尾叶桉与窿缘组树种间杂交种的生长特征

选定组配树种对桉树杂交种的特性起决定作用,但不同种间杂交种的生长表现常常不容易预测。为掌握华南地区桉树重要树种间杂交种的生长特征,促进桉树杂交育种的精准化,该文以父本为混合花粉的人工杂交种为遗传材料,以尾叶桉×巨桉为对照,进行了尾叶桉与桉树窿缘组树种(布拉斯桉、细叶桉、钝盖赤桉、昆北赤桉)的4种组配杂交种的生长特征研究。结果表明:在材积生长量上,尾叶桉与窿缘组树种杂交种低于尾叶桉×巨桉,但其内部树种间差异显著(P0.05),其中尾叶桉×昆北赤桉具有显著优势;尾叶桉与窿缘组树种杂交种的树高、胸径均显著小于尾叶桉×巨桉,但其高径比显著大于尾叶桉×巨桉(P0.05);尾叶桉与窿缘组树种杂交种具有高的和一致的保存率,且在不同组配间、家系间(组配内)均无显著差异,5年生值为84.4%～89.6%;尾叶桉与窿缘组树种杂交种的5年生材积的平均变异系数约为64%,组配间、家系间差异大,都大于尾叶桉×巨桉。尾叶桉与窿缘组树种杂交种的速生性、树形等与尾叶桉×巨桉间存在显著差异,尾叶桉与窿缘组树种杂交种的组配、家系间具有显著的生长差异,可为桉树遗传改良提供丰富的多样性。     

7种桉树花粉微观形态及其亲缘关系分析

为了解我国常用桉树树种的亲缘关系,利用扫描电镜观察7种桉属(Eucalyptus)树种的花粉形态。结果表明,粗皮桉(E.pellita)、窿缘桉(E. exserta)的7个花粉性状大多处于前2位,其中粗皮桉花粉的赤道面长、宽和面积最大,分别为17.522、17.090μm和300.830μm~2,而窿缘桉花粉的萌发沟长、宽和大小最大,分别为6.576、0.720μm和4.718μm~2;赤桉(E. camaldulensis)花粉的赤道面最小,韦塔桉(E.wetarensis)花粉的萌发沟最小。聚类分析表明,在信息保留87.5%时,7树种可以分为3组,粗皮桉和窿缘桉聚在一组,韦塔桉和巨桉(E. grandis)聚在一组,其余聚在一组。粗皮桉、窿缘桉的花粉外壁纹饰较光滑,细叶桉(E. tereticornis)和赤桉属常规,尾叶桉(E. urophylla)、韦塔桉和巨桉较粗糙。从花粉形态分析,粗皮桉和窿缘桉的亲缘关系较近,韦塔桉、尾叶桉的亲缘关系较远,细叶桉、赤桉和巨桉的亲缘关系与传统分类结果一致。因此,7种桉树花粉形态反映了一些新的亲缘关系,对桉树的杂交育种有指导意义。     

桉树杂交种对桉树枝瘿姬小蜂的抗性变异分析

植物种间杂交是一种普遍自然现象,杂交往往造成植物表型及生理变异,从而改变杂种抗虫性。与亲本种相比,杂种抗虫性可能增强或减弱,也有可能处于与亲本相似水平。初生、次生代谢物的质变与量变是引起杂种抗虫性变异的重要原因。近年来,桉树杂交育种已在世界范围内广泛应用并取得了显著成效,桉树杂交种间抗虫性表现参差不齐,因此,桉树是研究杂交种抗虫性变异机制的理想材料。以2个桉树杂交种巨细桉DH201-2、巨尾桉G9及桉树重要害虫桉树枝瘿姬小蜂为研究对象,比较了2个杂交种与其纯亲本种[(巨桉×细叶桉),(巨桉×尾叶桉)]间的抗虫性差异;同时,综合比较了品系间叶片性状(叶片厚度、含水率、比叶面积)、初生化合物(C、N、可溶性糖、可溶性蛋白)及次生化合物(总酚、单宁)差异,以研究桉树杂交种抗虫性变异的理化机制。结果表明:DH201-2感染桉树枝瘿姬小蜂的虫瘿数目显著高于其双亲本种,而G9上虫瘿数目显著低于其双亲本种。DH201-2与G9的叶片厚度与巨桉相近,而显著薄于另一亲本种。DH201-2叶片含水率显著高于细叶桉、与巨桉相近;G9叶片含水率则显著低于其双亲本种。相似的是,DH201-2和G9的比叶面积均显著高于其双亲本种。初生化合物方面,DH201-2叶片可溶性糖和可溶性蛋白含量均显著高于其亲本种,N含量则仅高于细叶桉;而G9叶片可溶性蛋白含量虽高于其双亲本种,可溶性糖含量则无显著差异,N含量显著低于其双亲本种。次生化合物方面,DH201-2叶片总酚和单宁含量显著低于其双亲本种,而G9则显著高于其双亲本种。因此,与其亲本种相比,DH201-2感虫性增加,而G9抗虫性增加;与桉树枝瘿姬小蜂发育相关的营养指标(如含水率、可溶性糖、N含量)及次生防御物质(如总酚、缩合单宁)在桉树杂交种组织内的含量差异影响了桉树杂交种对桉树枝瘿姬小蜂的抗性。在全球推行桉树杂交育种且桉树害虫数量逐年增加的大背景下,应加强对桉树杂交种抗虫性机制研究,为选育高抗品系及桉树产业可持续发展提供理论指导。     

水肥胁迫对尾叶桉无性系生长及叶片变异的影响研究

为选择尾叶桉(Eucalyptus urophylla)优良无性系,以20个尾叶桉无性系为材料,采用2因素(水分、养分)3水平完全随机区组设计,对水肥胁迫半年后尾叶桉苗木生长和叶片性状变异进行分析和评估。结果表明,尾叶桉的叶尖角、叶长、叶宽、叶周长和叶面积在不同水肥处理下差异显著,表明水分和养分会影响叶片的大小。苗木生长和叶片性状间大多数呈显著或极显著正相关,少数呈显著负相关或一定的负相关性。13种性状可综合为4个主成分,其累计贡献率达98%,说明这些性状具有极强的代表性。除地径的水分×养分互作不显著外,生长性状在水分、养分及水分×养分互作上达显著和极显著的水平。无性系在树高、地径和冠幅上的方差分量为2.19~149.59,重复力为0.16~0.45。以20%入选率,采用基因型值筛选出4个优良无性系:LDUA10、ZQUA9、ZQUA8和LDUA24,他们的树高、地径和冠幅比对照分别高出5.0%、12.8%和14.5%,为后续骨干亲本选择及优良无性系推广提供依据。     

尾叶桉(Eucalyptus urophylla)第一代育种群体的遗传多样性

本研究利用中性微卫星标记分析了尾叶桉第一代育种群体的遗传多样性水平和遗传结构。Hardy-Weinberg平衡检测表明尾叶桉第一代育种群体各天然种源内存在明显的杂合子缺失现象。标记和种源的遗传多样性参数统计都表明,尾叶桉育种群体各天然种源具有很高的遗传多样性。分子方差分析显示,尾叶桉育种群体的大部分遗传变异来自家系间,种源间的遗传变异分量很低,该结论被种源间很低的遗传分化水平再次佐证。尾叶桉育种群体内的亚群体分类(Structure分析)与各天然种源的地理分布不存在联系,但群体的内亚群体分类和基于Nei遗传距离的聚类比较吻合。本研究结论可为尾叶桉高世代的群体改良和优良杂交种亲本选配提供遗传基础信息。     

广东樟木头5种桉树的能量特征研究

对广东省东莞市樟木头林场5种6 a生巨桉(Eucalyptus grandis)、柳桉(E.saligna)、大花序桉(E.cloeziana)、粗皮桉(E.pellita)和托里桉(E.torelliana)的能量特征进行研究.结果表明:5种桉树不同组分的灰分含量和热值存在显著差异(P<0.01).灰分含量为0.16%-8.37%,其中巨桉、柳桉、粗皮桉和托里桉均是叶>皮>枝>根>干,而大花序桉为皮>叶>枝>根>干;各组分的干重热值为15.12-18.85 kJ g~(-1),均以叶最高、皮最低,巨桉与粗皮桉为叶>枝>干>根>皮;柳桉与托里桉为叶>干>枝>根>皮;大花序桉为叶>枝>根>干>皮;去灰分热值为16.37～19.87 kJ g~(-1),除粗皮桉为叶>枝>皮>干>根外,其它4种各组分的去灰分热值均与干重热值的变化趋势相同.5种桉树的平均干重热值和去灰分热值分别以巨桉、粗皮桉最高,但均以托里桉最低.     

尾叶桉无性系生长、干形和抗枝瘿姬小蜂综合选择

对尾叶桉60个无性系进行了生长量和桉树枝瘿姬小蜂的敏感性调查。结果表明, 生长性状在无性系单株间存在显著的相关性,而尾叶桉受姬小蜂的危害情况与生长性状间无显著相关性。对遗传参数的估算表明, 尾叶桉无性系抗桉树枝瘿姬小蜂水平有较高的重复力,可以通过无性系选择获得抗蜂、速生的尾叶桉无性系。最终通过独立淘汰法选择出6个优良的尾叶桉无性系。     

不同品种桉树叶挥发性成分的GC-MS分析

对不同品种的桉树叶挥发性成分进行了气质联用成分分析。采用水蒸气蒸馏法提取桉树叶片中的挥发性成分,并用气相色谱-质谱联用技术分析鉴定。在被鉴定的成分中,桉叶油素和4-松油烯醇为窿缘桉、尾巨桉、粗皮桉、尾叶桉、大叶桉五种桉树叶片的共有成分;柠檬桉叶的主要挥发成分为(L)-香茅醛和乙酸香茅酯。结果表明,不同品种桉树叶挥发性成分种类及其含量存在差异。     

洞庭青鲫形态性状遗传分析

为查明洞庭青鲫(Carassius auratusTungting)原种亲本种质的纯度,进行亲本、子一代之间形态学性状遗传传递规律的分析,测定了从北民湖引入的洞庭青鲫原种亲本27尾和子一代32尾,对其7项可比性状和可数性状进行统计分析,计算出各性状的均值、标准差、变异系数。对亲子之间各性状的综合差异性进行卡方检测。结果表明:亲子之间各性状的均值比较接近但子代比亲本平均多一片侧线鳞;各性状的变异系数,亲本和子代接近,且子代多数性状的变异系数小于亲本;卡方值为0.0172,说明亲子之间各性状的综合评定无显著差异。洞庭青鲫亲子间各性状统计分析说明,子一代不仅没有性状分离现象,而且基因有进一步纯化的趋势。由此推论:北民湖洞庭青鲫原种种群的纯度较高。     

盐胁迫对不同品种玉米苗期生长与叶片光合特性的影响

为研究盐胁迫对不同玉米品种玉米苗期生理性状的影响, 以玉米杂交种隆平206、秦龙14以及隆平206亲本(母本L239和父本L7221)为试验材料, 设置不同盐浓度处理, 分析玉米苗期生长与叶片光合特性的变化。结果表明, 盐胁迫下玉米植株高和地上部分鲜重显著下降, 随着盐浓度的增加, 其下降幅度增加; 两杂交种品种比较, 盐胁迫对秦龙14的影响较隆平206大; 隆平206两亲本比较, 盐胁迫对父本L7221较母本L239植株高与地上部分鲜重的影响更大。与对照相比, 盐胁迫显著增加玉米叶片色素含量, 且随着盐浓度的增加, 其增幅逐渐增加。盐胁迫显著增加叶片净光合速率, 但单叶光合速率逐渐降低, 两杂交种品种表现一致。可见虽然盐胁迫下单叶光合速率下降, 单位面积叶片的光合作用对玉米有一定的补偿作用。盐胁迫对秦龙14单叶光合速率的影响较隆平206大, 隆平206两亲本比较, 盐胁迫对父本L7221的影响较母本L239更大。     

Moderate-density molecular maps of Eucalyptus urophylla S. T. Blake and E. tereticornis Smith genomes based on RAPD markers

Moderate-density molecular maps were constructed for the genomes of Eucalyptus urophylla S. T. Blake and E. tereticornis Smith using RAPD markers and an interspecific cross between the two species. One hundred and eighty-three primers were employed to generate 245 and 264 parent-specific markers in E. urophylla and E. tereticornis, respectively, as well as 49 parent-shared markers. The normally segregating markers, including 208 (84.9%) specific to maternal E. urophylla, 175 (66.3%) to paternal E. tereticornis, and 48 shared by both parents, were used for framework map construction for each parental species. For maternal E. urophylla, the linkage map consisted of 23 linkage groups, 160 framework markers, and 60 accessory markers, defining a total map distance of 1504.6 cM and an average interval of 11.0 ± 8.07 cM. For paternal E. tereticornis, the linkage map contained 23 linkage groups, 126 framework markers, and 92 accessory markers, defining a total map distance of 1035.7 cM and an average interval of 10.1 ± 7.23 cM. Genome length was estimated at 1585.7 and 1507.5 cM for E. urophylla and E. tereticornis, respectively, indicating map coverage of 94.9 and 68.7% of the corresponding genomes. Construction of such maps will be valuable for quantitative trait loci (QTLs) detection, marker-assisted selection (MAS), comparative mapping, and whole genome based fingerprint characterization in Eucalyptus breeding programs.     

Verification of QTL linked markers for propagation traits in <Emphasis Type="Italic">Eucalyptus</Emphasis>

In a previous study, several quantitative trait loci (QTLs) affecting vegetative propagation traits were detected in a hybrid cross between Eucalyptus tereticornis and Eucalyptus globulus. The objective of this work was to confirm stable QTL linked markers (detected in different years) for propagation traits in an independent set of the same segregating population and in two related crosses involving the original E. globulus parent. Phenotypic averages of groups of individuals carrying alternative allelic forms of the stable QTL linked markers were statistically tested for significant differences. Adventitious rooting and petrification marker–trait associations, detected previously in the E. tereticornis parent, were verified in an independent sample of the original progeny. In the E. globulus parent, the QTL linked marker was only verified in one related genetic background. Verification was possible only for high-effect QTL linked markers. This study highlights the importance of sample size in QTL detection for low-heritability traits.     

不同松树种间杂交类型的可育性分析

探究不同松树种间杂交可育性,为松树种间杂交育种亲本选配提供依据,进而为松树的杂种优势研究积累材料。该研究利用随机区组设计,通过92个松树种间杂交组合与20个半同胞对照,分析9种松树种间杂交类型子代的平均球果产种数、平均球果产种量、百粒重、发芽率与成苗率5项育性指标,综合球果期、种期与苗期3个阶段的表现,利用模糊数学隶属函数法对不同松树种间杂交类型进行可育性综合评价。结果表明:加勒比松×湿地松(C×E)、湿地松×加勒比松(E×C)与湿地松×火炬松(E×T) 3种杂交类型育性表现优于或接近相应的半同胞对照,马尾松×湿地松(M×E)、马尾松×火炬松(M×T)、马尾松×加勒比松(M×C)、火炬松×加勒比松(T×C)、火炬松×马尾松(T×M)与火炬松×湿地松(T×E)杂交类型育性表现远低于半同胞对照,表现出低育性甚至不育。综合5项育性指标,亚组内杂交育性的整体表现明显优于亚组间杂交;湿地松与加勒比松为母本的3种杂交组合育性表现总体水平明显优于马尾松与火炬松为母本的另外6种杂交组合。9种杂交类型中除了火炬松×湿地松(T×E)外,均获得了具有生活力的杂交子代,尤其马尾松与3种国外松的杂交子代在相关研究中是首次获得,对松树种间杂交育种的研究具有重要意义。     

雷州半岛尾叶桉和湿加松人工林的蒸腾耗水规律

为正确认识大径材桉树及湿加松耗水规律,为地区人工林树种选择、栽培及抚育提供指导,应用TDP热扩散探针技术,对10年生尾叶桉和湿加松树干液流进行连续监测,并同步测定各气象因子,分析了雷州半岛地区尾叶桉和湿加松蒸腾耗水的日变化特征和季节变化规律,并与气象因子建立了相关模型。结果表明:尾叶桉和湿加松边材液流均表现出典型的昼高夜低的单峰型日变化特征,各月平均液流速率不同,且旱雨季差异显著;其中峰值尾叶桉雨季(0.127 cm/min)和旱季(0.096 cm/min)分别是湿加松雨季和旱季的1.30倍和1.57倍;日平均液流速率尾叶桉雨季(0.045 cm/min)和旱季(0.033 cm/min)分别是湿加松雨季和旱季的1.27倍和1.54倍;启动时间和迅速下降时间雨季两树种间差异不大,但旱季尾叶桉要提前湿加松约1—1.5 h启动,并晚0.5—1 h迅速下降。影响两树种边材液流速率的主要气象因子相同。尾叶桉人工林年平均单株日耗水量为12.79 L/d,是湿加松的1.33倍,林分蒸腾耗水量尾叶桉(582.16 mm)和湿加松(483.24 mm),分别占同期年降雨量的34.2%和28.4%,且两树种旱雨季蒸腾耗水量均雨季显著大于旱季。     

Oviposition preference but not adult feeding preference matches with offspring performance in the bronze bug Thaumastocoris peregrinus

Optimal foraging and optimal oviposition are two major forces leading to plant selection by insect females, but the contribution of these forces to the host‐selection process has been little studied for sucking herbivores. We studied feeding and oviposition behavior of a global pest, the bronze bug, Thaumastocoris peregrinus Carpintero & Dellapé (Heteroptera: Thaumastocoridae), using dual‐choice bioassays to evaluate the preference of females between host species, developmental leaf stage, or prior plant exposure to conspecifics. We assessed the link between these preferences and the performance of the offspring, by comparing survival and developmental time of nymphs reared on the various treatments. Finally, we compared the composition of the leaf wax of healthy and damaged leaves, and tested the effects of leaf wax on female preference behavior. Using healthy adult leaves of Eucalyptus tereticornis Sm. (Myrtaceae) as a reference, we found that females prefer to feed on Eucalyptus grandis W. Hill ex Maiden and E. tereticornis adult leaves that had been previously damaged by female conspecifics, whereas they reject juvenile leaves of E. tereticornis as food. Females also prefer to oviposit on leaves previously damaged by conspecifics but they rejected E. grandis as oviposition substrate. Nymphal performance varied among leaf treatments, suggesting a correlation with oviposition preference (but not feeding preference). Epicuticular wax extracts from damaged leaves contained higher concentrations of long‐chain, saturated linear alkanes, aldehydes, and alcohols than extracts from undamaged leaves. However, a choice assay failed to demonstrate an oviposition preference based on leaf surface wax chemistry. We discuss these findings in the context of the preference‐performance relationship.     

5种相思树和尾巨桉人工林土壤养分和酶活性特征

为揭示固氮树种土壤养分转化的酶学机制,对固氮树种[厚荚相思(Acacia crassicarpa)、黑木相思(A. melanoxylon)、卷荚相思(A.cincinnata)、大叶相思(A.auriculiformis)和马占相思(A.mangium)]及非固氮树种尾巨桉(Eucalyptusurophylla×E.grandis)人工林的土壤养分含量、酶活性及其相关性进行研究。结果表明,相思林40～60cm土层的pH均高于尾巨桉林;5种相思林土壤各土层的TP、TK含量均低于尾巨桉林,而20～40 cm土层的TC、TN含量均高于尾巨桉林,黑木相思林和马占相思林各土层的有效养分均显著高于尾巨桉林(P0.05)。0～10 cm土层中,相思林的土壤酸性磷酸酶和纤维素酶活性均高于尾巨桉林,大叶相思林的土壤脲酶、蔗糖酶、纤维素酶和芳基硫酸酯酶活性显著高于尾巨桉林(P0.05),卷荚相思林的土壤脲酶、纤维素酶、几丁质酶和淀粉酶活性显著高于尾巨桉林(P0.05)。相关分析结果表明,土壤脲酶、蔗糖酶和几丁质酶活性与AP显著负相关(P0.05),蔗糖酶和纤维素酶活性与NH4+-N显著负相关(P 0.05),脲酶、纤维素酶、芳基硫酸酯酶与土壤TK显著负相关(P0.05),几丁质酶活性与TN含量呈显著正相关(P0.05),土壤淀粉酶活性与NH4+-N呈显著正相关(P 0.05),过氧化氢酶活性与土壤TK含量呈显著正相关。可见,与尾巨桉人工林相比,在我国南方退化山地引种相思树可提高土壤关键酶的活性,对土壤有效养分具有明显改良作用,有利于退化地土壤的生态修复及人工林长期生产力的维持。     

Chromosome elimination and fragment introgression and recombination producing intertribal partial hybrids from <Emphasis Type="Italic">Brassica napus</Emphasis> × <Emphasis Type="Italic">Lesquerella fendleri</Emphasis> crosses

The intertribal sexual hybrids between three Brassica napus (2n = 38) cultivars and Lesquerella fendleri (2n = 12) with the latter as pollen parent were obtained and characterized for their phenotypes and chromosomal and genomic constitutions. F₁ plants and their progenies mainly resembled female B. napus parents, while certain characters of L. fendleri were expressed in some plants, such as longer flowering period, basal clustering stems and particularly the glutinous layer on seed coats related to drought tolerance. Twenty-seven F₁ plants were cytologically classified into five types: type I (16 plants) had 2n = 38, type II (2) had 2n = 38–42, type III (3) had 2n = 31–38, type IV (5) had 2n = 25–31, and type V (1) had 2n = 19–22. Some hybrids and their progenies were mixoploids in nature with only 1–2 chromosomes or some chromosomal fragments of L. fendleri included in their cells. AFLP (Amplified fragments length polymorphism) analysis revealed that bands absent in B. napus, novel for two parents and specific for L. fendleri appeared in all F₁ plants and their progenies. Some progenies had the modified fatty acid profiles with higher levels of linoleic, linolenic, eicosanoic and erucic acids than those of B. napus parents. The occurrence of these partial hybrids with phenotypes, genomic and fatty acid alterations resulted possibly from the chromosome elimination and doubling accompanied by the introgression of alien DNA segments and genomic reorganization. The progenies with some useful traits from L. fendleri should be new and valuable resource for rapeseed breeding.     

Quantitative trait dissection analysis in Eucalyptus using RAPD markers: 1. Detection of QTL in interspecific hybrid progeny, stability of QTL expression across different ages

 The objective of this study was to use random amplified polymorphic DNA (RAPD) to determine the genetic location and effects of genomic regions controlling wood density, stem growth and stem form in two species of Eucalyptus. Two hundred F₁ trees generated from an interspecific cross E. urophylla×E. grandis between two elite trees were used. Genetic maps were constructed for each parent with markers segregating in the 1:1 ratio in FS progeny. A total of 86 and 92 markers distributed among 11 linkage groups covered 1295 cM and 1312 cM for the E. urophylla and E. grandis parent, respectively. Traits were measured three times up to selection age (38 months). The magnitude of the phenotypic variation explained by the joint action of the segregating quantitative trait alleles indicated that genetic factors of large effect were involved in the control of the studied characters. Several regions controlling part of the variation for the studied traits were identified by interval mapping. Some regions of the genome exerted effects on more than one trait, providing a genetic explanation for at least some of the correlation between the traits. On the basis of an age-by-age analysis, a partial stability of QTL expression was observed with 68% of the QTL being expressed at two ages and 32% being age-specific. No QTL were significant for all three ages. Taking advantage of repeated measurements on the same material across different ages, we investigated with a maximum statistical power, the effect of marker genotype on traits, with age and QTL×age interaction effects being removed. A two-way analysis of variance made it possible to detect significant marker-trait associations over the period studied. Most of them had already been detected in the annual analysis. This result is very encouraging for the application of marker information to the early selection of hybrid trees to be vegetatively propagated for the production of clonal varieties. Received: 2 December 1996/Accepted: 4 April 1997