentage of callus induction was 10.6% on MS medium supplemented with 1 mg / l of NAA and 2 mg / l of BA also highest value of percentage of shoot formation 60 % on MS medium supplemented with 3 mg/ l of NAA and 2 mg /l of BA.

Categories of variables in analysis of genetic diversity in S1 progenies of Psidium guajava

Crossing and developing inbred lines have been promising options for guava breeding programs. The purpose of this study was to evaluate the genetic divergence among genotypes of S1 inbred guava families by means of the Gower’s technique and the Ward-MLM methodology, to verify the correlation and relative contribution of traits, as well as to identify descriptors with minimum efficiency for this species. The experiment was implemented at the Estação Experimental da Ilha Barra do Pomba, in the municipality of Itaocara, RJ, Brazil. A randomized block design with 18 inbred families, three replicates, and ten plants per plot was used for the experimental design. After 19 months from the planting of the experiment, the 61 earliest and most productive genotypes (individual plants) were evaluated. For this purpose, 29 descriptors were evaluated, of which fifteen were qualitative and fourteen, quantitative. The characteristics required to obtain the distance matrix were analyzed based on the Gower algorithm, and a comparative cluster between the dendrograms of the morphoagronomic variables was achieved from this matrix. Lastly, the Ward-MLM procedure was applied to form the clusters of inbred families. By using all 29 descriptors, greater efficiency was achieved in cluster discrimination. Hence, according to the results identified, it is not possible to indicate minimum descriptors for the culture. Using the Ward-MLM method, the descriptors that most contributed to the divergence among the genotypes were fruit flesh mass, fruit weight, fruit diameter, fruit flesh thickness, fruit placental mass, and fruit length. The most divergent genotypes can be recommended for further crosses or self-pollinations to develop new lines in the guava breeding program of UENF.

Genetic analysis and physiological relationships of drought response in fennel: Interaction with mating system.

The consequences of water deficit and its interaction with pollination system (deliberate selfing compared with open-pollination) on physiological, agronomic and phytochemical traits are not understood in fennel (Foeniculum vulgare Mill.). A research was started by creating selfed (S1) and half-sib (HS) families on a fennel germplasm in 2018. Populations were studied in the field, applying a normal and a water deficit condition during two years (2019-2020). Considerable genotypic variation was observed within S1 and HS families for all of the evaluated traits, demonstrating that selection for these traits would be successful. Consequences of water deficit were manifested as declined most of the traits; and significantly increased essential oil content, harvest index, and proline content, in both populations. Mandatory selfing reduced the performance of genotypes for most of the traits confirming the existence of inbreeding depression (ID) with higher values for plant dry weight, seed yield, essential oil content, and number of umbelets per umbel. In S1 population, some of the studied traits had higher heritability estimates under normal condition and some of them showed higher heritability under water deficit. Positive relationship between GCA and STI in OP population indicated that it is possible to identify genotypes having high values of combining ability and drought tolerance. Results of the present study suggest that physiological traits cannot be used as an indicator to distinguish drought-tolerant genotypes in S1 progenies, whereas in OP progenies Chl a, Chl b, TChl, CAR, PRO, and RWC, which had significant correlations with drought tolerance, may be used for this purpose. Based on the results contrasting genotypes were identified, which can be used to develop mapping populations for genome studies of drought tolerance and physiological traits of this species in future studies.

Development of a High-Density Genetic Map for Muscadine Grape Using a Mapping Population from Selfing of the Perfect-Flowered Vine ‘Dixie’

Intraspecific diversity of the immune grape Muscadinia rotundifolia Michaux. can serve as a rich source of valuable resistance loci to the most widespread pathogens and pests of grapevine. While only one Run1/Rpg1 resistance locus has been introgressed from M. rotundifolia to the Vitis vinifera gene pool, a number of other genes conferring resistance to powdery mildew and downy mildew have been identified in various Muscadinia cultivars. A larger introduction of Muscadinia varieties to the European continent would greatly facilitate experiments of interspecific crosses as well as stimulate biotechnological efforts to overcome the main barrier to F1 fertility caused by the differences in chromosome number. For the successful introduction of Muscadinia into the new European environment, it is necessary to overcome the difficulties associated with the physiological characteristics of the species, such as insufficient cold tolerance and very late fruit ripening. To facilitate the further discovery of valuable loci in Muscadinia and their transfer to grapevine breeding programs, we constructed a high-density linkage map using an S1 mapping population obtained from the self-pollination of M. rotundifolia cv. Dixie maintained on the southern coast of Crimea. Using ddRADseq, 3730 SNPs were ordered across 20 linkage groups spanning 2753.6 cM of the total map length. No segregation in resistance to diseases and pests was observed among the 'Dixie' S1 population, suggesting the presence of homozygous non-segregating resistant loci in the genetic background of 'Dixie'. Markers with high segregation distortion showed a bias towards chromosomal intervals on linkage groups 10 and 20, where loci affecting the survival of 'Dixie' S1 progeny may be localized. QTLs with significant additive and dominance effects were discovered on LG14 and LG18, affecting the morphological traits associated with the vigor of growth and adaptability of young Muscadinia vines in the conditions of Crimea.

Inbreeding depression and genetic variability of populations for green maize production

The production of green maize is considerable important for various regions of Brazil. It is vital that breeding programs of public institutions seek to meet the needs of this market sector, which has a relevant social role, mainly on small properties. The aim of this study was to estimate the inbreeding depression and the genetic components (m + a and d) of characters associated with green maize production and quality in three populations of different genetic basis: the variety UFG-Samambaia (P1), and two populations formed by crossing the commercial hybrids (P2 e P3). The S1 progenies of each population, the three S0 populations, and two checks were evaluated in a 14 × 14 triple lattice design. Agronomic and ear quality traits were evaluated. Genetic variability and greater inbreeding depression were observed for most of the traits among the P1 progenies. In P2 and P3, greater inbreeding depression was observed for male flowering, ear weight without straw, ear diameter, ear weight, female flowering, breakage and lodging, and grain color. The traits of ear quality, important for green maize production, had greater inbreeding depression than the agronomic traits, indicating that inbreeding depression and exploitation of heterosis should be considered in the selection process for these traits.

Combining ability and potential of s1 popcorn progenies for early selection

Evaluation of combined ability can eliminate lines that are inefficient and enable the subsequent program steps to be more successful. The objective of this study was to predict the general (gi) and specific (sij) combination ability of popcorn S1 progenies for early selection. A total of 288 topcrosses were performed under a randomized complete block design with two replicates at two sites (Campinas and Capão Bonito, São Paulo State, Brazil). Diallel analyses were performed using mixed models and the maximum likelihood restricted/best unbiased linear prediction method. Evaluated traits included grain yield (GY; kg ha-1), weight of 100 grains (g), and popping expansion (PE; mL g-1). Ear components were also evaluated, including ear length, ear diameter (cm), and the number of grain rows (unit). The S1 progeny 32 presented the highest gi for GY in Campinas, whereas progeny 46 presented the highest gi for GY in Capão Bonito. The S1 progeny, 114 was an important parent for the popcorn breeding program, because it presented high gi for the traits of agronomic interest at both sites. Combination 86×IAC12 exhibited a high sij, and the 86 parent presented the second-highest gi for PE in Campinas, and it should be used for high PE genotypes

Seed yield stability with modified essential oil content and composition in self-compatible progenies of bitter fennel (Foeniculum vulgare Mill.)

Genetic progress as the mean yield increase within self (S1), and open-pollinated (OP) plants from eight bitter fennel populations were studied using the best nine full-sib (S1) and their corresponding nine half-sib (OP) plants from each population for agro-morphological traits and essential oil characteristics during two years. The average of S1 populations showed depression for all studied characteristics particularly the number of effective umbels per plant (NEUP) as the main yield component. However, some of the best S1 progenies performed well with stable and comparable yield to OP progenies. In addition, self-pollination interestingly increased the percentage of four major compounds including α-pinene, limonene, fenchone, and estragole in the essential oil (EO). In most populations, α-pinene, limonene, and fenchone were 2–4 times higher in selected S1 genotypes compared to OP counterparts. An inbred plant with more than 10-fold higher estragole content than the normal range was also identified among the selected genotypes. Conversely, the percentage of (E)-anethole decreased due to self-pollination in all selected plants in both years. Therefore, it may be concluded that although self-pollination has deleterious effects on the population’s general fitness, it may lead to improvement in the composition of EO in high-performing selected genotypes of bitter fennel for specific purposes and further utilization in pharmaceutical industries.

Heritability estimates and genetic distance of s1 progenies from landrace maize populations

Heritability estimates and genetic distance of s1 progenies from landrace maize populations

Homoeologous recombination is recurrent in the nascent synthetic allotetraploid Arachis ipaënsis × Arachis correntina4x and its derivatives.

Genome instability in newly synthesized allotetraploids of peanut has breeding implications that have not been fully appreciated. Synthesis of wild species-derived neo-tetraploids offers the opportunity to broaden the gene pool of peanut; however, the dynamics among the newly merged genomes creates predictable and unpredictable variation. Selfed progenies from the neo-tetraploid Arachis ipaënsis × Arachis correntina (A. ipaënsis × A. correntina)4x and F1 hybrids and F2 progenies from crosses between A. hypogaea × [A. ipaënsis × A. correntina]4x were genotyped by the Axiom Arachis 48 K SNP array. Homoeologous recombination between the A. ipaënsis and A. correntina derived subgenomes was observed in the S0 generation. Among the S1 progenies, these recombined segments segregated and new events of homoeologous recombination emerged. The genomic regions undergoing homoeologous recombination segregated mostly disomically in the F2 progenies from A. hypogaea × [A. ipaënsis × A. correntina]4x crosses. New homoeologous recombination events also occurred in the F2 population, mostly found on chromosomes 03, 04, 05, and 06. From the breeding perspective, these phenomena offer both possibilities and perils; recombination between genomes increases genetic diversity, but genome instability could lead to instability of traits or even loss of viability within lineages.

Genetic and QTL mapping in African bermudagrass.

Cynodon transvaalensis Burtt-Davy is frequently used to cross with C. dactylon Pers. in the creation of F1 hybrid cultivars that are some of the most widely used in the worldwide turf industry. However, molecular resource development in this species is limited. Accordingly, the objectives of this study were to construct a high-density genetic map, and to identify genomic regions associated with establishment rate. In this study, we constructed the first high-density linkage map for African bermudagrass using a genotyping by sequencing approach based on 109 S1 progenies. A total of 1,246 single nucleotide polymorphisms and 32 simple sequence repeat markers were integrated in the linkage map. The total length of nine linkage groups was 882.3 cM, with an average distance of 0.69 cM per interval. Four genomic regions were identified to be associated with sod establishment rate. The results provide important genetic resources towards understanding the genome as well as marker-assisted selection for improving the establishment rate in bermudagrass breeding.

Recurrent selection in papaya: An effective strategy for the continuous development of new cultivars

Part of the success of a breeding program depends on the composition of the base population. Superior genotypes and unimproved dioecious varieties are sources of genes for traits of interest and excellent options for the formation of segregating populations. Here we describe the first cycle of recurrent selection (RS) in papaya and propose an effective strategy, unprecedented in the crop, to generate variability and new cultivars. Initially, the RS base population (UCP-C0) was developed with wide variability. Subsequently, 196 S1 progenies were obtained, evaluated in a trial, and the superior 40 S1 progenies were recombined. Among the traits of the selected progenies, high fruit yield (producing two to five fruits per axil) stands out. The S1 progenies were recombined and their seed bulk corresponds to the base population for the second cycle (UCP-C1). The results of the first cycle demonstrate the genetic potential of this population for the development of superior cultivars, and the breeding strategy applied is promising.

Genomic selection helps accelerate popcorn population breeding

AbstractRecurrent selection is a method for developing new popcorn (Zea mays L.) cultivars. We aimed to determine the selection accuracy and genetic gains for different selection strategies: estimates based exclusively on phenotypic data (PhEN), estimates based on phenotypic and genotypic data (PhEN + GEN), and estimates based exclusively on single nucleotide polymorphism (SNP) marker genotyping (GEN). For the GEN strategy, we tested, via simulation, the possibility of reducing the number of SNPs and increasing the training population. The traits evaluated were 100‐grain weight, ear height, grain yield, popping expansion, plant height, and popping volume. Field trials were undertaken with 98 S1 progenies at two locations in an incomplete block design with three replications. The progenies’ parents were genotyped with a panel of ∼10,507 SNPs. As predicted by the GEN strategy at different selection intensities, the average annual genetic gain for the different traits were 29.1 and 25.2% higher than those of PhEN and GEN + PhEN for 98 candidates; 148.3 and 140.9% higher for 500; and 187.9 and 179.4% higher for 1,000 selection candidates, respectively. Recurrent genomic selection may result in high genetic gain, provided that: (a) phenotyping is accurate; (b) selection intensity is explored by genotyping several progenies and increasing the number of candidates; (c) genomic selection is used for early selection; and (d) the model is adjusted for a few more cycles of phenotyping. The simulation suggests that desirable values of genetic gain may be obtained by reducing the number of SNPs and increasing the training population size.

BREEDING FOR DROUGHT TOLERANCE IN MAIZE

This study carried-out in four successive summer seasons (2015 to 2018) at the experimental farm of the faculty of agriculture, Menoufia University, in Shebin El-Kom, Egypt. In 2015 season, S1 recurrent selection procedure was provied (Tep#5 and Gemmeiza yellow), where 200 S0 plants from each population were selfed to produce S1 progenies. In 2016 season, kernels of 100 S1 lines that selected from each two populations were separately sown for evaluation under two water regimes, i.e normal irrigation (NI) and drought stress conditions (DS). In 2017 season, the highest 10% of S1 progenies (10 S1 progenies of first Population (Tep#5) and 10 % S1 progenies of second Population (GMY) were planted for randomly mated by bulking pollen from the S1 plants. kernels harvested, four blends of seeds were obtained (Tep#5-NI, Tep#5-DS, GMY-NI and GMY-DS). In 2018 summer season, for each population the original cycle (C0) and the improved cycle (C1) were evaluated under normal irrigation (NI) and drought stress (DS). The results could be summarized as follows: Evaluate of 100 S1 progenies (Tep#5 and Gemmeiza yellow) for drought tolerance. Analysis of variance showed significant differences among the genotypes (S1 progenies) for all studied traits under both normal and drought stress conditions for two populations. A significant average reduction of 59.88% and 61.93% in grain yield/plot of the 100 S1’s for Tep#5 and Gemmeiza yellow respectively, due to drought stress. The superiority of the selected 10 S1’s over the 100 S1’s in grain yield was higher under drought stress than under normal conditions. Evaluation of the effectiveness of S1 recurrent selection of the two cycles for Tep#5 and Gemmeiza yellow populations under normal and drought conditions. One cycle of S1 recurrent selection using water-stress as a selection environment caused a significant actual improvement of grain yield of the newely developed populations (Tep#5-DS and GMY-DS) over its original populations (Tep#5 and GMY) of 15.47 and 12.78% under water stress condition. The improved populations Tep#5-NI and GMY-NI developed by using normal irrigation as a selection environment showed significant actual improvements in grain yield under normal irrigation (12.46 and 9.06%) environment. Both water stressed and non-stressed selection environments were efficient in improving grain yield under target environments. The two improved populations showed significant superiority in grain yield/fed over origin population under normal and drought stress conditions.

Yield potential of green maize from partially inbred lines in top crosses

Selecting potential progenies in early inbred generations is an essential step towards the success of breeding programs. Given this, the use of top crosses assists breeders in selecting progenies to generate lines with the potential for hybrid yield. Thus, the purpose of this study was to assess the behavior of partially inbred progenies (S1) of maize with potential for green maize yield in top crosses and to evaluate the hybrid performance. Seventy-five top cross hybrids were generated from the cross between 75 S1 progenies and the F2 generation of the hybrid AG 1051. The 75 hybrids, the male tester (F2 generation of the hybrid AG 1051 as a broad genetic base tester), and the hybrid AG 1051 were sown in a block design with four replicates. The following traits were evaluated: husked ear yield; commercial ear yield; flowering; plant height; strawing; mean weight of grain mass in green maize stage; tassel branch number; ear row number; ear length; and ear diameter. The analysis of variance was performed estimating the general combining ability, and, from the means, the Scott & Knott test was conducted. The top cross hybrids that were prominent for commercial ear yield were those composed of partially inbred progenies 19, 48, 6, 28, and 42 with high GCA, suggesting a potential for the production of open pollination population or synthetic production as well.

Selection of parents for low nitrogen stress through the combining ability of maize partially inbred lines

The objective of this work was to estimate the general combining ability of partially inbred lines under high and low nitrogen (N) conditions and to select promising lines to obtain high yields for both conditions. Fifty-five partially inbred S1 progenies were evaluated using the top-cross method, where the lines were crossed with two testers. The 110 top-cross hybrids were evaluated for grain yield during the off-season of 2012 at two sites in the Brazilian Midwest. Partial diallel analysis was performed with the adjusted means of each of the individual analyses of the top crosses. The combining ability of partially inbred lines and testers as well as their interaction with N levels, was estimated for each site. The coefficient of concordance among 15 partially inbred lines selected by the highest general combining ability estimates for each N level was 0.60. The S1 lines 39, 11, 41, 55, 38, 37, 6, 8, and 14 were selected at both N levels. This indicates that these lines can be used to identify ideal hybrids for growing in the off-season in the Brazilian Midwest.

SNP-based mixed model association of growth- and yield-related traits in popcorn.

The identification of the genes responsible for complex traits is highly promising to accelerate crop breeding, but such information is still limited for popcorn. Thus, in the present study, a mixed linear model-based association analysis (MLMA) was applied for six important popcorn traits: plant and ear height, 100-grain weight, popping expansion, grain yield and expanded popcorn volume per hectare. To this end, 196 plants of the open-pollinated popcorn population UENF-14 were sampled, selfed (S1), and then genotyped with a panel of 10,507 single nucleotide polymorphisms (SNPs) markers distributed throughout the genome. The six traits were studied under two environments [Campos dos Goytacazes-RJ (ENV1) and Itaocara-RJ (ENV2)] in an incomplete block design. Based on the phenotypic data of the S1 progenies and on the genetic characteristics of the parents, the MLMA was performed. Thereafter, genes annotated in the MaizeGDB platform were screened for potential linkage disequilibrium with the SNPs associated to the six evaluated traits. Overall, seven and eight genes were identified as associated with the traits in ENV1 and ENV2, respectively, and proteins encoded by these genes were evaluated for their function. The results obtained here contribute to increase knowledge on the genetic architecture of the six evaluated traits and might be used for marker-assisted selection in breeding programs.