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。     

水稻淀粉合成相关基因对稻米RVA谱特征的影响

以优质粳型糯稻苏御糯为供体，品质较差的籼稻桂朝2号为轮回亲本，构建了BC₂F₄群体，通过发展分子标记，研究了淀粉合成相关基因Wx、Sbe1、Sbe3、Isa、Pul、SssⅠ等对稻米淀粉RVA谱特征的影响。结果表明Wx基因对RVA谱8个特征值的表现均起主要作     

利用基因示踪分子标记对水稻淀粉合成基因进行功能分析

细粒粘连淀粉合成酶、淀粉分支酶1和淀粉分支酶3是关系到水稻胚乳中淀粉生物合成的3种主要酶。为了鉴定籼稻品种93-11和粳稻品种日本晴基因组数据库中的同源区域，已经使用了编码相应淀粉分支酶1和淀粉分支酶3的Sbe1、Sbe3基因的通用序列。使用序列多样性来开发出基因示踪标记，以便区分这两个位点Sbe1和Sbe3中的籼稻等位基因和粳稻等位基因。     

小麦籽粒淀粉分支酶同工酶基因型与酶活性关系研究

测定了71个小麦品种的籽粒淀粉分支酶活性,并采用非变性聚丙烯酰胺凝胶电泳（Native-PAGE）,鉴定了分支酶同工酶的基因型,以明确小麦籽粒淀粉分支酶（SBE）各同工型等位基因的分布特点和基因型组成,阐明分支酶活性与分支酶同工酶基因型的相关性。结果表明,分支酶有SBEⅠ和SBEⅡ两个基因位点,SBEⅡ位点未显现多态性,SBEⅠ位点存在多样性。在SBEⅠ位点鉴定出A、B、D_ⅰ和D_ⅱ共4个等位基因位点,各等位基因位点出现频率分别为9.9%、76.1%、95.8%和57.8%;共检测到9种基因型,其中基因型D_ⅰD_ⅱB、D_ⅰB和D_ⅰD_ⅱ有较高的分布频率,分别为45.1%、28.2%和8.5%。从单一位点分析,分支酶活性与SBEⅠ位点有显著的相关性,与SBEⅡ位点相关性不显著。由此可见,小麦籽粒胚乳淀粉分支酶同工酶不同基因位点和基因型对酶活性具有不同的遗传效应。     

水稻Wx复等位基因基于PCR的功能标记开发与利用

直链淀粉含量是影响稻米食味品质的重要因素,主要由蜡质基因(Wx)调控,Wx基因座存在Wxa、Wxb、Wxin、Wxmw等多个复等位基因,通过分子标记辅助选择(marker-assisted selection,MAS)培育中低直链淀粉含量的水稻品种是提高稻米适口性的重要途径。Wx复等位基因的功能由单碱基核苷酸多态性(single nucleotide polymorphisms,SNP)决定,其检测依赖于测序或酶切,存在耗时多、费用昂贵等缺点。为提高选择效率,本文利用Wx复等位基因的SNP差异和四引物扩增受阻突变(tetra-primer ARMS-PCR)原理,进行PCR功能标记的开发。引物设计过程中,针对扩增效率低和非匹配的延伸2个技术难题,提出了调整错配位点的解决方案,成功开发了基于PCR技术的两对功能性标记Waxygt-ARMS2和Waxyac-ARMS2,可以准确区分上述复等位基因型,且具有操作简单、耗费较低的特点。利用新开发标记对辽宁省育成的部分水稻品种进行Wx基因型检测的结果表明,40份辽宁育成品种均携带Wxb基因,遗传基础单一。上述结果为利用Wx基因位点的分子标记培育中低直链淀粉含量的水稻品种,改良辽宁省水稻品种的食味品质提供了技术支撑。     

利用分子标记鉴定水稻品种的Wx等位基因及其与直链淀粉含量的关系

应用Wx基因的微卫星标记484/485和PCR-AccⅠ分子标记对93份籼、粳水稻品种（系）的Wx基因的多态性进行了研究,并探讨了不同基因型与直链淀粉含量的关系。484/485扩增结果表明,该微卫星标记表现为3种基因型,即Wx1Wx1、Wx2Wx2和Wx3Wx3,其中籼稻以Wx1Wx1和Wx3Wx3为主,粳稻以Wx2Wx2为主,具有Wx1Wx1和Wx2Wx的品种（系）直链     

人工老化对不同Wx基因型稻米品质及RVA谱的影响

为了解不同Wx基因型稻米在贮藏过程中的食用蒸煮品质和RVA谱变化,采用高温高湿人工加速老化方法,对5个携有不同Wx等位基因水稻品系的种子在87.5%相对湿度和42℃条件下分别处理0、5 d、10 d、15 d、20 d、25 d和30 d。结果显示,经高温高湿老化处理后,稻米直链淀粉含量、碱消值和胶稠度的变化不大,而RVA谱特征值在整个老化过程中存在较大波动。总体来看,消减值的变异系数最大,达20.71%;其次是崩解值和回复值,分别达到17.52%和14.25%;峰值时间和起浆温度的变异系数最小,只有2.34%和0.91%。不同Wx基因型稻米RVA特征值在老化过程中的稳定性并不一致。其中,Wxt基因型稻米的最高黏度和崩解值变异幅度最小;Wxg1基因型稻米的热浆黏度、消减值、回复值和峰值时间最为稳定;Wxg2基因型稻米冷胶黏度的波动最小。本研究结果,可为今后在水稻品质耐储藏实践中延缓稻米品质的劣变提供理论依据和参考。     

RVA谱在稻米蒸煮食用品质评价及遗传育种方面的研究进展

在稻米的品质改良中,利用粘度速测仪测定稻米淀粉粘度特性作为估计稻米食用品质一个很重要指标。这种测定具有测定简单快速和用量小的特点。美、日等发达国家已经广泛水稻品质育种中应用。中国在近些年开始应用。对稻米淀粉RVA谱在稻米蒸煮食用品质评价,稻米淀粉RVA谱遗传及在育种上应用的研究进展进行了总结并提出了一些可能研究利用方向。RVA谱能较好地区分AAC相似的品种的食味。RVA与稻米食味、米饭质地以及其它与米饭食味相关的理化指标均密切相关,已经在杂交育种和诱变育种等育种上应用。RVA谱主要受单基因（Waxy）加性效应控制,可在F4代及其以后种子进行选择。不同地点环境对RVA谱影响很大。     

稻米淀粉品质遗传与改良研究进展

本文介绍了稻米淀粉品质性状的含义和主要内容,较全面地总结了直链淀粉含量、糊化温度、胶稠度、RVA谱、支链淀粉结构、淀粉膨胀体积以及淀粉凝胶的质构和老化特性等性状的遗传研究进展.总结了淀粉品质与其它品质性状与农艺性状的遗传相关性,环境条件(灌浆结实期气温)及基因型×环境互作效应对稻米淀粉品质的影响,及分子辅助选择与基因工程技术改良稻米淀粉品质的研究进展.今后淀品质研究应集中在淀粉品质相关性状形成的基因网络解析、淀粉基因分子标记挖掘、淀粉品质的多基因聚合育种及淀粉品质分子设计的数据库建设.通过应用基础研究以及相关技术集成,特别是分子设计(聚合)育种技术的实践,有望培育出淀粉品质符合市场要求的优良品种.     

粳稻精米脂肪含量和组分对蒸煮品质的影响及其对氮素的响应

选用6个穗型不同的粳稻品种,采用7个氮肥处理,研究了精米中脂肪含量和组分对稻米直链淀粉含量和RVA特征值的影响及其对氮素的响应。结果表明,水稻精米中脂肪含量及组分存在显著的基因型差异。小穗型品种宁粳1号、早丰9号和武育粳3号精米中粗脂肪含量和淀粉脂(SL)含量分别大于或等于与之对应的大穗型品种宁粳2号、徐稻4号和9522; 精米中非淀粉脂(NSL)含量小穗型品种宁粳1号、早丰9号和武育粳3号均小于或相近于与之对应的大穗型品种宁粳2号、徐稻4号和9522。氮素对精米脂肪含量及组分的影响小于基因型,而且对于不同的基因型水稻氮素对脂肪的调控作用不同。精米中粗脂肪含量及各脂肪组分含量与直链淀粉含量(AC)及RVA特征值关系密切。精米中粗脂肪含量与脱脂前后的崩解值(BDV)呈极显著负相关,SL与直链淀粉含量(AC)、脱脂前后的消减值(SBV)和回复值(CSV)均呈显著或极显著负相关。从这些结果可以看出,精米中脂肪含量尤其是SL含量对稻米的蒸煮食味品质有显著影响,提高精米中SL含量能够提高稻米的蒸煮食味品质。     

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.