UVC-priming mediated modulation of forskolin biosynthesis key genes against Macrophomina root rot of Coleus forskohlii⿿A tissue culture based sustainable approach

Coleus forskohlii is susceptible to root rot disease that reduces yield of root specific metabolite forskolin. In this communication, we first time reported sustainable management of Macrophomina phaseolina root rot in C. forskohlii via Ultraviolet-C (UVC)-hormesis using tissue culture. Compact calli were developed using 2,4-dichlorophenoxy acetic acid (2.0 mg l^⿿1) and tolerance level of UVC exposure was optimized. Calli exhibited 88% viability, 8.4% relative growth in biomass and higher absorbance in 2,3,5-triphenyl tetrazolium chloride analysis subsequent to 10 min of UVC exposure. Pathogenicity of M. phaseolina was reduced in UVC-primed calli-regenerated plants compared with un-primed ones under controlled condition. Plant height, leaf number, shoot and root biomass significantly improved in UVC-primed calli-regenerated plants over un-primed ones when challenged by M. phaseolina in glasshouse. Significant elevation of economically important forskolin via up-regulation of key forskolin biosynthesis genes GGPP synthase, CfTPS2 and CfTPS3 highlighted the potentiality of UVC-priming to boost plant⿿s defence mechanism and protect from drastic economic loss.     

Isolation,origin and properties of enucleate plant microplasts

Summary Auxin-induced highly vacuolated thin-walled callus cells of several plant species, when ruptured, released large numbers of subcellular units most of which were enucleate. These enucleate microplasts are surrounded by an inner membrane of the cell, most probably derived from the tonoplast. When microplasts isolated fromSaintpaulia callus were cultured in a medium supplemented with growth substances they formed a thin wall and underwent budding. Microplasts could be useful for various studies in plant cell biology and for genetic manipulations.     

Effects of different gelling agents on the different stages of rice regeneration in two rice cultivars

Plant tissue culture technology offers a solution for meeting the increasing commercial demand on economically important plants such as rice, a widespread dietary staple. However, significant genotype-specific morphogenetic responses constitute a considerable on rice regeneration in plant biotechnology contexts. Aside from genotype dependency, the components of the nutrient media including gelling agents have an important impact on regeneration efficiency. The current study explores the effect of different gelling agents on various stages of rice regeneration in two Egyptian rice cultivars-Sakha104 and Giza178. Media solidified with varying concentrations of a variety of gelling agents (agar, bacto agar, gelrite and phytagel) were tested for their impact on the frequency of callus induction, shoot regeneration and rooting. The results indicated gellan gum (gelrite and phytagel) was superior to agar products (agar and bacto agar) for callus induction. By contrast, no significant differences were found between different gelling agents for shoot regeneration. Gellan gum and media solidified with bacto agar were found to lead to significantly higher root regeneration than agar. The Sakha104 cultivar showed better responses than Giza 178 for callus induction and similar performance to the Giza 178 cultivar for root regeneration irrespective of the gelling agent. This work provides insights into the impact of different gelling agents on the morphogenetic response of two rice cultivars and can be used to help maximize the frequency of rice regeneration.     

Callus cultures and bark from Norway spruce clones show similar cellular features and relative resistance to fungal pathogens

In field experiments, clones of Norway spruce [Picea abies (L.) Karst.] showed different degrees of resistance against pathogenic fungi inoculated into the bark that correlate with differences in polyphenolic parenchyma (PP) cells of the bark. Cells of spruce callus cultures, particularly towards the callus surface, resemble PP cells and this study looks at changes in callus cells during infection and the relative resistance of cultures from clones of low (weak) or high (strong) resistance to fungal infection. Callus cultures, initiated from trees with different resistance, were co-inoculated with Ceratocystis polonica (Siem.) C. Moreau and Heterobasidion annosum (Fr.) Bref. Callus cells from strong clones resemble PP cells of bark tissue from strong clones, having more polyphenolic bodies, while callus cells from weak clones are more similar to PP cells from those clones, which have less extensive phenolic bodies. Callus cultures from trees with weak resistance were more quickly overgrown by both species of pathogenic fungi than cultures from trees with strong resistance. Callus cells of infected cultures showed changes similar to activated PP cells of bark, including enhanced accumulation of polyphenolics. Phenolic bodies were more numerous and more extensive (larger and denser) in callus cells of strong versus weak clones under all conditions. Thus, callus cells may perform similar functions in defense as PP cells in the bark. Callus from trees of varying resistance seem to reflect the relative resistance of the trees from which they are derived, and this study indicates that some mechanisms of resistance can be studied using callus from trees of different resistance.     

The role of plant growth regulators on direct and indirect plant regeneration from various organs of <Emphasis Type="Italic">Leucaena leucocephala</Emphasis>

Prolific differentiation of shoot buds of Leucaena leucocephala was induced from the different plant parts viz. cotyledon, hypocotyl and leaf. Adventitious shoot bud formation was recorded with prudent application of N⁶-2- (isopentenyl) adenosine and 15% (v/v) coconut water. Coconut water alone was unable to produce any beneficial effect with regard to the shoot bud proliferation but the response was augmented with the increase in concentration of N⁶-2- (isopentenyl) adenosine. However supra-optimal level of N⁶-2-(isopentenyl) adenosine was inhibitory. Best response was recorded from the cotyledon explant at 2 mg dm⁻³ N⁶-2-(isopentenyl) adenosine compared to the other two explants. Comparative assessment was undertaken following the same experimental protocol in liquid shake culture. The regenerated shoot buds were subcultured in plant growth regulator-free medium where leafy shoot emergence was recorded. Optimum regeneration of roots was observed in these shoots in presence of 1 mg dm⁻³ α-naphthalene acetic acid. Plantlets were finally hardened following standard procedures before transplantation to the field. In another experimental set up, the de-embryonated cotyledons regenerated shoot buds via callus formation. The regenerated shoots and plantlets obtained through callus mediated organogenesis could be used for rapid multiplication and also for the genetic improvement of individual clones of Leucaena leucocephala.     

产藏红花素栀子愈伤组织的诱导和筛选

为解决藏红花资源问题,研究了栀子愈伤组织的诱导,并首次应用目视法和HPLC 方法对产藏红花素细胞系进行了筛选。结果表明栀子叶子愈伤组织优化的诱导条件为: 在添加1mg/L 2,4-D和 0.25 mg/L 6-BA的MS 培养基上, 25±1℃和31.74 mmol/m2s光照强度下每天光照16小时,培养15d后可获得100%的诱导率。种子愈伤组织也易诱导,在添加0.5mg/L 2,4-D 和 0.25 mg/L 6-BA的MS培养基上,25±1℃全时暗培养15d后可获得100%的诱导率。首次应用建立的目视法和HPLC 方法, 从90株细胞系中筛选出细胞系seed4,其藏红花素1 的含量是0.348mg/g,生长较快、不易褐化,兼顾了此次生代谢产物的含量和细胞的生长速度,为采用植物细胞工程法解决藏红花素资源短缺问题提供了种质资源。     

In vitro evaluation of some high yield potato (Solanum tuberosum L.) cultivars under imposition of salinity at the cellular and organ levels

Salinity and drought stress, which combines a lack of water and sodium toxicity, are more of the problems faced by plants and agricultural crops in newly reclaimed lands. Therefore, the direction of our research is to produce salinity-tolerant plants to increase the productivity of crops under conditions of salt stress. Potato callus was studied using different concentrations of NaCl (0.0, 50, 75, 100, 125, 150 and 200 mM). Shoot induction was obtained from callus treated with MS medium containing 4.0 and 5.0 mg l^?1 TDZ + 0.5 mg l^?1 GA3 with NaCl up to 125 mM and 150 mM for Rosetta and Victoria, respectively. When plantlets were cultured on MS medium containing 3.0 mg l^?1 kinetin and 1.0 mg l^-1paclobutrazol (PBZ) with 80 or 90 g l^?1 sucrose after two months gave a good microtuber per explant of Rosetta and Victoria cultivar which gave number of microtuber/plantlet (1.85) and (2.40) when plantlets treated with 125 mM and 150 mM NaCl of Rosetta and Victoria cultivar, respectively. In general, the results were shown in each treatment of NaCl and that amounts of proline at 125 and 150 mMNaCl were significantly more than 0.0, 50, 75 and 100 mM NaCl. This result is related to the role of proline in the osmotic adjustment of a higher concentration of salinity. The results showed that the amounts of sodium increased with increasing the salt concentration, but the amount of potassium decreased and also increased the Na+/K+ ratio with increasing the salt concentration. This research is important for in vitro potato plant regeneration, which requires optimization before genetic transformation can be achieved.     

细枝木麻黄离体培养过程中愈伤组织和再生芽的细胞组织学观察

为探讨细枝木麻黄(Casuarina cunninghamianaMiq.)愈伤组织分化过程的细胞组织学,对离体培养条件下的愈伤组织进行扫描电子显微镜和石蜡切片观察,分析愈伤组织的细胞分裂、分化以及芽再生的发生过程。结果表明,新鲜外植体培养于愈伤组织诱导培养基上,伤口处的薄壁细胞开始脱分化,培养1周后形成明显的愈伤组织;继续培养2周后,胚性愈伤组织形成,且表层细胞启动分化形成芽原基;培养4周,可肉眼观察到胚性芽原基,数量增多并逐渐分化形成不定芽;培养至第6周,生成不定芽,并大量增殖和分化。因此,细枝木麻黄是通过愈伤组织分化形成胚状体的途径进行植株再生的,为建立细枝木麻黄组织培养高效再生体系提供了理论依据。     

紫果猕猴桃幼胚愈伤组织诱导及植株再生

以紫果猕猴桃(Actinidia arguta var．purpurea)幼胚为外植体,诱导愈伤组织并进行植株再生。结果表明：不同的培养基和不同的培养条件对幼胚愈伤组织的诱导率及分化率不同;0．2mg／L ZT与0．5mg／L GA。配合使用有利于促进愈伤组织的诱导;7％蔗糖、600mg／L CH与400mg／L Gln都有利于促进愈伤组织的形成;在添加0．5mg／L 6-BA、0．05mg／L NAA与0．5mg／L GA3的MS培养基中植株的再生率达93．3％。     

Determination of ornithine, putrescine, N-methylputrescine and N-methylpyrroline pools in tobacco tissue by high-performance liquid chromatography

A procedure for the determination of metabolites of the biochemical pathway ornithine to N-methyl-δ¹-pyrrolinium salt (N-methylpyrroline) is described. Plant tissue was extracted with 0.5 M HCl and the extract purified on C₁₈-cartridges. Ornithine was reacted with o -phthaldialdehyde, putrescine and N-methylputrescine with dansyl chloride and the products were separated by reversed-phase high-performance liquid chromatography (HPLC). N-methylpyrroline was determined by cation-exchange HPLC without derivatization. The metabolites in the roots of tobacco ( Nicotiana ) species with different nicotine-producing capacities were determined. Furthermore, the specific activities of the enzymes ornithine decarboxylase (EC 4.1.1.17), putrescine N-methyltransferase (EC 2.1.1.53) and N-methylputrescine oxidase were determined. Both the metabolite pools and the enzyme activities were correlated with the different nicotine-producing capacities of the different tobacco species.