水稻栽培品种淀粉合成相关基因来源及其对品质的影响

为了明确高产水稻品种中与淀粉合成相关基因的性质，为稻米品质改良提供指导。严长杰等以53个典型的籼粳品种和近年育成的高产水稻品种为材料，分析了供试品种的理化品质和RVA谱特征，并利用根据籼粳基因组序列差异设计的Wx、Sbe1、She3基因的分子标记，检测了53个水稻品种的基因型，并分析了3个基因位点的遗传学效应。结果表明，3个分子标记均能很好地区分3个位点上等位基因的籼粳来源，根据3个位点的基因型可将53个品种分为6种类型。单个基因遗传效应分析表明：在不同基因型品种间淀粉的理化特性（AC，GC，RVA）存在显著或极显著差异，3个基因的联合效应在不同基因型组合间也存在显著的差异。     

籼粳稻基因组295个InDel标记的开发

插入/缺失(InDel)分子标记具有使用简单,结果清晰可靠的优点。本研究通过比对粳稻品种日本晴和籼稻品种93-11的基因组序列,在全基因组范围内设计了634对InDel候选标记,通过PCR检测比较2种粳稻(日本晴和台中65)和2种籼稻(93-11和黄华占)的多态性,发现295对标记在2种籼稻间及2种粳稻间均带型一致,而在籼、粳亚种间有多态性,因此这套295对标记可以在涉及籼粳亚种的基因定位和分子育种中应用。     

水稻苗期耐低温基因COLD1新功能标记的设计与验证

籼稻和粳稻在苗期耐低温基因COLD1的第4外显子存在1个功能性单碱基变异SNP2,粳型COLD1 ^Jap等位基因低温耐受性表现更强,具有重要的育种利用价值。通过籼粳杂交,可将粳型COLD1 ^Jap等位基因导入籼稻品种,提高其低温耐受力。为提高COLD1基因的选择效率,根据粳型COLD1 ^Jap与籼型COLD1 ^Ind基因存在的单核苷酸差异,结合扩增受阻突变体系PCR的技术原理设计功能标记。应用5个籼稻品种、5个粳稻品种、1个籼粳杂交F₁个体以及1个籼粳杂交F₂群体对功能标记进行检测验证。结果表明,所设计的功能标记可准确区分纯合粳型COLD1 ^Jap、纯合籼型COLD1 ^Ind和杂合基因型,其扩增带型与基因型完全一致,是一种鉴定COLD1基因的有效方法。该标记弥补了前人设计的衍生型酶切扩增多态性序列功能标记费用昂贵、操作复杂及费工费时等不足,可广泛应用于水稻COLD1基因的资源鉴定和分子标记辅助选择育种。     

水稻亚种间、品种间杂交揭示杂草稻的起源和进化

杂草稻是在稻田或可耕地周边生长的类似杂草并兼有野生稻和栽培稻特性的稻属植株或群体。迄今对杂草稻的发生和进化尚有很多的争论和假说,本研究通过水稻亚种间和品种间的杂交试验以及亲本与杂交后代籼粳分化分子标记的遗传分析,对杂草稻起源和进化途径进行了探讨并提出了相应的防控策略。研究结果显示:亚种间和品种间特定亲本杂交组合(7个籼/粳,4个籼/籼)的后代中均可分离出类似杂草稻的植株,其频率为籼/粳>籼/籼;籼粳交或籼籼交F2-F4代群体中产生类似杂草稻植株的频率随世代增加呈现递增趋势(F2最低为1.26%,F4最高为15.35%),这与双亲的遗传背景有密切关系,即籼、粳亚种的遗传背景差距越大,其杂交组合后代中产生杂草稻的机率越高;籼/粳交组合安山稻/9311F3代分离群体中类似杂草稻的植株以籼型为主(占52.8%);韩国粳稻品种安山稻在籼粳组合中不论作母本或父本,杂交后代都易产生类似杂草稻单株,这可能与其籼粳组分遗传异质性较高有关;粳/粳组合后代中未鉴定出类似杂草稻的植株,预示粳稻品种间杂交可能不易产生杂草稻。本研究为杂草稻的防控和利用研究提供参考依据。     

黄河流域豫北粳稻区杂草稻特性及其发生机制分析

杂草稻泛指生长在稻田及其周边被视为杂草的稻株,在国内外不同生态稻区均有不同程度的发生,但有关中国河南省豫北地区杂草稻特性及其发生状况鲜有报道。本研究以河南省黄河流域豫北粳稻区采集到的56份杂草稻为试验材料,考察其生物学特征特性;利用RID14引物鉴定红色果皮Rc位点基因型并与表型比对;同时通过34对In Del分子标记检测籼粳分化,分析了该区域杂草稻的特性、遗传分化及其可能发生的机制。研究结果表明:(1)黄河流域豫北粳稻区杂草稻大部分为淡黄色和黄褐色斑点的颖壳、多数无芒和红色果皮、易落粒、千粒重低,株高、分蘖、穗粒数与栽培品种有明显差异;(2)杂草稻果皮颜色的表型多样,89.29%为红色或者褐色(由浅至深)、10.71%为白色,其基因型与表型鉴定结果高度一致,红色果皮杂草稻在Rc位点均无14 bp缺失;(3)InDel标记和籼粳分化分析表明:56份杂草稻中有44份是典型籼型杂草稻、5份为籼型杂草稻、3份为偏籼型杂草稻、4份为中间型杂草稻,它们之间的遗传差异小;通过聚类分析,56份杂草稻中的92.86%的属于籼型杂草稻,7.14%属于中间型杂草稻,与当地粳型栽培稻有着较远的亲缘关系。根据研究结果推断,黄河流域豫北粳稻区杂草稻的发生,可能主要经由曾经种植过的籼粳栽培品种杂交而产生,或者是种植的杂交品种收获后落粒的后代去驯化而产生。本研究为黄河流域豫北地区杂草稻的防控提供了理论依据。     

中国普通野生稻与栽培稻种SSR多样性的比较分析

采用48对SSR引物对288份我国普通野生稻和栽培稻的遗传多样性进行比较分析。结果显示, 共检测到505个等位基因, 每个位点的等位基因数变幅为5~20, 平均10.5个; 平均Nei基因多样性指数(He)为0.731, 变幅为0.384(RM409)~0.905(RM206)。普通野生稻遗传多样性高于栽培稻种, 栽培稻等位基因数和平均Nei基因多样性指数分别为普通野生稻的70.2%和88.2%, 其中, 栽培稻地方品种和选育品种等位基因数分别为普通野生稻的65.4%和53.0%, 选育品种等位基因数仅为地方品种的81.1%。AMOVA分析表明, 总变异的10.3%是由于种间SSR遗传差异所引起的, 不同SSR位点种间的分化程度不同, 在0.7%~46.3%之间, 有43个位点种间遗传分化达到显著水平, 其中以RM427分化最为明显, 达46.3%。聚类分析表明, 中国普通野生稻总体偏粳, 极少数广东、海南材料偏籼。     

贵州旱稻种质资源的SSR遗传多样性分析

本研究利用24对水稻微卫星（SSR）标记对源自贵州部分县乡种植以及早期基因库收集的112份地方旱稻材料的遗传多样性进行分析,结果共检出187个等位基因,每个位点的等位基因变幅为4～13个,平均Nei＇s基因多样性指数为0.6431,平均香农指数为1.3669。籼粳亚种均具有较高的遗传多样性,前者稍高于后者,但差异不明显。黔西南州拥有最多的种质,存在丰富的遗传变异,是贵州旱稻种质资源遗传多样性分布中心。分子方差分析表明,旱稻种质总变异的88%是由各地区内的群体间差异造成,地区间和各个群体内的遗传变异较小,均为6%。不同地区旱稻种质的遗传分化程度不一,变幅为2%～18%。聚类分析将供试旱稻材料较为明显地分为籼粳两个类群,而地理分组不明显。     

水稻氮高效利用基因NRT1.1B InDel分子标记的开发与应用

水稻NRT1.1B基因是已经克隆并进行功能验证的氮高效利用基因,具有很高的应用价值。根据籼粳稻NRT1.1B基因的基因组序列比对发现,籼型NRT1.1B基因及粳型NRT1.1B基因内含子序列中存在插入/缺失位点。对30个常规籼粳稻的NRT1.1B基因内含子序列进行PCR扩增、测序及序列比对,发现NRT1.1B基因内含子存在6个In Del位点,籼型NRT1.1B基因比粳型NRT1.1B基因缺失55 bp。根据插入/缺失位点设计出In Del分子标记,对15个籼稻常规稻品种、15个粳稻常规稻品种、3个籼粳杂交稻品种及20个F2代育种材料进行NRT1.1B籼粳基因型鉴定。检测实验表明与通过NRT1.1B基因的SNP位点开发的功能标记的检测完全一致。通过该标记可以准确鉴定NRT1.1B基因的纯合籼型、纯合粳型及杂合基因型,该方法成本低、简单、可靠,可用于NRT1.1B基因的鉴定和分子标记辅助育种。     

基于高通量测序的大麦In Del标记开发及应用

分子标记是遗传研究的基础工具,广泛应用于遗传多样性研究、种质鉴定、遗传图谱构建和基因定位等领域。本研究基于大麦的全基因组重测序数据鉴定出的二态性SNP位点,开发出遍布全基因组的118对InDel引物。以49份不同地理来源的大麦种质检测其有效性,筛选出2个等位基因的共显性InDel标记72对,进一步对288份大麦种质进行遗传距离分析及构建系统发育树。结果显示,筛选到32个有效性的核心InDel标记,覆盖大麦7条染色体上,平均PIC为0.44,平均MAF为0.34;基于InDel标记位点的供试大麦的系统发育树结果揭示供试大麦具有丰富的遗传多样性,且能够将具有相同地理来源的多数品种聚为一类。表明开发的32个二态性InDel标记可有效地用于鉴定品种间的亲缘关系,且丰富了大麦品种鉴定的分子标记。上述核心InDel标记在大麦品种鉴定、大麦资源亲缘关系分析以及群体划分方面具有一定的理论意义和应用价值。     

东乡野生稻与日本晴多态性标记的开发

东乡野生稻是分布于全球最北端的一种普通野生稻,与亚洲栽培稻基因组差异较大,目前缺少覆盖其全基因组的分子标记。本文以东乡野生稻和日本晴为材料,通过筛选已有的1017个标记,并利用东乡野生稻基因组重测序信息设计的217个InDel标记,共检测出203个标记在东乡野生稻与日本晴间呈现多态性。这些标记均匀分布于12条染色体,平均间隔1.9 Mb,基本覆盖东乡野生稻全基因组区域。通过对籼粳亚种的检验分析,发现该套多态性分子标记在东乡野生稻与粳稻杂交后代群体基因型分析上具有较高的应用价值。本研究结果为发掘东乡野生稻的有利基因以及分子标记辅助选择育种提供了有力的工具。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form. This revised version was published online in July 2006 with corrections to the Cover Date.