大葱三交种制种技术研究

大葱的杂种优势利用是实现大葱高产、稳产的重要途径。大葱一代杂交种在产量、抗性方面均有明显的杂种优势,作为异花授粉作物大葱在一代杂交种制种过程中因亲本不育系回交多代,生活力弱,花球小等原因,制种产量较低。为进一步应用杂种优势及降低制种成本,利用100%雄性不育单交种开展大葱三交种的研究工作,为大葱三交种高产制种技术提供参考。     

Nitrogen Dioxide-Induced Responses in Brassica campestris Seedlings： The Role of Hydrogen Peroxide in the Modulation of Antioxidative Level and Induced Resistance

This article investigates the responses of Brassica campestris seedlings to an acute level of nitrogen dioxide (NO₂) exposure in a plant growth chamber, and examines whether pretreating plants with hydrogen peroxide (H₂O₂) will alleviate NO₂-caused injury. Twenty-eight-day-old B. campestris plants sprayed with 10 mmol L⁻¹ H₂O₂ aqueous solution (corresponding to approximate 1.0 mg H₂O₂ per single plant) were exposed to different concentrations of NO₂ (0.25, 0.5, 1.0, and 2.0 μL L⁻¹, respectively) for 24 h under controlled environment. To measure the plant biomass, the plants were fumigated with the same NO₂ concentrations as mentioned above for 7 h per day (8.00-15.00) for 7 days. As a control, charcoal filtered air alone was applied. Data were collected on plant biomass, total chlorophyll, photosynthetic rate, stomatal conductance, nitrate and nitrate reductase (NR), antioxidative enzymes, ascorbate (ASA), and malondialdehyde (MDA), immediately after exposure. The results showed that exposure to a moderate dose of NO₂ (e.g., 0.25 μL L⁻¹) had a favorable effect on plants, and the dry weight of the above-ground part increased, whereas the exposure to high NO₂ concentrations (e.g., 0.5 μL L⁻¹ or higher) caused a reduction in the plant biomass and the total chlorophyll, when compared with the control. In addition, at 0.5 μL L⁻¹ or higher NO₂ concentrations, prominent increases in the MDA level and superoxide dismutase (SOD) and NR activities were observed. Exposure to 1 μL L⁻¹ and higher NO₂ resulted in necroses appearing on older leaves, and an increase in catalase (CAT) activity, decrease in ASA content, increased accumulation of NO₃, and reduction in photosynthesis, when compared with the controls. No changes were detected in stomatal conductance under NO₂ fumigation. The pretreatment with 10 mmol L⁻¹ H₂O₂ alleviated significantly NO₂-caused biomass decrease and photosynthetic inhibition when compared with H₂O₂-untreated plants. Under NO₂ fumigation, further induction in SOD and CAT activities occurred in H₂O₂ treated plants when compared with H₂O₂-untreated plants. The effect of NO₂ on the ASA and MDA contents was also absent in H₂O₂-treated plants. However, the H₂O₂ treatment did not alter the nitrate content and NR activity in plants under NO₂ fumigation. The H₂O₂ treatment caused a lower rate of stomatal conductance. Taken together, these data suggest that fumigation with an acute level of NO₂ causes oxidative damage to B. campestris seedlings. The H₂O₂ pretreatment markedly protects plants against NO₂ stress and this may be associated with inducible antioxidative level. NO₂ fumigation contributes, at least in part, to the enhanced levels of nitrate in B. campestris leaves.     

Bioavailability of Zn as affected by root-induced changes of pakchoi cultivars with different Zn efficiencies

Background, aim, and scope  The Zn content in the human body is tremendously higher than that in the plant. It is vulnerable to Zn nutrition deficiency in the human body. Those who consume less animal products are subject to Zn deficiency and mainly live in the developing regions. The preventive measures against Zn deficiency in the human body, for example, Zn supplements from chemicals and Zn-fortified food, are expensive and often unattainable. We have been working on finding solutions to Zn malnutrition by screening Zn-efficient varieties of crops which can absorb more Zn from Zn-deficient soils and transfer more Zn to the edible part of crops. Pakchoi is a popular vegetable in many parts of the world. The Zn deficiency in the human body could be rectified by consuming Zn-efficient pakchoi cultivars. Rhizosphere is the ‘hotspot’ for plant–soil–microbe interactions, and the rhizospheric interactions play a key role in the micronutrient acquisition. However, little attention has been paid to the rhizosphere effects of different plant genotypes on the expression of nutrient efficiency. The aim of this study was to examine the difference of rhizosphere effect between two pakchoi cultivars with different Zn efficiencies. Materials and methods  A Zn-deficient calcareous purple soil was collected from central China. There were two Zn treatments, one with Zn addition (5 mg kg⁻¹ soil) and the other, which acts as a control, with no Zn addition. Two pakchoi cultivars were Wuyueman of Zn-efficient and Heiyoubaicai of Zn-inefficient plants. Ten seeds of each pakchoi cultivar were sown in the rhizobag. The plastic pot was filled with 0.8 kg soil with 37% of the soil in the rhizobag. The seedlings were harvested on day 45 after planting. The rhizosphere and bulk soil samples were analyzed for their physical and chemical properties, microbial biomass, and Zn concentrations. Zn in the plants was also determined. Results  The cultivar Wuyueman demonstrated a much higher depletion rate of available Zn in the rhizosphere than did the cultivar Heiyoubaicai. The available Zn in the rhizosphere of Wuyueman was lower in the rhizosphere soil (0.47 mg kg⁻¹) compared with that in the bulk soil (1.08 mg·kg⁻¹), and the depletion rate of available Zn was 56.5% under Zn deficiency. This was closely associated with the capacity of cultivar Wuyueman to take up more Zn from the soil, especially under Zn-limiting conditions. The rhizosphere pH of pakchoi cultivars was lower than that in the bulk soil, while the microbial biomass carbon in the rhizosphere was significantly higher than that in the bulk soil. Under Zn-deficient conditions, the rhizosphere pH of the cultivar Wuyueman was lower but the microbial biomass carbon was higher than those of the cultivar Heiyoubaicai. Discussion  Soil-available Zn was substantially depleted in the rhizosphere of two pakchoi cultivars, with the greater depletion rate being found in the cultivar Wuyueman rather than in the cultivar Heiyoubaicai, especially under Zn-deficient conditions. This was related to the mobilization of Zn induced by the plants with different Zn efficiencies and, thus, Zn bioavailability in the rhizosphere. The pH decrease and the increase of microbial biomass carbon in the rhizosphere of the cultivar Wuyueman might have contributed to the translocation of Zn in its rhizosphere, which allows Zn to be absorbed more easily by Wuyueman than by Heiyoubaicai. This suggests that root-induced changes in the rhizosphere of pakchoi have a certain effect on the expression of zinc efficiency. Conclusions  Root-induced changes mobilized Zn in the rhizosphere of two pakchoi cultivars and increased its bioavailability. The rate of Zn mobilization was higher in the rhizosphere of the Zn-efficient cultivar than that of the Zn-inefficient cultivar at low Zn levels. Recommendations and perspectives  Root-induced changes in the rhizosphere are important factors for the nutrient dynamics and, thus, also for the mineral nutrition of plants. Soil conditions near the roots are different from those in the bulk soil. Many results have shown that these differences depend on soil properties, fertilizer application, plant species, and other factors. Further research should focus on the environmental effects of the rhizosphere on nutrient availability.     

不结球白菜抗病育种的研究：Ⅲ.矮抗一号新品种的选育

1984～1989年在对种质资源抗芜箐花叶病毒(TuMV)鉴定的基础上,采用系谱选择和母系选择法相蛄合的途径,选育出综合性状优良的矮抗一号新品种。其特点:(1)高产:生产试验平均亩产达3121.5kg.比对照矮脚黄增产16.1％;(2)抗病:TuMV和霜霉病人工鉴定病情指数为22.17和5.8,比对照矮脚黄降低72.2％和87.1％。与田间鉴定结果一致;(3)优质:叶片重/叶柄重达0.70,比对照提高48.9％。雏生素C、灰分和叶柄中可溶性固形物等营养成分含量均高于对照,而粗纤雏含量低;(4)商品性好:植株矮,叶片大,叶柄短且宽,符合喜食白梗菜地区的消费习惯。     

西府海棠与珠美海棠果实维生素C含量的测定及比较

维生素c是衡量果蔬品质的重要指标之一。为了准确评价海棠果实中维生素c的含量,本试验采用紫外分光光度法和碘量法对西府海棠和珠美海棠鲜果及干果中的维生素C含量进行了测定。结果表明：两种方法测定海棠果的维生素c含量存在差异,碘量法测得数值略高;西府海棠鲜果维生素C含量高于珠美海棠0．53～0．61mg／100g,西府海棠干果维生素c含量高于珠美海棠0．1～0．2mg／100g。此研究为海棠营养价值的进一步开发利用提供了理论指导。     

不结球白菜抗病育种的研究——Ⅳ.矮抗二号和矮抗三号新品种的选育

1984～1989年在对不结球白菜种质资源抗芜菁花叶病毒(TuMV)鉴定的基础上,利用杂种优势育种技术,以抗病矮脚黄雄性不育两用系为母本、抗病矮脚黄和雪克青自交系为父本,选育出综合性状优良的矮抗二号和矮抗三号新品种。其特点:(1)丰产:生产试验平均产量分别达52.4和56.6t/hm~2,比对照矮脚黄分别增产29.9%和40.2%;(2)抗病:两品种 TuMV 和霜霉病人工鉴定病情指数比对照分别降低79.5%、98.7%和69.8%、88.0%;(3)优质:矮抗二号叶片重/叶柄重比对照提高17.0%,矮抗三号略低于对照,但其 V~c 灰分、叶片和叶柄中可溶性固形物含量等主要营养成份均高于对照,且纤维素含量低;(4)商品性好:矮抗二号叶柄短且宽,色白。矮抗三号叶柄短且宽,色绿白,分别符合全国大部分喜食白梗菜和青梗菜两大类型地区的消费习惯。     

种植密度对普通白菜花芽分化和现蕾的影响

为了解种植密度对普通白菜(BrassicacampestrisL.ssp.chinensisMakino)花芽分化和现蕾的影响,试验测定分析了75#普通白菜50孔穴盘与72孔穴盘植株生长发育的形态指标。结果表明,50孔穴盘植株前期叶片数低于72孔穴盘植株,随着植株生长,50孔穴盘植株营养生长旺盛,花芽分化较早,分化级数较高,抽薹现蕾率较高。     

大葱雄性不育的研究和应用进展

雄性不育技术的研究对大葱杂种优势的进一步利用具有推进作用.介绍了大葱雄性不育的类型、大葱雄性不育花器官的形态特征和花粉发育的细胞学研究情况、大葱雄性不育生物分子学的研究情况,总结了利用大葱雄性不育创制的不育系及育成的杂种一代在生产上的应用情况,并对大葱雄性不育杂种优势的利用进行了展望.     

不结球白菜L-半乳糖酸-1,4-内酯脱氢酶基因(GLDH)cDNA片段克隆与RNAi表达载体构建

根据植物中hpRNA(hairpin RNA)原理,选择GLDH基因cDNA序列同源性较低区域设计1对携带双酶切位点的特异引物,以不结球白菜‘苏州青’叶片为材料提取总RNA,利用RT-PCR技术克隆了GLDH基因片段。构建中间克隆载体,经过3次亚克隆将测序正确的GLDH基因片段分别以正向和反向两种形式插入到间隔基因YYT的两端,经鉴定已插入到植物表达载体中,成功地构建了干扰GLDH基因表达的RNAi植物双元表达载体pRNAi-GLDH,并将表达载体转化到农杆菌菌株LBA4404中,为深入研究GLDH基因功能提供有效的工具。     

葱蛋白质和氨基酸分析

蛋白质和氨基酸是葱营养品质的重要构成因素，其含量在不同类型、不同品种之间差异很大。分葱的蛋白质和氨基酸含量均较高，长白型大葱含蛋白质丰富而氨基酸较少，短白型大葱则相反，蛋白质含量虽少但氨基酸含量较高，鸡腿型大葱两者含量皆低。在１１份测试材料中，寿葱１号、葱子葱和日本分葱１号的蛋白质和氨基酸含量较高，是营养价值较高的优良品种，章丘大葱的蛋白质含量高，太９号氨基酸含量丰富，是进行优质育种的优良原始材料。蛋白质和总氨基酸含量之间存在极显著相关性：ｙｐｒ＝－０．２３７７＋１．９５６１ｘａａ（ｒ＝０．７８７９＊＊）。在所测１７种氨基酸中，Ｇｌｕ、Ａｓｐ、Ａｌａ、Ｌｅｕ、Ｖａｌ、Ｌｙｓ和Ｐｈｅ含量较高，占总氨基酸的７２．６１％～７６．０４％，其中Ｇｌｕ含量最高，占总氨基酸的３２．４２％～４１．９８％。Ｇｌｕ和氨基酸总量之间还存在极显著相关性：ｙａａ＝０．１９７８＋１．９７８５ｘＧｌｕ（ｒ＝０．９２４９＊＊）。