We describe the first reported intergeneric, which naturally occurs between two subspecies belonging to different genera, Dactylorhiza fuchsii subsp. sooana (genus Dactylorhiza) and Pseudorchis ...albida subsp. tricuspis (genus Pseudorchis), as x Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020. The hybrid was found and digitally photographed for the first time by Hajnalka Kertész in June, 2020, within Terra Siculorum, in one of the Natura 2000 protected areas, known as Harghita Madaras, ROSCI00090. Following detailed morphometric analysis using 67 characters and molecular karyological analyses, we identified this unique specimen as an intergeneric hybrid, new to science. The hybrid, an F.sub.1 generation plant, most likely representing a single intergeneric pollination event, is phenotypically intermediate between its parental species in most of the characters scored, but it significantly closely resembles Pseudorchis albida subsp. tricuspis parent. Since several individuals of the parental species occurred in near proximity, within 1-10 meters distance, we suggest that the production of this hybrid required a minimum travel distance of ca 1-10 meters, by the pollinators and frequent exchange of pollen between the parental species was very likely. The parental species and the hybrid, which display a considerable synchronicity in their flowering time, overlap in the pollinator community, sharing various species of Hymenopterans and Dipterans, very abundant in the heathland. This Terra Siculorum hybrid is thus best described as a rarely occurring intergeneric hybrid that shows strong Pseudorchis albida subsp. tricuspis parental dominance in inheritance patterns.
Using full-spectrum LED lights, six light treatments of 11 h, 12 h, 13 h, 14 h, 15 h, and CK (greenhouse natural light) were designed to examine the response of Populus euramericana plantlets to ...light duration in the greenhouse. Every 15 days during the 150-day experiment, plantlet height (H), ground diameter (GD), number of nodes (NN), number of leaves (NL), and the relative chlorophyll content(SPAD) were measured. The response of plantlets to different light durations was demonstrated by establishing and screening growth models, and rhythm and relative chlorophyll content were statistically analyzed. The light duration had a significant effect on the H and GD of Populus euramericana, and their growth was positively correlated with light duration. The short full-spectrum LED lighting duration will affect the rhythm and prematurely halt the growth of H, but the GD will continue to expand. The Gomperz model has the best fitting effect for the growth of Populus euramericana plantlets under LED lighting, with all R2s values greater than 0.89. Long light duration has a greater growth potential, and the rapid growth lasts longer. The delay in the cessation of the increase in the NN was a result of the increased illumination time. Compared with natural light, LED light lessens the NL. Poplar plantlets will have a lower SPAD value if the light duration exceeds 14 h. In the process of growing plantlets in the greenhouse, both light quality and light duration should be considered. In actual production, a combination of natural and artificial light can improve efficiency.
Recent studies have shown that one of the parental subgenomes in ancient polyploids is generally more dominant, having retained more genes and being more highly expressed, a phenomenon termed ...subgenome dominance. The genomic features that determine how quickly and which subgenome dominates within a newly formed polyploid remain poorly understood. To investigate the rate of emergence of subgenome dominance, we examined gene expression, gene methylation, and transposable element (TE) methylation in a natural, <140-year-old allopolyploid (Mimulus peregrinus), a resynthesized interspecies triploid hybrid (M. robertsii), a resynthesized allopolyploid (M. peregrinus), and progenitor species (M. guttatus and M. luteus). We show that subgenome expression dominance occurs instantly following the hybridization of divergent genomes and significantly increases over generations. Additionally, CHH methylation levels are reduced in regions near genes and within TEs in the first-generation hybrid, intermediate in the resynthesized allopolyploid, and are repatterned differently between the dominant and recessive subgenomes in the natural allopolyploid. Subgenome differences in levels of TE methylation mirror the increase in expression bias observed over the generations following hybridization. These findings provide important insights into genomic and epigenomic shock that occurs following hybridization and polyploid events and may also contribute to uncovering the mechanistic basis of heterosis and subgenome dominance.
We describe the first reported intergeneric, which naturally occurs between two subspecies belonging to different genera, Dactylorhiza fuchsii subsp. sooana (genus Dactylorhiza) and Pseudorchis ...albida subsp. tricuspis (genus Pseudorchis), as x Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020. The hybrid was found and digitally photographed for the first time by Hajnalka Kertész in June, 2020, within Terra Siculorum, in one of the Natura 2000 protected areas, known as Harghita Madaras, ROSCI00090. Following detailed morphometric analysis using 67 characters and molecular karyological analyses, we identified this unique specimen as an intergeneric hybrid, new to science. The hybrid, an F.sub.1 generation plant, most likely representing a single intergeneric pollination event, is phenotypically intermediate between its parental species in most of the characters scored, but it significantly closely resembles Pseudorchis albida subsp. tricuspis parent. Since several individuals of the parental species occurred in near proximity, within 1-10 meters distance, we suggest that the production of this hybrid required a minimum travel distance of ca 1-10 meters, by the pollinators and frequent exchange of pollen between the parental species was very likely. The parental species and the hybrid, which display a considerable synchronicity in their flowering time, overlap in the pollinator community, sharing various species of Hymenopterans and Dipterans, very abundant in the heathland. This Terra Siculorum hybrid is thus best described as a rarely occurring intergeneric hybrid that shows strong Pseudorchis albida subsp. tricuspis parental dominance in inheritance patterns.
The objective of this work was to evaluate the losses in the process, survival, uniformity and growth during an entire short rotation of a clonal planting of Eucalyptus grandis x Eucalyptus urophylla ...in Brazil as a function of the different morphological characteristics of the seedlings considered a proxy of seedling quality. Seedlings were classified in descending order of quality by the following treatments: A > B > C. Treatment D was composed of prime seedlings 180 days old in the nursery. Treatment A and B experienced a mortality rate of 3% 30 days after planting, while seedlings C and D showed a mortality rate of 8%. Throughout the entire planting process, treatment C had the highest total losses of 24%, which was 15% higher than the average of the other three treatments. The quality of seedlings, as determined by the IQD, positively correlated with stem diameter, leaf biomass, and PH50 at 60 days of age. However, these relationships lost significance at later ages, and the DQI could not explain the variation in volume and stand uniformity (PV50) along the rotation. Despite early differences, from 36 to 64 months, only old seedlings (Treat. D) showed a difference in wood volume to the other treatments.
Intense artificial selection over the last 100 years has produced elite maize (Zea mays) inbred lines that combine to produce high-yielding hybrids. To further our understanding of how genome and ...transcriptome variation contribute to the production of high-yielding hybrids, we generated a draft genome assembly of the inbred line PH207 to complement and compare with the existing B73 reference sequence. B73 is a founder of the Stiff Stalk germplasm pool, while PH207 is a founder of Iodent germplasm, both of which have contributed substantially to the production of temperate commercial maize and are combined to make heterotic hybrids. Comparison of these two assemblies revealed over 2500 genes present in only one of the two genotypes and 136 gene families that have undergone extensive expansion or contraction. Transcriptome profiling revealed extensive expression variation, with as many as 10,564 differentially expressed transcripts and 7128 transcripts expressed in only one of the two genotypes in a single tissue. Genotype-specific genes were more likely to have tissue/condition-specific expression and lower transcript abundance. The availability of a high-quality genome assembly for the elite maize inbred PH207 expands our knowledge of the breadth of natural genome and transcriptome variation in elite maize inbred lines across heterotic pools.
Hybrids between Pinus brutia Ten. and Pinus halepensis Mill. have mainly been investigated with respect to their growth rate. Less attention has been paid to factors that contribute to their ...resistance to drought, although the hybrids have been shown to thrive over P. brutia in semi-arid regions. To understand the superior hybrid phenotype, we investigated morphological traits, growth parameters, and physiological response to drought stress in P. brutia, P. halepensis, and their vigorous hybrids. Rooted cuttings were propagated from mature trees and were examined in a high-throughput gravimetric system to evaluate their response to drought. Higher root-to-shoot ratio, needle length, and leaf mass per area (LMA) were observed in the hybrids compared to the two parental species. P. halepensis demonstrated higher transpiration rates (E) and stomatal conductance (gsub.sc ) than P. brutia, and an earlier reduction in E and gsub.sc in response to drought stress. Similar to P. brutia, the hybrids showed low E and gsub.sc , and an early stomatal closure in response to drought similar to P. halepensis. Our study suggests that the hybrids exhibit a unique combination of traits that may contribute to forest resilience in semi-arid regions undergoing climate change.
Key message
The review outlines past failures, present status and future prospects of hybrid wheat, and includes information on CMS/CHA/transgenic approaches for male sterility, heterotic groups and ...cost-effective hybrid seed production.
Hybrid varieties give increased yield and improved grain quality in both cross- and self-pollinated crops. However, hybrid varieties in self-pollinated crops (particularly cereals) have not been very successful, except for hybrid rice in China. In case of hybrid wheat, despite the earlier failures, renewed efforts in recent years have been made and hybrid varieties with desirable attributes have been produced and marketed in some European countries. This review builds upon previous reviews, with a new outlook and improved knowledge base, not covered in earlier reviews. New technologies have been described, which include the
Hordeum chilense
-based CMS–fertility restorer system, chromosomal XYZ-4E-
ms
system and the following transgenic technologies: (1) conditional male sterility involving use of tapetum-specific expression of a gene that converts a pro-toxin into a phytotoxin causing male sterility; (2) barnase-barstar SeedLink system of Bayer CropScience; (3) split-barnase system that obviates the need of a barstar-based male restorer line; and (4) seed production technology of DuPont-Pioneer that makes use of transgenes in production of male-sterile lines, but gives hybrid seed with no transgenes. This review also includes a brief account of studies for discovery of heterotic QTL, genomic prediction of hybrid vigour and the development of heterotic groups/patterns and their importance in hybrid wheat production. The problem of high cost of hybrid seed due to required high seed rate in wheat relative to hybrid rice has also been addressed. The review concludes with a brief account of the current efforts and future possibilities in making hybrid wheat a commercial success.
Natural hybridization has been considered a source of taxonomic complexity in Cryptocoryne. A combined study of DNA sequencing data from the internal transcribed spacer (ITS) of nuclear ribosomal DNA ...and the trnK-matK region of chloroplast DNA was used to identify the parents of Cryptocoryne putative hybrids from Peninsular Malaysia. Based on the intermediate morphology and sympatric distribution area, the plants were tentatively identified as the hybrid Cryptocoryne xpurpurea nothovar. purpurea. The plants were pollen sterile and had long been considered as hybrids, supposedly between two related and co-existing species, C. cordata var. cordata and C. griffithii. The status of C. xpurpurea nothovar. purpurea was independently confirmed by the presence of an additive ITS sequence pattern from these two parental species in hybrid individuals. An analysis of the chloroplast trnK-matK sequences showed that the hybridization is bidirectional with the putative hybrids sharing identical sequences from C. cordata var. cordata and C. griffithii, indicating that both putative parental species had been the maternal parent in different accessions.
Background In recent years, sugarcane has attracted increasing attention as an energy crop. Wild resources are widely used to improve the narrow genetic base of sugarcane. However, the infertility of ...F.sub.1 hybrids between Saccharum officinarum (S. officinarum) and Erianthus arundinaceus (E. arundinaceus) has hindered sugarcane breeding efforts. To discover the cause of this infertility, we studied the hybridization process from a cytological perspective. Results We examined the meiotic process of pollen mother cells (PMCs) in three F.sub.1 hybrids between S. officinarum and E. arundinaceus. Cytological analysis showed that the male parents, Hainan 92-77 and Hainan 92-105, had normal meiosis. However, the meiosis process in F.sub.1 hybrids showed various abnormal phenomena, including lagging chromosomes, micronuclei, uneven segregation, chromosome bridges, and inability to form cell plates. Genomic in situ hybridization (GISH) showed unequal chromatin distribution during cell division. Interestingly, 96.70% of lagging chromosomes were from E. arundinaceus. Furthermore, fluorescence in situ hybridization (FISH) was performed using 45S rDNA and 5S rDNA as probes. Either 45S rDNA or 5S rDNA sites were lost during abnormal meiosis, and results of unequal chromosomal separation were also clearly observed in tetrads. Conclusions Using cytogenetic analysis, a large number of meiotic abnormalities were observed in F.sub.1. GISH further confirmed that 96.70% of the lagging chromosomes were from E. arundinaceus. Chromosome loss was found by further investigation of repeat sequences. Our findings provide insight into sugarcane chromosome inheritance to aid innovation and utilization in sugarcane germplasm resources. Keywords: Chromosome, Meiosis, Pollen, FISH, Cell genetics
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