玉米自交系幼胚愈伤组织诱导的条件优化

本研究以铁7922、H99、丹598和丹988四个玉米自交系的幼胚为材料,对影响愈伤组织诱导和继代的几个重要因素进行研究。结果表明,2mg/L的2,4-D有利于胚性愈伤组织的形成,基因型、培养基、胚龄和4℃冷存时间对其也有明显影响。此外,添加KT、Ca2+和AgNO3,H99和丹988的胚性愈伤率明显提高,而铁7922的胚性愈伤率则有所下降。此外,Ca2+的添加对丹598的胚性愈伤率没有明显影响。     

不同品系橡胶树花药愈伤诱导和体胚发生研究

为建立橡胶树不同品系的体胚发生和植株再生体系,为不同品系橡胶树良种生产奠定基础。以橡胶树优良品系‘热研106’、‘热试59’、‘热试62’的花药为材料,采用正交设计,对不同品系、不同植物生长调节剂配比培养基的花药愈伤和体胚诱导效果进行了研究。[结果]结果表明：3个品系的愈伤诱导率和体胚诱导效率差异明显,同一品系不同培养基的愈伤诱导率和体胚诱导效率差异明显;愈伤诱导培养基中的植物生长调节剂对下一阶段的体胚诱导有明显影响。根据本研究,‘热研106’的花药愈伤诱导最佳浓度组合为2,4-D 1 mg/L+NAA 2 mg/L+KT 1 mg/L,‘热试59’的花药愈伤组织诱导最佳浓度组合为2,4-D 0.5mg/L+NAA 1 mg/L+KT 1 mg/L,‘热试62’的花药愈伤组织诱导最佳浓度组合为2,4-D 1 mg/L+NAA 1 mg/L+KT 1 mg/L。‘热试62’的体胚发生最佳浓度组合为KT 3 mg/L+NAA 0.05 mg/L+GA3 0.05 mg/L+6-BA 0.5 mg/L。[结论]本研究获得了不同品系的愈伤诱导和体胚发生最佳培养基组合,为多品系橡胶树花药植株再生体系的建立奠定了基础。     

糯玉米的成熟胚培养

以糯玉米成熟胚为外植体作离体培养,研究在培养基中添加植物激素,硝酸银及有机物等对玉米愈伤组织的诱导和胚性愈伤继代生长的影响。结果表明：在诱导培养阶段,N6+6-BA 0.2mg/L+2,4-D 2mg/L的培养基诱导率最高,愈伤质量好;在继代培养阶段,MS+6-BA 0.2mg/L+2,4-D 2mg/L +AgNO310mg/L或CW (Coconut Water) 10%的培养基可改善胚性愈伤的质量。     

菠萝花药愈伤组织诱导及褐变影响因素初探

以菠萝为试材,筛选了花药愈伤组织诱导最适激素组合,同时通过正交试验研究了基因型、取样时期及添加AgNO3等因素对菠萝花药培养过程中愈伤组织诱导及褐变的影响。结果表明：菠萝花药培养诱导愈伤组织最佳激素组合为2 mg/L 2,4-D+0.08 mg/L TDZ;正交试验三个因子对愈伤组织诱导的影响主次顺序为AgNO3>取样时期>基因型,对褐变影响主次顺序为AgNO3>基因型>取样时期,其中AgNO3最适浓度为50 mg/L。     

玉米优良自交系成熟胚愈伤组织诱导

玉米是重要的粮食作物和饲料作物,建立稳定、高效的玉米转化体系无疑具有重要的理论意义和应用价值。试验对自交系492、自交系26及自交系758的成熟胚愈伤组织诱导和植株再生的条件进行了摸索。结果表明在诱导培养基中添加4mg/L的2,4-D,可显著提高成熟胚愈伤组织诱导率;在继代培养基中添加10mg/L的AgNO_3、150mg/L的L-半胱氨酸,玉米成熟胚的胚性愈伤组织诱导率高。     

降低玉米成熟胚愈伤组织褐化的初步研究

本研究以k12、137等2个骨干自交系的成熟胚为外植体,以N6培养基为基本培养基,研究培养基中附加甘露醇、Vc、活性炭并辅以生长调节物质6-BA、2,4-D对玉米成熟胚愈伤组织褐化的影响。结果表明:培养基中附加甘露醇、Vc、活性炭对愈伤组织的褐化影响不同,其抗褐化能力为:甘露醇(20g/L)Vc(2mg/L)活性炭(2g/L)空白。辅助添加6-BA、2,4-D时防治褐化作用更加明显,且添加的浓度不同,防治效果也不同,其中N6培养基+20g/L甘露醇+0.2mg/L6-BA+4mg/L2,4-D效果最佳。另外,暗培养能显著减轻褐化的发生,有利于愈伤组织的形成。     

甜瓜松散型胚性愈伤组织诱导

为建立甜瓜松散胚性愈伤组织再生体系，给分子标记辅助育种、转基因育种、诱变育种等新型的育种技术提供优质材料，以甜瓜成熟叶片为外植体，调节培养基中激素、蔗糖浓度以及愈伤组织继代次数诱导甜瓜松散型胚性愈伤组织。结果表明，在2,4-D的作用下叶片能诱导出愈伤组织，在MS+0.1 mg/L 6-BA+2.0 mg/L 2,4-D+20 g/L蔗糖的培养基上，可以获得结构松散、质地较软呈黄绿色的愈伤组织；诱导松散型愈伤组织最佳培养基为MS+0.5 mg/L 6-BA+1.0 mg/L 2,4-D+30 g/L蔗糖，经过3次继代后可以获得生长速度较快，结构松散、质地较硬呈黄绿色的松散型愈伤组织；在MS+0.25 mg/L 6-BA+0.25 mg/L 2,4-D+40 g/L蔗糖的培养基上愈伤组织胚性化最好，继代5次，可获得结构松散、质地较硬，生长速度较快的松散型胚性愈伤组织。     

宁夏枣树花药离体培养再生体系的建立

采用宁夏3个特色枣树品种的花药为外植体,探索MS培养基中不同激素、激素的不同浓度配比对愈伤组织诱导、不定芽分化的影响,建立其愈伤组织诱导及不定芽再生体系。结果表明,细胞分裂素6-BA对宁夏枣树胚性愈伤组织诱导起重要作用,AgNO3对愈伤组织分化不定芽影响显著。经过正交试验分析得出,最佳诱导培养基为MS+6-BA 1.0 mg/L+2,4-D1.0 mg/L+IBA 0.4 mg/L;最佳分化培养基是：MS+6-BA 1.5 mg/L +IBA 0.6 mg/L +AgNO3 0.5 mg/L。在最佳诱导培养基中灵武长枣诱导率最高,达89.0%,在最佳分化培养基中同心圆枣分化率最高,达88.0%。     

高羊茅高效组织培养再生体系的建立

植物分子育种与基因功能鉴定是建立在高效的组织培养再生体系基础上的。本研究以高羊茅(Festuca arundinacea Schreb)为材料,探讨了不同外植体状态、基本培养基类型、外源激素组合与固化剂种类与浓度对愈伤组织诱导的影响,并进行了愈伤组织分化长芽与生根研究。结果表明:愈伤组织诱导过程中,离体成熟胚比完整种子作外植体愈伤组织出现早、质量优、诱导率高;基本培养基的选择上以N6诱导率最高,MS最低;激素组合研究中高羊茅三个品种(SAFari, FirewarⅡ, Barleduc)在无6-BA培养基中,生长激素选择上都是2,4-D优于IAA,2~2.5 mg/L 2,4-D在三个品种中诱导率都在50%以上,而在添加0.5 mg/L 6-BA时诱导率都偏低;固化剂选择上则以Phytagel与Agarose二都最优,Phytagel固化剂最佳诱导浓度为2~4 g/L。分化长芽最佳培养基为MS+0.1 mg/L 2,4-D+0.1 mg/L 6-BA+0.5 mg/L NAA+20 mg/L AgNO3+2%蔗糖+0.6%琼脂,生根壮苗最佳培养基为1/2MS+0.5 mg/L NAA+3%蔗糖+0.3%Phytagel。本研究为高羊茅的高效转基因体系建立与CRISPR基因功能研究提供准备。     

2种甜玉米自交系幼胚再生体系的建立

本试验研究不同基因型、幼胚大小、培养基类型及培养基添加物对2种甜玉米(2-105和2-118)自交系幼胚愈伤及胚性愈伤组织诱导率的影响。结果表明,基因型、培养基类型、幼胚大小及不同浓度脯氨酸和2,4-D处理对愈伤及胚性愈伤诱导率影响差异均显著。2种基因型最适宜的基本培养基为N6培养基,且2-118的愈伤及胚性愈伤诱导率显著高于2-105。幼胚在1.5~2.0 mm时,2-105和2-118的愈伤及胚性愈伤诱导率均最高,分别在77%和51%以上。2-105和2-118在脯氨酸浓度分别为650 mg/L、750 mg/L时幼胚的愈伤及胚性愈伤诱导率最高,且显著高于其它2个水平。2种基因型在2.5 mg/L的2,4-D诱导下愈伤及胚性愈伤诱导率均最高,且均显著高于其它2个水平。本研究获得了2种甜玉米自交系的再生体系,为甜玉米遗传转化和分子育种提供基础。     

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.