体细胞突变体HX-3抗水稻白叶枯病基因的鉴定

以感病杂交稻恢复系明恢63的成熟胚为外植体,利用离体筛选技术获得了抗水稻白叶枯病细胞突变体HX-3。连续8年以我国长江流域白叶枯病代表菌析浙173（IV型）对HX-3的R1到R9代进行抗性鉴定,HX-3的抗病性可以稳定遗传。抗性遗传分析表明HX-3的抗性由1对显性核基因控制。1999～2000年连续两年利用我国、菲律宾和日本的32个水稻白叶枯病菌株,测定HX-3及IRBB1等13个具不同显性抗病基因的近等基因系抗性,HX-3抗谱广,且与已知显性抗病基因的抗谱不同。在此基础上,以抗白叶枯病近等基因系IRBB4、IRBB7、CBB12和IRBB21和HX-3杂交,进行等位性分析,4个杂交组合的F2代均出现抗、感分离,说明HX-3与这4个基因不等位。综合以上研究结果,HX-3具有1个新的抗白叶枯病基因,暂命名为Xa-25(t）。     

转不可翻译PVY^N CP基因烟草的抗病性分析

我们曾报道表达不可翻译PVY^N CP基因的转基因烟草抗病性是由RNA介导的,其抗病性类似于转录后的基因沉默(PTGS)。本研究以这类不同抗性的T0代转基因烟草植株为材料,对自交后的T1代转基因植株的遗传和抗病性进行了分析,并选取部分T1代抗病株系自交留种。对T2代RNA介导抗病性转基因植株进行了分子分析和一系列抗病性研究。结果表明,含1—2个转基因拷贝的T0代感病植株,在T1代中的Km抗性分离符合单位点插入的3：1的遗传规律;含3个或3个以上转基因拷贝的T0代中抗或高抗植株,在T1代中的Km抗性分离符合多位点插入的15：1或63：1的遗传规律。大多数T1、T2代转基因植株的抗病性与转基因拷贝数成正相关,转基因在T1、T2代植株中能够转录表达,且转基因植株之间转基因mRNA在细胞质中的积累水平与转基因植株的抗病性成负相关。转基因植株的抗病性能够在T1、T2代中遗传,且T2代转基因植株的抗病性具有以下特征：1)既抗病毒粒体又抗病毒RNA的侵染,且这种抗病性不受接种物剂量的影响;2)抗病谱较窄,只对PVY的某些株系具有高度抗病性;3)与传毒方式无关,既抗摩擦接种又抗带毒蚜虫接种;4)与植株的发育阶段没有关系。     

国际水稻所水稻新株系的抗性评价

为了进一步扩大我国稻种资源,丰富水稻育种材料,引进了165份国际水稻研究所在非洲进行穿梭育种的水稻新株系,于2011年和2012年在湖北生态条件下进行稻瘟病抗性、白叶枯病抗性和褐飞虱抗性的评价。评价结果表明,在165份新株系中有14份株系在宜昌和恩施2个稻瘟病病圃鉴定均表现抗或中抗稻瘟病,有40份株系同时高抗或抗白叶枯病菌株ZHE173和GD1358,有19份株系抗或中抗褐飞虱,有7份株系同时抗白叶枯病和稻瘟病,有8份株系同时抗白叶枯病和褐飞虱,有1份株系同时中抗稻瘟病、褐飞虱和白叶枯病。部分材料正在作为中间材料用于水稻育种。     

转不可翻译PVYN CP基因烟草的抗病性分析

我们曾报道表达不可翻译PVY~N CP基因的转基因烟草抗病性是由RNA介导的,其抗病性类似于转录后的基因沉默(PTGS)。本研究以这类不同抗性的Tn代转基因烟草植株为材料,对自交后的T1代转基因植株的遗传和抗病性进行了分析,并选取部分T_1代抗病株系自交留种。对T_2代RNA介导抗病性转基因植株进行了分子分析和一系列抗病性研究。结果表明,含1-2个转基因拷贝的T_0代感病植株,在T_1代中的Km抗性分离符合单位点插入的3∶1的遗传规律;含3个或3个以上转基因拷贝的T_0代中抗或高抗植株,在T_1代中的Km抗性分离符合多位点插入的15∶1或63∶1的遗传规律。大多数T_1、T_2代转基因植株的抗病性与转基因拷贝数成正相关,转基因在T_1、T_2代植株中能够转录表达,且转基因植株之间转基因mRNA在细胞质中的积累水平与转基因植株的抗病性成负相关。转基因植株的抗病性能够在T_1、T_2代中遗传,且T_2代转基因植株的抗病性具有以下特征:1)既抗病毒粒体又抗病毒RNA的侵染,且这种抗病性不受接种物剂量的影响;2)抗病谱较窄,只对PVY的某些株系具有高度抗病性;3)与传毒方式无关,既抗摩擦接种又抗带毒蚜虫接种;4)与植株的发育阶段没有关系。     

无选择标记和载体骨干序列的Xa21转基因水稻的获得

利用双右边界T-DNA载体通过根癌农杆菌介导法将水稻白叶枯病广谱抗性基因Xa21导入杂交稻重要恢复系C418中。T0代共获得27个独立转基因株系,通过田间抗性鉴定与PCR分析,有17个株系的Xa21基因分子鉴定为阳性,且对白叶枯病原菌P6生理小种具有抗性。通过对17个株系的后代植株进行田间抗性鉴定,分子标记辅助选择及Southern杂交分析,结果显示4个株系的T1代植株中能分离出无潮霉素标记基因的Xa21转基因植株。无选择标记Xa21转基因株系的获得率为15%。PCR检测还表明,这些无选择标记的Xa21转基因植株不带有载体骨架序列。通过对转基因后代进一步的抗性鉴定与PCR辅助选择,获得了无选择标记和载体骨架序列的转基因Xa21纯合的抗白叶枯病水稻。     

水稻抗白叶枯病基因Xa-25的分子定位

Xa-25是从体细胞突变体HX-3中鉴定出的水稻抗白叶枯病基因。通过花药培养构建了02428(粳稻)和HX-3(籼稻)的双单倍体(DH)群体,该群体包含了129个稳定株系,以我国长江流域水稻白叶枯病的代表菌株浙173对DH群体进行抗病性鉴定,抗病株系数和感病株系数分别为62和67。共选用覆盖水稻12条染色体的300对SSR引物对02428和HX-3进行多态性分析,有74对引物在双亲之间表现差异。利用这些差异引物对DH群体进行连锁分析,从而将抗白叶枯病基因Xa-25定位到第4染色体长臂末端的两个SSR标记RM6748和RM1153之间,连锁距离分别为9．3cM和3．0cM。     

大豆抗灰斑病主基因的发现与遗传研究

利用高抗品种东农9674与感病品种杂交,在田间多个生理小种共存条件下研究大豆灰斑病抗性的遗传规律,发现杂交后代的抗性表现具有明显的质量性状遗传特征,F1代表现完全显性,F2代的抗感分离比例在个别组合接近3:1。采用数量性状的主要基因-多基因混合遗传模型对抗性的遗传进行模型的判别与遗传参数的估计,发现抗性遗传存在明显的主要因效应,分别符合一个主基因 多基因加显性模型及两个基因独立遗传模型。主基因的加性、显性以及主基因之间的相互作用普遍存在,对抗病性的遗传起很大作用。     

粳稻杂交育种中应用花粉植株的某些优点和存在问题

1976年用花药培养方法从粳稻F_1杂种获得600余丛花粉绿苗,诱导率平均为5％。在长成的花粉植株中,自发加倍的二倍体约占50％。 在生长于温室的自发加倍二倍体花粉植株(H_1)与生长于大田的后代(H_2)之间,观察到抽穗日期有显著相关(n=37,r=0.714),千粒重有相关但不显著(n=37,r=0.301),结实率无相关,这种情况部分与花粉植株H_1的倍数性混乱有关。 114个花粉植株H_2株系中只有二个株系出现明显分离。由一个F_1杂种产生的花粉植株之间,性状的变异很宽,数量性状呈连续正态分布,超亲变异很明显。相当部分株系的抗稻瘟病性劣于亲本。 从二个F_1杂种的78个花粉植株中选出二个有良好耐寒性与抗稻瘟病的品系。对它们的农艺性状进行二年观测,未见生活力衰退。 认为,由粳稻杂种F_1所培养的花粉植株的纯合性与类型多样性有利于优良重组体的准确选择与迅速稳定,目前主要是产生二倍体花粉植株的效率太低限制了花粉植株有成效地应用。     

药用野生稻转育后代一个抗白叶枯病新基因的定位

从药用野生稻渗入后代选育的水稻株系B5表现为高抗褐飞虱、白背飞虱和白叶枯病。对B5与籼稻品种明恢63杂交组合的187个重组自交系(RILs)进行了抗白叶枯病接种鉴定,采用分离集团分析法(Bulked Segregant Analysis,BSA),在第1染色体上筛选到与水稻抗白叶枯病基因相连锁RFLP分子标记。利用RILs抗病性表现型鉴定资料和构建的分子标记连锁图谱,将抗白叶枯病基因定位在第1染色体短臂的C904和R596之间,这两个分子标记间遗传距离为1．3cM。该基因对RILs群体抗病性变异的贡献率为52．96％,是一效应值较大的主效基因。这一抗白叶枯病基因不同于已报道的抗白叶枯病基因的位点,因此将其命名为Xa29(t)。     

甘薯品种抗黑斑病鉴定及其遗传趋势

对2745份甘薯品种及育种材料的黑斑病抗性鉴定结果表明,高抗型占7．7％,抗病型占17．7％,中抗型占23.2％,感病型占27．2％,高感型占24．2％。对898份材料及其亲本的抗性分析表明,不同抗性组合后代中均可分离出高抗至高感类型的材料,杂交后代的抗性强弱随双亲抗性水平的增加而提高。相关分析显示,甘薯品种抗黑斑病性与其它主要经济性状间没有相关关系。采用品种阃杂交育种技术先后育成了一批高产、优质的抗病型优良品种。     

刺芹侧耳自交S1代若干性状的遗传分化

本文选用刺芹侧耳Pleurotus eryngii24号(广杏)为自交材料,对其自交S1代群体的质量性状(颜色、畸形、生长特性)和数量性状(形状、产量、大小、数目)进行了综合分析。分析结果表明:自交后代的出菇率为70%,自交导致后代群体菌丝平均生长速度和平均产量都低于亲本,16%的后代菌株单产高于亲本,最高单产达204.0g,高出亲本45.7%。木屑培养基上菌丝日均生长速度与产量无显著相关性(R=-0.028)。均菇数目与单产成显著正相关性(R=0.543)。大部分菌株(52%)菌盖颜色为亲本颜色(灰色),自交后代出现20%非亲本形状(棒状)菌株,畸形菇占19%。后代群体盖径、柄径、柄长的变异程度相当,差异性不显著。可根据育种目标对自交子代的较优菌株进行定向选择利用。     

Producing commercially attractive,uniform true potato seed progenies: the influence of breeding scheme and parental genotype

The production of attractive, uniform true potato seed (TPS) progenies was investigated. Four breeding schemes were compared: intercrossing tetraploid cultivars (cv x cv); doubled dihaploids x cultivars (ddh x cv); cultivars x diploid unreduced-gamete producers (cv x FDR) and doubled dihaploids x diploid unreduced-gamete producers (ddh x FDR). Fifty three progenies and five clones were grown in a glasshouse in a randomised complete block design with three replicates of 25 plants per progeny and clone. Each plant's tubers were counted and the colour, shape, quality of skin finish, flesh colour, and commencai attractiveness (which includes yield) recorded. The most uniform progenies were also selected by visual comparison with the clones. For mean attractiveness, differences (P < 0.001) between breeding schemes and between progenies within breeding schemes were detected. The cv x cv and cv x FDR progenies were more attractive than clonal controls. There were significant additive and non-additive effects for attractiveness in all breeding schemes except cv x FDR. There were between-progeny differences (P < 0.001) for uniformity for all characters. Progenies uniform for one character could be variable for other traits. Breeding schemes gave different levels of uniformity (P < 0.001) for all characters except shape and flesh colour, but none gave low levels of variation for all traits. Doubled-dihaploid parents increased the variation in progenies. There were uniformity differences (P < 0.001) between progenies within breeding schemes for all characters. Evidence of additive and nonadditive genetic variation for uniformity in all traits was detected. In each breeding scheme, parents with good general combining ability (GCA) for uniformity in several characters were identified. Visually selected uniform progenies had parents with good GCAs for uniformity in a range of traits and high specific combining abilities (SCAs) for several traits. A desynaptic first-division restitution (FDR) clone and a male-sterile doubled-dihaploid clone had the best GCAs for tuber uniformity in TPS progenies. Achieving multitrait uniformity in TPS is problematic but may be aided by the selection of parents with GCAs for uniformity coupled with progeny testing to allow for non-additive effects.     

PHENOTYPIC VARIATION IN TRISOMICS OF CLARKIA UNGUICULATA

Vasek , F. C. (U. California, Riverside.) Phenotypic variation in trisomics of Clarkia unguiculata. Amer. Jour. Bot. 50(4): 308–314. 1963.—Progenies of 3n × 2n crosses included, in addition to diploids, plants trisomic for 1, 2, 3, 4, 5, 6 or 7 chromosomes. Means and variances were calculated for 15 phenotypic traits, including 3 width/length ratios, in one set of progenies, and for 10 of the traits, including 2 of the ratios, in another set of progenies. In 25 trait comparisons, including 15 different traits, the means for each chromosome number class were heterogeneous in 11 comparisons, which included 8 different traits. Single trisomics differed significantly from diploids in 5 comparisons (4 different traits). Despite these significant differences the variation followed no particular pattern except that sepal length increased and pollen fertility decreased with chromosome number, and trisomics, as a group, sometimes differed from diploids with regard to the width/length ratio of leaves or petals. The variances were heterogeneous in 5 comparisons (4 different traits). Sepal length and pollen fertility were the only traits for which single trisomics were more variable than diploids and for which the entire population was more variable than diploids. In addition, in 4 progenies of self-pollinated trisomics, diploids and trisomics (which within each progeny were trisomic for the same Chromosome) differed significantly in mean value in only 3 traits (out of 60 trait comparisons). Variances were significantly different in 6 comparisons (4 different traits) but, surprisingly, diploids were more variable than trisomics in 3 of these 6 comparisons. Except for sepal length, pollen fertility and some width/length ratios, a wide variety and number of extra chromosomes rarely had a significant effect on the mean or variability of various phenotypic traits, and single specific extra chromosomes had very little effect except sometimes on pollen fertility or an occasional ratio. A large amount of variation, probably caused by the environment and the general genetic background, may obscure possible specific trisomic phenotypes. Morphological identification of specific trisomics is considered impractical in this species.     

Introgression of genes from Oryza officinalis Well ex Watt to cultivated rice,O. sativa L.

Summary Sterile AC hybrids between cultivated Oryza sativa (AA) and a distant wild species, O. officinalis (CC), were backcross to O. sativa. Most of the BC₁ progenies were allotriploid (AAC), a few were hypotriploid. AAC progenies were again backcrossed to O. sativa. BC₂ progenies consisting of disomic or aneuploid individuals were examined for the presence of O. officinalis traits. Eleven different traits from O. officinalis were identified in these progenies. Segregation data in the subsequent generations suggest that these traits are monogenic in nature. Two of these genes — for resistance to BPH and WBPH — are of value in rice improvement. The extremely low recovery of recombinant progenies is in agreement with the very low amount of pairing between A and C genomes. Because of this restricted recombination, the genotype of the recurrent parent was reconstituted after two backcrosses only. Thus, the BC₂ progenies look remarkably similar to O. sativa. Most of them are stable and fertile and also interfertile with other O. sativa breeding lines. Some of the BPH-and WBPH-resistant progenies are comparable in yield to the best O. sativa parents and are being evaluated as varietal possibilities.     

黄牡丹远缘杂交后代花粉粒特征

为揭示牡丹远缘杂交后代花粉粒的特征,测定了以肉质花盘亚组黄牡丹为母本,革质花盘亚组栽培品种‘日月锦’、‘层中笑’、‘百园红霞’等为父本的10个远缘杂交组合,共计11个亲本、25个后代的花粉畸形率和萌发率,用扫描电镜观察了花粉粒形态,同时也观察了花和叶的形态特征。结果表明:与双亲相比,杂交后代的花粉量极少,花粉粒萌发率极低,畸形率极高,畸形花粉粒扭曲、破碎或粘成团块状。25个杂交后代的花粉粒均为超长球形,具三拟孔沟,与母本黄牡丹和绝大多数父本一致;但杂交后代的花粉粒小于双亲,外壁纹饰类型受父本影响较大,为小穴状、穴状、网状和粗网状。结合前人的观察结果,25个杂交后代中15个与父本的纹饰类型一致,与母本纹饰类型一致的杂交后代仅有6个,与父母本纹饰类型均不同的杂交后代有4个。形态观察发现杂交后代具有父本的花盘革质、心皮被毛的特征,而小叶分裂程度较母本减轻但小叶裂片较母本加宽;花径则介于父母本之间。其中,心皮被毛、小叶裂片加宽可以结合花粉粒特征作为以黄牡丹为母本的远缘杂交后代的形态识别标记。     

分子标记辅助选择改良蜀恢527对白叶枯病的抗性

以含抗性基因Xa2 1和Xa4的抗白叶枯病近等基因系IRBB6 0为供体亲本 ,以不抗白叶枯病强恢复系蜀恢5 2 7为轮回受体亲本 ,连续回交 3代 ,自交 1代 ,在分离世代用分别与Xa2 1和Xa4紧密连锁的标记pTA2 48和MP12对目标基因Xa2 1和Xa4进行辅助选择 ,直至BC3F2 。在BC3F2 中选出株型、粒型、播抽期等农艺性状与蜀恢 5 2 7相似且pTA2 48和MP12的扩增带型纯合的 10个单株 ,用 10 0个RAPD和 12 0对SSR引物进行背景选择 ,决选出 5个单株 ,作为改良的蜀恢 5 2 7。抗性分析表明 ,这些改良的蜀恢 5 2 7株系对我国菌系CⅠ CⅦ和来自菲律宾的P1 和P6 均表现抗性 ,说明抗性基因已成功导入蜀恢 5 2 7中并表达。同时对pTA2 48和MP12在亲本间的多态性和选择的准确性也进行了分析 ,结果显示这两个标记在亲本间的多态性明显 ,共显性 ;选择的准确率分别在 97%和 83%以上 ,可以用其进行标记辅助选择。     

Okra-leaf accessions of the upland cotton (Gossypium hirsutum L.): genetic variability in agronomic and fibre traits

Okra-leaf types of the upland cotton have the potential to be competitive to the normal-leaf types in yield and fibre quality, in addition to its potential resistance to insect pests and drought. Okra-leaf cotton accessions, collected at Cotton Research Institute, Faisalabad, Pakistan, were evaluated in respect of genetic variance and relative performance in half- and full-sib crosses (combining ability) for 2 years. Variation due to parents x years interaction was significant for lint percentage, seed weight and earliness index, resulting in moderately low but significant genetic variance across environments (years) for these traits. Interaction of environment with general combining ability was significant for seed yield, seed weight, and earliness index. General combining ability variation, contributed by females and males together, accounted for 71% of the total variation available for seed cotton yield, 60% of that for seed weight and height to node ratio each, and 75% of that for earliness index. Specific combining ability variation accounted for 85% and 51% of the total variation available for lint percentage and staple length, respectively. The contribution of female parents to general combining ability variation was higher than that of male parents for seed cotton yield, seed weight, height to node ratio, and earliness index. Okra-leaf accessions HR-VO-MS and HR107-NH were predicted to produce progenies having high yield, HR109-RT high lint percentage, while HR100-Okra, Gambo-Okra and HR-VO-1 were predicted to impart early crop maturity to their progenies by reason of their good general combining ability for these traits. The results also provided evidence that genes controlling high yield in HR-VO-MS and HR107-NH were different from those controlling high yield in HR109-RT. The set of genes controlling the high earliness index in HR100-Okra and that in HR-VO-MS also appeared to differ in expression.     

云南“大粒水稻”对稻白叶枯病的抗性遗传

云南地方品种——云南大粒抗水稻白叶枯病菌“江陵691”,其抗性由2对具重叠作用的隐性抗性基因控制,与IR28、南粳15的显性抗病基因不等位;也与已命名的xa-5、xa-8、xa-9和xa-13 4个抗性基因也不等位。     

云南红花种质资源主要农艺性状的遗传多样性分析

为加强红花种质资源的研究利用,对筛选出的66份云南红花优异种质资源16个形态性状进行聚类分析与主成分分析。结果表明:云南红花种质资源具有丰富的遗传多样性,多样性指数最高的是果球着粒数,其次是株高、最末分枝高度和千粒重;性状变异系数最大的是分枝总数,其次分别是单株有效果球数和第一分枝高度,最小的为顶果球直径;基于各种质间形态性状的遗传差异,把66份红花种质聚类并划分为6大类群。第Ⅰ类群可作为有增产潜力的亲本材料,第Ⅲ类群可作为高产量目标选育的亲本,第Ⅳ类群可作为大粒型选育亲本,第Ⅴ类群可作为高含油量选育目标亲本,第Ⅵ类群既是大粒型又是高含油量双重选育目标亲本。11个数量性状的主成分分析结果表明,前4个主成分累计贡献率达82.59%,第一主成分反映植株高度,第二主成分反映产量构成因子,第三、第四主成分分别反映千粒重和果球着粒数。研究结果表明云南红花地方种质资源的变异较大,遗传较丰富。     

Paternity analysis in a progeny test of Cryptomeria japonica revealed adverse effects of pollen contamination from outside seed orchards on morphological traits

To evaluate the effects of pollen contamination from outside of Cryptomeria japonica seed orchard on the growth performance (height and diameter at breast height, DBH) and morphological traits (stem straightness and basal stem straightness), paternity testing using seven microsatellite markers was performed in a progeny test. In the studied progeny test, high rates of inconsistency were found between the observed and expected genotypes. The average rates of pollen contamination from outside the orchard and self-fertilization were 58.47% and 0.65%, respectively. We divided the individuals of the studied progeny test into two groups based on their genotype data, for which: (1) both parents were elite trees and (2) only the mother trees were elite trees, and then compared them with respect to the growth performance and morphological traits of progenies using data at 20 and 30 years old. Significant adverse effects of contaminating pollen were detected in relation to straightness, but not tree height and DBH. The results suggest that the genetic gains for straightness generally show higher narrow-sense heritability than growth traits, which should be increased by reduction of pollen contamination. Breeding with paternal analysis (BWPA) is an effective approach for evaluating breeding materials based on maternal and paternal information revealed by DNA markers. The use of BWPA in progeny test allows effective forward- and backward selection without laborious and time-consuming tasks. In this study, we also suggest that the significant pollen contamination and paternal deviation found in the open-pollinated progeny test are serious impediments for BWPA.