[The investigation on the situation of biting pencils among part pupils in Harbin, Guangzhou, and Beijing].

Objective: To investigate the prevalence of biting pencils among pupils living in Harbin, Guangzhou, and Beijing and to compare the differences among these cases. Methods: Stratified sampling method was used to select four elementary schools in Harbin and Guangzhou from April 2015 to April 2016. Firstly, Simple random sampling method was used in every grade (grade 1-grade 5) to select 3 or 4 classes (71 classes in total).After the sample selection, questionnaire surveys were conducted among pupils and their guardians (anyone of their guardians) who belonged to these classes. Secondly, the study extracted part of these pupils to conduct a field survey. Every school was classified by grade, and every grade adopted the method of random sampling to select one classes (20 classes in total). Meanwhile, the study randomly selected pupils from 10 classes in 2 elementary schools in Beijing. All together, 1 627 pupils participated in the field survey. The questionnaire included general information about the students and their guardians, the situation of biting pencils, the awareness of the harm of biting pencils, etc.; the field survey considered if participates' pencils have tooth marks and the severity of the marks, etc. χ(2) was applied to test and compare the differences among pupils of different genders and different cities. The comparison focused on the proportion of students who bited pencils, the proportion of pencils with tooth marks and the proportion of students and guardians already awared of the harm of biting pencils, etc. Results: The number of the valid questionnaires in Harbin and Guangzhou were 1 842, and 1 210, respectively. The occurrence rate of pupils biting pencils in Harbin (18.0% (333/1 842)) was higher than that in Guangzhou (11.3% (137/1 210)) (χ(2)=29.16, P=0.001). Specifically, in Harbin, the rate of boys biting pencils was 21.9% (212/965), which was higher than girls (13.8% (121/877)) (χ(2)=27.04, P=0.001). Similarly, in Guangzhou, the rate of boys biting pencils was 14.5% (92/632), which was also higher than girls (7.7% (45/578)) (χ(2)=15.34, P=0.001). The awareness rate of the harm of biting pencils among students from these two cities were 88.5% (1 611/1 819), and 90.8% (1 098/1 208), respectively, and the difference was statistically significant as well (χ(2)=4.39, P= 0.020). Compared with these data, the awareness rate of the harm of biting pencils among guardians from these two cities were 74.7% (1 339/1 791), and 79.4% (832/1 047), respectively as well as the statistically significant difference appeared (χ(2)=9.83, P=0.007). The result of field survey showed the rate of tooth-marked pencils in Harbin, Guangzhou and Beijing was 30.5% (187/613), 14.8% (79/534), and 28.3% (136/480), respectively. The difference was also statistically significant (χ(2)=42.68, P=0.001). The degree of tooth marks was mainly mild, while the percentage of mild degree in Guangzhou (54.4%(43/79)) and Beijing (41.2% (56/136)) was apparently higher than that of Harbin (39.0% (73/187)). The difference was not statistically significant (χ(2)=7.01, P=0.136). Conclusion: The behavior of biting pencils existed universally among pupils in Harbin, Guangzhou, and Beijing , which the situation of pupils biting pencils in Harbin and Beijing was more serious than that in Guangzhou. Pupils, parents and teachers should pay attention to such a behavior.

Development of EST-PCR markers for Thinopyrum intermedium chromosome 2Ai#2 and their application in characterization of novel wheat-grass recombinants.

A series of expressed sequence tags-derived polymerase chain reaction (EST-PCR) markers specific to chromosome 2Ai#2 from Thinopyrum intermedium were developed in this study using a new integrative approach. The target alien chromosome confers high resistance to barley yellow dwarf virus (BYDV), which is a severe virus disease in wheat. To generate markers evenly distributed on 2Ai#2, a total of 105 primer pairs were designed based on mapped ESTs from 8 bins of wheat chromosome 2B with intron-prediction by aligning ESTs with genomic sequences of the new model plant Brachypodium distachyon. Eight and seven polymorphic markers on the short arm and the long arm of chromosome 2Ai#2, respectively, were obtained with a polymorphism rate of 14.3%. These chromosome 2Ai#2-specific EST-PCR markers were then used in tracing and exploring the structural variation of the alien chromosome in the population derived from the immature embryo culture of the cross between N452, a 2Ai#2(2D) substitution line, and common wheat CB037. Two centric fusion of translocations involving 2Ai#2 short or long arm with wheat chromosome 2D and some new genetic stocks including telosomes with the alien chromosome short or long arm were identified in the SC(3) generations, which provided basic materials to further study the mechanism of the BYDV resistance. BYDV tests in two field seasons suggest that the BYDV resistance was mainly conferred by the short arm, gene interaction on both arms of the alien chromosome was discussed.

[Genetic analysis and gene deduction of powdery mildew resistance in T. durum-Ae. squarrosa amphidiploids].

Eleven seedlings with resistance and two amphidiploids with disease resistance at all developmental stage were screened by using No. 15 isolate of E. graminis f. sp. tritici to inoculate 99 T. durum-Ae. squarrosa amphidiploids. The two amphidiploids with disease resistance at all developmental stage, M53 and M81, and their Ae. squarrosa parents were resistant to No. 15 isolate of powdery mildew payhogen, but their T. durum parents were susceptible. Therefore, the powdery mildew resistance of M53 and M81 were derived from Ae. squarrosa. Amphidiploid M74, which had the same durum parent as M53 but different Ae. squrrosa parent, was susceptible to No. 15 isolate in adult stage. M29 and M35, which had the same durum parent as M81 but different Ae. squarrosa parent were susceptible in all stage. These results were also proved that the powdery mildew resistance genes were derived from Ae. sqarrosa. Genetic analysis showed that powdery mildew resistance gene in M53 or M81 was a single dominant gene. A series of lines with known powdery mildew resistance genes and two unknown lines were used to test response patterns with 14 differential isolates of E. graminis f. sp. tritici. The response patterns in M53 and M81 were different from Pm1 to Pm21 and indicated that M53 and M81 conferred a new powdery mildew resistance gene respectively.

Molecular characterization of a Thinopyrum intermedium group 2 chromosome (2Ai-2) conferring resistance to barley yellow dwarf virus.

The wheat--Thinopyrum intermedium addition lines Z1 and Z2 carry 21 pairs of wheat chromosomes and one pair of Th. intermedium chromosomes (2Ai-2) conferring resistance to barley yellow dwarf virus (BYDV). GISH results using the genomic DNA of Pseudoroegneria strigosa (S genome) as the probe indicated that the 2Ai-2 chromosome in Z1 and Z2 is an S-J intercalary translocation. Most of the 2Ai-2 chromosome belongs to the S genome, except for about one third in the middle region of the long arm that belongs to the J genome. The results of detailed RFLP analyses confirmed that the 2Ai-2 chromosome is extensively homoeologous to wheat group 2 chromosomes. Some new RFLP markers specific to the 2Ai-2 chromosome were identified. A RAPD marker, OP-R16(340), specific to the 2Ai-2 chromosome, was screened. We converted the RAPD marker into a sequence-characterized amplified region (SCAR) marker (designated SC-R16). The study establishes the basis for selecting translocation lines with small segments of the 2Ai-2 chromosome and localizing the BYDV resistance gene when introgressed into a wheat background.

[Molecular cytogenetic characterization of a new wheat line YW443 with resistance to barley yellow dwarf virus].

A new wheat line YW443 with BYDV resistance and good traits was developed from the combination of PP9-1/Shan7859¿Fengkang 8. The wheat line YW443 was identified by BYDV resistance analysis, genomic in situ hybridization (GISH), RFLP and RAPD analysis. The results indicated as follows: (1) YW443 was resistant to GPV and GAV strains of BYDV; (2) YW443 is a homozygous wheat-Thinopyrum intermedium translocation line with a pair of BYDV resistance genes; (3) The 7StL segment of Th. intermedium carring BYDV resistance gene was transferred onto the distal end of the wheat chromosome 7D long arm, the line YW443 was 7DS.7DL-7StL translocation; (4) A RAPD marker OPR19(-900) could detect the DNA of Th. intermedium 7StL in L1 and L1 derivatives including translocation lines YW443, YW642 etc. The markers may be used as a selecting marker for the BYDV resistance breeding program.

[Identification of the barley chromosome in wheat by GISH and RFLP].

The barley chromosome in wheat was identified by genomic in situ hybridization (GISH) in which biotin labelled total genomic DNA of barley Betzes was used as probe and the unlabelled total DNA of common wheat Chinese Spring (CS) as blocking DNA. A series of wheat materials were tested as follows: two disomic alien substitution and monosomic alien addition lines, 2n = 43; two monosomic alien substitution lines, 2n = 42; seven disomic alien substitution lines, 2n = 42. RFLP probe psr131 on the short arm of the homologous group 2 was used to analyze the barley chromosome in wheat. The result indicated that there was a same band in barley Betzes and substitution line A5. The chromosome 2A of A5 was substituted by the chromosome 2H of barley. These materials will be useful in transferring the valuable genes in the chromosome 2H to wheat.

The use of cell culture for subchromosomal introgressions of barley yellow dwarf virus resistance from Thinopyrum intermedium to wheat.

Barley yellow dwarf virus (BYDV) resistance has been transferred to wheat from a group 7 chromosome of Thinopyrum (Agropyron) intermedium. The source of the resistance gene was the L1 disomic addition line, which carries the 7Ai-1 chromosome. The resistance locus is on the long arm of this chromosome. BYDV resistant recombinant lines were identified after three or more generations of selection against a group 7 Th. intermedium short arm marker (red coleoptile) and selection for the presence of BYDV resistance. One recombinant line produced by ph. mutant induced homoeologous pairing and 14 recombinant lines induced by cell culture have been identified. Resistance in seven of the cell culture induced recombinants has been inherited via pollen according to Mendelian segregation ratios for up to eight generations. Meiotic analysis of heterozygotes indicates that the alien chromatin in the cell culture induced recombinants is small enough to allow regular meiotic behaviour. The ph-induced recombinant was less regular in meiosis. A probe, pEleAcc2, originally isolated from Th. elongatum and that hybridizes to dispersed repeated DNA sequences, was utilised to detect Th. intermedium chromatin, which confers resistance to BYDV, in wheat backgrounds. Quantification of these hybridization signals indicated that the translocations involved a portion of alien chromatin that was smaller than the complete long arm of 7Ai-1. Restriction fragment length polymorphism analysis confirmed the loss of the short arm of 7Ai-1 and indicated the retention of segments of the long arm of 7Ai-1. Two 7Ai-1L DNA markers always assorted with the BYDV resistance. A third 7Ai-IL DNA marker was also present in seven of eight recombinants. In all recombinants except TC7, the 7Ai-1L markers replaced the 7DL markers. None of the wheat group 7 markers was missing from TC7. It is concluded that all the resistant lines are the result of recombination with wheat chromosome 7D, except line TC7, which is the result of recombination with an unidentified nongroup 7 chromosome.