Intraspecific Crosses Research Articles

Fine Mapping and Candidate Gene Analysis of Two Major Quantitative Trait Loci, qFW2.1 and qFW3.1, Controlling Fruit Weight in Pepper (Capsicum annuum).

Fruit weight is an important agronomic trait in pepper production and is closely related to yield. At present, many quantitative trait loci (QTL) related to fruit weight have been found in pepper; however, the genes affecting fruit weight remain unknown. We analyzed the fruit weight-related quantitative traits in an intraspecific Capsicum annuum cross between the cultivated species blocky-type pepper, cv. Qiemen, and the bird pepper accession, "129-1" (Capsicum annuum var. glatriusculum), which was the wild progenitor of C. annuum. Using the QTL-seq combined with the linkage-based QTL mapping approach, QTL detection was performed; and two major effects of QTL related to fruit weight, qFW2.1 and qFW3.1, were identified on chromosomes 2 and 3. The qFW2.1 maximum explained 12.28% of the phenotypic variance observed in two F2 generations, with the maximum LOD value of 11.02, respectively; meanwhile, the qFW3.1 maximum explained 15.50% of the observed phenotypic variance in the two F2 generations, with the maximum LOD value of 11.36, respectively. qFW2.1 was narrowed down to the 1.22 Mb region using homozygous recombinant screening from BC2S2 and BC2S3 populations, while qFW3.1 was narrowed down to the 4.61Mb region. According to the transcriptome results, a total of 47 and 86 differentially expressed genes (DEGs) in the candidate regions of qFW2.1 and qFW3.1 were identified. Further, 19 genes were selected for a qRT-PCR analysis based on sequence difference combined with the gene annotation. Finally, Capana02g002938 and Capana02g003021 are the most likely candidate genes for qFW2.1, and Capana03g000903 may be a candidate gene for qFW3.1. Taken together, our results identified and fine-mapped two major QTL for fruit weight in pepper that will facilitate marker-assistant breeding for the manipulation of yield in pepper.

One Genome, Multiple Phenotypes: Would Rhodnius milesi Carcavallo, Rocha, Galvão & Jurberg, 2001 (Hemiptera, Triatominae) Be a Valid Species or a Phenotypic Polymorphism of R. neglectus Lent, 1954?

Species of the Rhodnius genus have a complex taxonomy because the events of phenotypic plasticity and cryptic speciation make it difficult to correctly classify these vectors. During the taxonomic history of the genus, five synonymization events occurred. Additionally, some authors suggest that R. milesi possibly represent only phenotypic polymorphisms of R. neglectus. Thus, we analyzed the specific status of R. milesi in relation to R. neglectus using phylogenetic studies with the mitochondrial gene cytochrome B and the study of reproductive barriers. The phylogenetic reconstruction grouped R. milesi together with R. neglectus from different localities, demonstrating that these taxa represent the same species based on the phylogenetic species concept. Experimental crosses demonstrate the absence of pre- and postzygotic barriers under laboratory conditions. Additionally, when the hatch rates of crosses are compared to intraspecific crosses, it can be noted that they are high and very similar. Finally, the mortality rate of the hybrids does not indicate hybrid inviability, the absence of chromosome pairing errors does not indicate hybrid sterility, and the proportion between male and female hybrids demonstrates that Haldane’s rule was not acting. Therefore, we perform the formal synonymization of R. milesi with R. neglectus.

Plant Hormone Pathway Is Involved in Regulating the Embryo Development Mechanism of the Hydrangea macrophylla Hybrid.

The research is aimed to elucidate the role of plant hormones in regulating the development of hybrid embryos in Hydrangea macrophylla. Fruits from the intraspecific cross of H. macrophylla 'Otaksa' × 'Coerulea' were selected at the globular, heart, and torpedo stages of embryo development. Transcriptome sequencing and differential gene expression analysis were conducted. The results showed that fruit growth followed a single "S-shaped growth curve, with globular, heart, and torpedo embryos appearing at 30, 40, and 50 d post-pollination, respectively, and the embryo maintaining the torpedo shape from 60 to 90 d. A total of 12,933 genes was quantified across the three developmental stages, with 3359, 3803, and 3106 DEGs in the S1_vs_S2, S1_vs_S3, and S2_vs_S3 comparisons, respectively. Among these, 133 genes related to plant hormone biosynthesis and metabolism were differentially expressed, regulating the synthesis and metabolism of eight types of plant hormones, including cytokinin, auxin, gibberellin, abscisic acid, and jasmonic acid. The pathways with the most differentially expressed genes were cytokinin, auxin, and gibberellin, suggesting these hormones may play crucial roles in embryo development. In the cytokinin pathway, CKX (Hma1.2p1_0579F.1_g182670.gene, Hma1.2p1_1194F.1_g265700.gene, and NewGene_12164) genes were highly expressed during the globular embryo stage, promoting rapid cell division in the embryo. In the auxin pathway, YUC (Hma1.2p1_0271F.1_g109005.gene and Hma1.2p1_0271F.1_g109020.gene) genes were progressively up-regulated during embryo growth; the early response factor AUX/IAA (Hma1.2p1_0760F.1_g214260.gene) was down-regulated, while the later transcriptional activator ARF (NewGene_21460, NewGene_21461, and Hma1.2p1_0209F.1_g089090.gene) was up-regulated, sustaining auxin synthesis and possibly preventing the embryo from transitioning to maturity. In the gibberellin pathway, GA3ox (Hma1.2p1_0129F.1_g060100.gene) expression peaked during the heart embryo stage and then declined, while the negative regulator GA2ox (Hma1.2p1_0020F.1_g013915.gene) showed the opposite trend; and the gibberellin signaling repressor DELLA (Hma1.2p1_1054F.1_g252590.gene) increased over time, potentially inhibiting embryo development and maintaining the torpedo shape until fruit maturity. These findings preliminarily uncover the factors affecting the development of hybrid H. macrophylla embryos, laying a foundation for further research into the regulatory mechanisms of H. macrophylla hybrid embryo development.

Phenotypic characterization and gene mapping of hybrid necrosis in Triticum durum–Haynaldia villosa amphiploids

Key messagePhenotypical, physiological and genetic characterization was carried out on the hybrid necrosis gene from Haynaldia villosa, and the related gene Ne-V was mapped to chromosome arm 2VL.Introducing genetic variation from wild relatives into common wheat through wide crosses is a vital strategy for enriching genetic diversity and promoting wheat breeding. However, hybrid necrosis, a genetic autoimmunity syndrome, often occurs in the offspring of interspecific or intraspecific crosses, restricting both the selection of hybrid parents and the pyramiding of beneficial genes. To utilize the germplasms of Haynaldia villosa (2n = 2x = 14, VV), we conducted wide hybridization between durum wheat (2n = 4x = 28, AABB) and multiple H. villosa accessions to synthesize the amphiploids (2n = 6x = 42, AABBVV). This study revealed that 61.5% of amphiploids derived from the above crosses exhibited hybrid necrosis, with some amphiploids even dying before reaching maturity. However, the initiation time and severity of necrosis varied dramatically among the progenies, suggesting that there were multiple genetic loci or multiple alleles in the same genetic locus conferring to hybrid necrosis in H. villosa accessions. Genetic analysis was performed on the F2 and derived F2:3 populations, which were constructed between amphiploid STH59-1 with normal leaves and amphiploid STH59-2 with necrotic leaves. A semidominant hybrid necrosis-related gene, Ne-V, was mapped to an 11.8-cM genetic interval on the long arm of chromosome 2V, representing a novel genetic locus identified in Triticum-related species. In addition, the hybrid necrosis was correlated with enhanced H2O2 accumulation and cell death, and it was influenced by the temperature and light. Our findings provide a foundation for cloning the Ne-V gene and exploring its molecular mechanism.

Fruit sugar and organic acid composition and inheritance analysis in an intraspecific cross of Chinese cherry

Chinese cherry is an economically significant fruiting cherry species within Rosaceae family. Soluble sugar and organic acid are crucial factors affecting fruit flavor, while the genetic basis for these traits in Chinese cherry remains largely unknown. In this study, we determined sugar and acid components in 190 and 187 representative hybrids from an intraspecific cross of Chinese cherry over two consecutive years. Fructose and glucose were the major sugars in both progeny and parents, but their contents varied considerably between years. Fructose represented a higher proportion in progeny than in parents. Malic acid was the most predominant component, accounting for a relatively stable proportion (∼70%) for both years. The F1 population exhibited wide phenotypic variations, with coefficient of variation ranging from 6.57% to 108.63%. Regarding inheritance patterns, sugars tended towards smaller values, while malic acid exhibited significant transgressive heterosis. Sugars and acids were primarily governed by 2 MG-AD or 2 MG-EA model. Major gene heritability exceeded 88% for acids but much lower (12%–75%) for sugars. These results suggest that acid contents might be controlled by two major genes, while sugars are mainly governed by polygenes. This study provides a theoretic basis for understanding genetic predisposition underlying sugar-acid fractions in Chinese cherry fruit.

Quality assessment of flax advanced breeding lines varying in seed coat color and their potential use in the food and industrial applications

BackgroundWith the increasing consumer awareness of the strong relationship between food and health, flax became a promising functional food due to its bioactive nutraceutical composition. Intra-specific crosses of eight contrasting flax genotypes were performed previously, and within segregating F6 progeny families, we investigated a close-up composition of phytochemicals derived from whole seeds.ResultsThe considerable genetic variation among the flax F6 families suggested that intra-specific hybridization is essential in flax breeding to obtain and broaden genetic variability and largely affirmed the opportunity for selecting promising lines. Also, significant variations in the targeted metabolite contents and antioxidant properties were observed among brown and yellow-seeded families. Notably, brown-seeded families expressed the highest average values of saturated fatty acids, protein, fiber, tocopherol, phenolics, SDG, and SECO lignans. Yellow-seeded families represented the highest average content of unsaturated fatty acids and mucilage. The cultivation year significantly affects flaxseed’s composition and functional properties, presumably due to temperature, humidity, and sunshine time differences. Interestingly, the seeds obtained in warmer conditions were more potent and had more chemical constituents. The favorable genetic correlations among all evaluated traits suggest the possibility of joint genetic selection for several nutritional and phytochemical characteristics in flax. The current study highlights the importance and utilization of 19 top families as their seeds and oil play imperative roles in the pharmaceuticals and food industries. The antioxidant capacity of the seeds showed that families 84B, 23B, 35Y, 95Y, 30B, 88B, and 78B serve as a natural source of dietary antioxidants beneficial to human health. To increase the oxidative stability of the flaxseed oil, the quality evaluation identified some families with low levels of linolenic acid.ConclusionsThese findings are essential to improving flaxseed’s nutritional quality and therapeutic properties through a bulk breeding program.

Identification of RILs for agronomic and grain quality traits in rice through Intraspecific crosses

Identification of RILs for agronomic and grain quality traits in rice through Intraspecific crosses

Fusarium species associated with citrus blackfly (Aleurocanthus woglumi) from an agroecological polyculture in Brazil, including an augmented description of F. volatile

ABSTRACT The objectives of this study were to report Fusarium species associated with Aleurocanthus woglumi (Hemiptera: Aleyrodidae) collected from citrus leaves from an agroecological polyculture in Brazil, assess sexual reproductive mode of the species with unknown sexual stages, and provide an augmented description of F. volatile, for which we discovered a sexual stage. Nineteen Fusarium isolates were recovered from A. woglumi. These fungi belong to three species complexes, i.e., the F. chlamydosporum species complex (FCSC), the F. fujikuroi species complex (FFSC), and the F. incarnatum-equiseti species complex (FIESC). Based on multilocus phylogenetic analyses, the species were identified as F. annulatum, F. chlamydosporum, F. pernambucanum, F. sulawesiense, F. verticillioides, and F. volatile. Our results suggest that three species whose sexual stages are unknown (F. chlamydosporum, F. sulawesiense, and F. volatile) are also heterothallic. Intraspecific crosses of F. sulawesiense and F. volatile produced protoperithecia, whereas 66.7% of F. volatile crosses produced fertile perithecia. We provide an augmented description of the latter species to include characteristics of its sexual morph and those observed in the asexual morph that had not yet been described for the species. This study highlights the potential of researching insect-associated fungi to increase knowledge about the diversity, taxonomy, and versatility of Fusarium in ecosystems.

Mapping QTL for vernalization requirement identified adaptive divergence of the candidate gene Flowering Locus C in polyploid Camelina sativa.

Vernalization requirement is an integral component of flowering in winter-type plants. The availability of winter ecotypes among Camelina species facilitated the mapping of quantitative trait loci (QTL) for vernalization requirement in Camelina sativa. An inter and intraspecific crossing scheme between related Camelina species, where one spring and two different sources of winter-type habit were used, resulted in the development of two segregating populations. Linkage maps generated with sequence-based markers identified three QTLs associated with vernalization requirement in C. sativa; two from the interspecific (chromosomes 13 and 20) and one from the intraspecific cross (chromosome 8). Notably, the three loci were mapped to different homologous regions of the hexaploid C. sativa genome. All three QTLs were found in proximity to Flowering Locus C (FLC), variants of which have been reported to affect the vernalization requirement in plants. Temporal transcriptome analysis for winter-type Camelina alyssum demonstrated reduction in expression of FLC on chromosomes 13 and 20 during cold treatment, which would trigger flowering, since FLC would be expected to suppress floral initiation. FLC on chromosome 8 also showed reduced expression in the C. sativa ssp. pilosa winter parent upon cold treatment, but was expressed at very high levels across all time points in the spring-type C. sativa. The chromosome 8 copy carried a deletion in the spring-type line, which could impact its functionality. Contrary to previous reports, all three FLC loci can contribute to controlling the vernalization response in C. sativa and provide opportunities for manipulating this requirement in the crop.

Studying the effect of heterosis and predicting the prospects of hybrid spring wheat populations in breeding for productivity and drought resistance

Background. In combination breeding, information about the degree of superiority of hybrids in productivity and drought resistance over their parents in early generations, as well as the possibility of preserving their advantages in subsequent generations, are of great practical interest.Materials and methods. In 2018–2021, 16 hybrid populations of spring bread wheat of the 1st through 4th generations, obtained from intraspecific crosses among parent cultivars, were studied at the Federal Agricultural Research Center of the NorthEast. The hybrids and their parents were tested in the field for productivity and in the laboratory for drought resistance. Inheritance types were determined by the degree of phenotypic dominance of plant characters. Statistical processing of the results was carried out using correlation and variance analyses.Results. Hybrids that demonstrated heterosis in the number of grains per ear had an advantage on this basis in subsequent generations. The inheritance type of the 1000 grain weight did not determine the level of this character in older generation hybrids. There was a change in the type of inheritance for the number of radicles during the transition from normal to stressful conditions. Hybrids that showed heterosis in seedling weight in the control and the experiment were distinguished by higher rates in subsequent generations. A significant negative correlation was found between grain yield and the number of radicles formed with a lack of moisture, and a positive correlation between grain yield and the weight of seedlings. Seven promising hybrid combinations fusing productivity with drought resistance were identified.Conclusion. The analysis of hybrids from early generations according to the degree of phenotypic dominance of the number of grains per ear and number of radicles in the experiment, and the weight of seedlings in the control and the experiment can be quite informative for use in breeding programs.

“In Vitro” Ovule Culture to Improve Genetic Variability in Hydrangea macrophylla

In flowering plants, such as Hydrangea macrophylla, the main breeding objective is to increase genetic variability in ornamental traits. This study investigates in vitro techniques, through ovule culture, to overcome the hybridization barriers and increase the efficiency of crossing in Hydrangea macrophylla in which breeding has been hampered by a fairly long breeding cycle and lack of information about its genetic resources. Two different types of media were compared, Gamborg B5 and Murashige and Skoog basal salts, to verify the germination rate of immature ovules in different intraspecific crosses. The germination rate and viability of the seedlings were influenced by the parental genotypes in the different combinations of crossing, highlighting, in some cases, the poor compatibility between some of them. The crossing combination “Parental A × Parental B”, showed the highest germinated ovules percentage (78.3%). The media used seem to less affect the ovule germination while mainly influencing the development and growth of the young seedlings and in particular the number of leaves, the branching attitude, and root length, with the Gamborg medium determining up to a 30% increase, compared to MS medium. In addition, we tested the effectiveness of using SSR markers to assess the parentage of the putative hybrids even though only three out of twelve SSR markers showed allelism. Although the number of SSR markers was low, they were allowed to profile the parentage according to Mendelian laws.

Mitochondrial uniparental inheritance achieved after fertilization challenges the nuclear-cytoplasmic conflict hypothesis for anisogamy evolution.

In eukaryotes, a fundamental phenomenon underlying sexual selection is the evolution of gamete size dimorphism between the sexes (anisogamy) from an ancestral gametic system with gametes of the same size in both mating types (isogamy). The nuclear-cytoplasmic conflict hypothesis has been one of the major theoretical hypotheses for the evolution of anisogamy. It proposes that anisogamy evolved as an adaptation for preventing nuclear-cytoplasmic conflict by minimizing male gamete size to inherit organelles uniparentally. In ulvophycean green algae, biparental inheritance of organelles is observed in isogamous species, as the hypothesis assumes. So we tested the hypothesis by examining whether cytoplasmic inheritance is biparental in Monostroma angicava, a slightly anisogamous ulvophycean that produces large male gametes. We tracked the fates of mitochondria in intraspecific crosses with PCR-RFLP markers. We confirmed that mitochondria are maternally inherited. However, paternal mitochondria enter the zygote, where their DNA can be detected for over 14 days. This indicates that uniparental inheritance is enforced by eliminating paternal mitochondrial DNA in the zygote, rather than by decreasing male gamete size to the minimum. Thus, uniparental cytoplasmic inheritance is achieved by an entirely different mechanism, and is unlikely to drive the evolution of anisogamy in ulvophyceans.

Hazelnut (Corylus domestica Kos. et Opal.) breeding results for anthropoadaptability

Aim. Hazelnut (Corylus domestica Kos. et Opal.) fruits are valuable raw materials for the confectionery industry, the production of biologically active additives to food products and feed, as well as for obtaining from hazelnut oil the liposomal nanoemulsions and nanodispersions, which are part of medicinal preparations. The domestic hazelnut production level is insufficient and unable to satisfy either the needs of the processing industry or the demand of the population of Ukraine for fresh nuts. This motivated the search for ways to improve the assortment of this nut-bearing crop, foremost the creation of new cultivars in possession of anthropoadaptive features complexes. Methods. Study of the alien and originating in the NDP "Sofiyivka" of the NAS of Ukraine Corylus spp. specimens. During hybridization, the sleeve cages made of dense FPP-15 (Petrianov filter linen) fabric were used to isolate branches with female flowers. Pollination was done without removing the cages, injecting pollen into the cage with insufflator MO-03. The parental pairs' selection for crossing, and growing, evaluation, and selection of hybrid seedlings was done using standard methods. Results. It turned out that the segregation spectra for economic and useful traits of the anthropoadaptive complex in the progeny of seedlings from controlled intraspecific crosses did not significantly differ from the seedlings obtained as a result of free cross-pollination of hazelnut cultivars of the NDP "Sofiyivka" collection. Instead, the involvement of specimens of C. chinensis and C. avellana 'Fuscorubra' in the hybridization contributed to obtaining a number of new hazelnut cultivars. At the same time, in contrast to literature data, hybrids from pollination of hazelnut cultivars with C. chinensis pollen were better than in reciprocal combinations. So new highly productive cultivar 'Sofiivskyi 15' was selected from the seedling population of ('Garibaldi'×C. chinensis). Conclusions. This discrepancy between the results of our crosses and the literature data can be explained by the fact that our C. chinensis specimens were introduced not from the initial natural area (China South-Central), but from the collection of Berlin Botanical Garden (Botanischer Garten Berlin-Dahlem) where they could spontaneously be pollinated with some other Corylus spp. The advantages of our new hazelnut cultivars: 'Sofiyivsky 1'; "Sofiyivsky 2"; and 'Sofiyivsky 15', which have been included in the State register of plant varieties suitable for dissemination in Ukraine since 2019, testify to the effectiveness of hazelnut breeding for anthropoadaptability.

Embryo Rescue in Plant Breeding.

Embryo rescue (ER) techniques are among the oldest and most successful in vitro tissue culture protocols used with plant species. ER refers to a series of methods that promote the development of an immature or lethal embryo into a viable plant. Intraspecific, interspecific, or intergeneric crosses allow the introgression of important alleles of agricultural interest from wild species, such as resistance or tolerance to abiotic and biotic stresses or morphological traits in crops. However, pre-zygotic and post-zygotic reproductive barriers often present challenges in achieving successful hybridization. Pre-zygotic barriers manifest as incompatibility reactions that hinder pollen germination, pollen tube growth, or penetration into the ovule occurring in various tissues, such as the stigma, style, or ovary. To overcome these barriers, several strategies are employed, including cut-style or graft-on-style techniques, the utilization of mixed pollen from distinct species, placenta pollination, and in vitro ovule pollination. On the other hand, post-zygotic barriers act at different tissues and stages ranging from early embryo development to the subsequent growth and reproduction of the offspring. Many crosses among different genera result in embryo abortion due to the failure of endosperm development. In such cases, ER techniques are needed to rescue these hybrids. ER holds great promise for not only facilitating successful crosses but also for obtaining haploids, doubled haploids, and manipulating the ploidy levels for chromosome engineering by monosomic and disomic addition as well substitution lines. Furthermore, ER can be used to shorten the reproductive cycle and for the propagation of rare plants. Additionally, it has been repeatedly used to study the stages of embryonic development, especially in embryo-lethal mutants. The most widely used ER procedure is the culture of immature embryos taken and placed directly on culture media. In certain cases, the in vitro culture of ovule, ovaries or placentas enables the successful development of young embryos from the zygote stage to maturity.

Selection of Short-Day Strawberry Genotypes through Multivariate Analysis.

Strawberries are produced in tropical regions using imported cultivars adapted to temperate and subtropical climates. These cultivars, under tropical conditions, produce below their genetic potential. Through multivariate analyses, the objective was to evaluate and select short-day strawberry genotypes based on intraspecific crosses, product characteristics, and fruit quality. The genotypes were obtained from the cross between 'Camino Real' (female parent) and the first-generation genotypes RVCA16, RVCS44, RVFS06, RVFS07, and RVDA11 (male parent), obtained in previous selections. The experimental design consisted of augmented blocks with standard controls, consisting of first-generation genotypes and commercial cultivars. The fruits were harvested and evaluated for productivity and post-harvest characteristics: total fruit mass (MTF), total number of fruits (TFN), average fruit mass (AFM), commercial fruit mass (CFM), fruit commercial number (CFN), average commercial mass of fruits (ACFM), total soluble solids (TSS), firmness (F), brightness (L), hue angle (°Hue), and chroma (C). The selection index of Mulamba and Mock (1978) was used with an intensity of 3% to obtain superior genotypes and submitted to multivariate analysis for comparative purposes. Of the 1500 genotypes evaluated, it was possible to select 44 genotypes with characteristics superior to the 13 controls. The RVDA11CR59 genotype showed better values for the attributes of interest, but the RVCS44CR population, from the cross between 'Camino Real' × RVCS44 ('Camarosa' × 'Sweet Charlie'), obtained the highest number (16) of individuals among those selected. Significant traits had high heritability but were not necessarily reflected in high selection gain. Coefficients of genetic variation were high, indicating sufficient genetic variability to select genotypes for these traits. When multivariate analyses were used, it was possible to group the selected genotypes into the same cluster according to the similarity and balance in the responses to the evaluated variables, demonstrating that these analyses help other parameters choose superior genotypes. The multivariate analysis allowed the selection of more balanced genotypes for production and post-harvest traits for tropical climates.

Screening of recombinant inbred lines for resistance to bacterial leaf blight pathotypes in rice (Oryza sativa L.)

In the present investigation 16 recombinant inbred lines (RIL’s) developed from the intra-specific cross between YH3 and AKDRMS 21-54 through Marker Assisted Pedigree Breeding Method were screened along with their parents and the checks, namely, BPT 5204, TN1 and Improved Samba Mahsuri (ISM) against IxoPt-20 pathotype at the ICAR-Indian Institute of Rice Research, Hyderabad during Rabi 2021-22 and a new pathotype of Xanthomonas oryzae pv. oryzae causing Bacterial Leaf Blight disease in rice at Regional Agricultural Research Station, Maruteru during Kharif 2022 to identify pathotype specific resistant sources. Morpho-Molecular screening was adopted to evaluate the recombinant inbred lines over two locations in the consecutive seasons of Rabi 2021-22 and Kharif 2022. Based on per cent diseased leaf area, the genotypes were scored and categorised as per the Standard Evaluation System (SES) scale provided by International Rice Research Institute (IRRI). The results revealed all 16 RIL’s to be either resistant (10) or moderately resistant (6) to IxoPt-20 pathotype. However, only five RIL’s were found to be resistant, while four RIL’s were moderately resistant for the new virulent pathotype. Seven RIL’s with resistant to moderately resistant reaction for IxoPt-20 pathotype, showed moderately susceptible reaction for the new virulent pathotype. Among the resistant RIL’s identified for each pathotype, BPT-1901-72-10-6, BPT-1901-108-4-1 and BPT-1901-111-3-2 were found to be uniformly resistant, while, BPT-1901-45-8-6 and BPT-1901-163-1-18 were uniformly moderately resistant to both IXoPt-20 and the new virulent pathotype at Hyderabad and Maruteru, respectively, indicating their potential as genetic stocks for development of new cultivars resistant to bacterial leaf blight disease.

Construction of a genetic linkage map and QTL mapping of fruit quality traits in guava (Psidium guajava L.).

Guava (Psidium guajava L.) is an important fruit crop of the Indian sub-continent, with potential for improvements in quality and yield. The goal of the present study was to construct a genetic linkage map in an intraspecific cross between the elite cultivar 'Allahabad Safeda' and the Purple Guava landrace to identify the genomic regions responsible for important fruit quality traits, viz., total soluble solids, titratable acidity, vitamin C, and sugars. This population was phenotyped in field trials (as a winter crop) for three consecutive years, and showed moderate-to-high values of heterogeneity coefficients along with higher heritability (60.0%-97.0%) and genetic-advance-over-mean values (13.23%-31.17%), suggesting minimal environmental influence on the expression of fruit-quality traits and indicating that these traits can be improved by phenotypic selection methods. Significant correlations and strong associations were also detected among fruit physico-chemical traits in segregating progeny. The constructed linkage map consisted of 195 markers distributed across 11 chromosomes, spanning a length of 1,604.47 cM (average inter-loci distance of 8.80 markers) and with 88.00% coverage of the guava genome. Fifty-eight quantitative trait loci (QTLs) were detected in three environments with best linear unbiased prediction (BLUP) values using the composite interval mapping algorithm of the BIP (biparental populations) module. The QTLs were distributed on seven different chromosomes, explaining 10.95%-17.77% of phenotypic variance, with the highest LOD score being 5.96 for qTSS.AS.pau-6.2. Thirteen QTLs detected across multiple environments with BLUPs indicate stability and utility in a future breeding program for guava. Furthermore, seven QTL clusters with stable or common individual QTLs affecting two or more different traits were located on six linkage groups (LGs), explaining the correlation among fruit-quality traits. Thus, the multiple environmental evaluations conducted here have increased our understanding of the molecular basis of phenotypic variation, providing the basis for future high-resolution fine-mapping and paving the way for marker-assisted breeding of fruit-quality traits.

Identifying successful combinations by fertility index in old garden roses and hybrid tea roses crosses.

The success of rose breeding programs is low due to poor seed sets and germination rates. Determining fertile parents and cross combinations that show high compatibility could increase the effectiveness of breeding programs. In this study, three rose varieties belonging to Rosa × hybrida (Jumilia, First Red and Magnum), and two old garden rose species (Black Rose and Cabbage Rose) with known ploidy levels were reciprocally crossbred under controlled conditions to determine the successful crosses by checking fertility. The pollen germination rate (PG), crossability rate (CR), seed number per fruit (SNpF), seed production efficiency (SPE), seed germination rate (SGR), fruit weight (FW), seed weight (SW) and stigma number (SiN), etc. were recorded. Comprehensive fertility index value was calculated. Principal component analysis (PCA), correlation matrix, and hierarchical heat map were used to evaluate the data. The findings showed that old garden roses had more viable pollen than hybrid tea roses. The crossing success improved as pollen fertility increased. Also, female parent fertility improved crossing success just as much as pollen fertility. Although the pollen fertility and stigma numbers were low, some combinations had higher CR and SPE. The maximum SPE (from 8.67% to 19.46%) was determined in combinations where Black Rose was the female parent despite the lower stigma number and low pollen fertility. The highest CR was recorded in Black Rose × First Red (94.36%). All combinations in which Black Rose was used as the female parent had a more stable CR. The SNpF of combinations where hybrid rose varieties were female parents and old garden roses were pollen parents was higher than other combinations where hybrid rose varieties were both female and pollen parents. The SPE in intraspecific crosses was lower than that obtained from interspecific crosses. Moreover, the SGR decreased in combinations that produced heavier seeds. The results suggested that SPE is a more accurate parameter than SNpF in demonstrating combination success in breeding programs. Black Rose × First Red, Black Rose × Jumilia, Black Rose × Magnum and Black Rose × Cabbage Rose combinations can be used successfully as the PCA and heat map showed. Black Rose showed better performance as both seed and pollen parents according to the comprehensive fertility index. From the correlation matrix, it is understood that the number of stigmas cannot be an important criterion in parent selection. Old garden roses can be used as parents to increase the success of breeding programs. However, it is necessary to reveal how successful they are in transferring desired characteristics such as scent, petal number, and color.

Maternal patterns of inheritance alter transcript expression in eggs

BackgroundModifications to early development can lead to evolutionary diversification. The early stages of development are under maternal control, as mothers produce eggs loaded with nutrients, proteins and mRNAs that direct early embryogenesis. Maternally provided mRNAs are the only expressed genes in initial stages of development and are tightly regulated. Differences in maternal mRNA provisioning could lead to phenotypic changes in embryogenesis and ultimately evolutionary changes in development. However, the extent that maternal mRNA expression in eggs can vary is unknown for most developmental models. Here, we use a species with dimorphic development— where females make eggs and larvae of different sizes and life-history modes—to investigate the extent of variation in maternal mRNA provisioning to the egg.ResultsWe find that there is significant variation in gene expression across eggs of different development modes, and that there are both qualitative and quantitative differences in mRNA expression. We separate parental effects from allelic effects, and find that both mechanisms contribute to mRNA expression differences. We also find that offspring of intraspecific crosses differentially provision their eggs based on the parental cross direction (a parental effect), which has not been previously demonstrated in reproductive traits like oogenesis.ConclusionWe find that maternally controlled initiation of development is functionally distinct between eggs of different sizes and maternal genotypes. Both allele-specific effects and parent-of-origin effects contribute to gene expression differences in eggs. The latter indicates an intergenerational effect where a parent’s genotype can affect gene expression in an egg made by the next generation.

Potential Gene Flow Between <i>Gossypium hirsitum</i> and <i>Abelmoschus esculentus</i> Through Interspecific Hybridization

The introduction of transgenic varieties of cotton (<i>Gossypium hirsitum</i>) in Cameroon has posed numerous concerns. One of the most concern was the horizontal transfer of the <i>Bt</i> gene to related species such as <i>Abelmoschus esculentus</i>. The current study was conducted to assess the occurrence <i>Bt</i> gene transfer from <i>Gossypium hirsitum </i>to<i> Abelmoschus esculentus</i>. To achieve this, the stigma receptivity periods and the viability of pollen grains were evaluated. The fruit set rates of 675 controlled intra- and interspecific crosses were assessed. The results showed that stigma receptivity and pollen grain viability are optimal at anthesis in both species, with a longer duration over 24 hours in <i>G. hirsitum</i>. Intra-specific crosses within the two species have shown fruit set rates of nearly 60-80%. Interspecific crosses gave a fruit set rate close to 2%, especially when <i>A. esculentus</i> is used as the female parent, and zero results in reciprocal crosses. The finding of the study pointed out that the possibility of horizontal transfer of a transgene to cotton relatives. In future studies, it would be useful to monitor the fate of seeds from interspecific crosses between both species and assess the agro-morphological and molecular characteristics of these possible hybrids.