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。     

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。     

啤酒大麦品种甘啤4号成熟胚再生体系的建立

建立啤酒大麦品种甘啤4号成熟胚再生体系可为其遗传转化奠定基础。本研究以甘啤4号成熟胚为材料,研究不同诱导培养基对其愈伤组织诱导及分化的影响,并通过添加不同浓度梯度的Ag NO3(0,2.5 mg/L,5.0 mg/L,7.5 mg/L,10.0 mg/L,15.0 mg/L)和ABA(0,0.1 mg/L,0.3 mg/L,0.5 mg/L,0.7 mg/L,1.0 mg/L),观察其愈伤组织形态变化,统计出愈率、绿点率,探索适宜甘啤4号成熟胚组织培养的条件。同时在0、7 d、14 d、21 d和二叶期分别测定成熟胚再生过程中SOD、POD、CAT活性、MAD、可溶性蛋白及内源激素(IAA,ABA,GA3)的含量,为优化成熟胚再生体系准备条件。研究结果表明:培养基NMB较适宜甘啤4号成熟胚再生培养,发现添加适量Ag NO3和ABA有助于愈伤组织的诱导及分化,但Ag NO3处理的效果较ABA明显,其诱导甘啤4号愈伤组织的最适浓度分别为7.5 mg/L和0.5 mg/L;观察到不同时期酶活性大致均呈现先上升后下降的趋势,内源激素含量也随着培养时期的不同有所差异。研究结果可为添加外源激素、进一步优化培养条件奠定了基础。     

苏玛栎胚性愈伤组织诱导及体胚发生

取苏玛栎成熟大树基部萌条进行离体培养,利用无菌苗茎段成功诱导出胚性愈伤组织,并进一步诱导出子叶期的体细胞胚胎。试验结果表明:苏玛栎茎段置于添加2 mg/L 2,4-D和0.2 mg/L KT的MS培养基上,黑暗培养30 d后,诱导出愈伤组织;将胚性愈伤组织置于添加3 mg/L BA和0.5 mg/L NAA的MS培养基上,黑暗培养40 d,有利于胚性愈伤的增殖;转入添加0.5 mg/L ZT和0.1 mg/L NAA的MS培养基中,黑暗培养60 d后,原胚团经历球形胚、心形胚、鱼雷形胚,发育至子叶胚阶段,但诱导率最高仅为10%。本研究为苏玛栎种质资源保存、无性繁殖和遗传改良提供了一定的科学依据。     

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。     

玉米幼胚再生体系的建立

为建立高效稳定的玉米再生体系,以玉米幼胚为受体材料,研究了基因型对胚性愈伤组织诱导率的影响以及适宜玉米幼胚生长的诱导培养基、继代培养基、分化培养基及生根培养基。结果表明,基因型可显著影响胚性愈伤组织诱导率,H99×A188的诱导率最高(45.28%);N6培养基适合用于胚性愈伤组织的诱导同时也适合继代培养;激素组合为MS+6-BA 1.0 mg/L+KT 2.0 mg/L的分化培养基出苗率和转化率最高,易成活;1/2MS培养基附加IBA1.0 mg/L和1.0 g/L活性炭适合于生根培养。     

冰灯玉露体细胞胚诱导及其形态学和解剖学分析

以多肉冰灯玉露(Haworthia cooperivar)叶片为外植体,诱导、增殖胚性愈伤组织和植株再生;用Spurr树脂包埋组织切片技术对颗粒状的胚性愈伤组织进行形态学和组织结构特征进行研究。结果表明,外植体在改良的MS+1.5 mg/L 6-BA+0.5 mg/L IAA培养基上可诱导出淡黄色、颗粒状的胚性愈伤组织,其诱导率高达66.7%。胚性愈伤组织在MMS+1.5 mg/L 6-BA+0.4 mg/L IAA培养基上增殖效果最佳,其净增殖量高达14.73 g。胚性愈伤组织上分化的胚状体为乳白色球形或心形结构,由细胞核大、胞质浓密、内含淀粉颗粒的、分裂旺盛特征的细胞构成。内部的胚性愈伤组织呈螺旋状或椭圆形。这些愈伤组织在添加0.1～0.2 mg/L IAA的MMS培养基上进一步发育形成体细胞胚,并在愈伤组织表面分化形成完整的丛生小植物体,体细胞胚在MMS+0.1 mg/L IAA培养基上再生形成根系粗壮的完整的小苗。小苗经驯化后移栽,成活率达100%。该研究为冰灯玉露快速繁殖与分子育种提供了技术支撑。     

野生平贝母体细胞胚胎发生及植株再生体系的建立

以野生平贝母根尖为外植体,应用均匀设计法筛选其最适合的胚性愈伤组织及胚性细胞复合体诱导、体细胞胚烫发育及植株再生的培养基,建立了平贝母体细胞胚胎发生体系.结果表明,平贝母根尖胚性愈伤组织及胚性细胞复合体诱导最适宜的培养基为:ER(Eriksson,1965)+6-BA 1.0 mg/L+IAA2.0 mg/L+2,4-D 0.1 mg/L,诱导率为95%;体胚发育及植株再生最适宜的培养基为:ER+6-BA 1.00mg/L+IAA 0.10mg/L,体胚萌发率为100%,萌发的体胚在发育培养基上继续培养40d后全部发育成完整植株.对不同阶段培养材料的形态结构及超微结构的观察证明了平贝母体细胞胚胎的发育过程.     

通过多种培养基优化长白落叶松体细胞胚再生

为建立稳定高效的落叶松体细胞胚再生体系,本研究以长白落叶松未成熟合子胚作为外植体材料,选择生长良好的胚性愈伤组织,依次通过液体培养基A,半固体培养基B,固体培养基C三种成熟培养基诱导体细胞胚形成。其中,愈伤诱导培养基为S培养基+2,4-D 1.0 mg/L+6-BA 0.5 mg/L+KT 0.3 mg/L,蔗糖20 g/L,琼脂3 g/L;继代培养基为S培养基+2,4-D 0.15 mg/L+6-BA 0.05 mg/L+KT 0.05 mg/L,蔗糖30 g/L,琼脂6 g/L;成熟培养基A为S培养基+PEG-4000 100 g/L+ABA 15 mg/L+Ag NO310 mg/L,蔗糖45 g/L的液体培养基;成熟培养基B和C分别为添加了2 g/L和10 g/L琼脂的成熟培养基A。该方法体胚成熟时间为32 d左右,同步率为78.0%,正常形态体胚比例为83.0%。正常形态体胚形成效率可达223.0个/g胚性愈伤,体细胞胚萌发率可达47.2%。相较于单一成熟培养基,缩短成熟时间,使体胚生成更同步,并提高了体胚产量和质量。为落叶松体胚再生的商业化提供了途径,为大规模化育种繁殖、生理生化研究和转基因改良带来极大的方便,具有较大实际应用价值。     

不同诱导条件对尾巨桉愈伤组织及体胚诱导的影响

本研究以尾巨桉无性系(32-29)无菌苗茎段作为外植体,进行组织培养及植株再生研究,通过优化不同浓度的植物生长调节剂组合以及LM、1/2LM以及MS不同培养基和不同浓度蔗糖溶液、不同温度的预处理,探讨尾巨桉胚性愈伤组织诱导的适宜培养基和培养条件。结果表明,在添加了1.5 mg/L 2,4-D与1.0 mg/L6-BA的改良1/2LM培养基上,茎段外植体培养6 d后愈伤组织诱导率达96%以上。将愈伤组织接种在0.01 mg/L TDZ+0.2 mg/L NAA激素组合的培养基中体胚诱导率最高可达到19.5%。本研究为尾巨桉胚状体诱导及植株再生提供了借鉴与参考。     

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.