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1.
The psbQ gene encoding a 16-kDa polypeptide of the oxygen-evolving complex of photosystem II has been isolated from Arabidopsis thaliana and characterized. The gene consists of a 28 nucleotide long leader sequence, two introns and three exons encoding a 223-amino-acid precursor polypeptide. The first 75 amino acids act as a transit peptide for the translocation of the polypeptide into the thylakoid lumen. Expression studies show that the gene is light-inducible and expresses only in green tissues with high steady-state mRNA levels in leaves. Using this gene as a probe, restriction fragment length polymorphism between two ecotypes, Columbia and Estland, has also been detected. 相似文献
2.
Flowering in Wolffia microscopica, a short-day plant, couldbe induced with salicylic acid (SA), under long days. Aspirin,benzoic acid and salicylaldoxime were also effective for inductionof flowering in this duckweed. Amonsgt these, SA is the mosteffective compound, as it could induce flowering even at 107M. Flowering was further enhanced when Wolffia fronds were subjectedto short days, in the presence of SA. However, SA neither showedany effect on flowering ofW. microscopica in the absence ofEDTA in the nutrient medium, nor could it, by itself, supporteven the vegetative growth. The probable mechanism of actionof SA has also been discussed. It appears that the effect cannotbe due simply to chelation of metal ions and perhaps the salicylmoiety itself exerts a specific effect. (Received March 15, 1983; Accepted May 6, 1983) 相似文献
3.
The present investigation dealt with the effect of the two granular systemic nematicides aldicarb and carbofuran, individually and in combination with 100 mg · 1-1 GA3, on plant growth and root knot formation in C. frutescens var. California Wonder. Both nematicides and GA3 were applied as a seed-dip treatment. GA3 increased seed germination and seedling growth. All concentrations (2 to 20 g a.i. · 1-1) of aldicarb and carbofuran, when applied independently, reduced seed germination and length of epicotyl and hypocotyl. However, application of these nematicides in combination with 100 mg · 1-1 GA3 showed antagonistic behaviour. All the treated seedlings were inoculated with 1000 nematode larvae of Meloidogyne incognita. Vegetative parameters of the plant were studied 15 days after transplantation. A combination of GA3 (100 mg · 1-1) with different concentrations of nematicides showed a synergistic effect on treated plants. Root knot index in plants treated with nematicides was found to be reduced with increasing concentrations of both nematicides. Maximum reduction in root knot index was observed at highest dose (20 g a.i. · 1-1) of both nematicides, when applied in combination with 100 mg · 1-1 GA3. Proteolytic activities were decreased in plants treated with both aldicarb and carbofuran. Supplementation of the nematicides with GA3 resulted in an increase in enzyme activities of the treated plants. Toxic residues increased with increasing concentration of both nematicides, whereas it was reduced at highest concentration of both nematicides when applied in combination with GA3. 相似文献
4.
The life-history ofNeurospora in nature has remained largely unknown. The present study attempts to remedy this. The following conclusions are based on
observation ofNeurospora on fire-scorched sugar cane in agricultural fields, and reconstruction experiments using a colour mutant to inoculate sugar
cane burned in the laboratory. The fungus persists in soil as heat- resistant dormant ascospores. These are activated by a
chemical(s) released into soil from the burnt substrate. The chief diffusible activator of ascospores is furfural and the
germinating ascospores infect the scorched substrate. An invasive mycelium grows progressively upwards inside the juicy sugar
cane and produces copious macroconidia externally through fire- induced openings formed in the plant tissue, or by the mechanical
rupturing of the plant epidermal tissue by the mass of mycelium. The loose conidia are dispersed by wind and/or foraged by
microfauna. It is suggested that the constant production of macroconidia, and their ready dispersal, serve a physiological
role: to drain the substrate of minerals and soluble sugars, thereby creating nutritional conditions which stimulate sexual
reproduction by the fungus. Sexual reproduction in the sugar- depleted cellulosic substrate occurs after macroconidiation
has ceased totally and is favoured by the humid conditions prevailing during the monsoon rains. Profuse micro-conidiophores
and protoperithecia are produced simultaneously in the pockets below the loosened epidermal tissue. Presumably protoperithecia
are fertilized by microconidia which are possibly transmitted by nematodes active in the dead plant tissue. Mature perithecia
release ascospores in situ which are passively liberated in the soil by the disintegration of the plant material and are,
apparently, distributed by rain or irrigation water. 相似文献
5.
Suresh Chand Purnima Basu Neeti Maheshwari 《Journal of plant biochemistry and biotechnology.》1994,3(1):53-54
Somatic embryogenesis and regeneration of plantlets was achieved In callus cultures derived from cotyledonary leaf pieces of Hyoscyamus muticus L on MS medium enriched with 2 mg/l 2,4–0 and 0.5 mg/l BAP. For embryogenesis and organogenesis varying concentrations of NAA with or without BAP were added In the medium. Organogenesis was also achieved when callus was transferred to the hormone free medium. 相似文献
6.
Akalla Mahalakshmi Satish C. Maheshwari Paramjit Khurana 《Journal of plant biochemistry and biotechnology.》1993,2(1):61-65
Protoplasts were isolated from the basal meristematic region of leaves from 6-day-old seedlings of wheat (Triticum aestivum). Protoplasts divided when cultured on MS medium (as agarose beads) in presence of nurse tissue. Donor seedlings when grown on BAP-supplemented MS medium were found to be considerably superior for protoplast isolation and culture than when grown on MS basal medium, in terms of protoplast viability, cell wall formation and cell division frequency. In addition, reduction of ammonium content of the culture medium, together with a dark Incubation, led to a high protoplast division frequency of about 70%. Microcolonies of 10-to 12-celled stages were obtained in Triticum aestivum, varieties HD 2329, HD 2285, Kalyan Sona, Arjun and CPAN 1676. 相似文献
7.
Excised shoot tips of Cuscuta reflexa Roxb. (dodder), a rootless and leafless angiospermic plant parasite, were cultured in vitro for the study of the control of lateral bud development by the apex. In a chemically defined medium lacking hormones, the basal bud alone developed into a shoot. The addition of coconut milk to the growth medium induced the activation of multiple lateral buds, but only a single bud developed further into a shoot. The decapitation of this shoot induced the development of another shoot and the process could be repeated. This showed the controlling effect of the apex in correlative control of bud development. Application of indole-3-acetic acid to the shoot tip explant delayed the development of the lateral bud. Gibberellic acid A3 induced a marked elongation growth of the explant and reinforced apical dominance. The direct application of cytokinin to an inhibited bud relieved it from apical dominance. A basipetally decreasing concentration gradient of auxin may prevail at the nodes. Bud outgrowth is probably stimulated by cytokinin produced locally in the bud. 相似文献
8.
Summary The protoplasts ofNicotiana plumbaginifolia required darkness for cell regeneration and colony formation. Maximal plating efficiency of the protoplasts could be achieved by keeping the cultures in dark instead of light or dark/light sequence. Only two days of darkness prior to the illumination at 400 or 3,000 lux resulted in appreciable plating efficiency, than those of light from the beginning, but these values could not match the high plating efficiency in total darkness. 相似文献
9.
A new polyhydroxy pregnane designated as cissogenin has been isolated from the seeds of Marsdenia tenacissima. Its structure has been established as 3β,11α,12β,14β,20 S-pentahydroxy-pregn-5-ene. 相似文献
10.