脱落酸对棉花体细胞胚胎发生的影响

【目的】研究脱落酸(Abscisic acid, ABA)对棉花体细胞胚胎发生过程中下胚轴脱分化和再分化的影响,优化体细胞胚胎发生体系和初步解析脱落酸调控棉花体细胞胚胎发生分子机制。【方法】以棉花品种中棉所24(CCRI 24)下胚轴为外植体,设置5个ABA浓度0、0.02、0.04、0.06、0.08μmol·L~(-1),分别以A0、A1、A2、A3、A4表示,添加至MSB(MS培养基+B5维生素)培养基诱导愈伤和胚性愈伤,研究ABA对棉花下胚轴初始细胞脱分化、愈伤组织诱导和胚性愈伤组织诱导的影响。【结果】ABA促进下胚轴初始细胞脱分化;显著提高愈伤组织的脱分化率和增殖率;0.02μmol·L~(-1)ABA显著提高胚性愈伤分化率,0.04～0.08μmol·L~(-1)ABA显著降低胚性愈伤分化率。ABA处理后胚性愈伤和非胚性愈伤的增殖率均显著提高且质地受到影响。0.02～0.08μmol ABA处理下,LBD和LBD在愈伤起始期上调表达。0.02μmol·L~(-1)ABA处理下,在愈伤增殖早期和中期BBM、LEC1和AGL15上调表达,愈伤增殖后期FUS3、LEA、ABI3基因上调表达。【结论】脱落酸调控的棉花体细胞胚胎发生与相关标记基因的时空性表达密切相关,这些基因表达水平的增加是ABA调控愈伤和胚性愈伤分化的分子基础。     

脱落酸对棉花体细胞胚胎发生的影响

【目的】研究脱落酸(Abscisic acid, ABA)对棉花体细胞胚胎发生过程中下胚轴脱分化和再分化的影响,优化体细胞胚胎发生体系和初步解析脱落酸调控棉花体细胞胚胎发生分子机制。【方法】以棉花品种中棉所24(CCRI 24)下胚轴为外植体,设置5个ABA浓度0、0.02、0.04、0.06、0.08μmol·L^-1,分别以A0、A1、A2、A3、A4表示,添加至MSB(MS培养基+B5维生素)培养基诱导愈伤和胚性愈伤,研究ABA对棉花下胚轴初始细胞脱分化、愈伤组织诱导和胚性愈伤组织诱导的影响。【结果】ABA促进下胚轴初始细胞脱分化;显著提高愈伤组织的脱分化率和增殖率;0.02μmol·L^-1ABA显著提高胚性愈伤分化率,0.04~0.08μmol·L^-1ABA显著降低胚性愈伤分化率。ABA处理后胚性愈伤和非胚性愈伤的增殖率均显著提高且质地受到影响。0.02~0.08μmol ABA处理下,LBD和LBD在愈伤起始期上调表达。0.02μmol·L^-1ABA处理下,在愈伤增殖早期和中期BBM、LEC1和AGL15上调表达,愈伤增殖后期FUS3、LEA、ABI3基因上调表达。【结论】脱落酸调控的棉花体细胞胚胎发生与相关标记基因的时空性表达密切相关,这些基因表达水平的增加是ABA调控愈伤和胚性愈伤分化的分子基础。     

小枣发育枝愈伤组织类型及细胞学观察

在金丝小枣发育枝离体培养过程中,不同种类和浓度的激素及光照条件对诱导愈伤组织的质量有明显影响。２,４－Ｄ和暗培养易诱导出疏松的Ⅱ型愈伤组织,ＩＢＡ及光照培养则有利于致密的Ｉ型愈伤组织形成。Ⅱ型愈伤组织未分化出芽,而Ｉ型具有较强的再分化能力。继贷繁殖时２,４－Ｄ浓度超过１ｍｇ／Ｌ将导致Ⅰ型愈伤组织大量转化为Ⅱ型。不同类型愈伤组织的染色体倍体变异明显不同,再生植株无性系根尖细胞染色体倍性则相对稳定。     

籼、粳、糯稻成熟种胚体细胞培养力的差异

在相同的培养条件下,比较了不同类型水稻成熟种胚体细胞培养力的差异。结果,糯稻的愈伤组织诱导率和生长速度高于粳稻和籼稻。就愈伤组织质地和色泽而论,籼稻趋向于紧密型、淡黄色,粳稻趋向于松散型、鲜淡黄色,糯稻趋向于粘质状、淡黄色。而籼稻的愈伤组织绿苗分化率、绿苗+绿芽分化率和体细胞培养力高于粳稻和糯稻。这些结果为利用种胚培养进行水稻品种改良提供了一定的理论依据。     

荚用菜豆松散型胚性愈伤组织保持体系的诱导方法

本研究旨在为诱导再生成苗提供基础材料,为进一步开展荚用菜豆育种相关研究奠定基础。以荚用菜豆无性细胞（茎、叶、子叶等器官）为试验材料,通过筛选植物激素及其最佳组合,获得了以细胞质浓密的圆球形细胞为主体的松散型愈伤组织细胞团。最终筛选出诱导无性细胞产生普通愈伤组织的“诱导培养基Ⅰ号”：MS +2,4-D 1 mg/L+蔗糖30 g/L。进一步研究获得了“诱导培养基Ⅱ号”：MS + 6-BA 0.25 mg/L + 2,4-D 0.5 mg/L+ AgNO₃ 10 mg/L。此培养基可以诱导和保持松散型胚性愈伤组织。本研究筛选出可以将无性细胞诱导为松散型胚性细胞团,并且维持胚性细胞继续增殖的系列培养基,解决了诱导过程中愈伤组织褐化问题,创建了一套诱导荚用菜豆松散型胚性愈伤组织的新方法。     

茄子花药愈伤诱导及不定芽分化研究

以4个茄子品种的花药为外植体,研究茄子诱导花药愈伤组织及不定芽分化。结果表明,西安绿茄,豫艺2号主要分化黄白色紧密型愈伤,这种类型的愈伤分化不定芽较多,翠绿二号,黑仙子分化黄白色松散型愈伤。松散型和紧密型愈伤组织均能分化出绿苗,但松散型愈伤分化的绿苗畸形率高,容易生长缓慢,玻璃化。豫艺2号和西安绿茄适合在F 1培养基上分化,而翠绿二号和黑仙子在F 2上更适合。翠绿二号、西安绿茄、豫艺2号在第5周转分化时分化率最高,黑仙子在第4周转时分化率最高,分别为20%,107%,78%,20%。     

TDZ对橡胶树花药愈伤组织诱导和体细胞胚发生的影响

为了提高橡胶树优良品种的愈伤组织诱导和体细胞胚发生的频率,促进其花药植株再生体系的优化,以橡胶树品种‘云研73-477’、‘热垦525’和‘云研77-2’的花药为外植体,研究不同浓度的TDZ对愈伤组织诱导和细胞胚胎发生能力的影响。结果表明,在愈伤组织诱导实验中,MS+TDZ 0.2 mg/L+ 6-BA 1 mg/L+2,4-D 1.5 mg/L+NAA 0.5 mg/L+椰子水50 mL/L+蔗糖70 g/L效果最好,诱导率均达到最大,分别为98%、98.67%、28.6%,当TDZ浓度逐步升高时,其诱导率又有所下降。在体细胞胚诱导实验中,愈伤组织诱导阶段加入TDZ对体细胞胚的发生有抑制作用;将愈伤组织转移到不含TDZ的培养基中继代增殖后,体细胞胚的诱导率随继代次数的增加呈上升趋势;愈伤诱导阶段使用的TDZ浓度越低越利于体细胞胚的分化;在体胚诱导阶段以TDZ代替KT后,体细胞胚诱导率较低,且分化出的体胚为畸形胚。这表明TDZ虽然有利于愈伤组织的产生和生长,但不利于体细胞胚的发生。     

灿、粳、糯稻成熟种胚体细胞培养力的差异

在相同的培养条件下，比较了不同类型水稻成熟种胚体细胞培养力的差异。结果，糯稻的愈伤组织诱导率和生长速度高于粳稻和灿稻。就愈伤组织质地和色泽而伦，灿稻趋向于紧密型、淡黄色，粳稻趋向于松散型、鲜淡黄色，糯稻趋向于粘质状、淡黄色。而灿稻的愈伤组织绿苗分化率、绿苗＋绿芽分化率和体细胞培养力高于粳稻和糯稻。这些结果为利用种胚培养进行水稻品种改良提供了一定的理论依据。     

低酚陆地棉直接体细胞胚胎发生和植株再生

选用低酚陆地棉无菌苗下胚轴为材料进行全固体组织培养,直接诱导获得了胚性愈伤组织,并进一步分化为再生植株.结果表明,激素是影响棉花直接体细胞胚胎发生的重要因素.MSB培养基中添加2,4-D有利于愈伤组织的形成,却不能直接诱导获得胚性愈伤组织.MSB培养基中添加IBA和BA也不能直接诱导获得胚性愈伤组织.MSB培养基附加适当浓度的IBA和KT能直接诱导出胚性愈伤组织.最适激素组合(1.0 mg/L IBA,0.5 mg/L KT)能使诱导棉花下胚轴产生大量胚性愈伤组织,并且在3个月内就可肉眼观察到不同发育时期的胚.MSB培养基中附加1.0 g/L谷氨酰胺和0.5 g/L天门冬酰胺有利于胚萌发成苗.本研究建立了简便高效的棉花直接体细胞胚胎发生和植株再生培养体系,从胚性愈伤组织诱导到植株再生约需5～6个月时间.     

中国樱桃体细胞胚的诱导

探讨了基因型、发育期和植物生长调节剂对中国樱桃(Prunus pseudocerasu L.)体细胞胚诱导的影响.结果表明,长5mm左右的未成熟种子胚性愈伤组织诱导率较高；细胞分裂素/GA接近1,甚至无细胞分裂素时易于诱导胚性愈伤组织;生长素中NAA更适合胚性愈伤组织诱导.     

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.     

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.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

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.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

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.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

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.