普通荞麦愈伤组织诱导及其分化的正交设计试验研究

用正交设计法研究不同激素处理及不同外植体对普通荞麦愈伤组织诱导及分化过程中的影响。结果表明，在本实验设计中，2，4-D是诱导普通养麦愈伤组织的主要因素；诱导愈伤组织的最佳培养基为MS＋2．0mg／L 2，4-D＋1．5mg,／L 6-BA；愈伤组织分化的主要因素是6-BA；愈伤组织分化的最佳培养基为MS＋2．5mg／L 6-BA＋1．0mg／LKT。     

紫花地丁的组织培养和植株再生

以未成熟种子萌发的子叶和下胚轴为外植体建立了紫花地丁的组织培养及植株再生体系，结果表明最适愈伤组织诱导培养基为MS＋2，4-D 0．5mg／L＋6．BA0．5mg／L或者MS＋2．4-D1mg／L＋6-BA 0．2mg／L，愈伤组织诱导率可达100％，将生长良好的愈伤组织转入分化培养基可诱导芽或根的分化，其中诱导芽的最适培养基为MS＋6-BA1mg／L＋2。4-D0．5mg／L，诱导根的最适培养基为MS＋2，4-D1mg／L＋6-BA 0．2mg／L，两种器官分化途径均能有效再生成苗。     

宁夏主栽水稻品种高频再生体系的建立

通过对宁夏多个主栽水稻品种愈伤组织的培养,结果表明,诱导水稻愈伤组织的最适培养基是:N6+2mg/L 2,4-D+0.5/L水解酪蛋白+0.5g/L L-脯氨酸+8g/L琼脂+30g/L蔗糖;水稻愈伤组织最适分化培养基是:MS+2mg/L 6-BA+0.5mg/L NAA;水稻的最适生根培养基为:MS+0.5mg/L NAA.筛选出了诱导愈伤组织和愈伤组织分化的最适激素浓度配比和最适分化条件.     

油梨愈伤组织诱导及分化研究

摘要：[目的]研究不同激素及外植体类型对‘哈斯’油梨（Persea Americana Mill.cv.Hass）愈伤组织诱导及分化的影响,筛选最佳诱导条件和外植体。[方法]通过间接器官发生途径。主要探讨（1）单一激素萘乙酸（1-Naphthylacetic acid,NAA）、2,4-二氯苯氧乙酸（2,4-dichlorophenoxy acetic acid,2,4-D）;6-苄氨基腺嘌呤（6-Benzylaminopurine,6-BA）分别与2,4-D和NAA 结合时对‘哈斯’油梨叶片愈伤组织的诱导效应。（2）不同外植体（叶片、叶柄、茎尖、茎段）在相同条件下（基本培养基：MS+1 mg/L 2,4-D+0.5 mg/L 6-BA+0.1NAA mg/L）的愈伤组织诱导效应。（3）单一激素 6-BA（或与NAA结合）对油梨愈伤组织芽分化的效应。[结果]结果表明：以MS为基本培养基,（1）添加1.0 mg/L 2,4-D/NAA,其诱导效果最佳,诱导率分别为45.3%和20.2%;但NAA诱导的愈伤质地较佳。（2）1 mg/L NAA与1.0 mg/L 6-BA结合,诱导效果较好,其诱导率最高可达84%。（3）诱导愈伤组织的最适外植体为茎段,其诱导率≥72.8%。叶柄次之,叶片和茎尖较差。[结论]综上,不同激素种类及其浓度和外植体类型对‘哈斯’油梨愈伤组织诱导影响显著。最佳诱导培养基为MS+1.0 mg/L NAA+1.0 mg/L 6-BA+30 g/L蔗糖+7g/L琼脂。愈伤组织诱导最佳外植体为茎段,但诱导形成的愈伤组织难以分化出芽。     

冬小麦成熟胚高频愈伤组织形成和分化的适宜条件研究

以4个冬小麦品种的成熟胚为外植体,研究了温度预处理、愈伤组织诱导培养基中2,4-D浓度和分化培养基激素种类及其配比对小麦成熟胚愈伤组织形成和分化的影响。结果表明,与室温25℃相比,低温4℃预处理能明显改善愈伤组织的形成率。适宜愈伤组织形成的诱导培养基中2,4-D浓度以4 mg/L为宜,分化培养基中含有1 mg/LKT 2 mg/L 6-BA较仅含有1 mg/L KT或2 mg/L 6-BA能明显促进愈伤组织的分化。相同培养条件下,不同品种间的愈伤组织形成和再生能力存在较大差异。因此,进行低温种子预处理、愈伤组织诱导过程中采用适宜的2,4-D浓度,以及分化过程中采用适宜的激素组合是冬小麦高频愈伤组织形成和分化的重要条件。     

提高水稻愈伤组织再生频率的研究

以长时间继代的水稻成熟胚愈伤组织为试验材料,研究激素配比、继代方式、干燥处理和添加物对分化的影响。结果表明,分化培养基中加3 mg/L BA对分化有利;继代培养基中加入3 mg/L ABA,以麦芽糖代替蔗糖,或以甘露醇代替部分蔗糖在一定程度上可以改善愈伤组织状态,提高分化率;干燥处理能明显提高愈伤组织分化率;分化培养中添加一定浓度的AgNO3和CuSO4有利于愈伤组织分化。     

影响籼粳稻杂交F1花药培养效果的因素分析

以津稻291/IRBB60籼粳杂交F1、反交F1及其亲本的花药为外植体,对诱导和分化培养基、激素配比及有机附加物和高温预培养时间等影响花药培养效果的因素进行研究。结果表明,在SK3基本培养基中添加2 mg/L 2,4-D,1 mg/L NAA和1 mg/L KT比只添加2 mg/L 2,4-D的愈伤诱导率高0.67～2.78个百分点;在诱导培养基中添加水解酪蛋白能明显提高正交F1的愈伤诱导率;MS 1 mg/L NAA 2 mg/L 6-BA 0.5 mg/L KT分化培养基得到了较高的绿苗分化率;正交F1的愈伤诱导率、绿苗分化率和花培力显著高于反交F1;30℃高温预培养36 h,正交F1花培力达到最高值。     

甘草愈伤组织再分化的研究

以多年野生乌拉尔甘草的不同营养器官为外植体进行愈伤组织诱导,试验结果表明:适宜的愈伤组织诱导培养基为:MS+BA2mg/L+2,4D0·5mg/L;分化培养基为:MS+BA2mg/L+NAA1·0mg/L;以甘草芽做外植体愈伤组织分化率达到100%。利用愈伤组织进行再分化是较为理想的增殖途径,其繁殖系数达20~40倍。比芽的增殖系数高2·5倍。     

龙芽槐木愈伤组织诱导及胚状体发生初探

以樵木幼茎及根为试材，添加不同种类和浓度的激素，进行愈伤组织诱导、胚状体发生及幼苗分化。结果显示，幼茎在MS＋2，4-D1．0mg／L培养基上愈伤组织诱导率最高。愈伤组织在MS＋BA1．0mg／L＋NAA0．04mg／L培养基上胚状体形成最多，幼苗分化率达92．5％，并能保持旺盛的再生能力。     

天蓝苜蓿花药愈伤组织诱导及再生体系的建立

为获得天蓝苜蓿单倍体再生植株,本研究以野生天蓝苜蓿花药为外植体,采用正交设计L₁₆(4⁴)筛选适宜天蓝苜蓿愈伤组织诱导培养基,比较不同基本培养基及生长调节剂组合筛选适宜的分化培养基,并用1/3MS、1/2MS和MS添加不同浓度的NAA研究不定生根。结果表明:天蓝苜蓿现蕾15~25 d的花药其愈伤组织诱导效果最好,高达60.5%。4℃低温预处理2~4 d有利于愈伤组织诱导,诱导率达77.2%。适宜花药愈伤组织诱导的培养基为NB+2,4-D 1.0 mg/L+NAA 0.5 mg/L+6-BA 0.5 mg/L+TDZ 1.0 mg/L,诱导率达78.5%。比较不同基本培养及生长调节剂的不同组合发现,NB培养基愈伤组织分化效果优于B₅和MS,NB+NAA0.5 mg/L+6-BA 2.0 mg/L适宜愈伤组织的分化,分化率为66.3%。不定芽在1/3MS+NAA 0.5 mg/L中培养,生根率最高,为86.55%。本研究建立了天蓝苜蓿花药培养再生体系,获得了单倍体植株,为天蓝苜蓿的育种实践及基因组学研究提供基础材料。     

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.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

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.     

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 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.     

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.