水稻新黄绿叶基因YGL9的分子定位

叶色突变体是研究高等植物光合作用、叶绿素代谢途径、叶绿体结构与功能分子机制的理想材料。本研究从EMS(ethyl methane sulfonate)处理的缙恢10号(Oryza sativa L.ssp.indica)诱变群体中发现了一个苗期呈现黄绿色、抽穗期渐变为淡绿色的叶色突变体,命名为yellow green leaf 9(ygl9)。与野生型相比,ygl9苗期和分蘖期光合色素极显著降低,抽穗期光合色素显著降低,气孔长度、气孔导度和蒸腾速率极显著增加,净光合速率无明显变化。透射电镜观察表明,ygl9的嗜锇小体增多、基粒模糊、基质片层减少且疏松,但叶绿体结构基本完整。遗传分析显示该突变性状受1对隐性核基因调控。利用西农1A/ygl9 F2群体中的759株隐性单株,最终将YGL9定位在第3染色体短臂SSR标记S03-1和In Del标记Ind03-19之间,遗传距离分别为0.13 c M和0.07 c M,物理距离为63 kb。本研究为YGL9基因的克隆和功能分析奠定了基础。     

香果树组织培养技术研究

采用香果树幼树叶片作外植体,接种到附加不同浓度的KT和ZT组合的MS培养基上,诱导植株再生.结果表明,最适宜香果树叶片愈伤组织诱导和芽增殖的培养基是MS KT 1.0 ZT 2.0,愈伤组织诱导率达35.6%,芽增殖倍数为2.8倍;比较理想的生根培养基是1/2 MS IAA 0.5和1/2 MS IBA 0.5,生根率分别为65%和75%.试管苗移栽最理想的移栽基质是泥炭与珍珠岩(5∶1)的混合物,移栽成活率达95.2%.     

Carbon and nitrogen dynamics in a phosphorus-deficient soil amended with organic residues and fertilizers in western Kenya

The contribution of organic resources to the restoration of soil fertility in smallholder farming systems in East Africa is being tested as an alternative to costly fertilizers. Organic inputs are expected to have advantages over fertilizers by affecting many biochemical properties controlling nutrient cycling. Our study examined changes in soil C and N, C and N mineralization, microbial biomass C (MBC) and N (MBN), and particulate organic matter (POM) in a P-limiting soil in western Kenya after applications of organic residues and fertilizers to overcome P limitation to crops. Leaf biomass from six different tree (shrub) species was incorporated into the soil at 5 Mg ha^–1 for five consecutive maize growing seasons, over 2.5 years. Triple superphosphate was applied separately at 0, 10, 25, 50, and 150 kg P ha^–1 in combination with 120 kg N ha^–1 as urea. Soil inorganic N, soil organic C, mineralizable N, and total C in all POM fractions and total N in the 53- to 250-m POM fraction increased following addition of all organic residues compared to the control. Whether there was an advantage of organic residue incorporation over inorganic fertilizer use depended on the soil parameter studied, the organic residue and the rate of fertilization. Most differences were found in N mineralization where 14.4–21.6 mg N kg^–1 was mineralized in fertilizer treatments compared to 25.2–30.5 mg N kg^–1 in organic residue treatments. C and N mineralization and the 53- to 250-m POM fractions were the most sensitive parameters, correlating with most of the studied parameters. Organic residues can contribute to improved soil nutrient cycling while the magnitude of their contribution depends on the biochemical properties of the residues.     

Nutrient release from decomposing leaf mulches of karité (Vitellaria paradoxa) and néré (Parkia biglobosa) under semi-arid conditions in Burkina Faso, West Africa

Information on decomposition and nutrient release from leaf litter of trees in agroforestry parkland systems in Sub-Saharan Africa is scarce despite the significant role of these trees on soil fertility improvement and maintenance. Decomposition and nutrient release patterns from pruned leaves of the two most common species of parklands of the semi-arid zone of West Africa: Vitellaria paradoxa C.F. Gaertn (known locally as karité) and Parkia biglobosa (Jacq.) Benth. (known locally as néré), were investigated by a litter-tube study in Burkina Faso. Litter quality, methods of leaf exposure to the soil and combination with fertilizers were the factors studied. Leaves of néré had a higher nutrient content (C, N, P, Ca) and contained more ash and lignin than leaves of karité. Karité leaves had a greater content of K, cellulose and polyphenols. The pruned leaves of karité and néré showed two distinct decomposition patterns. Néré leaves decomposed more rapidly, with less than 32% of the initial weight remaining after the rainy season (4 months) while karité leaves decomposed more slowly with 43% of the leaf litter remaining after the rainy season. Addition of urea and compost did not significantly affect the rate of decomposition. Significant interaction was observed between species and method of leaf exposure for the first sampling date. Leaf litter of néré buried in soil gave the highest weight loss (34% of the initial mass in 1 month) compared with exposed leaf litter of néré and karité, and buried leaf litter of karité. Except for N, nutrient release patterns were similar for both species but the nutrient release rates were higher for néré leaves compared with karité leaves. N was immobilised in karité leaves most likely due to low N and high phenolic content. The rate of nutrient release from karité leaves followed the general trend K>P>N.     

水稻叶片保绿性的分子遗传研究进展

植物叶片的衰老是植物在长期进化过程中形成的适应机制,与收获器官的形成及营养转运密切相关,受植物内部因素调节,属于不可逆转的过程。作物叶片过早衰老将导致同化能力降低,影响作物的产量和品质。加强植物叶片功能研究将有助于改善我国农作物品质、增加产量。水稻作为我国的第一大粮食作物,延缓水稻叶片衰老,延长其光合功能期对提高产量有着重要的意义。本文将从水稻叶片保绿性的概念和分类、叶片保绿过程中叶绿素的功能及其降解等生理生化特点、叶片保绿性的表型遗传和基因效应等遗传特性以及叶片保绿性分子调控等几个方面的进行综述。理清水稻叶片保绿性的分子遗传机制,对具高保绿能力叶片的高产水稻品种选育及高产潜力水稻种质资源的挖掘都具有重要指导意义。     

A partial root zone drying irrigation strategy for citrus—Effects on water use efficiency and fruit characteristics

In Australian irrigated citriculture, fruit yield and quality outcomes are not tightly related to levels of plant available water, which raises the possibility of using mild water stress applied to part of the root zone, i.e. partial root zone drying, to stimulate physiological mechanisms that reduce tree water use by changing the relationship between stomatal conductance and ambient evaporative conditions.The PRD technique alternates irrigation such that one side of the tree root zone is allowed to dry whilst the other side is irrigated. This significantly reduces the wetted soil volume at any point in time, whilst always maintaining a readily available water supply to part of the root zone. By adopting this irrigation strategy water use of mature Navel orange trees C. sinensis (L.) Osbeck was reduced and water use efficiency was increased. The technique did not induce excessive fruitlet drop and crop yield was unaffected. Both fruit size and juice percentage slightly decreased whereas total soluble solids percentage (TSS) and juice acid percentage increased. As water use was reduced and juice quality attributes were increased, this technique has obvious benefits for juice fruit production.PRD offers an advantage over conventional deficit irrigation strategies because it helps reduce water use by separating the biochemical signaling responses to water deficit in the dry part of the root zone from the physical effects of reduced stomatal conductance due to lower water availability, allowing developmental processes associated with plant growth to remain unperturbed. Irrigating a reduced root zone volume in this way reduces crop water requirement. However, it is also important to understand that this technique pushes the crop to its limits and should only be applied to well established healthy trees.When applying PRD irrigation, it is important that water is supplied with sufficient frequency and depth of wetting to meet the water needs of the whole plant.     

Inter- and intra-specific interactions of Lumbricus rubellus (Hoffmeister, 1843) and Octolasion lacteum (Örley, 1881) (Lumbricidae) and the implication for C cycling

Earthworms are important engineering species of many terrestrial ecosystems as they play a significant role in regulating C turnover. The effects of earthworms on moderating C decomposition processes differ across species and with interactions between species, which is not fully understood. We carried out an experiment to study the interactions of Lumbricus rubellus and Octolasion lacteum, and their effects on soil respiration. Laboratory mesocosms were set up using tulip poplar (Liriodendron tulipifera) leaf litter and varying densities of earthworms in single and combined species treatments. CO₂ efflux rate was used as an indicator of C decomposition rates, and measured with CO₂ sensors every five days over one month. L. rubellus induced higher leaf consumption rate and higher CO₂ efflux than O. lacteum; meanwhile O. lacteum grew more than L. rubellus. Both litter consumption rate and growth rate of earthworms decreased with increasing earthworm density. Soil CO₂ efflux increased with increasing earthworm density (from ∼1-2 μg CO₂ g⁻¹ hr⁻¹ with no earthworms to ∼ 4 μg CO₂ g⁻¹ hr⁻¹ with 8 earthworms). Combining the two species had a synergistic effect on leaf litter consumption, and neutralizing effects on soil respiration. The data suggest that the strength of intra- and inter-specific interactions among earthworm ecological groups varies at different absolute and relative densities, leading to altered leaf litter decomposition and C cycling.     

施肥对南果梨树叶片叶绿素含量、抗氧化酶活性及膜脂过氧化程度的影响

通过测定不同施肥处理对南果梨树叶片中叶绿素含量、过氧化物酶活性及丙二醛含量等指标,比较施肥后不同时期、不同叶位的生理指标变化,探讨施肥对果树叶片抗氧化和膜脂过氧化程度的影响,为维持叶绿素的稳定提供理论依据。结果表明:果树叶片的叶绿素含量与过氧化物酶活性呈极显著正相关关系,与丙二醛含量呈显著负相关关系。叶绿素含量和过氧化物酶活性随着氮肥用量的增加、磷肥用量的减少呈增高趋势,随着钾肥用量的增加呈先升高后降低趋势;丙二醛含量随着氮、钾肥用量的增加呈降低趋势,随着磷肥用量的增加呈现先降低后升高趋势。适宜用量有助于提高南果梨树叶片叶绿素含量、抗氧化酶系统的抗氧化能力、抗逆境性能。     

白菜品种叶片色泽参数相关和聚类分析

用色差计和叶绿素仪对白菜亚种3个变种（普通白菜、乌塌菜和薹菜）19个品种的叶片颜色和叶绿素含量进行测定,并对色泽参数进行了相关分析和聚类分析。结果表明,供试品种间叶绿素含量及色泽参数差异显著;色泽比（h）和饱和度（C）与叶绿素含量呈一定相关性。聚类分析将供试品种分为叶色较浅和叶色较深两类;绿秀、PAK、矮脚黄、塌地乌3号、精品塌地乌与日本品种夏帝、华冠、冬赏味颜色相近。用色差计检测白菜叶片颜色方法可行,并具有操作简单、成本低、时间短、无损伤等优点。     

不同的碳氮源对牡丹花链格孢菌叶斑病菌生长影响

以牡丹花链格孢菌叶斑病病菌为试材,研究不同碳、氮源对病菌菌丝生长的影响.结果表明:适宜病菌菌丝生长的碳源为D-木糖,氮源为NH4Cl;适宜病菌孢子萌发的碳源为蔗糖、D-木糖、麦芽糖、D-果糖,氮源为Ca(NO3)2、尿素.