Changes in root morphology accompanying mycorrhizal alleviation of phosphorus deficiency in micropropagated Annona cherimola Mill. plants

The effect of the mycorrhizal inoculation on survival rate, growth, nutrient uptake and root morphology during the acclimatization period and plant establishment of micropropagated juvenile or adult cherimoya plants (Annona cherimola Mill.) was determined. Although mycorrhizal colonization did not improve the survival rate of plants, which was already high in non-inoculated plants, it had a positive effect on plant development (shoot length, leaf number, leaf area and fresh and dry weights). Mycorrhizal juvenile plants tripled the macronutrients and increased by four the micronutrient uptake, and mycorrhizal adult plants increased by two phosphorus and all micronutrients, with copper uptake increased five times. Moreover, mycorrhizal colonization changed the root morphology of adult plants increasing three-fold the total number of roots, doubling the number of first-order laterals and increasing second-order laterals by four. Total root length was also increased three-fold, adventitious root length was almost doubled, first-order laterals tripled and second-order roots length increased four-fold. The effect of mycorrhizal colonization seems to be stronger or different in juvenile than in adult plants, suggesting that ontogenic stage is an important factor determining mycorrhizal effect and the plant performance during the acclimatization period.     

Vesicular-arbuscular mycorrhizal inoculation of micropropagated fruit trees

Micropropagated plantlets of OH x F 51 and GF 677, respectively pear (Pyrus communis L.) and peach (Prunus persica x Prunus amygdalus) clonal rootstocks were inoculated during an early weaning stage of acclimatization with Glomus sp. Both rootstocks were well colonized, although the infection of OH x F 51 spread more slowly. At the end of initial vegetative growth, mycorrhizal plants of both rootstocks showed a three-fold increase in shoot length over control plants. Mycorrhizal plants also had longer internode and greater fresh mass. The root/shoot ratio was especially altered by arbuscular mycorrhizal inoculation in OH x F 51 plants, which showed a greater increase in shoot rather than in root biomass. The growth-promoting ability of endomycorrhizal fungus persisted throughout the experimental period: Glomus sp. induced a greater development of both rootstocks in the second growing year, after overwintering. Colonization of micropropagated plants by arbuscular mycorrhizal fungus appears to alter the carbohydrate status in stems and roots. Mycorrhizal plants always had a higher content of total soluble sugar, although there were no differences in soluble carbohydrate concentration between inoculated and uninoculated plants. Starch accumulation was found only in mycorrhizal plants of the peach rootstock.     

Arbuscular mycorrhizae in micropropagation systems and their potential applications

Over the past few years, micropropagation techniques are being widely used as an important and advantageous tool for rapid propagation of several commercially important varieties of horticultural and forest tree species. Although, this technology has got several successful applications, low survival rates and poor growth while shifting these plantlets to field conditions are the most common problems which hinders its usage for commercial plant production practices. Inoculation of arbuscular mycorrhizal fungi (AMF) to the roots of micropropagated plantlets plays a beneficial role on their post-transplanting performance. This review discusses the multiple roles played by AMF in the establishment of micropropagated plantlets. Different techniques of mycorrhization and the constraints pertaining to the use of these techniques are also discussed.     

Arbuscular mycorrhizal inoculation of micropropagated persimmon plantlets

Summary

Growth, development and nutrient status of micropropagated persimmon (Diospyros kaki) ‘Rojo Brillante’ in response to inoculation with two species of arbuscular mycorrhizal (AM) fungi were studied under nursery conditions. The species of AM fungi were Glomus intraradices and G. mosseae. Shoot growth depression and low root colonization percentage were observed to G. mosseae inoculation. Shoot and root growth enhancements were observed for plants colonised by G. intraradices. Inoculated plantlets with G. intraradices and high level of controlled-release fertilizer signi®cantly decreased shoot height in relation to treatment with low fertilization level. Furthermore, G. intraradices had unique effects on the mineral status of the persimmon plantlets. N and Ca were significantly increased and decreased, respectively, within the shoot tissue of plants colonised by G. intraradices. Early inoculation with G. intraradices appears to favour growth of micropropagated persimmon plantlets.     

丛枝菌根真菌对芋组织培养苗生长的影响

 于温室盆栽条件下研究了丛枝菌根(AM) 真菌Gigaspora rosea、Glomus mosseae 和Glomus versi-forme 对芋(Colocasia esculenta) 组织培养苗移栽成活率、矿质营养、光合速率及生长的影响。结果表明, 接种AM真菌能提高芋组织培养幼苗移栽成活率和叶片光合速率, 降低气孔阻力; 其叶片和根内氮、磷、钾含量和生长量显著高于不接种对照。认为接种有效AM真菌是促进组织培养苗健康生长的重要技术。     

In vitro culture establishment and multiplication of the Prunus rootstock ‘Adesoto 101’ (P. insititia L.) as affected by the type of propagation of the donor plant and by the culture medium composition

The establishment of new in vitro cultures from mature woody plants is often a difficult task due to the little growth of initial explants. Since the explant origin plays an important role, in this work the effect of the origin of the explants (micropropagated or conventionally propagated plants) on both establishment and multiplication of the in vitro cultures has been studied using different culture media. Best results during establishment were obtained with explants taken from micropropagated plants. The multiplication rate of new cultures was strongly affected by the type of propagation of the mother plants. Thus, while the cumulative number of shoots increased sharply in cultures originated from micropropagated plants, cultures originated from cutting-derived plants showed only a moderate increase. Culture medium composition influenced the multiplication rate. After nine subcultures, a significantly lower number of shoots was found on QL medium than on MS or on WP. The positive effect of micropropagation of donor plants on the establishment and multiplication of new in vitro cultures is discussed in terms of a possible reinvigoration during in vitro culture.     

Optimization of Factors Affecting <Emphasis Type="Italic">In vitro</Emphasis> Establishment, <Emphasis Type="Italic">Ex vitro</Emphasis> Rooting and Hardening for Commercial Scale Multiplication of Silk Banana (<Emphasis Type="Italic">Musa</Emphasis> AAB)

Factors concerning aseptic culture establishment and hardening were studied in detail in choicest Silk Banana. Effect of size of sucker (small, medium and large), carbon concentration (10, 20 and 30 g/l), season of initiation (wet and dry) and pre-treatments such as segmentation and incision to the explants were studied during initiation. Further, hardening related factors such as substrates used for primary and secondary hardening, nursery nutrition (source and frequency of application) and pre-treatments for ex vitro rooting were also studied. Results revealed that small suckers were most suited for initiations with the least contamination, maximum establishment and higher percentage of greening. Lower concentration of sucrose, though delayed greening, resulted in 100?% establishment of explants. Initiations performed during the drier period were completely free from the fungal contamination and showed less bacterial contamination than those performed during the rainy season. Segmentation of explant into four parts during first subculture supported maximum shoot proliferation by overcoming apical dominance. Coir pith was observed to be the most congenial substrate during primary hardening, whereas coir pith alone or sand: red earth: coir pith (1:1:1) supported superior performance of plantlets during secondary hardening. Single application of mono ammonium phosphate improved growth of plantlets during secondary hardening. Pre-treatment with mono ammonium phosphate gave the best response in terms of rooting and hardening of un-rooted micro-shoots. Thus, the discussed methodology could help the industries to take up commercial scale propagation of Silk Banana.     

Development of a regeneration protocol through indirect organogenesis in prickly pear cactus (Opuntia ficus-indica (L.) Mill)

An indirect organogenesis regeneration protocol for Opuntia ficus-indica (L.) Mill var “Blanco sin Espinas” is described. One centimeter square cladode explants sections from previously micropropagated prickly pear plants were cultured in Murashige and Skoog (MS) basal medium supplemented with 20 different combinations of 2,4-dichlorophenoxy acetic acid (2,4-D) and benzyladenine (BA). The best calli induction and regeneration response were observed when 2.26 μM 2,4-D and 2.21 μM BA combination was applied to the nopal explants. Regenerating calli was capable of forming new buds when transferred to MS basal medium supplemented with 0.5 μM BA (proliferation medium). Shoot elongation and rooting were achieved on MS medium without plant growth regulators. Excellent acclimatization to greenhouse conditions was observed for all transferred plantlets. By this procedure no morphological differences were observed between the regenerated and mother plants. This protocol may be also utilized to carry out plant regeneration after genetic transformation, in order to develop transformed plants without the presence of chimeric zones.     

提高大樱桃矮化砧木吉塞拉试管苗移栽成活率的研究

研究了影响大樱桃矮化砧木吉塞拉试管苗移栽于温室和大田成活的因素,认为影响试管苗温室锻炼成活的最重要的因素是镰刀真菌（Ｆｕｓａｒｉｕｍ ｅｑｕｉｓｅｔｉ）引起的立枯病,使用壮苗在干净的河沙基质上培养,发病率低,成活率高,最高可达９４％以上。露天炼苗,砂壤土栽植,遮荫网覆盖等措施可提高试管苗在大田的成活率,最高可达９５％以上,几万株试管苗已成功地移栽于大田。     

葡萄试管苗在移栽过程中叶解剖和根系活力的变化

葡萄试管苗通过分步驯化后,能够高频率的成活。观察和测定了各驯化阶段叶解剖结构和根系活力的变化,结果表明,试管苗叶片薄,组织稀疏,气孔突起,开口大,根系活力极低。通过分步炼苗,叶片逐渐向旱生结构变化,根系活力迅速增强。这是试管苗逐渐适应低湿和自然光照的解剖和生理变化。     

Vegetative and yield component characteristics of micropropagated muscadine grape (Vitis rotundifolia Michx.)

SUMMARY

Evaluations were made of the field performance of micropropagated (tissue cultured axillary buds) versus conventionally rooted softwood cuttings of muscadine grape, Vitis rotundifolia Michx. Trunk cross-sectional area did not differ between treatments during three years of field evaluation following planting. There were no differences in leaf area and dry weight or shoot number in the two propagation types; leaf morphology was normal with no apparent juvenile characteristics. Yield components including flower number per shoot and inflorescence, fruit number, total fruit weight and yield efficiency were greater in micropropagated plants during the second year, the first year of cropping; differences diminished and yield components were not different in year three. Performance of tissue cultured plants was therefore as good as, or surpassed, conventionally propagated plants during early vine establishment.     

圆叶海棠无糖培养生根研究

为了探索新的砧木快速繁殖的方法,以圆叶海棠离体新梢为供试材料,采用自行设计的无糖培养箱和环境控制系统,进行无糖培养生根研究,比较无糖培养与有糖培养海棠离体新梢光合指标和根系形态指标之间的差异。结果表明:增加光照强度和提高CO2浓度,改善了海棠离体新梢生长的环境条件;与有糖培养相比,无糖培养促进了植株的生长发育。主要表现在:植株健壮且根系发达,有大量的侧根形成;植株的根系活力、光合作用、调节气孔开闭和控制蒸腾速率等方面显著提高。无糖培养提高了海棠离体新梢对环境的适应能力。     

Monitoring the genetic fidelity of micropropagated plantlets of Spondias mangifera Willd. using RAPD marker assays

Summary

Random amplified polymorphic DNA (RAPD) markers were used to screen for clonal fidelity in in vitro-propagated plantlets of Spondias mangifera produced through direct organogenesis. One micropropagated plantlet was selected at random after each sub-cultural passage (six sub-cultures), along with the donor plant, for RAPD marker analysis. Twenty-five RAPD primers were used to study genetic similarities or dissimilarities with the mother plant as well as among the regenerated plants. Individual primers showed that the same pattern of RAPD markers was shared by all in vitro-propagated plantlets and the mother plant. No variation was observed among the micropropagated progenies. Thus, in vitro-regenerated plantlets of S. mangifera were clonally uniform and genetically stable.     

不同菌剂对丰香组培苗生长发育和白粉病抗性的影响

以丰香草莓微繁殖苗为试材,分别以重茬土和混合基质为栽培基质,比较研究了丛枝菌根真菌(AMF)菌剂、木霉(Trichoderma)菌剂和有效微生物群(EM)菌剂对草莓植株生长发育和生理生化指标、产量、白粉病抗性等的影响。结果表明,无论是重茬土还是混合基质,供试的3种微生物菌剂处理后均可促进丰香草莓微繁殖苗的生长势,提高草莓叶片叶绿素、蛋白质、可溶性糖和淀粉质量分数,增加果实产量,其中AMF菌剂处理的效果显著,其叶面积和叶片叶绿素质量分数均是CK的1.5倍左右,产量比CK增加68.6%(重茬土)、39.5%(混合基质)。AMF菌剂处理和木霉菌剂处理植株中β-1,3-葡聚糖酶的活性是CK植株的2.6～5.5倍。在提高草莓微繁殖苗白粉病抗性上,木霉菌剂处理的效果最为显著,在重茬土和混合基质上,木霉菌剂处理植株的病情指数分别为36.7和19.2,分别为CK植株的51.8%和59.1%。     

High multiplication frequency and genetic stability for commercialization of the three varieties of micropropagated tea plants (Camellia spp.)

RAPD and microsatellite markers were used to determine the genetic fidelity of micropropagated plants from the three varieties of tea plant derived from explants of field grown mother bush as well as in vitro germinated seedlings. Rate of shoot multiplication was better from nodal explants than from shoot tips. A maximum of 32–33 shoots was observed in cotyledonary node in 1/2 MS medium with BAP (6 mg/l), GA₃ (1 mg/l) and IBA (0.5 mg/l). 90% of the in vitro derived microshoots were micrografted into rootstocks. The micropropagated plantlets showed both cytological and genetical stability. SSR primers showed complete stability among the regenerants. The results convinced that plants derived from axillary as well as adventitious mode of propagation can be genetically true to type. This cost effective technique would help in fast clonal propagation at a commercial scale.     

丛枝菌根真菌对番茄渗透调节物质含量的影响

采用盆栽试验研究了不同浓度NaCl (0.5%和1% ) 胁迫下, 接种丛枝菌根真菌(AMF) 对番茄生长和渗透调节物质含量的影响。结果表明: 盐胁迫下, 与未接菌番茄相比, 接种AMF番茄能显著增加植株的生长, 促进叶片和根系可溶性糖的积累, 增加叶片可溶性蛋白含量及根系脯氨酸含量, 使植株耐盐能力增强。接菌株可溶性糖及可溶性蛋白的增加以及根系脯氨酸的大量积累在AMF提高番茄耐盐的渗透调节机制中具有重要的作用。     

中国石蒜组培苗体细胞无性系变异的ISSR和SRAP检测

以中国石蒜离体培养再生的幼苗为试材,首次采用ISSR和SRAP分子标记对再生苗的遗传稳定性进行了检测,以探讨体细胞无性系变异情况及成因.结果表明:所选用的14条ISSR引物共产生191条带,其中只有1条为多态性条带,并且该条带表现为新增条带;SRAP标记所选用的15对引物共扩增出219条带,其中3条为多态性条带,表现为共有条带缺失.综合2种分子标记检测结果来看,再生植株表现出的体细胞变异率极低(0.97％).现有数据同时也表明,已建立的离体培养体系在保存中国石蒜种质资源和遗传改良上是稳定、可行的.     

Relationship between vegetative and rhizome characters and final rhizome yield in micropropagated ginger plants (Zingiber officinale Rosc.) over two generations

Correlation and path analysis for yield and yield contributing characters in two types of micropropagated ginger plants (plantlets directly regenerated from aerial stem explants and plantlets regenerated from aerial stem derived callus) were carried out over first and second generations in two varieties viz. var. ‘Jamaica’ and var. ‘Varada’. Irrespective of the regeneration method, the in vitro derived plants showed high positive correlation and maximum positive direct effect of circumference of cormlets, length of cormlets and number of cormlets with the rhizome yield in the first generation. But tiller number exhibited negative correlation and negative direct effect with the rhizome yield in the first generation. In the second generation of the aerial stem regenerated plants, tiller number, number of nodes per cormlets, circumference of cormlets, number of cormlets and plant height exhibited high positive correlation and maximum direct effect with rhizome yield. However, in the second generation also, the callus regenerated plants showed the same trend as in the first generation. Even though the tiller number showed positive significant correlation with rhizome yield, it showed negative direct effect with the yield.     

Effect of substrate,medium composition,irradiance and ventilation on jojoba plantlets at the rooting stage of micropropagation

The effect of substrate, medium composition, irradiance and ventilation on rooting percentage, and root morphology and functioning with respect to mineral uptake was investigated in jojoba [Simmondsia chinensis (Link) Schneider]. Plantlets grown on Sorbarod plugs embedded in perlite accumulated more biomass and showed better rooting than plantlets grown on Sorbarod plugs embedded in agar. In plants grown on the latter substrate, the addition of sucrose to water or salts media promoted rooting and accumulation of shoot and root biomass. On perlite, rooting was high in all treatments, while root growth was enhanced only by 2% sucrose. Sucrose and irradiance had a positive synergistic effect on plantlet growth. Doubling the irradiance from 58 to 116 μE m⁻² s⁻¹ and using high ventilation (22-mm membrane) failed to improve rooting but promoted the ability of the stomata to close, thereby reducing water loss under ambient conditions. High irradiance and ventilation lowered the chlorophyll content, but without impairing biomass accumulation. Plantlets grown under enhanced ventilation and 0.5% sucrose formed fine roots within the cellulose plug and thick roots on the vessel floor. With the 2% sucrose supplementation, the roots were generally thicker, with very few thin roots being formed. ³⁶Cl uptake into plantlets and transport to the leaves decreased in plants exposed to a high sucrose concentration. Acclimatization of jojoba plantlets was improved by enhancing ventilation.     

Alterations in flower and seed morphologies and meiotic chromosome behaviors of micropropagated rhubarb (Rheum rhaponticum L.) ‘PC49’

Variations in flower and seed and meiotic chromosome behaviors were investigated in micropropagated rhubarb (Rheum rhaponticum L.) ‘PC49’. The results showed that micropropagated plants had significantly higher variations in flower and seed morphologies and chromosome behaviors than plants derived from crown division. The results demonstrated that micropropagated plants grew 2–5 stamens, 8–13 stigmas, and 2–7 seed-wing, compared to 3 stamens, 9 stigmas and 3 (rarely 4) seed-wing in crown-derived plants. Additionally, alteration in chromosome behaviors (i.e. lagging and bridging) was observed only in micropropagated plants. All the results suggest that somaclonal variation may have been involved in micropropagated rhubarb ‘PC49’.