Search

Cucumber (Cucumis sativus L.) is a major vegetable crop grown globally, with a cultivation history of more than 3000 years. The limited genetic diversity, low rate of intraspecific variation, and extended periods of traditional breeding have resulted in slow progress in their genetic research and the development of new varieties. Gamma (γ)-ray irradiation potentially accelerates the breeding progress; however, the biological and molecular effects of γ-ray irradiation on cucumbers are unknown. Exposing cucumber seeds to 0, 50, 100, 150, 200, and 250 Gy doses of 60Co-γ-ray irradiation, this study aimed to investigate the resulting phenotype and physiological characteristics of seedling treatment to determine the optimal irradiation dose. The results showed that low irradiation doses (50–100 Gy) enhanced root growth, hypocotyl elongation, and lateral root numbers, promoting seedling growth. However, high irradiation doses (150–250 Gy) significantly inhibited seed germination and growth, decreasing the survival rate of seedlings. More than 100 Gy irradiation significantly decreased the total chlorophyll content while increasing the malondialdehyde (MDA) and H2O2 content in cucumber. Transcriptome sequencing analysis at 0, 50, 100, 150, 200, and 250 Gy doses showed that gene expression significantly differed between low and high irradiation doses. Gene Ontology enrichment and functional pathway enrichment analyses revealed that the auxin response pathway played a crucial role in seedling growth under low irradiation doses. Further, gene function analysis revealed that small auxin up-regulated gene CsSAUR37 was a key gene that was overexpressed in response to low irradiation doses, promoting primary root elongation and enhancing lateral root numbers by regulating the expression of protein phosphatase 2Cs (PP2Cs) and auxin synthesis genes.Key message: Low doses of γ-ray irradiation promoted seedling growth; CsSAUR37 was identified and overexpression of CsSAUR37 was found to promote primary root elongation and hypocotyl elongation, and increases in lateral root numbers; Cucumber exhibited phenotypic variations under γ-ray irradiation. These findings provided a foundation for constructing cucumber mutant libraries and excellent materials for understanding the mechanisms underlying γ-ray irradiation. [ABSTRACT FROM AUTHOR]

Abstract Background Intracranial pediatric germ cell tumors (GCTs) are rare and heterogeneous neoplasms and vary in histological differentiation, prognosis and clinical behavior. Germinoma and mature teratoma are GCTs that have a good prognosis, while other types of GCTs, termed nongerminomatous malignant germ cell tumors (NGMGCTs), are tumors with an intermediate or poor prognosis. The second group of tumors requires more extensive drug and irradiation treatment regimens. The mechanisms underlying the differences in incidence and prognosis of the various GCT subgroups are unclear. Results We identified a distinct mRNA profile correlating with GCT histological differentiation and prognosis, and also present in this study the first miRNA profile of pediatric primary intracranial GCTs. Most of the differentially expressed miRNAs were downregulated in germinomas, but miR-142-5p and miR-146a were upregulated. Genes responsible for self-renewal (such as POU5F1 (OCT4), NANOG and KLF4) and the immune response were abundant in germinomas, while genes associated with neuron differentiation, Wnt/β-catenin pathway, invasiveness and epithelial-mesenchymal transition (including SNAI2 (SLUG) and TWIST2) were abundant in NGMGCTs. Clear transcriptome segregation based on patient survival was observed, with malignant NGMGCTs being closest to embryonic stem cells. Chromosome copy number variations (CNVs) at cytobands 4q13.3-4q28.3 and 9p11.2-9q13 correlated with GCT malignancy and clinical risk. Six genes (BANK1, CXCL9, CXCL11, DDIT4L, ELOVL6 and HERC5) within 4q13.3-4q28.3 were more abundant in germinomas. Conclusions Our results integrate molecular profiles with clinical observations and provide insights into the underlying mechanisms causing GCT malignancy. The genes, pathways and microRNAs identified have the potential to be novel therapeutic targets.

Using TH 880-F type dust tester and low pressure impactor (LPI), the size-segregated atmospheric particulates were collected, the particle size distribution characteristics and the content of lead were analyzed in the unorganized emission area (1 and 2) from the Blast and ISA furnaces within a lead-zinc smelter in Yunnan province. The results showed that lead in PM 2.5 (fine particulate matter, particle size <2.5 μm) accounted for 66.6% and 43.1% of PM 10 (particulate matter, particle size <10 μm) and TSP(total suspended particle, particle size<100 μm) in unorganized emission area 1, and the corresponding proportions in the unorganized emission area 2 were 54.1% and 38.7%, all these showed that the lead pollution mainly existed in small size particles. There was a close correlation between the lead content in the unorganized emission particulate matter and the wind direction and wind speed in the surface meteorological data, followed by the wind energy density. In lead smelting area, the correlation of lead content in the unorganized emission particulate matter with the wind direction and wind speed was the highest, followed by the wind energy density w . In the slag field, the correlation between lead content in the unorganized emission particulate matter and the vertical distribution of the temperature ( γ ) of the boundary layer was the highest, followed by the component u and v , and then the wind energy density w .

In order to determine the fragment size of Triticum timopheevii chromosome segments introduced into wheat background and physically map the Pm6 gene, a total of 72 primers (including SSR and STS primers) were used to analyze the eight introduced introgression lines containing Pm6 gene. Referring to the available mapping information of the analyzed markers on chromosome 2B, Pm6 was physically located in distal part of the long arm of chromosome 2B at the region of Bin 2BL-6. The introgressed fragment sizes of the chromosome 2G in different introgression lines was determined to be as follow (from short to long): IGV1-465

The dominant male sterility gene Ms2 in wheat has been widely used in recurrent selection and variety improvement. Identification of genes associated with the male sterility in Ms2-carrying wheat will help us understand how Ms2 functions. Using a pair of isogenic lines of Ms2, subtractive hybridization was conducted with cDNA from bulked spikelets at meiophase of sterile plants as the tester and cDNA from the same tissues of fertile plants as the driver. Two major bands at 270 bp and 450 bp were obtained by suppression PCR (polymerase chain reaction) of the subtractive cDNA. A total of 882 recombinants from PCR product cloning were isolated for reverse Northern analysis. The results demonstrated that up to 90% of the inserts in the library were up-regulated in the sterile spikelets. Twenty-one unique inserts from this library were sequenced. Similarity search showed that eighteen of them were homologous to ESTs (expression sequence tags) derived from spike or anther tissues at meiophase. The chromosome locations of nine of the ESTs were determined using C.S. (Chinese spring) nulli-tetrasomic lines, one of which was assigned to chromosome group 4 that includes chromosome 4D where Ms2 is located. In addition, four additional ESTs could also be assigned to this group according to their homology to BACs (bacterial artificial chromosomes) or PAC (P1 artificial chromosomes) of rice chromosome 3. The expression patterns of eight of the inserts examined displayed increased expression in spikelets and anthers of the sterile plants.

In order to transfer the genes for salt tolerance and disease resistance from Thinopyrum bessarabicum into wheat, the hybrid progenies between T. aestivum cv. Chinese Spring and T. aestivum cv. Chinese Spring-amphiploid Th. bessarabicum were screened. A set of T. aestivum-Th. bessarabicum disomic addition lines was developed with the assistance of mitotic chromosome C-banding and genomic in situ hybridization (GISH), as well as GISH on meiotic M I chromosome preparations. The results indicated that all the wheat chromosomes in the lines remained unchanged karyotypically, while the added Th. bessarabicum chromosomes paired regularly in meiosis. The developed disomic addition lines were designated temporarily as DAJ1, DAJ2, DAJ3, DAJ4, DAJ5, DAJ6 and DAJ7 respectively. Determination of the homoelogous groups of the added Th. bessarabicum chromosomes and localization of the genes for salt tolerance and disease resistance are undergoing.

To understand wheat powdery mildew resistance mechanism, reverse-transcription polymerase chain reaction (RT-PCR) and cDNA library screening were performed to isolate the full-length cDNA of wheat thaumatin protein gene from wheat-Haynaldia villosa 6VS/6AL translocation line. The putative amino acid sequence of this gene consists of 173 amino acid residues, and is an acid polypeptide. It was highly homologous to thaumatin proteins isolated from other plants, so it is designated as TaTLP1 (GenBank accession number: AF384146). Northern blot analysis of TaTLP1 showed that the transcription difference obviously existed between resistant wheat-Haynaldia villosa 6VS/6AL translocation line and susceptible "Yangmai 5". The result of western blot showed that the protein expression product of TaTLP1 gene in wheat seedling leaf was a soluble cytoplasm protein, whose expression was induced by fungus Erysiph graminis and apparently related to disease resistance of the 6VS/6AL translocation line. Southern blot indicated that the TaTLP1 gene had 1-2 copies in wheat genome, and had been localized on the specific region of 7B and 7D chromosomes in wheat.

Wheat scab can cause significant yield lost and quality decrease as well as toxicoses in animals and humans. Sumai 3, a resistant cultivatr to scab, is widely used in the wheat breeding of scab resistance. To study the inheritance of resistance to scab in Sumai 3, the highly susceptible cultivar Chuan 980 was crossed with Sumai 3 and backcrossed with Sumai 3 as a recurrent parent for seven times, thus a near-isogenic line S016 susceptible to scab was developed. S016 was evaluated in five regions and a period of two years for resistance to spread of scab in spike. Results showed that S016 was as highly susceptible to wheat scab as one of the parent Chuan 980. Molecular markers (RFLP, RAPD) were screened to identify chromosome regions of negative element of resistance gene (s) in S016. The DNA polymorphism between the near-isogenic lines was showed using six restrict enzymes (EcoRI, EcoRV, HindIII, Dra I, BamH I, Xba I) and 85 probes located in wheat chromosome 2D. Among the amplified bands of 450 10-mer random primers, OPH191400 and OPH191200 were perhaps linked to negative regulator element. Some reported probes linking to scab resistance gene(s) did not show any polymorphism between this near-isogenic line and their generation.

A pair of degenerate primers were designed based on NBS (nucleotide binding site, NBS) domain of resistance(R) gene and used to perform PCR with cDNA from the translocation line 6VS/6AL of Triticum aestivum-Haynaldia villosa. A clone (N7) characterized with NBS was obtained by sequencing analysis. Two specific primers were designed from the N7 sequence and used to screen a genomic TAC (transformation-competent artificial chromosome, TAC) library of 6VS/6AL consisting of ca. 2 x 10(6) clones. The library was stored as clone pools in twenty-two 96-well plates, each well containing approximately 1000 TAC clones. TAC plasmids were prepared from all the 2112 pools. Using a pooled PCR screening procedure, a positive TAC clone having a 40 kb insert was obtained. The positive clone was confirmed by Southern hybridization with the NBS fragment as a probe. The results indicate that the pooled PCR method is effective for screening of genomic libraries having large number of clones.

Twenty six DNA probes from seven homoeologous groups of triticeae were screened to reveal the RFLP between 45 wheat-R. kamoji derivatives and their parents R. kamoji, Chinese Spring, Yangmai 5. The result showed that the introduced R. kamoji chromosomes in 16 wheat-R. kamoji alien chromosome lines including additions, substitution or putative translocations were grouped into homoeologous group 1, 3, 5, 6 and 7. Alien chromosome pairs could be readily transmitted into the descendants. The added chromosomes in K139, K141, K214, K218, K219 and K224 disomic addition lines were grouped into homoeologous group 1, but the added chromosomes in K214 and K218 were different from K219 and K224 which originated from different genomes of R. kamoji. Ditelosomic addition line K147 might involve a R. kamoji chromosome long arm homoeologous to group 1 of wheat, and the added R. kamoji 1 L chromosomes in K139, K141 and K147 probably derived from different three genomes of R. kamoji. U chromosome of R. kamoji. showed homology to wheat homoeologous group 1. Homoeologous group 1 chromosome of R. kamoji, particularly its long arm is related to genes for scab resistance. Result also demonstrated a possible rearrangement occurred between homoeologous group 1 and group 6 of R. kamoji. Two R. kamoji chromosomes introduced in K203 were grouped to homoeologous group 1 and 6, respectively. In K166, the introgressed R. kamoji chromosome involved the short arm of group 5. Another alien chromosome line K177 was revealed as to be with introduced chromosome involving group 5L, 6S and 7SL of R. kamoji. Results also confirmed the homoeology between S, H and Y genomes of R. kamoji.

To isolate genes related to resistance to Erysiphe graminis (Blumeria graminis) DC. f. sp. tritici in wheat (Triticum aestivum L.), differential display analysis was conducted for mRNA extracted from seedlings of a wheat-Haynaldia villosa 6VS/6AL translocation line 92R137 that contains a powdery mildew resistance gene Pm21. A full-length cDNA sequence named TaTST (Triticum aestivum thiosulfate sulfurtransferase) homologous to the thiosulfate sulfurtransferase (rhodanese) in Datisca glomerata was isolated. Northern blot showed that the expression of TaTST was enhanced after infection with Erysiphe graminis. TaTST was mapped on the short arm of 6B chromosomes of wheat through Southern blot and GSP-PCR using Chinese Spring nullisomic/tetrasomic lines and ditelosomic lines. There is a homologue of TaTST on 6VS too.