若干相同生态位的畜禽寄生蠕虫群落关系分析

在具有相同生态位的畜禽寄生蠕虫构成的２９个种对中,多数不具亲和性,仅２对具有明显亲和性,且均为家畜寄生蠕虫,即寄生山羊瘤胃的鹿同盘吸虫和长菲策吸虫,以及大肠的微管食道口线虫和辐射食道口线虫;种间关系程度则多为负关联,其中完全负关联的有１２对,仅有４对表现出不同程度的正关联;家畜寄生蠕虫的种群值明显高于家禽。分析结果提示,相同生态位的畜禽寄生蠕虫的种间关系普遍存在在负关联的缺少亲和性的现象,寄生空间     

杨树溃疡病病原——葡萄座腔菌科真菌间关系的系统学初探

利用ITS rDNA序列对我国杨树溃疡病的葡萄座腔菌科病原真菌进行系统发育学分析,共得到4种葡萄座腔菌科病原真菌:Botryosphaeria dothidea,Neofusicoccum parvum,Diplodia seriata和D.mutila。它们与相应的无性型或有性型一一对应。其中,D.seriata在我国是第一次报道为杨树的病原。研究了试验菌株与国内外已报道菌株间的系统发育学关系,分析了它们与环境间的联系。结果表明B.dothidea具有高度的种内遗传多样性。这些结果对葡萄座腔菌科真菌在全球的分布作了必要的补充,也为杨树溃疡病的研究和防治提供进一步的理论基础。     

种间互作对苹果/白三叶复合系统根系生长及分布的影响

设置苹果(Malus demestica Borkh)和白三叶(Trifolium repens L.)单作与间作栽培处理,通过根箱试验研究种间互作对苹果、白三叶根系生长及其分布的影响。结果表明:种间互作导致苹果根系生长发育的正效应和白三叶根系生长发育的负效应;苹果、白三叶不同径级根系对种间互作的响应能力不同,细根比粗根表现出较强的可塑性;苹果细根占总根中的比例提高,而白三叶细根占总根中的比例则降低;种间互作对苹果、白三叶不同径级根垂直分布格局影响不明显,但对不同径级根在各土层中的分布比例产生了明显影响,苹果粗根和细根均有下移的趋势,细根下移的趋势更明显,而白三叶细根分布有上移的趋势,粗根则无明显变化。总之,种间互作对苹果、白三叶根系生长发育及其垂直分布产生了一定的影响,对不同径级根生长及其垂直分布的影响不同。     

花生栽野种间杂交异源多倍化早期世代基因表达变化分析

为了进一步认识花生种间杂交异源多倍体进化过程中的基因表达变化规律,采用cDNA-HFO-TAG技术,研究花生种间杂交组合(四倍体栽培种‘仲恺花4号’×二倍体野生种Arachis. diogio)杂种F_1和早期多倍体世代S0~S3的基因表达变化情况。14条HFO-TAG引物共扩增出121条cDNA片段,其中差异片段84个,主要包括三种类型:亲本转录物完全沉默(3个),双亲转录物在后代部分材料中沉默(59个)和新转录物激活(22个),上述变化在F1代即开始发生。筛选其中大小为500~2 000 bp的35个TDFs进行克隆测序,有27个和NCBI数据库中已录入的基因具有较高的相似性,包括抗逆相关基因(10条)、未知功能蛋白基因(8条)、能量与代谢相关基因(7条)和转录因子相关的基因(2条)。这些研究结果进一步表明在花生种间杂交异源多倍化早期发生着快速、剧烈的基因表达变化,从中获得的差异基因片段,有助于了解花生属种间杂交异源多倍化早期分子机制变化,这对有效利用野生花生种质优异基因具有重要意义。cDNA-HFO-TAG技术简单、有效且实用,完全适用于花生属基因表达变化研究,可以作为花生属及其它物种基因表达变化分析技术的有效补充。     

Plant characteristics associated with weed competitiveness of rice under upland and lowland conditions in West Africa

Weeds are a major constraint to rice (Oryza spp.) production in West Africa. Superior weed competitive rice genotypes may reduce weed pressure and improve rice productivity. Two upland and two lowland experiments were conducted in southern Benin to examine genotypic variations in weed-suppressive ability and grain yield under weedy conditions, and to identify plant characteristics that could be used as selection criteria for improved weed competitiveness. A total of 19 genotypes, including Oryza sativa and Oryza glaberrima genotypes and interspecific hybrids developed from crossing O. sativa and O. glaberrima, were grown under weed-free and weedy conditions in an upland with supplemental irrigation and in a flooded lowland. In weedy plots, hand weeding was done once or not at all. Mean relative yield loss across all genotypes due to weed competition ranged from almost 0% to 61%. Large genotypic variations in weed biomass and grain yield under weedy conditions were found. Visual growth vigor at 42 and 63 days after sowing (DAS) under weed-free conditions significantly correlated with weed biomass at maturity in both upland and lowland experiments (R² = 0.26–0.48). Where weed pressure was low to moderate, with mean relative yield loss less than 23%, the multiple regression models using grain yield and plant height at maturity or only grain yield measured under weed-free conditions as independent variables could explain 66–88% of the genotypic variation in grain yield under weedy conditions. At higher weed pressure (mean relative yield loss: 61%), as observed in one of the upland experiments, biomass accumulation of rice at 42 days after sowing was associated with higher grain yield under weedy conditions. Biomass accumulation also significantly correlated with visual growth vigor at the same sampling dates. Therefore, we conclude that grain yield, plant height at maturity and visual growth vigor at 42–63 DAS under weed-free conditions appear to be useful selection criteria for developing superior weed competitive rice genotypes.     

草莓属植物染色体观察及种间杂交研究初报

通过对从国内外所收集到的部分野生草莓的染色体数目的观察得知，野生草莓中二倍体类型居多，占１２份，八倍体类型３份。在国内首次发现了五倍体类型结合植物学性状观察确定，６份属于森林草莓；２份属于黄毛草莓；１份属于五叶草莓，２份属于弗州草莓；１份属于智利草莓；２份为种间杂种，还有３份的分类地位尚需进一步研究确定，利用五倍体草病莓杂交，得到了育性较高的六倍体植株。     

Relationships among species of Hystrix Moench and Elymus L. assessed by RAPDs

To assess the generic delimitation and the interspecific relationships between Hystrix and Elymus, three Hystrix and 10 Elymus species were used for random amplified polymorphic DNA(RAPD) assay. Of the 54 primers tested, 26 (48%) produced polymorphic products. A total of 167 products amplified from 16 primers were selected for RAPD analysis, among which 156 (93.4%) amplified products were found to be polymorphic among the 13 species. The polymorphism produced by each primer ranged from 4 to 13, with an average of 9.8. Data were used to generate Jaccard's similarity coefficients and to construct a dendrogram using UPGMA in the NTSYS computer programs. It is concluded from this study that: (1) there were clear differences between Hystrix and Elymus, which possibly suggest that Hystrix is a valid genus; (2) great diversity existed among the species of Hystrix and Elymus; (3) the species similar to each other in morphological characters were grouped together; (4) the species from neighboring geographical regions were clustered; (5) the species with the same genomes and polyploidy level were clustered together; (6) RAPD results are comparable with those obtained from studies on morphology and cytology. It is a useful additional method for assessing the relationships among genera and species in Triticeae.     

应用AFLP标记分析枣品种亲缘关系

从分子水平研究宁夏红枣品种系统发育和亲缘关系,为宁夏枣种质资源的保护和利用提供科学依据。利用AFLP标记方法对原产宁夏地区7个枣品种和6个从区外引种的枣品种基因组DNA进行分析。筛选出的5对AFLP引物组合对13个供试材料共扩增出351条DNA带,其中301条为多态带(占85.75%),平均每个引物扩增多态性带70条。13个材料间的遗传相似系数为0.376～0.957。UPGMA聚类表明,13个材料在相似系数0.85处被划分为5个类。宁夏地域相对狭小,品种交流频繁,从而造成该产区枣品种间亲缘关系较近,演化关系复杂。枣虽然品种资源丰富、分布范围广泛,但遗传多样性相对较小。     

禾豆间作氮素高效利用机理及农艺调控途径研究进展

为保障粮食安全,农业生产中化肥使用极为普遍,但过量使用,往往引起地下水污染、温室效应加剧、生物多样性降低等多种环境和生态问题。禾豆间作系统由于不同作物生物学特性和氮素利用存在差异,进行合理调控可充分发挥生物固氮优点,从而减少化肥投入,提高生产效益,是一种稳产、高产、高效可持续的种植体系。该系统中"氮转移"、"氮阻遏"消减和氮素时空分异是目前研究的热点,也是促进豆科作物固氮、减少化肥投入的有效途径,可实现禾、豆两种作物对氮素的高效利用。特别是该系统中作物品种、施氮制度、空间布局以及种植密度等农艺措施是对种间关系进行调控的必要手段,合理优化可有效促进禾/豆间作竞争与互补协同作用,增强氮素协调利用,从而挖掘两种作物对氮素高效利用的生物学潜力。为此,本文基于前人研究成果和农业可持续发展观点,重点综述了国内外有关禾豆间作氮素高效利用主要机理及相关农艺调控途径的研究现状,旨在为构建简易、高产、高效、氮肥节约型禾豆间作模式提供有力的科学依据和理论支撑。     

接种菌根真菌与施磷对豆禾混播体系生物量及竞争力的影响

丛枝菌根真菌(Arbuscular mycorrhizal fungi, AMF)是陆地生态系统中一类重要的土壤微生物,能与约80%的陆地植物形成互利共生关系。本研究通过构建紫花苜蓿(Medicago sativa)单播、无芒雀麦(Bromus inermis)单播、紫花苜蓿与无芒雀麦(1∶1)混播组合,设置接种AMF和磷添加处理,探讨土壤有效磷水平与AMF互作对紫花苜蓿和无芒雀麦混播体系地上生物量及竞争力的影响。结果表明：与不接种AMF处理相比,接种AMF处理下紫花苜蓿单播体系地上生物量提高17.59%,无芒雀麦单播和混播地上生物量分别降低10.23%和10.26%。施磷处理下,接种AMF对单播和混播地上生物量无显著影响。混播体系中无芒雀麦的地上竞争率大于紫花苜蓿,接种AMF对紫花苜蓿地上竞争率无显著影响,使无芒雀麦地上竞争率降低56.41%。接种AMF使混播体系中紫花苜蓿地上磷吸收量提高66.12%,对无芒雀麦地上磷吸收量无显著影响,缓解了无芒雀麦对紫花苜蓿的竞争排除作用。综上所述,紫花苜蓿与无芒雀麦构建的(1∶1)混播体系中AMF能有效抑制禾草无芒雀麦的地上竞争力,利于豆禾混播体...