氮肥对2个杨树品种碳氮代谢的影响

研究以‘丹红’杨(美洲黑杨)和‘通辽1号’杨(小叶杨)为材料,在田间进行施氮肥和不施氮肥处理,分析2个杨树品种的生长性状、碳氮相关代谢物和发育木质部转录组的变化特征,探讨不同杨树品种氮肥利用的生理机制,为杨树的氮高效利用遗传育种奠定基础。结果表明:(1)‘丹红’杨和‘通辽1号’杨的总生物量在施氮处理后分别比不施氮处理提高了1.69倍和1.10倍;‘丹红’杨的总生物量在施氮肥和不施氮肥条件下分别是‘通辽1号’杨的13倍和10倍。(2)施氮处理显著抑制‘丹红’杨和‘通辽1号’杨树皮和木质部中总氮和多种水解氨基酸的含量,但是没有明显影响木质部的总碳、纤维素、半纤维素和木质素含量。(3)施氮处理显著影响了2个杨树品种发育木质部碳固定、糖代谢、氨基酸合成等碳氮代谢途径的基因的高表达,从而促进了植株生物量的积累。研究发现,施氮处理可以显著促进杨树发育木质部碳氮代谢途径相关基因的高表达,从而促进了杨树生物量的积累和生长;‘丹红’杨的木材产量在不同的氮素环境下都远远高于‘通辽1号’杨,更加适合人工林的大面积推广和种植。     

晋北典型针叶人工林叶功能性状特征及其与土壤因子的关系

为了解释植物叶片的资源分配特征及其与土壤因子间的适应策略,该研究以黄土高原东北缘山西省大同市新荣区油松、樟子松人工纯林及其柠条混交林为对象,采用样方法采集样木树冠中部生长良好的轮生枝中东西南北4个方向的枝条,并在每个枝条上选择里、中、外3处有代表性的当年生叶和多年生叶;采用 “S”形采样法在每个样方内选取9个取样点,用土钻采集各样点0～20 cm土壤样品;测定分析不同造林模式下油松、樟子松异龄叶功能性状特征、土壤理化性质以及二者的关系,为人工林培育及经营提供理论支撑。结果表明：(1)不同造林模式下油松及樟子松叶功能性状的差异集中在化学计量之间;随着叶龄增长,油松、樟子松均表现出干物质含量上升,氮磷含量下降的特征。(2)土壤全磷、全氮含量分别是油松当年及多年生叶的主要解释因子,土壤全磷与当年生叶碳氮比、有机碳、碳磷比均呈显著正相关关系,与全氮、叶面积及叶干物质含量呈显著负相关关系,土壤全氮与多年生叶全磷含量呈正相关关系,与叶有机碳、碳磷比、碳氮比则呈显著负相关关系。(3)樟子松当年生叶功能性状的关键土壤因子是土壤容重、全磷含量,其与叶碳氮磷的比值、干物质含量、碳含量呈正相关关系,而与氮磷含量呈负相关关系;多年生叶功能性状的关键土壤因子是土壤容重、含水量、pH,其与叶氮磷含量呈正相关关系,与碳含量、干物质含量、比叶面积等呈负相关关系。(4)油松及樟子松纯林的叶功能性状更易向关键土壤因子含量更高的方向偏移,说明与柠条混交可有效分异叶片生长对主要土壤因子的集中需求,但混交造林模式下林木长势有所衰弱;结合研究区资源匮乏现状,林木种植密度较大,竞争加剧了生存压力导致林木生长受限。     

转基因玉米HGK60在不同遗传背景下抗虫性鉴定及农艺性状分析

为研究转基因玉米HGK60在不同遗传背景下遗传稳定性和抗虫效果,利用转Bt cry1Ah基因的转基因玉米HGK60为供体,通过回交转育的方式将cry1Ah基因分别导入玉米自交系郑58、昌7-2、lx05-4、lx03-2,获得转基因玉米自交系HGK60-郑58、HGK60-昌7-2、HGK60-lx03-2、HGK60-lx05-4,并杂交获得HGK60-郑单958（HGK60-郑58 × HGK60-昌7-2）和HGK60-鲁单9066（HGK60-lx05-4 × HGK60-lx03-2）,转化体特异性PCR证明cry1Ah基因已转入不同遗传背景玉米中,ELISA检测不同遗传背景转基因玉米叶片中Cry1Ah蛋白表达情况,结果表明在不同遗传背景玉米自交系和杂交种中Cry1Ah蛋白表达没有显著差异;田间人工接虫和室内玉米螟抗虫性鉴定结果表明,不同遗传背景的转基因玉米高抗玉米螟,室内接虫后4 d幼虫死亡率达到100%;对不同遗传背景转基因玉米HGK60进行农艺性状分析,结果显示与受体对照玉米相比,两者之间农艺性状没有显著差异,转基因玉米HGK60可用于抗虫玉米品种的选育。     

寄主植物对桑寄生植物叶片功能性状的影响

为了解寄生植物叶片功能性状的差异及其影响因素,研究了西双版纳地区寄主植物对3种桑寄生植物叶片功能性状的影响,并分析了桑寄生植物与寄主植物叶片功能性状的相关性。结果表明,不同寄主植物的相同寄生植物叶片功能性状存在显著差异,来自7种寄主植物的五蕊寄生(Dendrophthoe pentandra)的叶片含水量(61.2%～70.1%)、氮含量(9.6～16.0 g/kg)、碳氮比(30.8～48.5)以及缩合单宁含量(3.3%～11.0%)等性状的差异较大;从4种寄主植物上获取的澜沧江寄生(Scurrula chingii var.yunnanensis)的叶片含水量(60.0%～71.7%)、碳含量(431.3～502.3 g/kg)和缩合单宁含量(3.8%～9.9%)等性状也呈现较大种间差异,而在2种寄主植物上的离瓣寄生(Helixanthera parasitica)的叶片功能性状没有显著差异。桑寄生植物与寄主植物的叶片含水量、总碳含量、总氮含量、碳氮比和缩合单宁含量呈显著的正相关。寄主植物作为桑寄生植物营养物质的主要来源,会影响桑寄生植物叶片的相应功能性状。桑寄生植物能从寄主植物获...     

4种槭树叶功能性状及其关系对季节变化的响应

以牡丹江地区的白牛槭（Acer mandshuricum）、茶条槭（Acer tataricum subsp. ginnala.）、糖槭（Acer saccharum）、五角槭（Acer pictum subsp. mono）4种槭树为研究对象,分别于春季、夏季和秋季进行取样,测定叶片性状指标（叶厚度、气孔长度、气孔宽度、气孔密度、叶脉密度、比叶面积及色素质量分数）,分析叶片各性状的季节变化趋势,并探讨色素与叶性状间在不同季节下的关系。结果如下：（1）4种槭树均表现为在夏季具有较高的叶厚度、较低的比叶面积和气孔密度,在秋季具较高的比叶面积和叶脉密度、较低的叶厚度。（2）4种槭树均为在夏季有较高的叶绿素a、b,在秋季色素质量分数均降低,季节变化区间分别为叶绿素a 77.40%~98.80%,叶绿素b 85.60%~99.53%,类胡萝卜素4.29%~78.52%。（3）色素与叶性状关系密切,季节动态下色素与比叶面积、气孔密度、叶脉密度正相关,与叶厚度、气孔长度、气孔宽度负相关（P<0.05）,但不同季节相关性略有差异。4种彩叶植物的叶片在应对不同季节的气候条件时形成了不同的构建策略,其叶片功能性状的变异体现了彩叶植物适应季节变化的权衡机制。     

珍稀濒危植物峨眉含笑种实表型性状的空间变异特征

通过分析珍稀濒危植物峨眉含笑（Michelia wilsonii）种子与果实的表型性状特征,研究其变异规律和空间自相关性,为峨眉含笑天然种群的保护利用工作提供依据。以雅安周公山的峨眉含笑为研究对象,测定12项种实表型性状指标,采用变异系数和半方差函数,探究峨眉含笑种实的空间变异特征。结果显示：（1）峨眉含笑种实表型性状的平均变异系数为27.59%,种实的形态变异程度最小,种子性状的变异程度比果实性状更为丰富。（2）聚合果下部的种子败育率与蓇葖败育率最高,分别为18.32%和38.22%;中部的败育率最低,分别为15.05%和23.45%。（3）半方差函数模型以指数和球状模型为主,呈聚集分布。除果实长、种子纵径和种子败育率外,其余9项指标具有中高等强度的空间自相关性。（4）9项指标的各向异性比接近于1,空间异质性表现为各向同性。因此,峨眉含笑种实表型性状在中等尺度的空间范围内具有丰富的变异性。     

THE MEASUREMENT OF SELECTION ON QUANTITATIVE TRAITS: BIASES DUE TO ENVIRONMENTAL COVARIANCES BETWEEN TRAITS AND FITNESS

The use of regression techniques for estimating the direction and magnitude of selection from measurements on phenotypes has become widespread in field studies. A potential problem with these techniques is that environmental correlations between fitness and the traits examined may produce biased estimates of selection gradients. This report demonstrates that the phenotypic covariance between fitness and a trait, used as an estimate of the selection differential in estimating selection gradients, has two components: a component induced by selection itself and a component due to the effect of environmental factors on fitness. The second component is shown to be responsible for biases in estimates of selection gradients. The use of regressions involving genotypic and breeding values instead of phenotypic values can yield estimates of selection gradients that are not biased by environmental covariances. Statistical methods for estimating the coefficients of such regressions, and for testing for biases in regressions involving phenotypic values, are described.     

MITOCHONDRIAL GENOTYPES HAVE NO DETECTABLE EFFECTS ON MERISTIC TRAITS IN CUTTHROAT TROUT HYBRID SWARMS

Efforts to detect effects of cytoplasmic genes are confounded by the problem of partitioning nuclear and cytoplasmic effects. In this study we test for effects of mtDNA haplotype on development in hybrid populations of cutthroat trout (Oncorhynchus clarki) with randomly associated nuclear and mtDNA genotypes. We have previously described several intraspecific hybrid swarms formed by interbreeding of westslope cutthroat trout (O. c. lewisi) and Yellowstone cutthroat trout (O. c. bouvieri). Genetic distance between these subspecies is high (Nei's D = 0.30; mtDNA P = 0.02), and diagnostic alleles at multiple nuclear loci and two distinct mtDNA haplotypes are present in the hybrids. Historical associations between alleles at nuclear loci and between cytotypes and nuclear alleles have largely decayed. We test for differences in meristic characters between fish with alternate mtDNA haplotypes. Counts and fluctuating bilateral asymmetry for these characters have been previously shown to be sensitive indicators of genetic differences that affect development. No differences were found between mtDNA types in meristic counts or fluctuating asymmetry. Therefore, the alternate mtDNA haplotypes had no detectable effect on development as measured by meristic counts in these hybrid populations. However, diagnostic alleles at one nuclear allozyme locus (CK-CI) were associated with several fin ray counts.     

ON THE LOW HERITABILITY OF LIFE-HISTORY TRAITS

Life-history traits such as longevity and fecundity often show low heritability. This is usually interpreted in terms of Fisher's fundamental theorem to mean that populations are near evolutionary equilibrium and genetic variance in total fitness is low. We develop the causal relationship between metric traits and life-history traits to show that a life-history trait is expected to have a low heritability whether or not the population is at equilibrium. This is because it is subject to all the environmental variation in the metric traits that affect it plus additional environmental variation. There is no simple prediction regarding levels of additive genetic variance in life-history traits, which may be high at equilibrium. Several other patterns in the inheritance of life-history traits are readily predicted from the causal model. These include the strength of genetic correlations between life-history traits, levels of nonadditive genetic variance, and the inevitability of genotype-environment interaction.     

Physiological and Molecular Basis of Susceptibility and Tolerance of Rice Plants to Complete Submergence

Rice plants are much damaged by several days of total submergence.The effect can be a serious problem for rice farmers in therainfed lowlands of Asia, and runs contrary to a widespreadbelief amongst plant biologists that rice is highly tolerantof submergence. This article assesses the characteristics ofthe underwater environment that may damage rice plants, examinesvarious physiological mechanisms of injury, and reviews recentprogress achieved using linkage mapping to locate quantitativetraits loci (QTL) for tolerance inherited from a submergence-tolerantcultivar FR13A. Progress towards identifying the gene(s) involvedthrough physical mapping of a dominant tolerance locus on chromosome9 is also summarized. Available physiological evidence pointsaway from responses to oxygen shortage as being inextricablyinvolved in submergence injury. An imbalance between productionand consumption of assimilates is seen as being especially harmful,and is exacerbated by strongly accelerated leaf extension andleaf senescence that are ethylene-mediated and largely absentfrom FR13A and related cultivars. DNA markers for a major QTLfor tolerance are shown to be potentially useful in breedingprogrammes designed to improve submergence tolerance.