Hybrid Progeny Research Articles

Rare and abundant bacterial communities in poplar rhizosphere soils respond differently to genetic effects

Interactions between plants and soil microbes are important to plant hybrid breeding under global change. However, the relationship between host plants and rhizosphere soil microorganisms has not been fully elucidated. Understanding the rhizosphere microbial structure of parents and progenies would provide a deeper insight into how genetic effects modulate the relationship between plants and soil. In this study, two family groups of poplar trees (A: parents and their two progenies; B: parents and their one progeny) with different genetic backgrounds (including seven genotypes) were selected from a common garden, and their rhizobacterial communities were analyzed to explore parent-progeny relationships. Our results showed significant differences in phylogenetic diversity, the number of 16S genes and the structure of rhizosphere bacterial communities (Adonis: R2 = 0.166, P < 0.01) between different family groups. Rhizosphere bacterial community structure was significantly dominated by genetic effects. Compared with abundant taxa, genetic effects were more powerful drivers of rare taxa. In addition, bacterial communities of hybrid progenies were all significantly more similar to their parents compared to the other group of parents, especially among rare taxa. The two poplar family groups exhibited differences between their rhizosphere bacterial co-occurrence networks. Group B had a relatively complex network with 2380 edges and 468 nodes, while group A had 1829 edges and 304 nodes. Soil organic carbon and carbon to nitrogen ratio (C/N) also influenced the rhizosphere bacterial community assembly. This was especially true for soil C/N, which explained 23 % of the β-nearest taxon index (βNTI) variation in rare taxa. Our results reveal the relationship of rhizosphere microorganisms between parents and progenies. This can help facilitate an understanding of the combination of plant breeding with microbes resource utilization and provide a theoretical basis for scientific advancement to support the development of forestry industry.

Development and characterization of a line with substitution of chromosome 4B of wheat Triticum aestivum L. on chromosome 4Hmar of wild barley Hordeum marinum ssp. gussoneanum (4x).

Introgressive hybridization is the main method of broadening the genetic diversity of bread wheat. Wild barley Hordeum marinum ssp. gussoneanum Hudson (2n = 4x = 28) has useful agronomical traits, such as high resistance to stress factors, that could be a potential source of new genes for bread wheat improvement. This study aimed to evaluate the possibility of introgression of H. marinum chromosomes into the genome of bread wheat using an incomplete amphiploid H. marinum ssp. gussoneanum (4x)-T. aestivum (Pyrotrix 28) (2n = 54) carrying the cytoplasm of wild barley. For this purpose, we crossed the line of bread wheat variety Pyrotrix 28 with an incomplete amphiploid, and then selected cytogenetically stable 42-chromosome plants with a high level of fertility in hybrid progeny. Genomic in situ hybridization (GISH) revealed a pair of H. marinum chromosomes in the genome of these plants. C- banding analysis confirmed that bread wheat chromosome 4B was replaced by wild barley chromosome 4Hmar. SSR markers Xgwm368 and Xgwm6 confirmed the absence of chromosome 4B, and EST markers BAWU808 and BAW112 identified chromosome 4Hmar in the genome of the isolated disomic wheat-barley substitution line. The study of this line showed that the substitution of chromosome 4B with chromosome 4Hmar resulted in a change of some morphological traits. It included intense anthocyanin coleoptile coloration, specific for H. marinum, as well as a lack of purple coloration of the ears in the leaf sheath, specific for Pyrotrix 28. Line 4Hmar(4B) showed increased performance for several traits, including plant height, number of spikes and tillers per plant, spikelet and grain number in the main spike, grain number per plant, but it had decreased values of 1000-grain weight compared to wheat. Cytogenetic stability and fertility of line 4Hmar(4B) indicated a high compensation ability of barley 4Hmar for wheat chromosome 4B and confirmed their homeology.

Genetic variation and heterosis of the interspecific abalone hybrid of Haliotis rubra and H. laevigata

The interspecific abalone hybrid of Haliotis rubra x H. laevigata is an important commercial species for abalone aquaculture in Australia. A selective breeding program is in operation to genetically improve hybrid performance for total weight, meat yield, and appearance traits (epipodium pattern and foot colour). This study provides estimates of heterosis for these traits and genetic parameters for the two parental species and their hybrid populations, measured using 73,107 individuals collected over 14 generations. Measurements were made at 1.5 and 2.5 years for total weight, meat yield and appearance traits. Genetic variation was significant for all evaluated traits and was predominantly due to additive genetic variation. The heritability (h2) estimates of total weight at 2.5 years for H. rubra and H. laevigata was 0.54 ± 0.03 and 0.45 ± 0.02, respectively, but higher in the hybrid population (0.57 ± 0.01). For other traits the h2 estimates of hybrid populations were within the range of those for pure species. The range of h2 (with SE) at 2.5 years for meat yield, epipodium pattern and foot colour were 0.27 (0.06) to 0.78 (0.04), 0.35 (0.05) to 0.62 (0.03), and 0.18 (0.03) to 0.30 (0.02), respectively. Heterosis was present for all traits except foot colour. Effects were strongest for total weight, with a 67% gain over the mid parent value, and less for meat yield, epipodium pattern, and foot colour with gains of 6%, 9% and 6% over mid parent value, respectively. Genetic correlations between pure species performance and hybrid performance for total weight were 0.45 (0.17) for H. rubra and 0.75 (0.06) for H. laevigata and ranged from 0.27 to 0.85 for other traits. These correlations were a basis for decisions about the commercial breeding strategy. The strategy adopted is a form of reciprocal recurrent selection which uses a hybrid progeny test. Selection is based on estimation of additive hybrid effects and measurements are made on both hybrid and pure species which are treated as separate and correlated traits.

Development and application of KASP marker for high throughput detection of the seedless trait in grapevine

Molecular marker-assisted selection (MAS) can significantly accelerate and improve the efficiency of the breeding process in seedless grape cultivars. In this study, we developed the KASP_VviAGL11 and VviAGL11_410 markers based on a single nucleotide polymorphism (SNP) site (Chr18: 26889437 (A/C)) of the VviAGL11 gene, and compared them with previously reported SSR markers p3_VvAGL11 and 5U_VviAGL11 by testing 101 cultivars and 81 F1 hybrid progenies. The results showed that both of the proposed markers obtained 100% accuracy rates in detecting allele A, which was closely associated with the seedless trait in grapes, while p3_VvAGL11 and 5U_VviAGL11 had lower accuracy rates due to their tendency to produce false positives. After careful evaluation of the technical advantages and disadvantages associated with these markers, we concluded that KASP_VviAGL11 was superior in terms of simplicity, cost-effectiveness, efficiency, and accuracy. Thus, we optimized the process of molecular MAS for seedless grapes, focusing on the KASP_VviAGL11 marker as a central component, to provide key technical support for the development of new seedless grape cultivars.

The genome-wide meiotic recombination landscape in ciliates and its implications for crossover regulation and genome evolution

Meiotic recombination is essential for sexual reproduction and its regulation has been extensively studied in many taxa. However, genome-wide recombination landscape has not been reported in ciliates and it remains unknown how it is affected by the unique features of ciliates: the synaptonemal complex (SC)-independent meiosis and the nuclear dimorphism. Here, we show the recombination landscape in the model ciliate Tetrahymena thermophila by analyzing single-nucleotide polymorphism datasets from 38 hybrid progeny. We detect 1021 crossover (CO) events (35.8 per meiosis), corresponding to an overall CO rate of 9.9 cM/Mb. However, gene conversion by non-crossover is rare (1.03 per meiosis) and not biased towards G or C alleles. Consistent with the reported roles of SC in CO interference, we find no obvious sign of CO interference. CO tends to occur within germ-soma common genomic regions and many of the 44 identified CO hotspots localize at the centromeric or subtelomeric regions. Gene ontology analyses show that CO hotspots are strongly associated with genes responding to environmental changes. We discuss these results with respect to how nuclear dimorphism has potentially driven the formation of the observed recombination landscape to facilitate environmental adaptation and the sharing of machinery among meiotic and somatic recombination.

Single-cell RNA sequencing and UPHLC-MS/MS targeted metabolomics offer new insights into the etiological basis for male cattle-yak sterility

The variety of species can be efficiently increased by interspecific hybridization. However, because the males in the hybrid progeny are usually sterile, this heterosis cannot be employed when other cattle and yaks are hybridized. While some system-level studies have sought to explore the etiological basis for male cattle-yak sterility, no systematic cellular analyses of this phenomenon have yet been performed. Here, single-cell RNA sequencing and UPHLC-MS/MS targeted metabolomics methods were used to study the differences in testicular tissue between 4-year-old male yak and 4-year-old male cattle-yak, providing new and comprehensive insights into the causes of male cattle-yak sterility. Cattle-yak testes samples detected 6 somatic cell types and one mixed germ cell type. Comparisons of these cell types revealed the more significant differences in Sertoli cells (SCs) and [Leydig cells and myoid cells (LCs_MCs)] between yak and cattle-yak samples compared to other somatic cell clusters. Even though the LCs and MCs from yaks and cattle-yaks were derived from the differentiation of the same progenitor cells, a high degree of overlap between LCs and MCs was observed in yak samples. Still, only a small overlap between LCs and MCs was observed in cattle-yak samples. Functional enrichment analyses revealed that genes down-regulated in cattle-yak SCs were primarily enriched in biological activity, whereas up-regulated genes in these cells were enriched for apoptotic activity. Furthermore, the genes of up-regulated in LCs_MCs of cattle-yak were significantly enriched in enzyme inhibitor and molecular function inhibitor activity. On the other hand, the genes of down-regulated in these cells were enriched for signal receptor binding, molecular function regulation, positive regulation of biological processes, and regulation of cell communication activity. The most significant annotated differences between yak and cattle-yak LCs_MCs were associated with cell-to-cell communication. While yak LCs_MCs regulated spermatogenic cells at spermatogonia, spermatocyte, and spermatid levels, no such relationships were found between cattle-yak LCs_MCs and germ cells. This may suggest that the somatic niche in male cattle-yak testes is a microenvironment that is ultimately not favorable for spermatogenesis.

Esterase Profile in Distinguishing Inbreeds F1 And Backcross Hybrids in Indian Major Carps

Esterase was surveyed in four different tissues namely skeletal muscle, heart, liver and kidney obtained from two Indian major carps viz.., rohu (Labeo rohita) and catla (Catla catla) pair crossed F1 hybrids of catla (y) x rohu (6), and back crossed hybrid progenies of (catla x rohu) (?) x catla (J) (BC1C) and of (catla x rohu) (?) x rohu (6) (BC1R). The enzyme was found to be highly polymorphic in different tissues of the inbred as well as in hybrids. Detailed scanning of different activity zones in the zymograms revealed that amidst 15 bands, band numbers 4 and 12 of liver and kidney tissues were found to be common in both the inbreeds and hybrids were probably characteristics bands to these two species and their hybrid progenies. Band 4 of rohu and 6/7 of catla were diagnostic bands of pure rohu and catla, respectively, regardless of the nature of the tissue. However, both the bands were present in F 1 hybrid and BC1C backcross progenies only. Another backcross i.e. BC1R could not manifest shared bandings of the parents perhaps because of cleavage into or fusion with other sister esterase isomorphs through homo- or hetero-polymerization. Only band 4 was found to be present across all the tissues in BC 1R renders its demarcation difficult from rohu inbreed. However, band 9 and 13 of liver in BC1R can distinguishit from F1and inbreeds. They are likely to be instrumental in distinguishing inbreeds from hybrids reliably. The mean pair wise similarity (S) based on esterase profile, between the parents (catla and rohu) and the developed progenies (F, hybrids, BC1C and BC1R) showed BC1C was genetically more diverse than the F 1hybrids and BC1R for esterase which may be used in carp breeding and improvement programme if it is found to be tightly linked with any characters of economic importance.

Breeding Value of Quality Protein Maize Inbreds

The cultivar with high and positive breeding value can be used as a good parent for breeding of traits in hybridization programs because they can better transfer the desirable characteristics to the progeny in each case. To obtain the breeding value present investigation was carried out in maize with 33 inbreds of maize and seven inbreds of QPM lines to assess the breeding value of maize progenies for the better selection. The progeny values ranged from 62.04 (UMI 48 x CO 1) to 126.26 (CML 145 x CO 1). The breeding value ranged from 0.17 (UMI 48 x CO 1) to 0.39 (CML 145 x CO 1). CML 145 x CO 1 had high breeding value (0.39) with high progeny mean. UMI 48 x CO 1 had low breeding value (-0.17) with low progeny mean (90.80). The parent CML 145 was the superior most both for perse mean (P38=126.26) as well as for its hybrid progeny mean (C2= 168).

Heterosis and Mixed Genetic Analysis of Flowering Traits in Cross Breeding of Day-Neutral Chrysanthemum (Asteraceae)

Day-neutral multiflora chrysanthemums can flower throughout the year without being influenced by daylength and have great application value in gardens. Studying heterosis and the genetic basis of important traits in day-neutral chrysanthemums can accelerate the breeding of new cultivars. In this research, a genetic population was constructed by crossing 135 F1 hybrid progeny from the day-neutral chrysanthemum ‘82-81-19’ (female parent) and the late-flowering chrysanthemum ‘388Q-76’ (male parent). Six traits, including abnormal (crown) bud, plant height, plant crown width, budding date, full flowering date, and number of petal layers, were selected for inheritance and heterosis analyses, and a single-generation major gene plus polygene mixed inheritance model was used to perform mixed inheritance analysis on these traits. The results indicated that the six traits were widely segregated in the F1 population, with the coefficient of variation (CV) ranging from 30% to 84%. The phenomena of heterosis and extra-parent segregation existed generally in F1 progeny, and the ratio of heterosis value of mid-parents (RHm) for the six traits was 45.5%, 2%, 2%, 6%, 6%, and −0.3%, respectively. The mixed genetic analysis showed that the abnormal (crown) bud and budding date were fitted to the B-3 model and controlled by two pairs of additive major genes. The plant height and plant crown width were fitted to the A-0 model, and no major gene was detected. The full flowering date was fitted to the A-1 model and was controlled by one pair of major genes. The number of petal layers was fitted to the B-1 model and controlled by two pairs of additive–dominant major genes. The heritabilities of major genes for abnormal bud, budding date, full flowering date, and the number of petal layers were 1.0, 0.9871, 0.7240, and 0.5612, respectively, indicating that these traits were less affected by environmental factors. Using a percentile scoring method, eight day-neutral chrysanthemum genotypes were selected from the hybrid progeny.

Mode of action studies confirm on-target engagement of lysyl-tRNA synthetase inhibitor and lead to new selection marker for Cryptosporidium.

Cryptosporidiosis is a leading cause of diarrheal-associated morbidity and mortality, predominantly affecting children under 5 years old in low-and-middle-income countries. There is no effective treatment and no vaccine. New therapeutics are emerging from drug discovery efforts. It is critical that mode of action studies are performed alongside drug discovery to ensure the best clinical outcomes. Unfortunately, technology to identify and validate drug targets for Cryptosporidium is severely lacking. We used C. parvum lysyl-tRNA synthetase (CpKRS) and DDD01510706 as a target-compound pair to develop both chemical and genetic tools for mode of action studies for Cryptosporidium. We adapted thermal proteome profiling (TPP) for Cryptosporidium, an unbiased approach for target identification. Using TPP we identified the molecular target of DDD01510706 and confirm that it is CpKRS. Genetic tools confirm that CpKRS is expressed throughout the life cycle and that this target is essential for parasite survival. Parasites genetically modified to over-express CpKRS or parasites with a mutation at the compound-binding site are resistant to treatment with DDD01510706. We leveraged these mutations to generate a second drug selection marker for genetic modification of Cryptosporidium, KRSR. This second selection marker is interchangeable with the original selection marker, NeoR, and expands the range of reverse genetic approaches available to study parasite biology. Due to the sexual nature of the Cryptosporidium life cycle, parental strains containing different drug selection markers can be crossed in vivo. Selection with both drug markers produces highly efficient genetic crosses (>99% hybrid progeny), paving the way for forward genetics approaches in Cryptosporidium.

Assessment of gene pool of black currant Federal Horticultural Center for Breeding, Agrotechnology and Nursery by resistance to currant gall mite in the Bryansk Region

Since controlling currant gall mite (Cecidophyopsis ribis Westw.) is a challenging and ineffective task, developing genetic resistance to the pest is one of the main priorities in breeding programs for Ribes nigrum both in Russia and abroad. The task was assigned at the FSBSO “Federal Horticultural Center for Breeding, Agrotechnology and Nursery” to combine efficiently the positive economic and biological traits of previously developed varieties with resistance to phytophagous pests in hybrid progeny. The study evaluates the genetic collection and hybrid material of black currant for resistance to currant gall mite, as well as identifies the most promising parent pairs for mite-resistant progeny. The research objects included 107 varieties of various genetic origins, 30 of which were of foreign breeding. An assessment of the genetic collection carried out for ten years (since 2012) during the seasons of mass manifestation of the currant gall mite and reversion, is presented. Approximately 1,200 seedlings, planted in 2017, were studied. The methodologies for studying fruit, berry, and nut crops were used to assess the degree of incidence of the currant gall mite. The statistical processing of experimental results was performed using the Microsoft Excel program. As a result, the genetic sources and donors of resistance to the currant gall mite were identified (Barmaley, Dar Smolyaninovoi, Kipiana, Svityazyanka, Chernooka, Wonderful Moment, Ben Hope, Big Ben, etc.). The promising combinations of crosses were identified based on the yield of seedlings resistant to Cecidophyopsis ribis: Ben Hope×Kipiana, Ben Hope×Dar Smolyaninovoi, Kipiana×Dar Smolyaninovoi, Barmalei×Dar Smolyaninovoi, Ben Tirran×Kipiana, 9-28-1/02×Bryansk Agate, Dar Smolyaninovoi×33-27-1, 33-27-1×Kipiana. In the progeny of these parental forms, the selected forms were identified (3-63-01, 3-63-02, 9-197-3, 3-16-1, 7-28-01, 8-123-1), which combine resistance to the currant gall mite with large fruits and tolerance to fungal diseases.

Performance of cotton expressing Cry1Ac, Cry1F and Vip3Aa19 insecticidal proteins against Helicoverpa armigera, H. zea and their hybrid progeny, and evidence of reduced susceptibility of a field population of H. zea to Cry1 and Vip3Aa in Brazil.

The genetically modified cotton DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 expressing Cry1Ac, Cry1F and Vip3Aa19 from Bacillus thuringiensis Berliner (Bt) has been cultivated in Brazil since the 2020/2021 season. Here, we assessed the performance of DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton expressing Cry1Ac, Cry1F and Vip3Aa19 against Helicoverpa armigera (Hübner), Helicoverpa zea (Boddie), and their hybrid progeny. We also carried out evaluations with DAS-21023-5 × DAS-24236-5 cotton containing Cry1Ac and Cry1F. In leaf-disk bioassays, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 was effective in controlling neonates from laboratory colonies of H. armigera, H. zea and the hybrid progeny (71.9%-100% mortality). On floral bud bioassays using L2 larvae, H. zea presented complete mortality, whereas H. armigera and the hybrid progeny showed <55% mortality. On DAS-21023-5 × DAS-24236-5 cotton, the mortality of H. armigera on leaf-disk and floral buds ranged from 60% to 73%, whereas mortality of hybrids was <46%. This Bt cotton caused complete mortality of H. zea larvae from a laboratory colony in the early growth stages, but mortalities were <55% on advanced growth stages and on floral buds. In field studies conducted from 2014 to 2019, DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton was also effective at protecting plants against H. armigera. In contrast, a population of H. zea collected in western Bahia in 2021/2022 on Bt cotton expressing Cry1 and Vip3Aa proteins, showed 63% mortality after 30 d, with insects developing into fifth and sixth instars, on DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton. We conclude that H. armigera, H. zea, and their hybrid progeny can be managed with DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton; however we found the first evidence in Brazil of a significant reduction in the susceptibility to DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton of a population of H. zea collected from Bt cotton in Bahia in 2021/2022.

The SlARF4-SlHB8 regulatory module mediates leaf rolling in tomato

Leaf is the main photosynthetic organ in plants and the primary energy source all along the plant life. Given the beneficial role of leaf rolling in improving photosynthetic efficiency and yield in specific environmental conditions, a better understanding of the factors and molecular mechanisms underlying this process is highly suited. Previously, the SlARF4 knocking out mutant exhibited upward curly leaf showed higher resistance to water deficit which driving us to uncover the function of SlARF4 in regulating the curly leaf formation. In this study, we unraveled the unexplored role of the SlARF4-SlHB8 module of transcription factors in the development of leaf rolling. Both SlARF4 loss-of-function and SlHB8 overexpressing tomato plants exhibited upward-rolled leaves, reflecting the active role of the two genes in controlling leaf rolling. Dual-luciferase reporter assays and phenotypic analysis of hybrid progenies suggested that SlHB8 acts downstream of SlARF4 in curly leaf formation. SlARF4 and SlHB8 influence the development of leaf palisade tissues via modulating the expression of genes associated with curly leaf formation. SEM analysis revealed no significant differences in leaf epidermal cells between the two leaf-rolling mutants and the wild type, indicating that curly leaves of arf4 and SlHB8-OE do not result from the asymmetric leaf epidermal cell growth. Our data provide novel insight into the molecular mechanism of abaxial-adaxial determination involving SlARF4 and SlHB8 and reveals that leaf rolling operates via different regulation mechanisms in tomato and Arabidopsis model plant.

Gene Genealogy-Based Mutation Analysis Reveals Emergence of Aus, Tropical japonica, and Aromatic of Oryza sativa during the Later Stage of Rice Domestication.

Asian rice (Oryza sativa L.) has become a model for understanding gene functions and domestication in recent decades; however, its own diversification is still controversial. Although the division of indica and japonica and five subgroups (aus, indica (sensu stricto), japonica (sensu stricto), tropical japonica, and aromatic) are broadly accepted, how they are phylogenetically related is not transparent. To clarify their relationships, a sample of 121 diverse genes was chosen here from 12 Oryza genomes (two parental and ten O. sativa (Os)) in parallel to allow gene genealogy-based mutation (GGM) analysis. From the sample, 361 Os mutations were shared by two or more subgroups (referred to here as trans mutations) from 549 mutations identified at 51 Os loci. The GGM analysis and related tests indicates that aus diverged from indica at a time significantly earlier than when tropical japonica split from japonica. The results also indicate that aromatic was selected from hybrid progeny of aus and tropical japonica and that all five subgroups share a significant number of the early mutations identified previously. The results suggest that aus, tropical japonica, and aromatic emerged sequentially within the most recent 4-5 millennia of rice domestication after the split of indica and japonica.

Homoeologous Chromosome Pairing and Alien Introgression in Backcrossing Progenies Derived from Hybrids Solanum tuberosum (+) Mexican 2x (1 EBN) B-Genome Potato Species

We applied a genomic in situ hybridization (GISH) to analyze the genomic constitution of and meiotic pairing in interspecific somatic hybrids, and in a wide subset of backcrossing derivatives (BC1–BC5), from three interspecific combinations involving the cultivated potato, Solanum tuberosum (AAAA genome), and three diploid (1 EBN) wild Mexican potato species (genome BB)—S. tarnii, S. pinnatisectum, and S. bulbocastanum. The theoretically expected genomic composition was detected in the somatic hybrids (AAAABB) and in the BC1 progeny (AAAAB), whereas in the subsequent BC2–BC4 generations, the partial loss of alien chromosomes was observed and almost all the BC5 genotypes showed a complete chromosome elimination of wild species. GISH revealed a homoeologous pairing between the chromosomes of the A- and the B-genomes in each of the hybrid progenies. Using GISH, we selected introgression lines with a single chromosome of the wild species in a potato genome background, as well as introgression lines with intergenomic recombinant chromosomes. Moreover, via molecular screening, BC hybrids with diagnostic markers for the R-genes conferring resistance to late blight disease and to the quarantine pest of the potato–Columbia root-knot nematode—were selected. The potential application of the results obtained for the planning of introgressive schemes directed to the breeding of advanced lines with multiple disease and pest resistance is discussed.

Evaluation of intergeneric F1 hybrid progenies of papaya (Arka Prabhath x Vasconcellea cauliflora and Arka Prabhath x Vasconcellea cundinamarcencis) for morphological, fruit and yield traits coupled with PRSV tolerance

Papaya is one of the most important fruit crops of tropical and subtropical regions of the world including India. Though India stands first in production in the world, the productivity is low as compared to other countries due to high incidence of papaya ring spot virus (PRSV-P) attack. As all the cultivated varieties under genus Carica are susceptible to PRSV, investigations were carried out to evaluate fifteen intergeneric hybrid progenies of Arka Prabhath x V. cauliflora and eighty-five progenies of Arka Prabhath x V. cundinamarcencis for morphological, fruit and yield traits coupled with PRSV- P tolerance. Out of fifteen, seven progenies of ‘Arka Prabhath’ x V. cauliflora viz., IGHF1S4-1, IGHF1S4-12, IGHF1S4-13, IGHF1S4-14, IGHF1S4-15, IGHF1S4-17, IGHF1S4-18 and out of eighty-five, six progenies of ‘Arka Prabhath’ x V. cundinamarcensis viz., IGHF1S1-17, IGHF1S1-19, IGHF1S6-20, IGHF1S2-14, IGHF1S5-12 and IGHF1S5-14 recorded desirable traits such as days to first fruiting (240 to 250 days), bearing height (48 to 74 cm), plant height (175 to 200 cm), trunk circumference (37 to 48 cm), fruit weight (1133.67 to 2202.00 g), pulp thickness (2.45 to 4.05 cm), TSS (11.50 to 13.80 ºBrix), fruits/tree (40 to 58) and yield (45.00 to 78.20 kg/tree) coupled with PRSV tolerance with disease score1 (only a few tiny chlorotic spots on leaves). These progenies were selected and forwarded for next generation (F2). The hybridity was also confirmed using SSR marker (mCpCIR59).

Genetic mapping of the pear scab resistance gene Vnlf using a pseudo-BC3 population derived from Japanese pear cultivars and European pear ‘La France’

Pear scab disease caused by Venturia nashicola is one of the most serious diseases of Asian pears. To facilitate the breeding of scab-resistant cultivars, we mapped and developed markers for a resistance gene from the European pear (Pyrus communis) cultivar ‘La France’. By using a pseudo-backcross strategy to introduce genes from ‘La France’ into Japanese pear (P. pyrifolia) cultivars, we developed a mapping population from a cross between Japanese pear ‘Akiakari’ and interspecific hybrid progeny line 537–14. The individuals in the mapping population were evaluated for resistance by inoculation testing in 2020 and 2021. The segregation ratio of resistant to susceptible individuals was 1:1, indicating that resistance is inherited as a single dominant gene, which we named Vnlf. A genetic linkage map was constructed using single-nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers. On the basis of the genetic map of 537–14, we narrowed down the putative region carrying Vnlf to 959 kb on chromosome 2 between SNPs Chr2_20220913 and Chr2_21180341. To facilitate marker-assisted selection in Japanese pear breeding programs, we developed SSRs closely linked to Vnlf, one of which (LFA02a09) showed complete linkage to the resistance phenotype in an inoculation test of 175 individuals. These linked markers will enable introgression of Vnlf into breeding materials without the need for inoculation tests and will facilitate pyramiding Vnlf with other scab resistance loci.

Phenotyping wood properties of Corymbia torelliana x Corymbia citriodora and Eucalyptus dunnii based on NIR spectra

ABSTRACT Selecting individuals in breeding programs for pulp production, the physical and chemical wood traits must be considered in the genotype selection. In this study, trees from hybrid progeny tests of Corymbia torelliana x Corymbia citriodora (CTOxCCT) and progenies of Eucalyptus dunnii (EDU) were investigated. Sawdust of genetically selected standing trees was collected, classified and prepared for near infrared (NIR) spectra readings. The chemical properties of the selected trees were determined through kraft pulping. Predictive models for each property were developed based on the reference data and NIR spectra. Two approaches for models were developed. The first approach, models were fitted with 25 samples of CTOxCCT, and in the second approach, models were fitted using 61 samples (25 of CTOxCCT and 36 of EDU). The estimated R²cv values were 0.60 and 0.73 for basic chip density, 0.37 and 0.65 for extractive contents, 0.56 and 0.53 for total lignin contents, 0.63 and 0.66 for S/G ratio, and 0.52 and 0.77 for screened pulp yield for the first and second approaches, respectively. All developed models have potential for ranking trees in breeding programs. NIR spectroscopy can potentially be applied as a high-throughput field phenotyping tool where thousands of varieties need to be evaluated.

Inheritance regularities of economic and valuable traits in selection of sugar beet simple cytoplasmic male sterile hybrids

Aim. To study the influence of parental components of the crossing on the manifestation of the traits “yield of root crops” and “sugar content” in the hybrid progeny for the production of simple CМS hybrids. To create high-yielding simple CМS hybrids as a parent component for the formation of experimental sugar beet hybrids on а CМS basіs. Methods. Field (experiments, phenological observations), laboratory (to determine sugar content), measuring and weighing (to determine the crop structure), statistical (mathematical processing of research results). Results. The nature of the inheritance of productivity traits for the formation of simple CМS sugar beet hybrids has been established. For different combinations of crossings, the value of the inheritance coefficients (h2) of the trait “yield of root crops” from the parent form (O-type line) to the hybrid varied within 0.11–0.71 and 0.52–0.63 from the maternal form (CМS line). The inheritance coefficients of the trait “sugar content” from the parental form were in the range of 0.46–0.53 and 0.42–0.55 from the maternal form. An intermediate type of inheritance was observed for the sugar content in root crops. The best CМS lines and O-type lines have been identified as sources of economic and valuable traits. Seven combining-capable simple CМS hybrids with a high level of basic productivity were created for further use as a maternal component in the selection of sugar beet hybrids on а CМS basіs. Conclusions. A significant influence of the maternal component genotype on the level of yield of root crops of simple CМS hybrids has been established. A regularity has been revealed that the higher the total combining ability of CМS lines, the lower the degree of transfer of the trait “yield of root crops” from the parental form (O-type line) to the hybrid. There is no “mother plant” effect on sugar content in root crops, and an intermediate type of inheritance was observed in hybrids. The use of simple CМS hybrids with an increased level of basic productivity as a maternal component will significantly increase the efficiency of the breeding process for creating competitive sugar beet hybrids on а CМS basіs.

Genome-wide association study of multiyear dynamic growth traits in hybrid Liriodendron identifies robust genetic loci associated with growth trajectories.

The genetic factors underlying growth traits differ over time points or stages. However, most current studies of phenotypes at single time points do not capture all loci or explain the genetic differences underlying growth trajectories. Hybrid Liriodendron exhibits obvious heterosis and is widely cultivated, although its complex genetic mechanism underlying growth traits remains unknown. A genome-wide association study (GWAS) is an effective method for elucidating the genetic architecture by identifying genetic loci underlying complex quantitative traits. In the present study, using a GWAS, we identified robust loci associated with growth trajectories in hybrid Liriodendron populations. We selected 233 hybrid progenies derived from 25 crosses for resequencing, and measured their tree height (H) and diameter at breast height (DBH) for 11 consecutive years; 192 972 high-quality single nucleotide polymorphisms (SNPs) were obtained. The dynamics of the multiyear single-trait GWAS showed that year-specific SNPs predominated, and only five robust SNPs for DBH were identified in at least three different years. Multitrait GWAS analysis with model parameters as latent variables also revealed 62 SNPs for H and 52 for DBH associated with the growth trajectory, displaying different biomass accumulation patterns, among which four SNPs exerted pleiotropic effects. All identified SNPs also exhibited temporal variations in effect sizes and inheritance patterns potentially related to different growth and developmental stages. The haplotypes resulting from these significant SNPs might pyramid favorable loci, benefitting the selection of superior genotypes. The present study provides insights into the genetic architecture of dynamic growth traits and lays a basis for future molecular-assisted breeding.