Elucidation of the infection process of Ustilaginoidea virens (teleomorph: Villosiclava virens) in rice spikelets

This study reports an efficient inoculation protocol that allowed cytological analysis of the infection process of the rice false smut pathogen Ustilaginoidea virens. Examination of serial semithin and ultrathin sections of infected spikelets showed that the primary infection sites for the pathogen were the upper parts of the three stamen filaments located between the ovary and the lodicules. The stigma and lodicules were also occasionally infected to a limited extent. The pathogen infected the filaments intercellularly and extended intercellularly along the filament base. The host cells were degraded gradually. The pathogen did not penetrate host cell walls directly and did not form haustoria. In the balls the ovary remained alive and was never infected. This suggests that the pathogen is a biotrophic parasite that grows intercellularly in vivo.     

鸭梨同源异型突变株的花器官分析

以20a树龄同一梨园中1株能稳定遗传的花器官变异鸭梨和普通鸭梨为试材,采用形态观测法进行了花芽发育、花粉萌发率、表观形态等方面的研究分析。结果表明:该突变株的花发育与普通植株花的正常发育最明显的差别在于花器官花瓣完全或部分缺失、雄蕊相应增多;花瓣对应位置的雄蕊花丝粗、花药大;花粉萌发率高;部分特化的花瓣上着生有花药。根据试验结果,推断该突变株可能是梨的花同源异型突变株,控制花器官发育的B功能区发生了突变引起花器官异常。该突变株为进一步认识植物花发育的内在调控机制、研究花的发育机理提供了可能。     

牡丹雄蕊的营养成分研究

作者对牡丹雄蕊的微量元素、维生素、蛋白质、脂肪、氨基酸、脂肪酸组成等营养成分进行了测定和分析,结果表明:牡丹雄蕊中蛋白质、K、Ca、Mg、P、Se等元素及碳水化合物、不饱和脂肪酸、VE含量、蛋白质质量较高,是一种较好的天然保健食品资源。     

Identification of potential molecular markers for flower sex determination in Vernicia fordii

Vernicia fordii is cultivated as an important woody oil tree, with a long history in China. It is a monoecious and diclinous species. Altering the sex ratio to increase the number of female flowers would lead to better yields. The mechanism of flower development is, however, not yet clear. In this study, the proteins that are differentially expressed between male and female flowers were isolated using a combination of two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionisation time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS). A proteomic analysis led to the identification of 14 proteins, of which two were expressed specifically in male flowers and 10 in female flowers. Among the 10 female-specific proteins, aspartic proteinase, ascorbate peroxidase, and cyclophilin were thought to be involved in stamen abortion and gynoecium formation during the development of female flowers. Further results suggested that these proteins might be the sex-related proteins that are the potential molecular markers for flower sex determination in V. fordii.     

甘薯组(Section Batatas)A系列与B系列种间杂种植株形态变异观察

通过甘薯组 A 系列野生种 I.triloba(2n=30)和 B 系列栽培种甘薯(J.batatas)(2n=90)种间杂交的胚珠培养获得种间杂种植株。对杂种植株生物学特性观察发现:①杂种植株在叶形、叶色、茎粗细、生根习性、开花习性和抗寒性等方面均产生变异。②杂种植株的花器中,雌雄蕊结构发生变异,全部花朵没有出现雄蕊,雌蕊却有1～5枚。③杂种植株体细胞染色体数目变动于2n=27—56范围内,观察平均数为2n=37.25,可确定种间杂种为混倍体。     

Chromosome doubling of haploid maize seedlings using nitrous oxide gas at the flower primordial stage

In maize, inbred lines are used for the production of hybrid varieties. Corn breeders and researchers have considered using haploids to develop inbred lines; however, this procedure has not been practically applied because of the inefficiency of chromosome doubling of maize haploid seedlings. In this report, a procedure has been developed to overcome this difficulty. Maize haploid seedlings obtained from eight different genotypes were treated with nitrous oxide gas (2 days at 600 kPa). Treatment at the six‐leaf stage (flower primordia formation stage) significantly increased the occurrence of fertile sectors on both tassels and ears so that approximately half (44%) of the treated haploids produced kernels after self‐pollination. In the control, only 11% of haploids produced selfed kernels owing to spontaneous chromosome doubling. A strong genotypic effect on the occurrence of fertile sectors after the treatment was observed. This procedure can be used for inbred line development in maize breeding programmes.     

Frost hardening spruce container stock for overwintering in Ontario

Difficulties overwintering container stock in northern Ontario led to the development of the extended greenhouse culture hardening regime for spruce seedlings. Laboratories to measure shoot frost hardiness and evaluate terminal bud development were established to monitor nursery crops being hardened using this regime. Information on frost hardiness and bud development provided by these laboratories has been used by nursery managers to determine readiness of container seedlings for overwintering. Since 1982, over 200 stock lots have been monitored by these operational laboratories. This database can be used to determine the importance of nursery cultural factors and seed source on frost hardening. The database shows large differences between nurseries in approach to hardening seedlings which were reflected in levels of freezing damage, winter desiccation and overwintering success. Rates of frost hardening (i.e., the interval between terminal bud initiation and attainment of a --15°C level of shoot frost hardiness) of crops produced in north central Ontario failed to show significant seed source effects. The rate of frost hardening was faster in crops producing fewer needle primordia in terminal buds.     

Early development and enlargement of wheat floret primordia suggest a role of partitioning within spike to grain set

Spike grain number, a major component in the yield of wheat, is suspected of being determined by the sudden death of most of the initiated floret primordia, which occurs at around booting. By counting twice weekly the number of floret primordia in the middle and top spikelets, the onset time for the death of floret primordia (T_d) was assessed in six genotypes of differing earliness and fertility subjected to three treatments that were applied during stem elongation. The variation in T_d was positively correlated with overall earliness, as well as with spike fertility. Ovary development and enlargement were quantified in eight specified positions within the spikes, but T_d could not be assigned to a developmental stage attained by any ovary. Development and enlargement were very strongly correlated with each other throughout the floret lifetime, yet with significant effects of genotype, treatment and position within spikes. In each position within a spike, the proportion of florets that set a grain correlated to the initial delay of development as compared to the most advanced floret (r² = 0.64), but this correlation was severely biased by genotype and the floret position effect. Better correlations were obtained with either the development or width of each ovary at T_d, thus highlighting the role of the preceding phase. The best prediction (r² = 0.93) was obtained from the ratio of ovary width to that of the most advanced floret at T_d. The importance of this width ratio emphasized the role of partitioning in grain set: only florets able to divert nutrients survived after T_d and eventually set a grain. This relationship was no longer biased by floret position, while some remaining variability due to genotype suggested potential for plant breeding: width ratios at T_d were generally related to the growth duration of various primordia, as well as to their relative growth rate.     

岩石壁上爬山虎茎产生不定根时木质部中激素与结构变化研究

为探索岩石壁上爬山虎木质生长茎自发产生不定根这一科学问题,以其3类茎为试材,用酶联免疫法检测茎木质部中激素含量及施入外源激素引发茎内产生不定根原基并发育时的激素水平。结果表明一年生爬山虎茎中不定根原基属于内起源。各试材木质部中生长素(IAA)以鲜重计最高为11.486 μg/g,最低为6.255 μg/g。细胞分裂素(CTK)以鲜重计最高为232.295 ng/g,最低为150.235 ng/g;但施入外源激素的一年生爬山虎茎内产生不定根原基时CTK最高为232.295 ng/g。茉莉酸(JA)含量远低于植物营养器官按鲜重计10~100 ng/g范围,但生根茎内浓度远高于不生根茎。而茉莉酸甲酯(Me-JA)在各试材木质部内含量极微,但生根茎内浓度远高于不生根茎。爬山虎生根茎木质部内IAA/CTK达到27~76,生根茎木质部内激素浓度远高于未生根茎,且外施激素使茎产生不定根时激素浓度均大幅升高,表明其茎自发产生不定根需要多种内源激素协同作用。     

Spring growth of Douglas-fir seedlings from two bud development regimes

The effect of two bud development treatments on post-dormancy shoot growth was investigated with 1-year-old container-grown Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. A difference in the date of budset and number of overwintering primordia was obtained by applying 8-hour or 17-hour photoperiods in growth rooms during summer months. Seedlings were then chilled for 14 weeks at 4 °C and finally held 2 months at 22 °C under either an 8-hour or 16-hour photoperiod. The new shoot growth of seedlings with early budset had greater length, stem unit numbers, average stem unit length, and dry weight. Stem unit number of the post-dormancy seedlings was unaffected by photoperiod during flushing. Significant free growth occurred only in late budset seedlings and accounted for 40% and 46% of the fixed growth under 16-hour and 8-hour flushing photoperiods, respectively.