Shoot buds of Adhatoda vasica Nees. isolated from multiple shoot cultures were encapsulated in 3% sodium-alginate with different gel matrices. Maximum conversion of the encapsulated shoot buds into plantlets was achieved on Gamborg’s B5 medium containing 4.65μM Kinetin and 50mgl-1 Phloroglucinol and the plantlets were successfully grown in soil.
An improved and producible protocol for in vitro regeneration of sorghum [Sorghum bicolor (L.) Moench] from shoot meristem explant is reported. By striking an optimal balance between a weak auxin like naphthalene acetic acid (NAA) and the cytokinin thidiazuron (TDZ), the isolated shoot meristems were manipulated to follow either organogenic or embryogenic pathway. There was no intermediate callus formation. Multiple buds were induced on enlarged meristems using MS medium with 5.0μM of TDZ, 17.72μM Benzylaminopurine (BAP), and 1.074μM NAA. To maximize the number of bud initials per explant, three parameters (seed size, germination technique, and age of explant) were studied. Five to 7-day-old shoot meristems responded best with ≥80% induction of bud initials. Seed size was not significant in influencing induction potential of the shoot meristems. Six weeks after in vitro culture, each meristem produced 35-40 shoot buds. Direct somatic embryogenesis (≥80% induction) was accomplished following a two-step culture procedure consisting of induction of multiple buds and formation of somatic embryos. A high frequency (700-1000) of somatic embryos per explant was obtained on MS medium with 17.72μM BAP and 2.69 μM NAA. Shoots from both organogenic and embryogenic pathways rooted on half-strength Murashige and Skoog (MS) medium with 8.28μM Indole 3-butyric acid (IBA) and 1.14μM Indole acetic acid (IAA). After one month on rooting medium, plants with well-developed roots were transferred to jiffy cups. Such plants were subsequently acclimatized in the glasshouse, and were grown till maturity; they showed normal seed set. Random amplified polymorphic DNA (RAPD) analysis of regenerants did not detect any DNA polymorphism.
Cultures were made of ovaries guineagrass (Panicum maximum) harvested in different seasons to obtain plant regeneration via somatic embryogenesis. Callus formation and plant regeneration occurred when the ovaries harvested 0-7 days after anthesis (DAA) in summer were cultured on Murashige and Skoog medium with suitable hormones. However, most of the ovaries harvested in winter did not form calli when cultured similarly. To determine the reason for this difference, flowers at 0-7 DAA were collected during both seasons and observed under Nomarski differential interference-contrast optics. The ovaries collected at 0-7 DAA in summer showed normal development and matured seed set-up. In contrast, most of the ovaries collected at 0-7 DAA in winter degenerated gradually. This result suggests that embryo-sac analysis of plant materials provides important information on whether plant materials are suitable for the induction of calli.
Callus tissue from the stems of Actinidia arguta (Actinidiaceae) produced the following eight ursane-type triterpenes: α-amyrin; uvaol; ursolaldehyde; ursolic acid; corosolic acid; asiatic acid; 2α, 3β, 24-trihydroxyurs-12-en-28-oic acid (4-epiasiatic acid); and 2α, 3α, 24-trihydroxyurs-12-en-28-oic acid. The tissue also produced three oleanane-type triterpenes (β-amyrin, oleanolic acid, and maslinic acid), and two phytosterols mixtures (sitosterol and stigmasterol). Seven of the eight ursane-type triterpenes (the exception being asiatic acid), the three oleanane-type triterpenes, and the two phytosterols mixtures were also isolated from A. chinensis and A. polygama callus tissues. Variations in the production ratios of two of the triterpenes (ursolic acid and oleanolic acid) and the two phytosterols mixtures (sitosterol and stigmasterol) were compared among callus tissues from the three plant species.
Transcript levels of alternative oxidase genes (AOX1a and AOX1b) of rice were studied under various stresses using a Northern hybridization analysis. The steady-state mRNA levels of these genes increased under low temperature, high salt and drought conditions, but not in the presence of exogenous ABA. Two DRE/CRT-like sequences are also found in the promoter region of AOX1a.
To analyze the mechanisms of salt-tolerance in a mangrove plant, Bruguiera sexangula, functional screening of cDNAs encoding proteins essential for the salt-tolerance was performed using Escherichia coli as a host organism. A transformant expressing the α subunit of cytosolic chaperonin containing TCP-1 (CCTα) homologue was found to have enhanced salt-tolerance. A similar function was also observed in CCTα from Arabidopsis thaliana. The amount of CCTα transcript in the mangrove-cultured cells did not change in response to salt-stress and the transcript was continuously produced in the presence of NaCl or not. The role of plant CCTα in salt-tolerance was discussed.
Arbuscular mycorrhiza is the most ubiquitous and oldest symbiosis between land plants and fungi in terrestrial areas. However, details of the symbiosis are largely unknown. DNA sequence information on arbuscular mycorrhizal fungi is currently being accumulated. An expressed sequence tag (EST) clone from Glomus intraradices encodes glutathione S-transferase (GST), GiGSTF1, whose sequence is significantly similar to that of plant phi-class GSTs, which is a subgroup of a large gene family in plant GST. This study analyzes the phylogenetic relationship between plant and fungal GSTs, and the origin of plant phi-class GST is discussed from the standpoint of plant evolution.
The biotransformation of a ketone and enone by plant cell cultures was investigated. It was found that the cultured cells of Marchantia polymorpha reduced preferentially the carbonyl group of 2-pentylcyclopentanone to produce the corresponding anti-2-pentylcyclopentanol. Hence, 2-pentylcyclopent-2-enone was hydrogenated by the cultured cells of Catharanthus roseus to give (R)-2-pentylcyclopentanone with high stereoselectivity.
We investigated the effect of a recombinant cystatin (proteinaceous cysteine proteinase inhibitor) cloned from carnation and expressed in Escherichia coli (rDC-CPIn) on the growth of phytopathogenic fungi. rDC-CPIn inhibited the growth of Phytophthora nicotianae, Botrytis cinerea, and Sclerotiana sclerotiorum. These results suggest that the cDNA for carnation cystatin could be useful for the generation of transgenic plants with increased defenses against fungal plant pathogens.
The one-step acylation of plant polyphenols, naringin (naringenin 7-neohesperioside) and rutin (quercetin 3-rutinoside), to the corresponding cinnamate esters was achieved by a lipase-catalyzed regioselective transesterification in a dry organic solvent. For acylation to the narigin molecule, the lipase preferentially catalyzed the acylation to the primary alcohol (C6” position of glucose) with less steric hindrance, while, in rutin, the secondary alcohol (C3” position of glucose) was acylated to the cinnamate ester by the lipase.