[Incidence and prognosis of olfactory and gustatory dysfunctions related to infection of SARS-CoV-2 Omicron strain: a national multi-center survey of 35 566 population]

Objective: This cross-sectional investigation aimed to determine the incidence, clinical characteristics, prognosis, and related risk factors of olfactory and gustatory dysfunctions related to infection with the SARS-CoV-2 Omicron strain in mainland China. Methods: Data of patients with SARS-CoV-2 from December 28, 2022, to February 21, 2023, were collected through online and offline questionnaires from 45 tertiary hospitals and one center for disease control and prevention in mainland China. The questionnaire included demographic information, previous health history, smoking and alcohol drinking, SARS-CoV-2 vaccination, olfactory and gustatory function before and after infection, other symptoms after infection, as well as the duration and improvement of olfactory and gustatory dysfunction. The self-reported olfactory and gustatory functions of patients were evaluated using the Olfactory VAS scale and Gustatory VAS scale. Results: A total of 35 566 valid questionnaires were obtained, revealing a high incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain (67.75%). Females(χ2=367.013, P<0.001) and young people(χ2=120.210, P<0.001) were more likely to develop these dysfunctions. Gender(OR=1.564, 95%CI: 1.487-1.645), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), oral health status (OR=0.881, 95%CI: 0.839-0.926), smoking history (OR=1.152, 95%CI=1.080-1.229), and drinking history (OR=0.854, 95%CI: 0.785-0.928) were correlated with the occurrence of olfactory and taste dysfunctions related to SARS-CoV-2(above P<0.001). 44.62% (4 391/9 840) of the patients who had not recovered their sense of smell and taste also suffered from nasal congestion, runny nose, and 32.62% (3 210/9 840) suffered from dry mouth and sore throat. The improvement of olfactory and taste functions was correlated with the persistence of accompanying symptoms(χ2=10.873, P=0.001). The average score of olfactory and taste VAS scale was 8.41 and 8.51 respectively before SARS-CoV-2 infection, but decreased to3.69 and 4.29 respectively after SARS-CoV-2 infection, and recovered to 5.83and 6.55 respectively at the time of the survey. The median duration of olfactory and gustatory dysfunctions was 15 days and 12 days, respectively, with 0.5% (121/24 096) of patients experiencing these dysfunctions for more than 28 days. The overall self-reported improvement rate of smell and taste dysfunctions was 59.16% (14 256/24 096). Gender(OR=0.893, 95%CI: 0.839-0.951), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), history of head and facial trauma(OR=1.180, 95%CI: 1.036-1.344, P=0.013), nose (OR=1.104, 95%CI: 1.042-1.171, P=0.001) and oral (OR=1.162, 95%CI: 1.096-1.233) health status, smoking history(OR=0.765, 95%CI: 0.709-0.825), and the persistence of accompanying symptoms (OR=0.359, 95%CI: 0.332-0.388) were correlated with the recovery of olfactory and taste dysfunctions related to SARS-CoV-2 (above P<0.001 except for the indicated values). Conclusion: The incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain is high in mainland China, with females and young people more likely to develop these dysfunctions. Active and effective intervention measures may be required for cases that persist for a long time. The recovery of olfactory and taste functions is influenced by several factors, including gender, SARS-CoV-2 vaccination status, history of head and facial trauma, nasal and oral health status, smoking history, and persistence of accompanying symptoms.

Modification of STIM2 by m6A RNA methylation inhibits metastasis of cholangiocarcinoma

Background

N6-methyladenosine (m⁶A) is the most frequent internal methylation of eukaryotic RNA (ribonucleic acid) transcripts and plays an important function in RNA processing. The current research aimed to investigate the role of m⁶A-STIM2 axis in cholangiocarcinoma (CCA) progression.

Methods

The expression of STIM2 (Stromal Interaction Molecule 2) in CCA was measured using quantitative polymerase chain reaction (PCR) and immunohistochemistry (IHC). STIM2 was examined in vivo for its effects on the malignant phenotypes of CCA cells. The m⁶A modification of STIM2 was assessed through MeRIP (methylated RNA Immunoprecipitation)-PCR.

Results

Based on the GEPIA (Gene Expression Profiling Interactive Analysis) 2 database findings, a low STIM2 mRNA (messenger RNA) level was related to a poor prognosis in individuals with CCA. Quantitative PCR and IHC assays indicated decreased protein satin in CCA tissues and were associated with extrahepatic metastasis. Vianude mice tail vein injection model indicated that increased STIM2 levels suppressed CCA cell metastasis in vivo, while KRT8 (keratin 8) was detected as the direct downstream target of STIM2-mediated CCA cell metastasis in vivo. Meanwhile, based on SRAMP database and MeRIP assays indicated that m⁶A alteration resulted in abnormal STIM2 expression in CCA via METTL14 and YTHDC2.

Conclusions

Our findings revealed the epi-transcriptomic dysregulation in CCA and metastasis by proposing a complicated STIM2-KRT8 regulatory paradigm based on m⁶A alteration.

[Effect of sublingual dust mite drops on single or multiple allergens allergic rhinitis in children]

Objective:Evaluation of the efficacy of standardized dust mite drops in sublingual immunotherapy(SLIT) for allergic rhinitis in children.Method:A retrospective analysis of 174 children who received SLIT with standardized dermatophagoides farinae drops for 2 years.These patients had been divided into two groups:monoasensitized group(n=61) and polysensitized group(n=113).The total medication score(TMS),total nasal symptoms score(TNSS) and inflammatory factors were evaluated before and after SLIT treatment.Result:①After SLIT treatment for 2.0 year,the TNSS in the monosensitized group is(11.27±1.46) and(3.48±1.50),polyasensitized group is (11.54±1.50) and (3.59±1.56),there are significant difference of TNSS between two groups(P<0.01).But the improvements of the TNSS between the two groups have no significant difference(P>0.05),the monosensitized group is(7.68±3.23); polysensitized group is (8.14±2.56). ②Two groups of children with TMS before and after treatment were obviously improved, monosensitized group is (1.67±0.43) and (0.52±0.40),polysensitized group is(1.64±0.44) and (0.55±0.41). There are significant difference of TMS between two groups(P<0.01).But the improvements of the TMS between the two groups have no obvious difference(P>0.05),the monsensitized group is(1.16±0.61); polysensitized group is(1.28±0.55).③Specific IgG4 serum is increased after treatment(P<0.01).④After immunotherapy,the expression of IL4 and IL-17α is downregulated, IL-2 and TGF-β1 is up-regulated.Conclusion:①Dust mites under the SLIT,can significantly improve the monosensitized and polyasensitized allergic children nasal symptoms,reduce the drug use, and two groups have the equivalent effect.②Dust mite drops SLIT,can be used to the monosensitized and polyasensitized allergic children.③The rise of dust mites specific IgG4 can be used as immunotherapy effective predictors.④After immunotherapy, Thl/Th2 /Thl7 and Treg can be rebalanced.

Prevalence of Mycoplasma pneumoniae: a cause for community-acquired infection among pediatric populaztion

BACKGROUND

Atypical pneumonia caused by Mycoplasma pneumoniae is a leading cause of mortality among the pediatric age group.

OBJECTIVES

Our study was designed to know the prevalence of M. pneumoniae in children with community-acquired pneumonia and the involvement in the cytoadherence to the respiratory epithelium by M. pneumoniae using electron microscopy and immuno-gold labeling technique.

MATERIALS AND METHODS

A total of 152 children of 1 month to 12 years of age of both sexes attending Hebei Provincial People's Hospital, Shijiazhuang, Hebei with diagnosed pneumonia were included in the study.

RESULTS

Out of 152 children 84 (55.3%) were males, and 68 (44.7%) were females. The mean age of the patients in the control group (50 patients) was 18.5 ± 3 months with 31 (62%) males and 19 (38%) females. IgM antibodies against M. pneumoniae were positive in 84 (55.3%) males and 68 (44.7%) females. Out of 50 patients 9 (18%) were found to positive for IgM M. pneumoniae antibodies of which four (44.4%) males and 5 (55.5%) females were positive. Our study observed that the gold particles were clustered on the filamentous extension of the tip of the cells. Out of 152 serum samples subjected to particle agglutination assay 138 (90.7%) were positive 1:320 titer, 9 were >1:80 and 3 showed titer was >1:40.

CONCLUSION

We suggest that clinicians should consider empirical therapy of broad spectrum antibiotics therapy to cover these atypical pathogens to reduce the severity before obtaining the serological results. From our study, we also suggest electron microscopic and biochemical studies for better diagnosis of these pathogens.

Physiological integration enhanced the tolerance of Cynodon dactylon to flooding

Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration.

Effects of mycophenolate mofetil on the expression of monocyte chemoattractant protein-1 and fibronectin in high glucose cultured human mesangial cells

The effects of high glucose on the expression of monocyte chemoattractant protein-1 (MCP-1) and the main component of the extracellular matrix, fibronectin (FN), were explored in human mesangial cells (HMCs), along with the intervention effects of mycophenolate mofetil (MMF) on these indicators. Cultured HMCs were divided into five groups: 1) normal control group (5 mM glucose); 2) high glucose group (30 mM glucose); 3) mannitol osmotic pressure control group (5 mM glucose + 25 mM mannitol); 4) high glucose + MMF-10 group (30 mM glucose + 10 μg/mL MMF); 5) high glucose + MMF-100 group (30 mM glucose + 100 μg/mL MMF). At 24, 48, and 72 h, reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay methods were used to detect the effects of MMF on MCP-1 mRNA and protein and FN expression in HMCs under high glucose conditions. MCP-1 mRNA and protein expressions and FN secretion significantly increased in HMCs of the high glucose group compared with the normal control group (P < 0.01), with the highest expression observed at 48 h. MMF could reduce the MCP-1 mRNA and protein and FN expression levels (P < 0.01), and the inhibition occurred in a dose- and time-dependent manner (P < 0.05). In conclusion, MMF could inhibit MCP-1 expression and the secretion of FN, indicating that it may delay the progression of glomerulosclerosis and interstitial fibrosis in diabetic nephropathy to ultimately achieve protective effects on the kidney.

Establishment and management of a liver tissue bank in China

AIM: To develop a standardized and well-rounded liver tissue bank available for hepatology research using well-characterized and optimally preserved liver tumor tissue samples.

METHODS: Standardized operational procedures were developed, and samples such as fresh-frozen surgical tissue samples, pre- and postoperative whole blood, urine and paraffin section samples were collected. Using the National Liver Tissue Bank (NLTB) data management platform, the database can be accessed and renewed automatically or manually with the Hospital Information System (HIS).

RESULTS: From Mar 2009 to Dec 2010, over 4000 individuals had been enrolled as liver tumor donors to the NLTB, including 2 500 cases of newly diagnosed hepatocellular carcinoma (HCC), and 1 500 cases of diagnosed begin or malignant liver tumors. Database access and sample preservation can be managed easily and correctly with the data management platform.

CONCLUSION: We established a standard liver tissue bank using high-quality well-characterized samples, which will become the cornerstone for hepatology research, especially the diagnosis and treatment of HCC and other liver diseases.

Effects of active immunization against GnRH on serum LH, inhibin A, sexual development and growth rate in Chinese female pigs

Surgical castration of young female pigs is common practice in Chinese pig farming today. The purpose of the present study is to investigate anti-GnRH immunization as a practical alternative to surgical castration for female pigs. Thirty-six Chinese female crossbred pigs (Chinese Yanan x Yorkshire) were selected from 12 litters, three pigs from each litter, at the age of 10-13 weeks. One pig from each litter was immunized with 62.5 microg D-Lys6-GnRH-tandem-dimer peptide conjugated to ovalbumin in Specol adjuvant at Week 0 (0 week post-vaccination, wpv), and a booster vaccination was given 8 weeks later (8 wpv). Its intact and castrate littermates (surgically castrated at the time of weaning, i.e. at 6 weeks of age) were administered the vehicle and served as controls. Antibody titers, serum LH and inhibin A were determined at the day of first vaccination, every 4 weeks thereafter and at the day of slaughter (18 wpv). At slaughter, ovaries were inspected for the presence of follicles and corpora lutea, and ovarian and uterine weights were recorded. Ten of twelve immunized pigs responded well to the immunization (immunocastrated animals), while the remaining two pigs responded poorly (nonresponders). Antibody titres in immunocastrated animals steadily increased after immunization, became maximal at 12 wpv and remained high until slaughter. Serum LH levels were reduced (P < 0.05) in immunocastrated pigs as compared to intact controls and surgical castrates. Serum inhibin A levels decreased after vaccination, and equaled surgical castrate levels from 8 wpv until the end of the experiment. Ovarian and uterine weights (1.3 +/- 0.2 and 43.9 +/- 11.4 g, respectively; mean +/- S.E.M.) were significantly lower (P < 0.05) in immunocastrates than in intact controls (9.4 +/- 1.1 and 390.9 +/- 67.2 g, respectively). Antibody titers were significantly lower (P < 0.05) in nonresponders than in immunocastrated pigs from 12 wpv to slaughter. Ovarian and uterine weights were similar in nonresponders and in intact controls. Macroscopically, no follicular structures were found in ovaries of immunocastrated pigs, while large follicles or corpora lutea were observed in the ovaries of both nonresponders and intact controls. Although not significant, immunocastrates had a numerically higher average daily gain than surgical castrates and intact controls (0.74 +/- 0.04 versus 0.66 +/- 0.04 versus 0.66 +/- 0.03 kg per day, respectively; mean +/- S.E.M., P = 0.09). Results obtained in the present study demonstrate that anti-GnRH immunization can be an attractive alternative to surgical castration for Chinese crossbred female pigs. Our results also question the beneficial effect of surgical castration on growth as compared to intact controls.

Active immunization against gonadotrophin-releasing hormone in Chinese male pigs

We have investigated, under the normal conditions of local Chinese pig farming, castration of young male pigs by vaccination with a newly developed vaccine against gonadotrophin releasing hormone (GnRH). Because of the very early onset of puberty, long fattening period and relatively harsh circumstances in Chinese pig production, an investigation of the endocrine response of Chinese breeds to this type of vaccination was of particular interest. Fifteen crossbred boars (Yorkshire x Yanan) from three different litters were randomly assigned to three groups of five animals each. The first group was immunized at 13 weeks of age with a GnRH tandem dimer OVA-conjugate in Specol and received a booster immunization 8 weeks later. The second group was injected with Specol alone and served as untreated controls. The remaining group was surgically castrated at the time of weaning (at 6 weeks of age). Pigs were fed ad libitum from weaning onwards. All animals were slaughtered at 31 weeks of age. Immunized boars had undetectable or low serum testosterone (0.09 +/- 0.12 ng/ml), low fat androstenone (0.05 +/- 0.01 microg/g) levels and very low testes weights (19.1 +/- 4.3 g). Intact controls had much higher serum levels of testosterone (9.76 +/- 4.81 ng/ml), fat androstenone levels (2.26 +/- 0.87 microg/g) and testes weights (114.3 +/- 29.41 g) at slaughter. Both the immunized and castrated group grew significantly faster than intact boars (p < 0.01). Average daily gains in immunized, castrated and intact animals were 0.69 +/- 0.08, 0.63 +/- 0.05 and 0.42 +/- 0.07 kg (mean +/- SD), respectively. The present data demonstrate for the first time that the newly developed anti-GnRH vaccine works very well under practical Chinese pig farming conditions, and can be an attractive alternative to surgical castration.

[The expression of transforming growth factor alpha and its receptor in nasal polyps]

OBJECTIVE

To assess the possible role of expression of TGF alpha and EGFR in nasal polyps and its relationship with PCNA labeling index.

METHOD

Specimens from 20 patients of nasal polyps were studied with immunohistochemical technique.

RESULT

The expression of TGF alpha, EGFR and PCNA were increased in the epithelium, gland cells and inflammatory cells of nasal polyps. There was a close correlation between the intensities of TGF alpha, EGFR and PCNA.

CONCLUSION

TGF alpha may play a key role in epithelial cell proliferation in nasal polyps.

[Vasomotor rhinitis following endoscopic sinus surgery: 5 cases report]

OBJECTIVE

To investigate the possibility of endoscopic sinus surgery causing vasomotor rhinitis.

METHOD

A retrospective study of 300 patients who received endoscopic sinus surgery. 5 cases out of 300 suffered from vasomotor rhinitis 1-3 weeks following endoscopic sinus surgery. Radio frequency cautery of agger nasi mucous was applied to all 5 patients.

RESULT

After 4-6 months of follow-up, 4 cases out of 5 with vasomotor rhinitis were effective and 1 improved.

CONCLUSION

Endoscopic sinus surgery may be causative factor for vasomotor rhinitis.

A molecular linkage map of tomato based on a cross between Lycopersicon esculentum andL. pimpinellifolium and its comparison with other molecular maps of tomato

The wild species related to the cultivated tomato, Lycopersicon esculentum Mill., are a rich source of useful genes for germplasm improvement and varietal development. Characterization and utilization of exotic germplasm can be accelerated by the use of molecular linkage maps. Recently, we have identified an accession (LA722) within L. pimpinellifolium Jusl., a closely-related, red-fruited wild species of tomato, which exhibits a number of desirable agricultural characteristics including salt tolerance, disease resistance, and high fruit quality. The limited DNA marker polymorphism between L. esculentum and L. pimpinellifolium, however, restricts the use of the high-density molecular map of tomato, which was previously constructed based on a cross between L. esculentum and L. pennellii Corr., for marker-assisted identification and utilization of useful genes in LA722. To overcome this problem, we have constructed a linkage map based on restriction fragment length polymorphisms (RFLPs) which were identified between LA722 and a fresh-market tomato breeding line (NC84173). The mapping population (consisting of 119 BC1 individuals) was genotyped for 151 RFLP markers, including 17 germination related and 2 potassium transporter cDNAs. The DNA markers spanned approximately 1192 cM of the tomato genome with an average distance of 7.9 cM between markers. The length of the map and the linear order of the markers were in good agreement with those of the previously published molecular maps of tomato, however, there were considerable differences in the distribution of recombinations along the chromosomes. Comparison of all seven published molecular maps of tomato, which were constructed based on different inter- and intraspecific crosses, indicated that some chromosomal regions were more stable than others in terms of the frequency of recombinations. Similarities and differences among tomato molecular maps are discussed in relation to phylogenetic relationships between parents of the mapping populations. In comparison, a L. esculentum ×L. pimpinellifolium map should be more useful than other interspecific maps for marker-assisted exploitation of genetic variation that exists within L. pimpinellifolium or L. esculentum; the latter is because of the extensive introgression of genes from L. pimpinellifolium into L. esculentum, which occurred over time by natural means or through plant breeding.Key words: Lycopersicon esculentum, L. pimpinellifolium, genetic marker, molecular map, recombination, restriction fragment length polymorphism (RFLP), tomato.

RAPD markers associated with salt tolerance in an interspecific cross of tomato (Lycopersicon esculentum×L. pennellii)

This study was conducted to identify randomly amplified polymorphic DNA (RAPD) markers associated with quantitative trait loci (QTLs) conferring salt tolerance during germination in tomato. Germination response of an F₂ population (2000 individuals) of a cross between UCT5 (Lycopersicon esculentum, salt-sensitive) and LA716 (L. pennellii, salt-tolerant) was evaluated at a salt-stress level of 175 mM NaCl+17.5 mM CaCl₂ (water potential ca. -9.5 bars). Germination was scored visually as radicle protrusion at 6-h intervals for 30 consecutive days. Individuals at both extremes of the response distribution (i.e., salt-tolerants and salt-sensitives) were selected. The selected individuals were genotyped for 53 RAPD markers and allele frequencies at each marker locus were determined. The linkage association among the markers was determined using a "MAPMAKER" program. Trait-based marker analysis (TBA) identified 13 RAPD markers at eight genomic regions that were associated with QTLs affecting salt tolerance during germination in tomato. Of these genomic regions, five included favorable QTL alleles from LA716, and three included favorable alleles from UCT5. The approximate effects of individual QTLs ranged from 0.46 to 0.82 phenotypic standard deviation. The results support our previous suggestion that salt tolerance during germination in tomato is polygenically controlled. The identification of favorable QTLs in both parents suggests the likelihood of recovering transgressive segregants in progeny derived from these genotypes. Results from this study are discussed in relation to using marker-assisted selection in breeding for salt tolerance.

Reversible primary hypothyroidism with blocking or stimulating type TSH binding inhibitor immunoglobulin following recombinant interferon-alpha therapy in patients with pre-existing thyroid disorders

OBJECTIVE

Treatment with recombinant interferon-alpha (rIFN-alpha) may induce autoimmunity. We have evaluated the effect of rIFN-alpha on pre-existing thyroid disease with special reference to changes in TSH receptor antibody.

DESIGN AND PATIENTS

Five patients, who had a history of autoimmune thyroid disease diagnosed between 2 and 16 years earlier (three patients had Graves' disease while two had Hashimoto's thyroiditis), were treated with rIFN-alpha for chronic hepatitis C. Before, during and after rIFN-alpha therapy, we determined thyroid function, antithyroid antibody, thyroid echogenicity and the surface phenotype of the peripheral and intrathyroidal lymphocytes.

RESULTS

Four of the patients developed overt hypothyroidism after 4-7 months of rIFN-alpha therapy, and two of them had a preceding history of low-uptake thyrotoxicosis. Recovery of thyroid function was observed in all four patients. Strongly positive blocking type TSH receptor antibody was detected and an increase in the percentage of CD19 positive cells in the intrathyroidal lymphocytes was also observed in three of the patients even though the goitre size increased in two of them. One of the patients became thyrotoxic later when stimulating type TSH receptor antibody became positive. Another patient suffered from reversible hypothyroidism although stimulating type TSH receptor antibody remained strongly positive throughout the clinical course.

CONCLUSIONS

Our data thus indicated a high incidence of an unusual type of reversible hypothyroidism with TSH receptor antibodies in patients with chronic hepatitis C and pre-existing autoimmune thyroid disease after recombinant interferon-alpha therapy through a mechanism involving both the humoral and cellular immune systems.

Mapping genes for resistance to barley stripe rust (Puccinia striiformis f. sp. hordei)

Two genes conferring resistance to the barley stripe rust found in Mexico and South America, previously identified as race 24, were mapped to the M arms of barley chromosomes 7 and 4 in a doubled haploid population using molecular markers and the quantitative trait loci (QTL) mapping approach. The resistance gene on chromosome 7 had a major effect, accounting for 57% of the variation in disease severity. The resistance gene on chromosome 4 had a minor effect, accounting for 10% of the variation in trait expression. Two pairs of restriction fragment length polymorphism markers are being used to introgress the resistance genes to North American spring barley using molecular marker-assisted backcrossing.

A molecular, isozyme and morphological map of the barley (Hordeum vulgare) genome

A map of the barley genome consisting of 295 loci was constructed. These loci include 152 cDNA restriction fragment length polymorphism (RFLP), 114 genomic DNA RFLP, 14 random amplified polymorphic DNA (RAPD), five isozyme, two morphological, one disease resistance and seven specific amplicon polymorphism (SAP) markers. The RFLP-identified loci include 63 that were detected using cloned known function genes as probes. The map covers 1,250 centiMorgans (cM) with a 4.2 cM average distance between markers. The genetic lengths of the chromosomes range from 124 to 223 cM and are in approximate agreement with their physical lengths. The centromeres were localized to within a few markers on all of the barley chromosomes except chromosome 5. Telomeric regions were mapped for the short (plus) arms of chromosomes 1, 2 and 3 and the long (minus) arm of chromosomes 7.

A comparison of Hordeum bulbosum-mediated haploid production efficiency in barley using in vitro floret and tiller culture

A high efficiency of Hordeum bulbosum-mediated haploid production in barley has been achieved using a floret culture technique in which florets pollinated with Hordeum bulbosum are cultured on modified N6 media containing 0.5 mg/l kinetin and 1.2 mg/l2,4-D. Cultures were maintained at 25 °C with a 16 h photoperiod for 9 days before embryo rescue. In a comparison of haploid production efficiency using five F1 hybrids from winter x winter and winter x spring barley crosses, 41.6 haploid plants/100 florets pollinated were produced using floret culture. Using detached tiller culture, 13.5 haploid plants/100 florets pollinated were produced. Higher efficiencies achieved with floret culture are attributed to the formation of larger, differentiated embryos. Such embryos lead to higher frequencies of plant regeneration. The F1 from a winter x winter cross was inferior in haploid production compared to F1s from winter x spring crosses. No genotype x technique interaction was observed.