Interspecific Crosses Research Articles

Introgression of Resistance to Multiple Pathotypes of Plasmodiophora brassicae from Turnip (Brassica rapa ssp. rapifera) into Spring B. napus Canola

Clubroot disease resistance has been introgressed from Brassica rapa into canola following different approaches including a B. napus × B. rapa interspecific cross; however, the details of this cross are not available. To extend our knowledge of this cross for the introgression of resistance to multiple pathotypes, we crossed a clubroot-resistant turnip with a susceptible canola and backcrossed the F1′s to canola. The backcross population was subjected to pedigree breeding with selection for clubroot resistance and canola-quality traits; selection for resistance to pathotype 3H and 3A was performed in the early and advanced generations, respectively. The advanced generation lines were also evaluated for resistance to 3H, 3A, 2B, and 5x, and for field resistance to clubroot, and agronomic and seed quality traits. Following this, we developed canola lines carrying resistance to multiple pathotypes and nuclear DNA content similar to B. napus. Resistance to 3H showed a weak correlation with other pathotypes whereas resistance to 3A showed a strong positive correlation with 5x indicating that resistance to these pathotypes was under a similar genetic control. Thus, the results demonstrate that resistance to multiple pathotypes can be introgressed from a turnip into a canola even when selection for resistance to single pathotype is performed in early generations.

Inter and intra-specific crossability studies on Mangifera species

Inter-specific and inter-varietal crosses were attempted using Mangifera indica cv. Amrapali as a female parent and M. odorata and M. indica cv. Vanraj as male donor parents (2016–19). Initial fruit set after 7 days of pollination (DAP) was 81.48%, which reduced to 2.48% at harvest. However, in inter-specific crosses, initial fruit set was 79.89%, which reduced to 0.45% at the time of harvesting. Progenies obtained from inter-varietal and inter-specific crosses were subjected to confirmation of parentage using SSR markers. Eight polymorphic SSR markers were used to estimate the paternity, maternity and new alleles in the hybrids. Based on fragment analysis, the paternity, maternity and new alleles of 12 inter-specific and 17 inter-varietal hybrids were estimated by finding a similar number of alleles between the offsprings and parents. Among inter-specific hybrids, AO2, AO7, AO11, and AO12 showed ≥50% of paternal allele inheritance, while AO1, AO2, AO4, AO5, AO7, AO8, AO9, AO10 and AO12 showed ≥50% of maternal allele inheritance. Inter-specific hybrids such as AO1, AO3, AO5, AO9, AO10 and AO11 inherited new alleles. Among inter-varietal hybrids, AV1, AV2, AV4, AV5, AV6, AV10, AV11, AV12, AV13, AV14, AV15 and AV17 possessed ≥50% paternal allele, while, AV1, AV2, AV3, AV5, AV6, AV7, AV8, AV10, AV11 and AV15 had ≥50% maternal allele. Three inter-varietal hybrids, viz. AV8, AV9 and AV16 inherited new alleles. It is concluded that SSRs markers are useful in ascertaining the parentage of hybrids obtained from inter-specific and inter-varietal crosses in mango.

Bruchid Resistance Study through Bulked Segregant Analysis: Used as a Preliminary Step for Next-Generation Sequencing

Seed beetles, commonly known as bruchids, are serious insect pests of Indian pulses inflicting high damage during storage. Earlier, a bruchid resistant rice bean landrace (TNAU Red) from Manipur and a susceptible mung bean variety (VRMGg1) from Tamil Nadu were reported and their inter-specific cross was made in Tamil Nadu Agricultural University. In the present study, seeds from the segregating populations (recombinant inbred lines, RILs) of VRM (Gg)1 and TNAU Red were evaluated for bruchid Callosobruchus maculatus Fabricius resistance following standard methods under laboratory conditions. Bulked segregant analysis (BSA) is an efficient method for quick identification of molecular markers linked to any specific gene or genomic region. BSA significantly reduces the scale and cost by simplifying the procedure compared to conventional method of analyzing the entire population. BSA was carried out using 3 marker systems with an attempt to identify markers associated with the present trait of interest. Two DNA bulks namely resistant bulk (RB) and susceptible bulk (SB) were grouped by pooling equal amount of DNA from 5 each of resistant and susceptible RILs based on bruchid responses such as seed damage (%), mean developmental days (MDP) and adult emergence from seeds. Marker analysis carried out with 41 polymorphic SSRs showed skewed segregation distortion towards the susceptible parent. However, out of 9 RAPDs and 10 ISSRs, 2 RAPD (OPB08 and OPX04) and 1 ISSR (UBC810) primers amplified an allele at 200 - 300 and 300 - 400 bp, respectively, in resistant parent and resistant bulk but not in susceptible parent and susceptible bulk. The amplification of resistant parent allele in resistant bulk may indicate the presence of bruchid resistant gene(s) in the resistant RILs. This experiment was aimed at verifying the presence of bruchid resistant lines carrying resistant gene(s) prior to further association mapping or QTL mapping studies. Further, such type of study can be applied as a preliminary step in NGS technology.
 HIGHLIGHTS
 
 Bruchids are the most damaging storage insect in pulses and other legumes causing great economic losses
 Bulk segregant analysis (BSA) conducted using three marker systems in an attempt to identify markers associated with bruchid resistance
 Categorization of RILs based on bruchid responses such as seed damage (%), mean developmental days (MDP), adult emergence from seeds and scoring done
 Marker analysis using BSA useful for verification of the presence of bruchid resistant lines carrying resistant gene(s) prior to further advanced studies such as QTL mapping, NGS, etc.
 
 GRAPHICAL ABSTRACT

Interspecific and intraspecific cross-compatibility of Durio kutejensis and hybrid Durio zibethinus x kutejensis

Abstract. Rudarmono, Ardiarini NR, Waluyo B, Ashari S. 2022. Interspecific and Intraspecific cross-compatibility of Durio kutejensis and hybrid Durio zibethinus x kutejensis. Biodiversitas 23: 1837-1843. Lai (Durio kutejensis) and Mandong (Durio zibethinus x kutejensis) fruits that have advantages and high consumer preference values. Fruit productivity and development of Lai and Mandong plant varieties are still not optimal. The aim of this study was to analyze the level of incompatibility of interspecific and intraspecific crosses between Lai (D. kutejensis) and Mandong (D. zibethinus x kutejensis hybrid) plants. Artificial crosses were made utilizing flower samples from Mahakam, Kutai, and Batuah types of Lai plants, as well as Mandong varieties of Mandong, employing a scheme of 20 crossings that included a combination of these varieties (12 treatments), as well as each variety from the same flower and tree (8 treatments). The intensity level and incompatibility classification were determined according to Wang's (1963) method, which was based on the number of fruits formed from artificial crosses, and the pollen incompatibility intensity level (IIL) was determined according to the ratio of flowers that produced fruit from the cross to the total number of flowers crossed. The results showed that overall crosses of the same flower (selfing) from three varieties of Lai and one variety of Mandong were incompatible. Lai Mahakam x Lai Batuah crosses yielded 14.28 % harvested fruit, Lai Mahakam x Lai Mahakam crosses yielded 18.75 % harvested fruit, Lai Kutai x Lai Kutai crossings yielded 14.81 % harvested fruit, while a cross of Durian Mandong x Lai Batuah yielded 16.67 % harvested fruit. It shows partially compatible. The complete compatibility value showed the number of harvested fruit ranged from 23.44 to 46.77%, with the most significant being obtained from a Lai Mahakam x Durian Mandong cross. The Mahakam, Kutai, Batuah, and Mandong varieties are compatible with all pollen sources.

Three-way cross hybrid abalone exhibit heterosis in growth performance, thermal tolerance, and hypoxia tolerance

Abalone is an economically important aquaculture resource worldwide, with high commercial value. Abalone productivity, stress resistance, and profitability have been improved by interspecific and intraspecific hybridization. In this study, a systematic comparative assessment of heterosis for survival, growth, thermal tolerance, and hypoxia tolerance in Haliotis gigantea (SS), H. discus hannai (DD), H. discus hannai♀ × H. fulgens♂ (DF), and three-way cross hybrids SS♀ × DF♂ and DF♀ × SS♂ was conducted. Two three-way cross hybrids, SS × DF and DF × SS, showed positive mid-parent heterosis in the growth rates of shell length and total wet weight in different months. The proportion of large individuals with higher total wet weight or shell length in DF × SS and SS × DF was higher than in other abalone species. The thermal and hypoxia tolerance of these abalone were assessed using Arrhenius break temperatures (ABT) and the breakpoint of dissolved oxygen (BPDO) of cardiac performance, respectively. The mid-parental heterosis values of ABT in SS × DF and DF × SS were 2.29% and 1.38%, respectively, while the BPDO values in SS × DF and DF × SS were − 11.48% and − 11.96%, respectively, confirming heterosis for thermal and hypoxia tolerance in these three-way cross hybrids. Overall, this is the first three-way interspecific cross of abalone, and the improvement of commercial traits can be achieved through a combination of selection and further hybridization among purebred and hybrid abalone.

Occurrence of albino seedling in Prinsepia utilis Royle

Albinism in plants is characterized by partial or complete loss of chlorophyll pigments and incomplete differentiation of chloroplast membranes. This is a very common problem encountered in interspecific crosses and tissue culture experiments including anther culture and generation of doubled haploids. This impairs photosynthesis and the plants eventually die at a young stage without reaching maturity. Environmental conditions such as light, temperature, media composition and culture conditions may key factors in determining the frequency of albino plant formation. This short communication reports the first instance of albinism recorded in Prinsepia utilis Royle. An albino seedling was observed during the standardization of nursery techniques.

Inheritance and mapping of QTLs for Ascochyta blight resistance in chickpea (Cicer arietinum)

There are very limited studies on the QTLs governing Ascochyta blight resistance which is a major problem in chickpea (Cicer arietinum L.) grown in North West Plain Zone of India in the cooler climates and world over. An interspecific mapping population consisting of 157 F2:3 lines developed by crossing a resistant parent ILWC129 (C. reticulatum) with a susceptible variety GL769 (C. arietinum L.), was evaluated (2019–20) and genotyped (2021) for genetic studies and mapping of resistance to Ascochyta rabiei (syn. Phoma rabiei), isolate 8(3968). The inheritance pattern gave 1R:2H:1S goodness of fit ratio with χ2 value of 0.4 indicating that resistance against isolate 8 of the pathogen governed by a single gene. Out of 831 SSR markers screened, 86 were found polymorphic with 10.3% polymorphism from which only 41 markers segregated in 1:2:1 ratio and could be mapped. Eight linkage groups with a cumulative distance of 1042.31 cM were formed with an average distance of 25.42 cM. This is probably the first report of inheritance studies and tagging of A. rabei race 8 (arr8) resistance gene using molecular markers in an interspecific cross with C. reticulatum.

Phenotypic Diversity in Wild and Cultivated Date Palm (Phoenix, Arecaceae): Quantitative Analysis Using Information Theory

The quantitative study of genetic diversity requires tools to describe quantitatively and in parallel the whole phenotypic diversity in order to produce meaningful comparisons. The genus Phoenix offers examples of species with very different levels of diversity or heterogeneity. Within Phoenix, date palm (Phoenix dactylifera L.) is a major food crop of global relevance. The concept of information entropy was introduced by Claude Shannon; although initially intended to evaluate data communication systems, it has been used to measure biodiversity in terms of richness, evenness and dominance. In the present work, we will use it to describe heterogeneity within the different taxonomic units in the genus Phoenix. The description of the Phoenix morphological diversity in the present work is based on 596 accessions or populations belonging to 43 mutually exclusive taxonomic units (species, subspecies, varieties, landrace groups and hybrids). As Phoenix is a dioecious palm genus, female and male individuals are described separately. Each accession or sample is described using 116 characters totaling 449 states. The Shannon information entropy index allows the quantitative representation of the different levels of heterogeneity in the various taxonomic units of the genus Phoenix. Morphology, consistency and coloration of fruit and seed, followed by the inflorescences and female flowers, comprise the taxonomic characters that contribute the most to heterogeneity. Vegetative characters contribute less than the characters of the reproductive organs as a whole. Phoenix dactylifera and related Mediterranean and Macaronesian taxa present the maximum heterogeneity. Immediately afterwards we find P. loureiroi and, behind, the group of P. pusilla. At the lower limit of heterogeneity, we find species restricted in their distribution area: P. rupicola, P. theophrasti, P. roebelenii and P. acaulis. Phoenix dactylifera conforms to a complex of landraces and cultivars that coexist as phenotypically well-defined geographical groups with numerous intermediate forms and the long-distance translocation of otherwise local cultivars. This results in high heterogeneity. For the western and eastern groups of Phoenix dactylifera, it is extremely difficult to find a set of well-defined differential characters. However, some of the variables analyzed here allow us to propose a set of their respective syndromes. The high phenotypic heterogeneity in various Phoenix species is related to the genetic diversity, age and ancestry of different taxa, hybridization events and introgressions prior to domestication, and selective pressures after domestication and, again, interspecific crosses after domestication.

Cross compatibility in intraspecific and interspecific hybridization in yam (Dioscorea spp.)

Yam (Dioscorea spp.) is a staple crop for millions of people in the tropics and subtropics. Its genetic improvement through breeding is being challenged by pre-zygotic and post-zygotic cross-compatibility barriers within and among species. Studies dissecting hybridization barriers on yam for improving the crossability rates are limited. This study aimed to assess the cross-compatibility, which yielded fruit set, viable seeds and progeny plants in an extensive intraspecific and interspecific crossing combinations in a yam genetic improvement effort to understand the internal and exogenous factors influencing pollination success. Cross-compatability was analyzed at the individual genotype or family level using historical data from crossing blocks and seedling nurseries from 2010 to 2020 at the International Institute of Tropical Agriculture (IITA). The average crossability rate (ACR) was lower in interspecific crossing combinations (6.1%) than intraspecific ones (27.6%). The seed production efficiency (SPE) values were 1.1 and 9.3% for interspecific and intraspecific crosses, respectively. Weather conditions and pollinator's skills are the main contributors to the low success rate in the intraspecific cross combinations in yam breeding. At the same time, genetic distance and heterozygosity played little role. Interspecific cross barriers were both pre-zygotic and post-zygotic, resulting from the evolutionary divergence among the yam species. Dioscorea rotundata had higher interspecific cross-compatibility indices than D. alata. Distant parents produced intraspecific crossbred seeds with higher germination rates compared to closest parents (r = 0.21, p = 0.033). This work provided important insights into interspecific and intraspecific cross-compatibility in yam and suggested actions for improving hybridization practices in yam breeding programs.

Extensive pollinator sharing does not promote character displacement in two orchid congeners.

Pollinator sharing between close relatives can be costly and can promote pollination niche partitioning and floral divergence. This should be reflected by a higher species divergence in sympatry than in allopatry. We tested this hypothesis in two orchid congeners with overlapping distributions and flowering times. We characterized floral traits and pollination niches and quantified pollen limitation in 15 pure and mixed populations, and we measured phenotypic selection on floral traits and performed controlled crosses in one mixed site. Most floral traits differed between species, yet pollinator sharing was extensive. Only the timing of scent emission diverged more in mixed sites than in pure sites, and this was not mirrored by the timing of pollinator visitation. We did not detect divergent selection on floral traits. Seed production was pollen limited in most populations but not more severely in mixed sites than in pure sites. Interspecific crosses produced the same or a higher proportion of viable seeds than intraspecific crosses. The two orchid species attract the same pollinator species despite showing divergent floral traits. However, this does not promote character displacement, implying a low cost of pollinator sharing. Our results highlight the importance of characterizing both traits and ecological niches in character displacement studies.

Karely, new variety of cut flower heliconia, suitable for the humid Mexican tropics

Objective: To describe Heliconia uxpanapensis x Heliconia latispatha var. Karely, interspecific variety generated for cut flower based on commercial standards. Design/Methodology/Approach: Interspecific hand pollination was carried out between H. uxpanapensis Gutiérrez Báez x H. latispatha Benth. The female parent is endemic to Mexico; it presents compact growth due to its pachymorphic rhizome, red and erect inflorescence, and bracts in distal position. H. latispatha grows expansively due to its leptomorphic rhizome, its inflorescence, composed of orange bracts, is erect and helical. The F1 hybrid was self-fertilized and produced viable seed. The mature zygotic embryos were germinated in vitro, the seedlings were acclimatized at six months and at ten months they were established in the field; Heliconia var. Karely was generated from this population. Results: Karely variety is F2 product of the interspecific cross between H. uxpanapensis x H. latispatha, it presents a compact growth habit, erect inflorescence, bracts in distal position of orange color with red border. The inflorescence is clean and healthy. The postharvest half-life is 15 days Study Limitations/Implications: Karely must be cultivated under an agroforestry system in conditions of 20 to 30 % shade for the adequate pigmentation of the bracts. In addition, it requires sandy-loam soil for proper development and growth of its inflorescence. Findings/Conclusions: Karely has ideal characteristics for cut flower and meets the characteristics established by the market.

Features of Chromosome Introgression from Gossypium barbadense L. into G. hirsutum L. during the Development of Alien Substitution Lines.

The creation of G. barbadense L./G. hirsutum L. chromosome-substitution lines is an important method to transfer agronomically valuable traits from G. barbadense into G. hirsutum. In this study, 30 monosomic lines of G. hirsutum from the Cytogenetic Collection of Uzbekistan, created in the genotypic background of line L-458, were used in crosses with the G. barbadense line Pima 3-79 to create substitution lines. In the course of this work, new monosomic lines were identified for chromosome 12 and monotelodisome 6 of the Atsubgenome and for chromosomes 17, 21, and 22 of the Dtsubgenome using chromosome-specific SSR markers and a well-defined tester set of cotton translocation lines (USA). Compared to those in the F1 hybrids, a strong decrease in the crossing and setting rates was found in the BC1F1 backcross lines, with the substitution of chromosomes 2, 4, 6, 7, and 12 of the Atsubgenome and 17, 18, 21, and 22 of the Dtsubgenome. The F1 and BC1F1 offspring from interspecific crosses differed in their transmission of univalents. Despite the regular pairing of chromosomes and the high meiotic index, interspecific aneuploid hybrids were characterized by a decrease in pollen fertility, which may indicate hidden structural variability in these genomes that did not affect meiotic division. The identification of chromosomes using chromosome-specific SSR markers in the early stages of plant development has greatly accelerated the detection of monosomic plants. The analysis of morphobiological traits revealed that monosomic F1 hybrids were more similar to the donor line, while BC1F1 hybrids were more similar to the recurrent parent but also showed previously undetected traits.

New Hybrid Spikelet Sterility Gene Found in Interspecific Cross between Oryza sativa and O. meridionalis.

Various kinds of reproductive barriers have been reported in intraspecific and interspecific crosses between the AA genome Oryza species, to which Asian rice (O. sativa) and African rice (O. glaberrima) belong. A hybrid seed sterility phenomenon was found in the progeny of the cross between O. sativa and O. meridionalis, which is found in Northern Australia and Indonesia and has diverged from the other AA genome species. This phenomenon could be explained by an egg-killer model. Linkage analysis using DNA markers showed that the causal gene was located on the distal end of chromosome 1. Because no known egg-killer gene was located in that chromosomal region, this gene was named HYBRID SPIKELET STERILITY 57 (abbreviated form, S57). In heterozygotes, the eggs carrying the sativa allele are killed, causing semi-sterility. This killer system works incompletely: some eggs carrying the sativa allele survive and can be fertilized. The distribution of alleles in wild populations of O. meridionalis was discussed from the perspective of genetic differentiation of populations.

Analysis of single nucleotide polymorphism and simple sequence repeat markers for the estimates of genetic diversity by using two oilseed Brassica napus populations carrying genome contents of Brassica oleracea

Reliable estimates of genetic diversity among the accessions in a breeding population is important knowledge for use in breeding. Among the different types of molecular markers, single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) are largely used by breeders; however, our knowledge of the reliability of the estimates of genetic diversity based on these two types of markers in multiple populations is limited. In this study, a doubled haploid (DH) and an inbred population developed from Brassica napus × Brassica oleracea interspecific crosses were used for comparative analysis of these two types of markers. The estimates based on SNP and SSR markers showed a stronger correlation in the inbred population which was expected to carry greater genetic diversity as compared to the DH population. This inference was also evident from the analysis of different diversity groups (least, intermediate, and most similar) of these two populations for significant difference between the groups for six agronomic and seed quality traits, where this analysis failed to differentiate the diversity groups of the DH population for any of the traits. However, both marker types could differentiate the diversity groups of the inbred population for several traits. Furthermore, the six sub-populations of the inbred population could also be differentiated by both marker types. Thus, the results demonstrate the greater utility of the SSR and SNP markers in a genetically diverse population. This knowledge can be used while grouping a breeding population for diversity groups; however, caution needs to be taken while using the markers in a genetically narrow population.

Identification of Two Major QTLs in Brassica napus Lines With Introgressed Clubroot Resistance From Turnip Cultivar ECD01.

Plasmodiophora brassicae causes clubroot disease in brassica crops worldwide. Brassica rapa, a progenitor of Brassica napus (canola), possesses important sources for resistance to clubroot. A doubled haploid (DH) population consisting of 84 DH lines were developed from a Backcross2 (BC2) plant through an interspecific cross of B. rapa turnip cv. ECD01 (resistant, R) with canola line DH16516 (susceptible, S) and then backcrossed with DH16516 as the recurrent parent. The DH lines and their parental lines were tested for resistance to four major pathotypes (3A, 3D, 3H, and 5X) of P. brassicae identified from canola. The R:S segregation ratio for pathotype 3A was 1:3, and 3:1 for pathotypes 3D, 3H, and 5X. From genotyping by sequencing (GBS), a total of 355.3 M short reads were obtained from the 84 DH lines, ranging from 0.81 to 11.67 M sequences per line. The short reads were aligned into the A-genome of B. napus “Darmor-bzh” version 4.1 with a total of 260 non-redundant single-nucleotide polymorphism (SNP) sites. Two quantitative trait loci (QTLs), Rcr10ECD01 and Rcr9ECD01, were detected for the pathotypes in chromosomes A03 and A08, respectively. Rcr10ECD01 and Rcr9ECD01 were responsible for resistance to 3A, 3D, and 3H, while only one QTL, Rcr9ECD01, was responsible for resistance to pathotype 5X. The logarithm of the odds (LOD) values, phenotypic variation explained (PVE), additive (Add) values, and confidence interval (CI) from the estimated QTL position varied with QTL, with a range of 5.2–12.2 for LOD, 16.2–43.3% for PVE, 14.3–25.4 for Add, and 1.5–12.0 cM for CI. The presence of the QTLs on the chromosomes was confirmed through the identification of the percentage of polymorphic variants using bulked-segregant analysis. There was one gene encoding a disease resistance protein and 24 genes encoding proteins with function related to plant defense response in the Rcr10ECD01 target region. In the Rcr9ECD01 region, two genes encoded disease resistance proteins and 10 genes encoded with defense-related function. The target regions for Rcr10ECD01 and Rcr9ECD01 in B. napus were homologous to the 11.0–16.0 Mb interval of chromosome A03 and the 12.0–14.5 Mb interval of A08 in B. rapa “Chiifu” reference genome, respectively.

Wild relatives of potato may bolster its adaptation to new niches under future climate scenarios

AbstractFood production strategies and patterns are being altered in response to climate change. Enhancing the adaptation of important food crops to novel climate regimes will be critical to maintaining world food supplies. Climate change is altering the suitability of production areas for crops such as potato (Solanum tuberosum L.) making future productivity, resilience, and sustainability of this crop dependent on breeding for climate adaptation, including through the introgression of novel traits from its wild relatives. To better understand the future production climate envelopes of potatoes, and the potential of its wild relatives to contribute to adaptation to these environments, we estimated the climate of potato in four future climate scenarios and overlapped the current climate of 72 wild relative species and potato with these future climates. We discovered a shift of up to 12.5% by potato from current to novel climate by 2070 and varying magnitudes of overlap by different wild relatives with potato, primarily driven by the extent of endemism. To address the threat of novel climate on potato production and with the wealth of data available for the agrobiodiversity in potato wild relatives, we systematically developed a prioritization value inspired by the logic of the breeder's equation for locating potentially beneficial species possessing local adaptability, climatic plasticity, and interspecific crossability. In doing so, 26 unique species by discrete climate combinations are found, highlighting the presence of unique species to use in adapting potato to changing local climates. Further, the 20 highest prioritized values belong to diploid species, enforcing the drive to shift into diploid breeding by the potato research community, where introgression of the local climate adaptability traits may be more streamlined.

Breeding an underutilized fruit crop: a long-term program for Hylocereus.

This review describes three decades of introduction, agro-technology development, breeding and selection of Hylocereus species, known as pitaya or dragon fruit, as an example of a holistic program aimed to develop the horticultural potential of a perennial underutilized fruit crop. Interspecific homoploid and interploid crosses and embryo rescue procedures produced improved hybrids, some of which have been released to farmers. Molecular tools and morphological and phenological comparisons between the parental species and the resulting hybrids provided valuable information on dominant/recessive traits and on genetic relationships that could be exploited for further hybridizations. In addition, Hylocereus were crossed with species of the closely related genus Selenicereus, producing valuable intergeneric hybrids. In situ chromosome doubling resulted in the production of autopolyploid lines, from which an understanding of the effect of increased ploidy on fruit traits and metabolomic profiles was obtained. Gamete-derived lines were produced, adding to our biobank homozygote lines that were subsequently used for further hybridization. Spontaneous chromosome doubling occurred in haploid gamete-derived Hylocereus monacanthus lines and in interspecific interploid Hylocereus megalanthus × H. undatus hybrids obtained from an embryo rescue procedure, resulting in plants with double the expected ploidy. Challenging technical problems were addressed by the development of protocols for DNA isolation, flow cytometry, in situ chromosome doubling, androgenesis, gynogenesis and embryo rescue following interspecific and interploidy crosses. Current research leading to the development of genomics and molecular tools, including a draft genome of H. undatus, is also presented. Perspectives for further development of Hylocereus species and hybrids are discussed.

Absence of major epigenetic and transcriptomic changes accompanying an interspecific cross between peach and almond.

Hybridization has been widely used in breeding of cultivated species showing low genetic variability, such as peach (Prunus persica). The merging of two different genomes in a hybrid often triggers a so-called “genomic shock” with changes in DNA methylation and in the induction of transposable element expression and mobilization. Here, we analysed the DNA methylation and transcription levels of transposable elements and genes in leaves of Prunus persica and Prunus dulcis and in an F1 hybrid using high-throughput sequencing technologies. Contrary to the “genomic shock” expectations, we found that the overall levels of DNA methylation in the transposable elements in the hybrid are not significantly altered compared with those of the parental genomes. We also observed that the levels of transcription of the transposable elements in the hybrid are in most cases intermediate as compared with that of the parental species and we have not detected cases of higher transcription in the hybrid. We also found that the proportion of genes whose expression is altered in the hybrid compared with the parental species is low. The expression of genes potentially involved in the regulation of the activity of the transposable elements is not altered. We can conclude that the merging of the two parental genomes in this Prunus persica x Prunus dulcis hybrid does not result in a “genomic shock” with significant changes in the DNA methylation or in the transcription. The absence of major changes may facilitate using interspecific peach x almond crosses for peach improvement.

Formation when using interspecific crossings in the Ribesia subgenus

The aim of the research was to study the offspring from the open pollination of ES 1674-30-30 by the main economically important traits for the crop and to isolate valuable genotypes. During the record, it was revealed that some seedlings inherited from the parent form a trait of apical fruiting. Of the 79 seedlings of such atypical plants, there were 18 seedlings, which was 23.7%. In all years of the observation, the average raceme length for the group of seedlings with apical fruiting exceeded the average for typical seedlings of this family. There were no significant differences in the weight of 100 berries between the groups of seedlings. It was found that plants with apical fruiting aged faster than ordinary seedlings. As a result of the research, it was found that the family 2521 was of breeding value for the yield of long-raceme seedlings resistant to fungal diseases.

Evolutionarily genetic dissection of flowering behavior in Asian wild and cultivated rice

Flowering behaviors (FBs) are important life-history and agronomical traits, and their genetic architecture and evolution are of great interest to crop breeders. Flowering behavior simply indicates days to the first-flowering time from germination (DFF) when considering only modern cultivars with small genetic variation, but flowering continuity as the result of asynchronous flowering can be relevant for the FB when an evolutionary variation is present. Evolutionary and genetic nature of asynchronous flowering has been unknown until now. Through daily observation, we recorded the first- and third-flowering date of a plant, and then calculated DFF and days to the third-flowering time from germination (DTF). Flowering asynchrony in a plant (FA) was defined as the equation, FA = DTF – DFF. Quantitative-trait locus (QTL) analyses were performed on DFF, DTF, and FA in each of two-density conditions in a paddy field by using 35 recombinant-inbred lines derived from an interspecific cross between domesticated rice (Oryza sativa L.) and an annual form of its wild relatives (O. rufipogon Griff.). The present results suggest the following points: (a) FA could have a genetic component that is independent of flowering genes; (b) genetic nature of FA might be polygenic and the majority of the QTLs associated with FA behaved in a complex density-dependent manner; and (c) FA might have been developed by feeding pressure of animals in their wild habitat.