玉米黄绿叶突变体表型鉴定及基因初步定位

叶色突变体是研究光合作用及叶绿体发育的重要材料。开展玉米叶色突变体的相关研究,对光形态建成、光合作用、基因功能注释、蛋白质功能及抗逆性机制的阐述具有重要的理论意义。本研究以黄绿叶突变体ygl-F17138为材料,与玉米自交系B73进行杂交,构建F2分离群体,进行遗传效应分析和基因初步定位。遗传分析表明,该突变性状由单个隐性核基因控制,且能稳定遗传。利用BSR-seq结合连锁分析的方法将该基因初步定位在第3条染色体上一个约9.2 Mb的区间内(chr.3:173087201~182203992),查询该区间内已知基因功能注释,未发现类似前人报道的调控黄绿叶性状基因,说明YGL-F17138基因可能是一个控制玉米黄绿叶发育未被挖掘的候选基因。     

一个玉米矮秆突变体K123d的遗传鉴定

矮秆已被广泛用于改良作物的抗倒伏性状,培育理想株型,从而提高作物产量。玉米矮秆突变体K123d由自交系K123自然突变产生。本研究比较该突变体与野生型主要农艺性状差异及其对赤霉素的敏感性;用K123d与株高不同的3个自交系分别构建F1、BC和F2群体,分析矮秆性状的遗传模式;以K169/K123d-F2为定位群体,采用集团分离分析法(BSA),运用SSR标记定位矮秆基因d123;参照br-2序列信息分段设计特异引物,同源克隆d123。结果表明,与野生型相比K123d株高降低35.59%,穗位高降低、节间缩短、叶片较直立,但结实率差,对赤霉素敏感;在F2群体和BC1群体中,正常植株与矮秆植株分离比例分别符合3∶1和1∶1,说明矮秆性状受1对隐性基因控制;其矮秆基因d123定位于第一条染色体上SSR标记umc1278和bnlg1564之间,遗传距离分别为12.8 c M和7.3 c M;同源克隆显示d123与br-2存在12个碱基替换,其中第4个外显子编码的一个谷氨酸被替换为赖氨酸。由此可见,矮秆突变体K123d为br-2的一个突变类型,对矮化育种具有进一步研究利用价值。     

玉米P25自交系抗锈病基因的遗传分析及SSR分子标记定位

以玉米南方型锈病免疫自交系P2 5和感病自交系F3 4 9及F1、F2 、B1和B2 为材料 ,采用主基因 多基因混合遗传模型研究了P2 5的抗病遗传规律。结果表明 :自交系P2 5的抗病基因为一主基因 ,表现为加性效应 ,没有检测出多基因 ,其在F2 、B1和B2 群体的遗传率分别为 81 88%、38 14 %和 5 5 1%。利用SSR分子标记技术 ,以组合P2 5×F3 4 9的F2 :3 家系作为构图群体 ,构建了玉米SSR遗传连锁图谱 ,并将玉米抗南方型锈病基因定位于 10号染色体上 ,与phi0 5 9标记的遗传距离为 5 8cM。     

一个新的番茄黄绿叶突变体表型鉴定与遗传分析

植物黄绿叶突变体不但在植物的光合作用、叶绿素的合成代谢途径、叶绿体的遗传分化与发育等一系列基础研究中具有重要作用,而且还可以作为标记性状应用到育种研究上。本研究以前期化学诱变得到的一个番茄黄绿叶突变体为材料,对其主要表型与光合作用特征特性进行鉴定分析,发现突变体从第1片真叶开始变黄,植株矮小,叶片叶绿素含量和净光合速率相对野生型极显著降低,叶绿体类囊体片层结构畸形。突变体和野生型进行正反交,分析其遗传方式。发现其F2群体正常叶与黄绿叶的分离比为3∶1,表明黄绿叶是由单个基因突变引起的隐性性状。本研究为后期的基因定位研究奠定了基础。     

一个新矮生玉米种质资源的发现与遗传鉴定

玉米矮生种质资源在育种工作中具有重要的利用价值。2002年在玉米种质资源扩繁与鉴定过程中,从玉米自交系K36中发现一株矮生突变体。随后通过连续自交,获得了纯合一致、稳定的矮生自交系,命名为矮2003。该矮秆材料在北京表现株高62．1cm,植株清秀,茎秆坚硬,结实正常。于不同时期用不同浓度赤霉素处理该材料显示其对赤霉素反应不敏感。矮2003与正常玉米自交系测交F1呈现高秆,F2与BC1高、矮秆分离比例分别符合3：1与1：1,遗传分析表明其矮生性状受一对主效单基因控制,表现为隐性遗传。所携带的矮生基因不同于已报道的玉米Dwarf8等。     

黄瓜白色果皮基因遗传规律及定位研究

以黄瓜嫩果深绿色果皮自交系1507(P1)和白色果皮自交系1508(P2)为亲本,构建6世代遗传群体(P1、P2、F1、F2、BC1P1、BC1P2),对黄瓜嫩果白色果皮基因(w)进行遗传规律分析和基因定位研究。结果表明,黄瓜白色果皮性状由隐性单基因(w)控制,深绿色对白色为显性。利用F2群体,结合分离群体分组分析法筛选得到了14个与w基因相关的SSR标记,构建了该基因的SSR连锁群,将其定位到黄瓜3号染色体上,两侧的标记为SSR23517和SSR23141,遗传距离分别为4.9cM和1.9cM。侧翼标记之间的物理距离为1 150kb,在该区域中共预测了500个候选基因。该研究对w基因的初步定位,为该基因精细定位及分子标记辅助选择育种奠定了良好的基础。     

黄金苗谷子苗期黄色的生理基础和黄苗基因初定位

黄金苗是一个苗期表现黄苗、后期叶色恢复绿色的优质谷子品种,植物学和农艺性状观察发现:黄金苗叶色由黄变绿发生在孕穗到抽穗期;叶绿素含量的动态分析表明:黄金苗的叶绿素a和叶绿素b含量在苗期均低于对照,但在抽穗期叶绿素a的含量基本恢复正常,但叶绿素b的含量一直极显著低于对照,说明相关突变影响了叶绿素的合成,特别是叶绿素b的合成。叶绿体超微结构比较分析表明:黄金苗苗期每个细胞中叶绿体数量,基粒类囊体的层数与对照相比有显著差异,抽穗期恢复正常后与对照不存在显著差异。受叶绿素的含量和叶绿体的数量及类囊体数量的影响,黄金苗的净光合速率显著低于对照。遗传分析表明:黄金苗的黄苗性状受一对隐性单基因控制,通过对F2分离群体进行黄苗基因的定位发现,突变发生在8号染色体。本研究的结果可为下一步突变基因的精细定位和基因功能研究打下良好基础,本研究还讨论了黄金苗的黄苗色在育种中作为标记性状的利用。     

花粉介导法获得耐草甘膦玉米植株及其耐性研究

为获得耐草甘膦转基因玉米植株,进而研究其除草剂耐性及外源基因的遗传特性,以质粒p BI101-aroA-M12为外源基因供体,以玉米自交系昌‘7-2’为受体,采用花粉介导法将外源基因导入玉米自交系中。PCR扩增、Southern杂交分析的结果证明获得了54个转基因植株;对其后代株系的分子检测及田间生物学鉴定,结果证明目的基因可以稳定遗传给后代植株,且赋予和提高了转基因植株的除草剂耐性。目的基因在转化体中的遗传规律研究,结果显示导入的目的基因在F2受体植株中以3∶1的比例发生遗传分离,符合孟德尔单因子显性遗传分离规律。ELISA分析和蛋白质浓度测定的结果证实目的基因在转化植株中得到表达,表达量介于40.5-112.6 ng/g叶片鲜重之间,目的基因表达量与该植株的除草剂耐性性状间呈极显著相关,r=0.942 3(P0.01)。最终研究获得了4个高草甘膦耐性的转基因纯合株系。     

问题解答

问为什么花斑枝条的紫茉莉会产生绿色、白色花斑三种植株? 答紫茉莉的花斑枝条是因含叶绿素的正常质体(叶绿体)和不含叶绿素的败育质体在枝条的细胞间分布不匀造成的.叶绿体位于细胞质中,它的遗传属于细胞质遗传.花斑枝条的绿色部分的细胞中含有正常的叶绿体,因而表现绿色;白色部分的细胞中含有败育的叶绿体,因而表现白色;白绿组织交界区域的某些细胞中,则同时含有正常叶绿体的败育叶绿体. 花斑枝条上的杂种能出现绿色、白色和花斑三种植株,是由于接受花粉的花在花斑枝条上着生的位置不同造成的.位于绿色部分的花,卵细胞质里含有正常的叶绿体,其杂种必然是绿色的植株;位于白色部分的花,卵细胞质里只含败育叶绿体,其杂种一定是白色的植株;位于白绿交界位置的花,它的卵细胞质中既有正常叶绿体又有败育叶绿体,所以受精卵细胞质里同     

玉米突变体（zb／zb）的叶绿体光合特性

常规育种中出现的偶然变异植株,用来作光合机理和遗传机理的研究,不需要复杂的生物技术操作手段,受到很多学者关注。植物的花斑叶是一种结构上的嵌合体。Hayden和Hopkins发现玉米(zae mays L.)的黄绿色突变体OYyg中缺少介于CPⅠ与CPⅡ之间的一条被他们称为复合体Ⅳ的小带。李玉湘和李继耕用玉米白色叶片和条纹叶片两种突变系,进行叶绿素蛋白复合体研究表明,纯白色突变系叶片中捕光叶绿素a/b蛋白复合体的合成受阻。本文用zb/zb与一正常自交系杂交,得到的F_1代为zb/zb基因型。将其分别播种后,对白色叶片和绿色叶片叶绿体膜的光合特性进行了多项比较研究。     

Inheritance of a recessive transgene-associated character controlling albinism in transgenic bean (Phaseolus vulgaris L.)

We identified a transgenic line exhibiting albinism during our work to introduce genes through genetic engineering in dry bean (Phaseolus vulgaris). The transgenic mother plant (R0) presented a normal phenotype and generated albino and normal green plants in the first generation (R1). The segregation ratio of the albino character in the R1 and R2 generations fitted the expected ratio for a character controlled by a single recessive gene linked to a foreign gus gene, suggesting that albinism could be a consequence of insertional mutation caused by introduction of the exogenous gene. Analysis by electron microscope revealed that the albino cells possessed no chloroplasts and a greater number of mitochondria when compared to normal green plants. This transgenic bean line may be used in understanding the genetic control of chloroplast genesis, for acquiring additional knowledge of genomic structure or in physiological studies. This is the first described transgene-associated mutant bean plant.     

Characterizing laboratory colonies of western corn rootworm (Coleoptera: Chrysomelidae) selected for survival on maize containing event DAS-59122-7

Event DAS‐59122‐7 is a novel transgenic trait designed to protect the roots and yield potential of maize from the insect pest corn rootworm Diabrotica spp. (Col.: Chrysomelidae). The increased pest status of corn rootworm, exceptional efficacy of this trait, and anticipated increases in farm efficiency and grower and environmental safety will drive adoption of this trait. Strong grower acceptance of this trait highlights the importance of science‐based and practical resistance management strategies. A non‐diapause trait was introgressed into two laboratory colonies of Diabrotica virgifera virgifera collected from geographically distinct locations: Rochelle, IL and York, NE. Both colonies were divided and each reared on maize containing event DAS‐59122‐7 or its near isoline. Selected and unselected colonies were evaluated for phenotypic change in larval development, injury potential and survival to adulthood during 10 and 11 generations. The F1 generation of both selected colonies displayed increased larval development, survivorship and measurable, but economically insignificant increases in injury potential on DAS‐59122‐7 maize. Survival rates of 0.4 and 1.3% in F1 generations of both selected colonies corroborate field estimates of survival on DAS‐59122‐7 maize. Over later generations, total phenotypic variation declined gradually and irregularly. Despite the absence of random mating, the tolerance trait could not be fixed in either population after 10 or 11 generations of selection. An allele conferring major resistance to DAS‐59122‐7 was not identified in either selected colony. The assessment also concluded that major resistance gene(s) are rare in populations of D. v. virgifera in the United States, and that a minor trait(s) conferring a low level of survival on DAS‐59122‐7 maize was present. The tolerance trait identified in this study was considered minor with respect to its impact on DAS‐59122‐7 maize efficacy, and the role this trait may play in total effective refuge for major resistance genes with recessive inheritance is the basis of future work.     

烤烟叶数、叶面积的遗传分析

以叶数较少、叶面积较小的烤烟品种丸叶为母本(P1),以叶数较多、叶面积较大的烤烟品种Coker319为父本,构建了6个世代分离群体,利用植物数量性状主基因+多基因混合遗传模型的联合分离分析方法,分析烤烟杂交组合丸叶×Co-ker319叶数、叶面积的遗传效应。结果表明:烤烟的叶数和叶面积均受2对加性-显性-上位性主基因+加性-显性-上位性多基因(E0)控制,其中叶数遗传以加性效应及显性×显性上位性效应为主,叶面积几种遗传效应差不多,其上位性效应>加性效应>显性效应,叶数和叶面积在B1世代的主基因遗传率分别为36.91%和2.13%,多基因遗传率分别为31.00%和19.53%,B2世代的主基因遗传率分别为51.60%和50.92%,多基因遗传率分别为16.84%和13.26%,F2世代的主基因遗传率分别为42.63%和30.32%,多基因遗传率分别为42.08%和12.18%,叶数和叶面积的主基因遗传率较高,适合在早代选择。     

Gene mapping related to yellow green leaf in a mutant line in rice (Oryza sativa L.)

A mutant, which derived from the restorer line Jinhui10 treated with EMS, showed completely yellow green leaves, and it had low chlorophyll content and poor agronomic characteristics during the growing stage. The F1 plants from the cross between normal × the mutant showed normal green leaves, and the segregation ratio of normal to yellow green leaves was 3 : 1 in F₂ population. It indicated that the trait was controlled by a single recessive nuclear gene, temporarily designated asygl3. The geneygl3 was mapped between RM468 and RM3684 with genetic distances 8.4 cM and 1.8 cM on chromosome 3. This result would be used as genetic information for fine mapping and map-based cloning ofygl3 gene.     

Discovery of second gene for solid dark green versus light green rind pattern in watermelon

The watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus) has high variability for fruit size, shape, rind pattern, and flesh color. This study was designed to measure the qualitative inheritance of rind phenotypes (solid dark green vs. light green). For each of the 2 families, "Mountain Hoosier" × "Minilee" and "Early Arizona" × "Minilee," 6 generations (P(a)S(1), P(b)S(1), F(1), F(2), BC(1)P(a), BC(1)P(b)) were developed. Each family was tested in summer 2008 in 3 environments in North Carolina. Phenotypic data were analyzed with the χ(2) method to test the segregation of Mendelian genes. Deviations from the expected segregation ratios based on hypothesized single dominant gene for solid dark green versus light green rind pattern were recorded, raising questions on the inheritance of this trait. Inheritance of solid dark green rind versus light (gray) rind showed duplicate dominant epistasis. Duplicate dominant epistasis gives rise to a 15:1 ratio (solid dark green:light rind pattern) in F(2) generation. When both the loci are homozygous recessive, we observe light rind pattern. The g-1 and g-2 genes were identified to control light green rind when in homozygous recessive form.     

Maize F<Subscript>1</Subscript> hybrid differs from its maternal parent in the development of chloroplasts in bundle sheath,but not in mesophyll cells: Quantitative analysis of chloroplast ultrastructure and dimensions in different parts of leaf blade at the beginning of its senescence

The quantitative changes of chloroplast ultrastructure and dimensions in mesophyll (MC) and bundle sheath (BSC) cells, associated with the onset of leaf senescence, were followed along the developmental leaf blade gradient of the third leaf of maize (Zea mays L.). To ascertain whether the rapidity of structural changes associated with the transition of chloroplasts from mature to senescent state is a heritable trait, the parental and the first filial generations of plants were used. The heterogeneity of leaf blade, associated with the development of maize leaf (with the oldest regions at the apex and the youngest ones at the base) was clearly discernible in the ultrastructure and dimensions of chloroplasts; however, there were differences in the actual pattern of chloroplast development between both genotypes as well as between both cell types examined. While the course of MC chloroplasts’ development at the onset of leaf senescence in maize hybrid followed that of its parent rather well, this did not apply for the BSC chloroplasts. In this case, each genotype was characterized by its own distinguishable developmental pattern, particularly as regards the accumulation of starch inclusions and the associated changes of the size and shape of BSC chloroplasts.     

Genetic dissection of seed shattering,agronomic, and color traits in American wildrice ( Zizania palustris var. interior L.) with a comparative map

A comparative map of American wildrice ( Zizania palustris var. interior L.) was used to identify loci controlling seed shattering, plant height, maturity, tiller number, plant habit, panicle length seed length, and color traits. Two to six significant quantitative-trait-loci (QTLs, P < 0.05) were detected for each trait evaluated, representing the first trait-mapping in wildrice. The chosen population was designed to emphasize the mapping of loci controlling the shattering trait, which is the most important trait in the management of this newly domesticated species. Three loci were detected that controlled the discretely categorized variation between shattering and non-shattering plants. Seed-shattering loci were detected and validated among the F(2) and F(3) generations. A multiple regression model with these three loci described 49.6% of the additive genetic variation. A genetic model with the same three loci including dominance and locus interactions predicted the shattering versus non-shattering phenotype at a success rate of 87%. The comparative map was based on mapped RFLP markers used in white rice ( Oryza sativa L.) and other grass species. Anchor loci provided a reference point for the identification of potential orthologous genes on the basis of white rice mutant loci and consensus grass species QTLs. Candidate orthologous loci were identified among all traits evaluated. The study underscores the benefits of extending trait analysis through comparative mapping, as well as challenges of QTL analysis in a newly domesticated species.     

Genome sequencing reveals agronomically important loci in rice using MutMap

The majority of agronomic traits are controlled by multiple genes that cause minor phenotypic effects, making the identification of these genes difficult. Here we introduce MutMap, a method based on whole-genome resequencing of pooled DNA from a segregating population of plants that show a useful phenotype. In MutMap, a mutant is crossed directly to the original wild-type line and then selfed, allowing unequivocal segregation in second filial generation (F(2)) progeny of subtle phenotypic differences. This approach is particularly amenable to crop species because it minimizes the number of genetic crosses (n = 1 or 0) and mutant F(2) progeny that are required. We applied MutMap to seven mutants of a Japanese elite rice cultivar and identified the unique genomic positions most probable to harbor mutations causing pale green leaves and semidwarfism, an agronomically relevant trait. These results show that MutMap can accelerate the genetic improvement of rice and other crop plants.