基于F3种子的胚乳性状QTL区间定位

文章提出了包括胚乳效应和母体效应的胚乳性状QTL定位的统计方法,该方法的实验设计是分子标记基因型信息来自F2母体植株和F3种子胚(或植株),胚乳性状表型值来自F3单粒种子胚乳,称之为两步等级设计。同时,用计算机全面模拟以验证该模型的可行性,模拟结果表明,只要群体足够大,该模型能较有效地进行胚乳性状QTL定位并精确地估计出胚乳QTL的各种遗传效应和母体效应。     

玉米籽粒性状的遗传模型研究

用１０个遗传上和籽粒形态性状上具有差异的玉米自交系,依多种可能的交配方法获得亲本Ｐ１、Ｐ２、Ｆ１（Ｐ１× Ｐ２）、Ｆ２、Ｂ１（Ｆ１×Ｐ１）、Ｂ２（Ｆ１× Ｐ２）及其相应反交ＲＦ１、ＲＦ２、ＲＢ１、ＲＢ２共１０个种子世代。种植２年。依广义遗传模型建立包括种子胚乳加性、胚乳显性、母体加性、母体显性和细胞质效应的遗传模型,运用种子数量性状的精细鉴别法［１］和混合模型分析法［２,３］,对粒长、粒宽、粒长宽比、粒厚及百粒重作了性状表达遗传机制的鉴别与探讨。单个组合的遗传模型精细测验表明,５个籽粒性状的遗传主要受母体显性和胚乳基因型（包括加性和灵性）的控制,一个组合的粒宽、粒厚和百粒重上还检测到细胞质效应。对２５对 Ｆ１正反交组合世代均值依ＭＩＮＱＵＥ法分析的结果表明,５个籽粒性状的遗传方差中,母体遗传方差占６０％以上,胚乳基因型方差低于４０％,粒长和百粒重还有细胞质效应,约占１０％～３０％。可见,籽粒性状的遗传特点是受多套遗传系统控制,其中以母体基因型的作用最大。     

基于BC_1F_（1：2）种子的胚乳QTL区间定位

提出了基于分子标记基因型信息来自BC_1F_1母体植株,胚乳性状表型值来自BC_1F_（1：2）单粒种子胚乳的试验设计的胚乳QTL定位的区间作图方法.同时,用计算机全面模拟以验证该模型的可行性,模拟结果表明,只要群体足够大,该模型能有效地进行胚乳性状QTL定位并能估计出胚乳QTL的各种遗传效应和母体效应.     

不同环境条件下粳型杂交稻米碾磨品质性状的遗传效应分析

采用包括基因型×环境互作效应的种子遗传模型,对粳型杂交稻稻米碾磨品质性状进行了遗传研究.结果表明:各碾磨品质性状除了受制于种子直接效应、细胞质效应和母体效应等遗传主效应外,还明显受到各基因型×环境互作效应的影响.其中糙米率性状以遗传主效应为主,而精米率、整精米率性状以基因型×环境互作效应为主.在遗传主效应中,糙米率性状主要受种子直接加性效应、母体加性效应的控制;在基因型×环境互作效应中,精米率和整精米率性状都是以种子直接加性×环境互作效应和母体加性×环境互作效应为主,细胞质×环境互作效应也起着较为重要的作用.大部分稻米碾磨品质性状的狭义遗传率均较高,其中糙米率性状以普通狭义遗传率为主,而精米率和整精米率性状则以互作狭义遗传率为主.另外,根据性状的遗传效应预测值对各亲本的育种利用价值作了评价.     

遗传教学应注意种子颜色与种皮颜色的区分

孟德尔在杂交实验中曾用过豌豆种子颜色这一相对性状,种子的颜色是指从种皮透出的子叶的颜色。但日常提到的种子颜色,大部分都不是真正种子颜色而是种皮的颜色,由于种皮是属于种子的一部分,所以一般情况这样提也还可以,但在讨论遗传问题时就应从发生角度予以区分,否则就会出现实验与理论的出入。把种子颜色定为子叶的颜色,就说明种子颜色决定了该种子自身的基因型。种子和果皮分别是由珠被和子房壁发育来的,因而它们实质上是母体分离出来的一部分,其基因型与母体的体细胞是相同的,杂交不可能改变这部分的基因型,而只能改变由受精的卵细胞和极核发育来的胚和胚乳细胞之基因型。所以杂交当代结     

基因型与环境互作对食用稻米重金属积累特性遗传的影响

采用包括种子、细胞质、母体植株三套遗传体系的种子数量性状的遗传模型和统计方法,分析了食用稻米汞、砷、铬、镉和铅等5个重金属积累特性遗传的基因型与环境互作．结果表明,5个重金属积累除了受制于种子、细胞质和母体植株三套遗传效应外,还明显受到基因型与环境互作效应的影响．在遗传主效应中,汞、铬和铅积累以母体植株显性效应及其与环境互作效应为主．砷和镉积累则以种子直接加性与环境互作效应和母体植株显性与环境互作效应为主,细胞质效应及其与环境互作效应对这2个重金属积累的影响也较为明显．     

胚乳性状数量基因的定位方法

将三倍体胚乳性状的数量遗传模型和二倍体性状数量基因（QTL）图构建方法相结合,导出双侧标记基因型下有关胚乳性状QTL的遗传组成、平均数和遗传方差分量,据之提出以某一区间双侧标记基因型胚乳性状的平均值为依变数,以该区间内任一点假定存在的QTL的加性效应d、显性效应h1和／或h2的系数为自变数,进行有重复观察值的多元线性回归分析,根据多元线性回归的显著性测验该点是否存在QTL,并估计出QTL的遗传效应。给定区间内任一点,皆可以此进行分析,从而可在整条染色体上作图,并以之确定QTL的数目和最可能位置,同时,在检测某一区间时,利用多元线性回归方法将该区间外可能存在的QTL的干扰进行统计控制,以提高QTL检测的精度。此外,还讨论了如何将之推广应用于其他类型的DNA不对应资料以及具复杂遗传模型的胚乳性状资料。     

稻米碾磨品质性状遗传主效应及其与环境互作的遗传分析

采用包括遗传主效应和基因型与环境互作效应的种子三倍体遗传模型,分析了不同环境条件下籼稻稻米碾磨品质的遗传特性。结果表明,各碾磨品质性状除了受制于种子基因效应、细胞质效应和母体植株基因效应等遗传主效应外,还会明显受到各遗传效应与环境互作效应的影响。其中精米重和精米率两个性状的表现主要是以遗传主效应为主,而糙米重和糙米率则以基因型ｘ环境互作效应为主。在各遗传体系中,除了精米率性状的种子直接遗传效应与环境的互作效应略大于母体植株遗传效应与环境的互作效应外,其他碾磨品质性状的母体植株基因的表达受环境条件的影响程度要大于种子基因。细胞质ｘ环境互作效应对精米重和糙米率的影响也较为重要。遗传效应预测值结果表明,Ｐ７和Ｐ８两个亲本的遗传主效应表现突出,可以明显改良杂交后代多数碾磨品质性状。Ｐ１和Ｐ２两个亲本的碾磨品质性状预测值在两年中的环境互作效应较为－致,不易受到外界条件的影响。上述亲本在水稻品质育种中可加以利用。     

双交组合种子性状的遗传模型及蒙特卡罗模拟分析

将Cockerham广义遗传模型的建模原理应用于双交方式的交配设计,针对二倍体种子和三倍体胚乳数量性状的遗传特点,提出了2个适用于分析种子品质性状的加性-显性-细胞质-母体模型,介绍了相应的统计分析方法,并进行了蒙特卡罗模拟分析。     

黑米中矿质元素铁、锌、锰、磷含量的遗传效应研究

采用禾谷类作物种子胚乳数量性状模型,分析黑米稻品种双列杂交Ｆ１和Ｆ２种子的Ｆｅ、Ｚｎ、Ｍｎ、Ｐ含量的遗传效应。结果表明,４种矿质元素含量同时受制于种子直接遗传效应、母体效应和细胞质作用影响。其中,Ｆｅ、Ｚｎ、Ｍｎ含量的种子直接效应比母体效应和细胞质效应的作用更大;Ｐ含量则主要受种子直接加性、母体加性和显性效应共同作用。Ｆｅ、Ｚｎ、Ｍｎ含量的种子直接遗传率较高,在杂种早代分别结合农艺性状选择单株上各     

不同环境下家蚕产量构成因素的通径分析及育种对策的探讨

利用52个家蚕品种在春秋两个季节的试验资料,对万头茧层量及其构成因素作了通径分析。结果表明:不同环境下,诸因素对万头茧层量的作用不完全相同,主要表现为幼虫生命率和茧层率在不同季节中的作用相对地变化。结合育种实践指出:(1)春用蚕品种的选育应在保证生命率的前提下努力提高茧层率和全茧量,而夏秋用品种的选育应在保证茧层率的前提下努力提高生命率和全茧量。 (2)为提高选择效果,春蚕期育种应以选择茧层率为主,夏秋期育种应以选择生命率为主。     

石刁柏胚乳愈伤组织的诱导及植株的再生

石刁柏已形成细胞的幼嫩胚乳,接种在附加有不同浓度的生长素(NAA)和细胞分裂素(BA)的 MS 培养基上,获得了愈伤组织。愈伤组织的诱导频率随生长素的浓度不同而异,可达65.9—83.1%。将胚乳愈伤组织转移到降低了生长素浓度或只含有低浓度生长素的分化培养基上,可陆续分化芽、根、芽丛和少量胚状体,个别的芽和胚状体能发育成小植株。切取1.5—5cm 长的芽,接种在诱导根的培养基上,或在 IBA50ppm 溶液中浸泡2小时,转移到 MS 基本培养基上,部分芽能生根形成完整植株。     

Induction of Endosperm Calluses and Regeneration of Endosperm Plantlets of Asparagus officinalis

The endosperm callus has been induced from the young endosperm of Asparagus officinalis L. on the MS supplemented with auxin. The induction frequency of callus amounts to 65.9%–83.1%. When the callus was transferred to the medium supplemented with lower concentration of NAA 0.1 ppm or containing BA 1 ppm and NAA 0.5 ppm, the differentiation of shoots, roots and a few embryoids began to occur. A few calluses and embryoids can develop into plantlets. The chromosome number in the cells from the same root tip and shoot apex of endosperm plantlet is very unstable. They can be euploids (n=10, 2n=20, 3n=30, 4n=40). or aneupl0ids (n=6, 7, 17, 25, 53).     

Genes active in developing wheat endosperm

This paper describes the construction and characterisation of a cDNA library from wheat endosperm tissue during the early stages of grain filling. Developing wheat endosperm tissue was characterised with respect to standard measures including dry weight, cytological appearance and timing of expression of major sources of mRNA such as the seed storage protein genes. In addition, the full complement of proteins present at mid-endosperm development was examined using 2D-electrophoretic techniques. Based on this characterisation, endosperm from the developing grain 8–12 days post-anthesis was chosen for isolating mRNA and preparing cDNA. At this stage in development the mRNA population is not yet dominated by the accumulation of mRNA from seed storage protein genes. A cDNA library, not normalised, containing a high percentage of full length cDNA clones was constructed and 4,319 clones sequenced ("single-pass"). Partitioning of the cDNA sequences into gene families and singletons provided the basis for quantifying the accumulation of sequence classes relative to the total number of sequences determined. The accumulation of gene families/singletons was not linear. However, mathematical modeling of the data suggested that the maximum number of different genes expressed is within the range of 4,500–8,000 (detailed in the Appendix). If an average is taken of these extremes, approximately 27% of the gene products were visible as proteins in the 2D-electrophoretic analysis. Analysis of a functional class of genes relevant to wheat grain end-use, namely the glutenin/gliadin seed storage protein class of genes, revealed a new category of gene characterised by a distinctive N-terminal domain and a reduced central repetitive domain. Electronic Publication     

Effect of pollen source and pollen ploidy on endosperm formation and seed set in pseudogamous apomictic Paspalum notatum

 It is generally accepted that most angiosperms require an accurate balance between maternal and paternal genome contribution for endosperm development. The endosperm balance number (EBN) hypothesis postulates that each species has an effective number which must be in a 2:1 maternal to paternal ratio for normal endosperm development and seed formation. The aim of this work was to investigate the effect of different sources and ploidy levels of pollen donors on endosperm formation and seed production of aposporous tetraploid (2n=4×=40) Paspalum notatum. Hand-emasculated spikelets of an apomictic 4× plant were dusted with pollen of 2×, 4×, 5×, 6× and 8× races of the same species; 3× and 4× races of a phylogenetically closely related species, P. cromyorrhizon; and 2× and 4× races of P. simplex, a species of a different subgenus. Experiments including self-pollination as well as emasculation without pollination were conducted for controls. Results indicated that apomictic 4×P. notatum is a pseudogamous species with effective fertilization of the two unreduced (2n) polar nuclei by a reduced (n) sperm. Endosperm development and seed production occurred independently of the species or the ploidy level of the pollen donor. However, seed germination rates were significantly lower than in the self-pollinated control when the pollen donor was 3×P. cromyorrhizon or 2× and 4×P. simplex. Aposporous embryo sacs in Paspalum contribute to endosperm formation with two unreduced (2n) polar nuclei, while the male contribution is the same as in sexual plants (n). Since sexual Paspalum plants fit the EBN hypothesis, the EBN insensitivity observed in apomictic plants might be a prerequisite for the spread of pseudogamous apomixis. The EBN insensitivity could have arisen as an imprinting consequence of a high maternal genome contribution. Received: 20 February 1998 / Revision accepted: 21 October 1998     

Differential gene expression during seed germination in barley (Hordeum vulgare L.)

A barley cDNA macroarray comprising 1,440 unique genes was used to analyze the spatial and temporal patterns of gene expression in embryo, scutellum and endosperm tissue during different stages of germination. Among the set of expressed genes, 69 displayed the highest mRNA level in endosperm tissue, 58 were up-regulated in both embryo and scutellum, 11 were specifically expressed in the embryo and 16 in scutellum tissue. Based on Blast X analyses, 70% of the differentially expressed genes could be assigned a putative function. One set of genes, expressed in both embryo and scutellum tissue, included functions in cell division, protein translation, nucleotide metabolism, carbohydrate metabolism and some transporters. The other set of genes expressed in endosperm encodes several metabolic pathways including carbohydrate and amino acid metabolism as well as protease inhibitors and storage proteins. As shown for a storage protein and a trypsin inhibitor, the endosperm of the germinating barley grain contains a considerable amount of residual mRNA which was produced during seed development and which is degraded during early stages of germination. Based on similar expression patterns in the endosperm tissue, we identified 29 genes which may undergo the same degradation process. Electronic Publication     

槐种子发育中胚乳细胞半乳甘露聚糖积累的研究

槐 ( Sophora japonica L.)开花约 60 d至种子成熟 ,为胚乳半乳甘露聚糖积累期。用组织化学方法 ,对储藏于胚乳细胞壁上的半乳甘露聚糖的形成积累进行了观察 ,结果表明 ,半乳甘露聚糖最先在邻近胚的胚乳细胞的粗面内质网的囊泡腔内形成 ,并通过细胞质膜分泌至细胞壁周围。此后 ,半乳甘露聚糖的积累逐渐向种皮方向扩展 ,及至种子成熟时 ,除糊粉层外 ,所有胚乳细胞几乎全由多糖所填充。此外 ,对半乳甘露聚糖发生部位及其积累过程的消长变化进行了讨论     

中华猕猴桃胚乳植株后代的观察

对438株定植的中华猕猴桃胚乳培.养的试管苗,经四年的田间观察,并进行连续二年结果分析。与对照的母株相比,胚乳植株在株形、叶片大小、果实形态及果实的主要营养成分含量上都有较大的变化。同时还发现,由同一块愈伤组织诱导的胚乳试管苗后代中也有雌、雄性别的分化。胚乳植株后代的多样性,可为中华猕猴桃的选种及品种繁育提供丰富的材料。