Effective Induction of Fertile Gametes in Oriental × Trumpet (OT) Lily by High Temperatures.

Lily is a very important bulb crop, and interspecific distant hybridization is a crucial method of lily breeding. However, F1 interspecific hybrids tend to be highly sterile due to low levels of genetic homozygosity. This can be addressed by meiotic polyploidization, which has the advantage of reducing breeding time and being able to promote genetic recombination resulting in many variant progenies. High temperatures have been proven to induce 2n gametes via hindering a spindle formation in several plants, but little has been reported in lilies. In the present study, after observing the correlation between the development of the pollen mother cells (PMCs) and the length of the buds, 28-31 mm long buds were selected as the experimental material, which were at the stage of prophase I-metaphase I. Individual buds were induced at different temperatures (40 °C, 42 °C, and 44 °C) and durations (4 h and 6 h) using self-made multiwire heating equipment, and successfully induced fertile male gametes.. The best results were achieved with treatment of 42 °C for 4 h, reaching a maximum fertile pollen induction rate of 36.64%, while bud mortality was 40%. Two chemicals, colchicine and oryzalin, were also used by injection, and only the treatment with oryzalin obtained fertile gametes, with the highest fertile gamete rate of 15.39% at a concentration of 0.005%, while the bud mortality was 36.67%. This suggests that high temperatures have a superior effect on lily 2n gamete induction. In addition, the pollen obtained from the 6 h induction of high temperature was significantly larger than that from the 4 h induction, with an average diameter of 138.64 µm and 107.88 µm, respectively, 2.35 and 1.84 times wider than haploid pollen. The fertile pollen was crossed with four cultivars and two species, and a total of 267 embryonic seeds were obtained, with the highest embryonic rate of 4.52% in OT lily 'Mister Cas' as the parent, which had a germination rate of 26.27%. This suggests that the method of high-temperature induction for fertile gametes probably has important significance for ploidy and distant hybrid breeding in lilies.

[The relationship between maxillary anterior impacted teeth and sagittal facial type].

PURPOSE: To investigate the relationship between impaction of maxillary anterior teeth and sagittal facial type and evaluate the dentofacial morphological characteristics of patients with maxillary teeth impaction. METHODS: Totally 90 patients with maxillary anterior teeth impaction were divided into 3 groups (one incisor impaction, one canine impaction and two canines impaction), and their cephalometric films were measured and analyzed. They were further divided into Class I, II and III facial types according to ANB and the constituent ratio were calculated. SPSS 17.0 software package was applied for Student's t test and chi-square test. RESULTS: SNA, A'-Ptm' and L1-NB were smaller than the normal value in the 3 groups. Convexity, L1-MP, ANB and Wits appraisal were smaller while AB plane angle, U1-NA and U1-NA were greater than the normal value in groups of one and two canines impaction; S'-Ptm', L1-NB were smaller while U1-L1 was greater than normal value in group of two canines impaction; Among the 3 groups, ANB and Wits appraisal were the smallest while AB plane angle was the greatest in group of two canines impaction. The sagittal facial type of 90 patients was mainly Class I (50%), but Class III in group of two canines impaction increased to 40%. CONCLUSIONS: Impacted maxillary anterior teeth might result in short maxillary basal bone. One canine impaction has the greatest influence than one incisor impaction on sagittal position of jaws. Two canines impaction has the greatest impact on sagittal facial type and tends to be Class III facial type.

[Root resorption after orthodontic treatment: a study of age factor and prevalence in anterior teeth].

PURPOSE: To investigate the impact of age factor on root resorption and the prevalence in anterior teeth during orthodontic treatment. METHODS: Sixty extraction cases treated with straight wire appliance were divided into adult group and child group, with 30 cases in each group.The panoramic radiographs pre-treatment and post-treatment were examined to measure the degrees of root resorption. A total of 360 anterior teeth in each group were evaluated. SPSS 13.0 software package was applied to perform statistical analysis. RESULTS: There was significant difference in root resorption index before and after treatment(P<0.01). The incidence of root resorption increased remarkably after orthodontic treatment. There was significant difference in the degree of root resorption in two groups (P<0.01). The prevalence of root resorption in anterior teeth was: upper central incisors, upper lateral incisors, lower central incisors, lower lateral incisors, upper canines and lower canines. CONCLUSIONS: The root resorption in adult patients are more obvious than child patients. The prevalence of root resorption in anterior teeth is different. Moderate or severe root resorption is prone to happen in upper central incisors or lateral incisors in adult patients.