Genetic divergence in two tropical maize composites after four cycles of reciprocal recurrent selection

Two tropical maize composites were subjected to four cycles of reciprocal recurrent selection to develop divergent inbred lines with good combining ability. This study was conducted to examine the extent of genetic diversity, changes in allele composition and genetic structure, of 100 randomly selected S₁ lines each from the original (C₀) and advanced (C₄) selection cycles of TZL COMP3 and TZL COMP4, genotyped using single nucleotide polymorphism (SNP) markers. Results revealed that the proportion of alleles at both low and high frequencies decreased from C₀ to C₄, whereas those at intermediate frequencies increased at C₄ in the two composites. More unique and other alleles were lost at C₄ in TZL COMP3 relative to those in TZL COMP4. The changes in different measures of genetic diversity were either small or negligible with selection in the two composites. The proportion of markers departing from Hardy–Weinberg equilibrium (HWE) decreased with selection, whereas the total number of pairs of markers in linkage disequilibrium increased with selection in the two composites. Examination of changes in population structures using a model‐based approach as well as cluster and multivariate analyses found a high degree of concordance in stratifying the 400 S₁ lines into four non‐overlapping groups corresponding to the two selection cycles each within the reciprocal composites. The observed molecular‐based divergence between cycles within the same composite and the clear differentiation between the complementary composites highlight the importance of reciprocal recurrent selection for preserving genetic diversity for long‐term selection. This increases the potential of the advanced selection cycles to sustain genetic gain in productivity of hybrids adapted to the savannas in West and Central Africa.     

喀斯特山区2个鲫鱼群体基于转铁蛋白的遗传多样性研究

为了解喀斯特山区2个不同鲫鱼群体在蛋白质水平的遗传多样性及其遗传差异,运用聚丙烯酰胺凝胶电泳方法对喀斯特山区2个群体鲫鱼的血清转铁蛋白电泳表型及多样性进行研究。结果表明:群体克隆多样性指数表现为草海鲫鱼(0.32)﹥红鲫(0.25,对照)﹥普安鲫鱼(0.13);3个鲫鱼群体的13个克隆由9个不同的等位基因产生,等位基因的频率分别为Tf~a0.144 9、Tf~b0.202 9、Tf~c0.036 2、Tf~d0.058 0、Tf~e0.007 2、Tf~f0.239 1、Tf~g0.014 5、Tf~h0.275 4、Tf~i0.029 0;普安鲫鱼与草海鲫鱼和红鲫无共享的基因型;普安鲫鱼与草海鲫鱼之间的遗传相似性指数较高(0.714 3),遗传距离较小(0.285 7)。总体来看,草海鲫鱼的克隆多样性水平较高,其转铁蛋白多样性程度较普安鲫鱼丰富;2个群体之间存在较近的亲缘关系,未达到遗传距离种的分化标准。     

野生大豆育成品种与其亲本间的遗传多样性比较

[目的]鉴定大豆育成品种与其亲本间的遗传多样性差异和遗传多态性信息含量,为大豆育种提供参考。[方法]采用SSR标记技术对大豆育成品种与其亲本间的遗传多样性进行分析。[结果]野生大豆亲本总等位变异数和特有等位变异数分别是栽培大豆亲本的1.31倍和3.63倍;平均多态性信息含量由大到小依次为野生大豆亲本(0.545 0)、育成大豆品种(0.478 7)、栽培大豆亲本(0.415 6)。[结论]野生大豆的遗传背景复杂,遗传多样性丰富,其外部形态和内在遗传基础都与栽培大豆有明显差异。     

Comparison of phenolic profiles and antioxidant activities in skins and pulps of eleven grape cultivars(Vitis vinifera L.)

Eleven grape cultivars were analysed to explore the variety differences of fresh grape phenolic profiles. The results showed that free phenolics were predominant in grape skins and pulps, and showed the higher antioxidant activities than bound. In 11 cultivars, Muscat Kyoho extracts had the highest total phenolic content in skins(10.525 mg GAE g~(–1) FW) and pulps(1.134 mg GAE g~(–1) FW), and exhibited the highest DPPH radical scavening capacity(EC_(50)=11.7 μg mL~(–1)) and oxygen radical absorbance capacity(ORAC) value(190.57 μmol TE g~(–1) FW) of free phenolic in skin. In addition, the most abundant phenolics in grape skins were found to be flavonoids such as kaempferol in Kyoho skin(541.2 μg g~(–1) FW), rutin, catechin and epicatechin in Muscat Kyoho skin(262.3, 86.3 and 70.0 μg g~(–1) FW, respectively). Furthermore, the principal component analysis showed a strong difference of phenolic profiles with the cultivars, existing forms and distributions. Pearson correlation coefficient analysis showed a significant linear correlation between total phenolic content and antioxidant activity(P0.05). Therefore, both skins and pulps were rich sources of bioactive phenolic compounds, and Muscat Kyoho was the ideal source among all samples.     

内蒙古桦木沟林场不同地貌野生花卉资源分布

内蒙古桦木沟林场地形地貌类型广泛,野花资源丰富,尚未得到有效开发。为了解野生花卉资源习性和生物学特征,开发利用野花资源,在路径调查的基础上,采用典型样地调查法,调查分析了其野花资源分布。共调查野花资源177种,隶属于40科129属,菊科、豆科、毛茛科等种类和种群数量较丰富。不同地貌Margalef丰富度指数1.35~8.28,Shannon-Wiener指数变异范围1.42~2.59,Simpson指数为0.59~0.96,湿地草甸、疏林草地物种多样性丰富,沙地多样性最低。湿度、光照等是影响野花多样性分布的重要因素。林场分布着丰富而有较大开发价值的喜光、耐荫、耐涝、喜湿、耐旱等不同生态型野生花卉。部分野生花卉资源濒危,亟需保护。     

基于全基因序列的中国北方3省(区)马铃薯Y病毒遗传多样性分析

本研究以马铃薯Y病毒(PVY)全基因组为基础,分析吉林、黑龙江和内蒙古3省(区)PVY群体遗传多样性和群体分化,并评估突变、重组、选择等遗传力所起的作用。根据已报道的PVY全基因序列保守区设计4对引物,采用片段重叠法对来自内蒙古和吉林的24个PVY分离物全基因序列进行测定,并联合NCBI中已登录的9个黑龙江分离物全基因组序列进行遗传多样性参数评估、群体分化检验和分子变异等分析。结果显示,我国北方3省(区)PVY群体遗传多样性高,其中内蒙古和黑龙江PVY群体遗传多样性高于吉林群体,并且3个群体之间呈现一定程度的遗传分化。分子变异分析发现在PVY基因组中存在1 786个变异位点,表明我国北方3省(区)PVY群体变异程度较高,并且这种高变异度有85.54%来自各个马铃薯种植区内PVY个体的遗传变异。重组分析和系统发育分析发现,我国北方3省(区)PVY群体中重组株系占比高达90.3%,并具有明显的株系多样性,表明PVY重组株系已成为我国北方3省(区)马铃薯种植区的流行株系。选择压力分析显示,使用FEL和IFEL法分别检测出501个和315个净化压力选择位点,这表明3省(区)PVY群体受净化选择压力为主。以上结果表明,中国北方3省(区)PVY群体遗传多样性高,突变、重组和自然选择都对遗传多样性和群体分化存在一定影响。     

磁处理改善豌豆根际土壤生物学性状

采用盆栽的方法,分析磁处理对豌豆根际土壤生物学性状的影响,旨在探究磁处理对豌豆根际土壤肥力及健康状况的影响。试验设置无处理（对照CK）,添加铁粉（A）、磁化铁粉（B）、场强为0.2特斯拉（T）磁铁+铁粉（C）以及0.2 T磁铁（D）的处理,基于高通量测序技术分析磁处理对豌豆根际土壤生物学性状的影响。结果表明：C处理显著增加豌豆根际土壤中可培养细菌和真菌数量,同时微生物生物量C、N、P与CK相比分别增加了34.0%、46.0%、44.2%;β-葡萄糖苷酶、氨肽酶、磷酸酶酶活性分别增加了24.6%、23.7%、31.8%;另一方面,C处理中土壤细菌丰富度和多样性指数Ace、Chao1、Shannon指数显著高于CK;属（Genus）分类水平韦恩图分析中上,CK处理特有的属细菌主要有3个：Sneathiella、Desulfurispora、nannocystaceae;A处理特有的属细菌有7个;B处理特有的属细菌亦有7个;C处理特有的属细菌有11个;D处理特有的属细菌有8个。综上所述,C处理能够显著提高豌豆根际土壤中可培养微生物数量、微生物生物量（C、N、P）、酶活性和细菌多样性等多项指示土壤肥力和健康状况的生物学指标,表明磁场强度为0.2 T的磁铁+5 g磁化铁粉处理具有提高土壤肥力抵御土传病害的能力。     

2006—2014 年民勤4 种典型荒漠群落结构 及物种多样性变化研究

根据2006—2014 年民勤荒漠植物4 个样区36 个样方调查数据，对该区沙蒿、梭梭、麻黄和白刺4种典型荒漠植物群落结构及物种多样性进行分析。结果表明：该区群落结构简单，物种相对单一且数量较少，植物都是以较低的芽位适应生境条件；灌木层物种的变化不大，草本层物种有所增加；多样性指数沙蒿群落、梭梭群落和白刺群落的略有增加，而麻黄群落略有减小；该区群落结构和物种多样性的变化主要由于草本层的物种变化引起。了解和掌握民勤荒漠植物群落的结构和物种多样性变化规律，对于推动干旱荒漠区植被恢复和物种多样性的保护提供依据。     

凤凰单丛茶树资源遗传多样性的ISSR分析

采用ISSR分子标记技术对48份凤凰单丛茶品种(系)进行了遗传多样性分析。选用10个多态性高、分辨力强的ISSR引物分别对供试材料基因组DNA进行扩增,共获得121个位点,其中多态位点带98个,多态位点比率(PPB)为81.0%。品种(系)之间的遗传相似系数变化范围在0.590 9~0.967 4之间。UPGMA聚类分析结果表明,在GS值为0.792的水平上供试材料可划分为7大类,其亲缘关系远近与地理来源关系不大且与香味类型没有必然的联系。     

观赏植物菌根真菌多样性研究进展

菌根真菌具有丰富遗传多样性、形态多样性、物种多样性、生态系统多样性和功能多样性。而观赏植物是重要的依赖菌根真菌的植物类群,对于美化环境、改善生态条件、促进经济发展等方面均具有重要价值,人们给予了众多研究,其中,观赏植物菌根真菌多样性研究表明观赏植物菌根真菌具有丰富的形态、物种和功能多样性。本文系统总结了国内外观赏植物菌根真菌多样性研究所取得的成果、存在的问题,并探讨了今后研究方向,旨在为进一步开展观赏植物菌根研究与应用提供依据。