大豆种间杂种早代回交和高代选择性回交性状改良效果的研究

分别运用早代(F_1)连续回交和高代(F_3)选择性回交两种交配方式,探讨了改良大豆种间杂种野生性状及最大限度遴选优良基因型的有效途径。结果表明,高代有选择地回交可以有效地保持野生大豆的高蛋白特性;同时,对提高百粒重和扩大黄色种皮类型入选率也有明显效果。早代随机回交使高蛋白、高亚油酸和丰产基因型频率大幅度下降。从育成超高蛋白(>45％)品种考虑(长期计划),野生种质渗入率不应低于0.25;而从育成普通高蛋白(<45％)品种考虑(短期计划),渗入率可以降到0.125以下。在大豆种间杂种后代,种皮色遗传较复杂,出现IIrrttW_1W_1gg基因型的机率非常低。不同种皮色的BC_0F_2单株分离产生含黄色种皮类型的能力为:黄褐(单株)>黄黑>褐绿>黑绿>黑>褐。野生大豆炸荚性的遗传比较简单,但不符合3:1分离模式,通过二次回交炸荚卒降至25％以下。本研究选择指数结果指出,在早代回交和高代回交后代,用对蛋白质含量有较强相关选择进度的生育期、茎粗和主茎节数,间接选择高蛋白基因型,将产生良好的效果。     

Root response to aerobic conditions in rice,estimated by Comair root length scanner and scanner-based image analysis

Precise evaluation of root system architecture is important for understanding how rice plants are adapted to non-puddled and non-flooded conditions in aerobic culture. The objective of this study was to compare estimates of root length by the Comair root length scanner and a flat bed scanner and image analysis software in rice grown in aerobic, near-saturated and flooded fields. Fine roots (diameter < 0.2 mm) accounted for >80% of root length in all hydrological conditions. The Comair root length scanner detected fewer fine roots than the software; root length estimated by the Comair scanner was between that of roots wider than 0.1 mm and roots wider than 0.2 mm estimated by image analysis software. Importantly, total root length under aerobic and near-saturated conditions was 10–30% of that under flooding by image analysis software, but not by the Comair scanner. Digital image analysis detected genotypic differences in fine root development in the subsurface layer in aerobic culture that the Comair root length scanner would have missed. Although root length measurement by image analysis software is still under development, this new tool will facilitate the phenotyping of root system architecture and shed light on the roles of fine roots in water-saving rice cultivation.     

The potential for gene flow from exotic eucalypt plantations into Australia's rare native eucalypts

Hybridisation through pollen dispersal from exotic plants is increasingly recognised as a threat to the genetic integrity of native plant populations. Its genetic impact can be greater in rare taxa, due to their vulnerability to pollen swamping by more abundant congeners. We assessed the likelihood of pollen dispersal from exotic eucalypt plantations into all of Australia's rare native eucalypts, and conducted a case study of Eucalyptus perriniana, which is rare in Tasmania. The Australia-wide study involved spatial analyses of the locations for each rare species superimposed on distributions of eucalypt plantations, which were combined with known taxonomically based reproductive barriers. Of the 74 nationally listed rare eucalypt taxa, 22 had locations within 10 km of plantations of the same genus, and eight were within 1 km. These eight proximal taxa are considered priorities for monitoring. In the most extreme case, 30% of point locations originating from herbarium records and field surveys for Eucalyptus conglomerata were within 1 km of exotic plantations. In the case study, E. perriniana revealed considerable reproductive compatibility with adjacent recently established Eucalyptus nitens plantations. However, F₁ hybridisation between these species was limited, with 0.2% of the 18,625 seedlings grown from 100 single-tree open-pollinated seedlots being hybrids. For now, the probability of exotic gene flow into E. perriniana appears to be low, however this probability is likely to increase as more E. nitens flowers in the surrounding landscape. These studies suggest that understanding the breeding system and biology of these populations may reveal surprising resistance to such exotic hybridisation as well as identifying high risk situations to focus conservation management.     

以早籼14、紫恢100和M3122为背景的导入系构建及其筛选鉴定

以国际合作网络征集的150余份材料,进行农艺性状观察,白叶枯病和稻瘟病的抗性鉴定,同时还进行了耐低磷、低氮筛选,获得大量数据,筛选了一批抗白叶枯病、稻瘟病、耐低磷、耐低氮资源,为分子育种的亲本利用和后代筛选提供参考。以早籼14、紫恢100、M3122为受体,以上述的150余份材料为供体,采用大规模杂交、2～3次回交、2～3次自交,培育以早籼14、紫恢100、M3122为背景的近等基因导入系5700多份,并对这些导入系进行抗旱、耐低氮、耐低磷、抗寒性及直链淀粉含量等初步筛选,获得了一批有目标性状的近等基因导入系,为新基因发掘、新品种选育提供重要的材料基础。并选育了3个有苗头的新品系进入省级预试、区试或生产试验,以进一步确定其利用价值。     

野生花生遗传物质渗入到栽培种的分子证据

花生属野生种具有高抗严重影响花生产量的主要病虫害的优良基因,花生区组二倍体野生种A.correntina对锈病、斑驳病毒病、PStV、蓟马、蚜虫、叶蝉、螨虫、玉米螟等多种病虫害也具有抗性.19份由珍珠豆型农家品种贺粤1号与A.correntina经可育性杂交获得三倍体F1代,F1代再经过人工染色体加倍、回交和多代自交选择,形成的能稳定遗传且性状优良的四倍体新品系,4份栽培品种和野生亲本A.correntina共24份材料用于SSR分析,40对SSR引物中有3对引物PM36、PM50、PM305,能在部分杂种后代（PM36：T60;PM50：J17、J20、J22;PM350：J7、S11、T62）中稳定地扩增出野生亲本的特异谱带,表明这些材料整合了野生亲本的遗传物质.SSR特异谱带可以作为这几份材料中野生亲本A.correntina的特异遗传标记.此外,有两对引物PM36、PM106能在一些杂种后代中扩增出父母本没有的DNA条带,使SSR分子标记表现出非共显性.     

大豆荚粒相关性状的QTL分析

利用Harosoy和Clark导入到红丰11为背景的初级回交导入系定位了大豆荚粒相关性状的QTL。在两套导入系群体中,对13个荚粒性状共检测到37个相关的QTL位点,分布在18个连锁群上。根据不同群体QTL检测情况,可将其分为3类：第1类为在两套群体同时检测到的QTL,共有23个,分布在13个连锁群上;第2类为只在Clark为供体亲本的群体中检测到的QTL,共有7个,分布在4个连锁群上;第3类为只在Harosoy为供体亲本的群体中被检测到的QTL,共有7个,分布在7个连锁群上。两套群体均检测到的23个QTL,并且有7个QTL与前人研究结果较一致,这些QTL位点为稳定主效的QTL,对荚粒性状贡献较大。本研究所构建的两套大豆回交导入系群体都是以红丰11作为轮回亲本,由于遗传背景较为一致,减小了其对QTL定位的干扰,排除了由于基因累赘所造成的偏差。因此QTL一致性较高,为标记辅助选择培育高产品种奠定了基础。     

基于昌7-2导入系发掘干旱胁迫下玉米产量相关QTL位点

以昌7-2为轮回亲本,自交系郑独青为供体亲本,采用回交和定向选择的方法构建高代导入系群体。通过玉米56K芯片对极端株系进行基因分型,以IciMapping逐步回归分析法进行穗重、穗粒重以及百粒重等QTL定位。结果表明,共获得分布于玉米第1、3、5、9、10共5条染色体上的10个QTL位点。其中,与穗重、穗粒重相关的各4个,与百粒重相关的2个。第1、5、10染色体上存在同时控制穗重和穗粒重的相同位点,加性效应均来源于郑独青,贡献率均在22%以上。此外,第10染色体相同位点还同时控制1个微效加性的百粒重QTL。在QTL定位的基础上,获得了多位点聚合的导入系,同时携带第1、5、10染色体上3个QTL位点的导入系,其产量性状表现优于轮回亲本昌7-2。     

Influence of Congeneric Aquaculture on Hard Clam (Mercenaria spp.) Population Genetic Structure

Throughout their range, hard clams of the genus Mercenaria support important commercial fisheries, and hard clam aquaculture is rapidly developing in several regions, including Florida, USA. Commercial hard clam aquaculture in Florida waters originated in the Indian River Lagoon during the late 1970s, but by the early 1990s the focus of the industry had shifted to Cedar Key on the west coast of the state. There, the species Mercenaria campechiensis predominates the natural hard clam population, whereas Mercenaria mercenaria is predominant in the local aquaculture industry. The two species hybridize extensively. The present study was conducted to estimate the genetic implications of M. mercenaria aquaculture on the natural population of M. campechiensis that occupies Cedar Key waters. We sampled a variety of marine and estuarine habitats surrounding Cedar Key and collected 257 hard clams for analysis of species-specific diagnostic allozyme loci, age, and the presence and stage of gonadal neoplasia. Results indicate that the composition of the hard clam population has changed since the advent of aquaculture (i.e., post-aquaculture). Members of the species M. mercenaria were practically nonexistent prior to the 1993 initiation of aquaculture in the area but increased significantly in abundance post-aquaculture, as did hybrid hard clams. There was no significant difference in the abundance of M. campechiensis pre- versus post-aquaculture. All genotype classes had a high incidence (>80%) of gonadal neoplasia, although it is not clear if this high incidence is a reflection of the introduction of aquaculture into the area or if neoplasia was a common feature of the population prior to 1993. Regardless, this finding is not consistent with previous reports that neoplasia is more common in hybrid hard clams. Overall, the results of this study provide clear evidence that culture of M. mercenaria can influence the genotype composition of naturally occurring congeneric populations in the vicinity of the culture operation. The long-term implications of that influence remain to be seen.     

大麦染色体1H至7H外源基因渗入系的构建及其分析

以96对SSR引物对BC₃F₂群体进行辅助筛选,构建了一组基本覆盖野生大麦ISR42-8染色体,并导入轮回亲本Scarlett的1H~7H全基因组的外源基因渗入系,为大麦QTL精细定位提供了良好的作图群体。这组渗入系一共66个,目标片段平均长度为27.6 cM,最长的系IL-52片段长度为100.5 cM,最短的系IL-50片段长度为1.5 cM。含单个渗入片段的有33个系。聚类分析结果表明,66个渗入系的遗传背景高度相似,遗传相似系数变幅为0.708~1.000,平均值为0.917。检测到一个位于4H染色体87.5 cM到110.0 cM区间的分蘖相关QTL,长度为22.5 cM,其中包含多态标记MGB396。     

利用ISSR标记分析黄山松与马尾松的基因渐渗

采用ISSR分子标记分析了马尾松(Pinus massoniana)和黄山松(Pinus hwangshanensis)的渐渗,遗传距离和聚类分析结果均表明:马尾松和黄山松在垂直分布重叠区内存在基因渐渗现象;在高海拔的地区渐渗群体趋向黄山松,在低海拔地区渐渗群体趋向马尾松。