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Lemna paucicostata, normally a short-day plant, can be inducedto flower under long-day conditions by providing a cytokininin a medium containing a high level of ferric citrate (5 x 104M).Interestingly, when a cytokinin and EDDHA are present togetherin the medium, flowering is induced even at low levels of iron(105 and 5 x 105M ferric citrate). However, inthe absence of a cytokinin, flowering takes place only undershort days. (Received September 30, 1968; ) 相似文献
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The present report is a part of our study on the reproductivebiology of a traditional Indian medicinal plant,Commiphora wightii,a source of guggul steroids. Field examination showed a predominantlylarge number of isolated and groups of female individuals. Onlyone andromonoecious and two exclusively male plants were recorded.Female plants set seed irrespective of the presence or absenceof pollen. Hand-pollination experiments and embryological studieshave confirmed the occurrence of non-pseudogamous apomixis,nucellar polyembryony and autonomous endosperm formation forthe first time in this plant, which is presently threatenedby over-exploitation. Commiphora wightii ; autonomous endosperm; guggul; medicinal plant; non-pseudogamous apomixis; nucellar polyembryony 相似文献
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ASHA GUPTA 《Botanical journal of the Linnean Society. Linnean Society of London》1994,115(3):247-259
Fungal fruiting bodies ignored in earlier palynological investigations of the Subathu and Dagshai Formations have been studied from sediments exposed in the Dadahu Jamtah area, Sirmaur district, Himachal Pradesh. Taxa belonging to the genera Notothyrites, Asterothyrites, Parmathyrites, Phragmothyriles and Microthyriacites have been identified. These fossils are comparable with taxa reported from many Early Tertiary assemblages from different parts of the country and indicate a warm and humid climate. 相似文献
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The effect of copper sulphate on morphology and physiology of Lyngbya nigra has been studied. The growth was inhibited in all treatments (0.4 to 80.0 μM) of copper sulphate. There were no apparent morphological changes up to 0.8 μM and during the first two days of treatment even in the higher concentrations of copper sulphate. In concentrations above 0.8 μM the first symptom of toxicity was the formation of separation discs in large numbers. The trichomes contracted longitudinally and the cells became swollen and constricted at the cross walls. The cells also became yellowish due to loss of photosynthetic pigments. Finally, in 4 μM and above, vacuoles appeared in large number indicating the moribund state of the cells. Copper sulphate increased respiration at 2 μM, and optimum effect was observed in 8 μM after 96 h. Inhibition of photosynthesis was detectable in 0.8 μM, and 100% inhibition took place in 8 μM after 96 h. In higher concentrations the effect was immediate, and a conspicuous inhibition of photosynthesis could be observed within 10 min. The copper content of the alga increased with increased concentration of copper sulphate while potassium content decreased. With rise in outside concentrations of copper, there was a comparatively great increase of absorption in 2 and 4 μM, while further increases were gradually less. The observations indicate that changes in the physiological activity of the alga under treatment are closely interlinked with marked changes in morphology. 相似文献
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Embryogenesis occurred in Nigella sativa L. (Fam. Ranunculaceae) leaf callus tissue when coconut milk was replaced from the Murashige and Skoog's (MS) medium by casein hydrolysate. On MS + IAA (0.5 mg/l) + casein hydrolysate (100 and 500 mg/l) medium, tissue gained a capacity of growing embryoids for a pro-longed culture period. At a concentration of 1000 mg/l casein hydrolysate suppressed the differentiating capacity after the fifth subculture. 2.4-D and kinetin had inhibitory effects on morphogenesis. Histology of the differentiated tissue revealed that the origin of roots, shoot buds and leaves were from groups of meristematic cells whereas embryoids were initiated by the repeated division of a single cell. 相似文献
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Construction of intersubspecific molecular genetic map of lentil based on ISSR, RAPD and SSR markers
MAMTA GUPTA BHAWNA VERMA NARESH KUMAR RAKESH K. CHAHOTA RAJEEV RATHOUR SHYAM K. SHARMA SABHYATA BHATIA TILAK R. SHARMA 《Journal of genetics》2012,91(3):279-287
Lentil (Lens culinaris ssp. culinaris), is a self-pollinating diploid (2n?=?2x?=?14), cool-season legume crop and is consumed worldwide as a rich source of protein (~24.0%), largely in vegetarian diets. Here we report development of a genetic linkage map of Lens using 114 F2 plants derived from the intersubspecific cross between L 830 and ILWL 77. RAPD (random amplified polymorphic DNA) primers revealed more polymorphism than ISSR (intersimple sequence repeat) and SSR (simple sequence repeat) markers. The highest proportion (30.72%) of segregation distortion was observed in RAPD markers. Of the 235 markers (34 SSR, 9 ISSR and 192 RAPD) used in the mapping study, 199 (28 SSRs, 9 ISSRs and 162 RAPDs) were mapped into 11 linkage groups (LGs), varying between 17.3 and 433.8 cM and covering 3843.4 cM, with an average marker spacing of 19.3 cM. Linkage analysis revealed nine major groups with 15 or more markers each and two small LGs with two markers each, and 36 unlinked markers. The study reported assigning of 11 new SSRs on the linkage map. Of the 66 markers with aberrant segregation, 14 were unlinked and the remaining 52 were mapped. ISSR and RAPD markers were found to be useful in map construction and saturation. The current map represents maximum coverage of lentil genome and could be used for identification of QTL regions linked to agronomic traits, and for marker-assisted selection in lentil. 相似文献
10.
ADITYA K. MANEK JEFF M. SEREDA SOM NIYOGI DOUGLAS P. CHIVERS 《Biological journal of the Linnean Society. Linnean Society of London》2012,105(4):832-841
Recent anthropogenic activities have caused deleterious effects to the stratospheric ozone layer, resulting in a global increase in the level of ultraviolet radiation (UVR). Understanding the way that organisms respond to such stressors is key to predicting the effects of anthropogenic activities on aquatic ecosystems and the species that inhabit them. The epidermal layer of the skin of fishes is not keratinized and acts as the primary interface between the fish and its environment. The skin of many species of fishes contains large epidermal club cells (ECCs) that are known to release chemicals (alarm cues) serving to warn other fishes of danger. However, the alarm role of the cells is likely secondary to their role in the immune system. Recent research suggests that ECCs in the epidermis may play a role in protecting the fish from damage caused by UVR. In the present study, we examined the effects of in vivo exposure to UVR on fathead minnows (Pimephales promelas), specifically investigating ECC investment, physiological stress responses, and alarm cue production. We found that fish exposed to UVR showed an increase in cortisol levels and a substantive decrease in ECC investment compared to non‐exposed controls. Unexpectedly, our subsequent analysis of the behavioural response of fish to alarm cues revealed no difference in the potency of the cues prepared from the skin of UV‐exposed or non‐exposed minnows. Our results indicate that, although nonlethal, UVR exposure may lead to secondary mortality by altering the fish immune system, although this same exposure may have little influence on chemically‐mediated predator–prey interactions. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 832–841. 相似文献