Inhibitory effect of cotyledons on plumule development in two alpine rosettes

Nautiyal, M. C.

doi:10.1139/b88-034

Cited by 7 publications

(8 citation statements)

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“…The hypocotyl dormancy strategy employed by P. hexandrum for survival in the alpine Himalayan environment was reported to be regulated by cotyledonary leaves (Purohit and Nautiyal 1986). In a previous observation, we found ''hypocotyl dormancy was broken whenever the temperature was favorable (20-25°C) but persisted at 10-15°C or lower''.…”

Section: Introductionmentioning

confidence: 63%

“…Firstly, the seeds mature and germinate in large numbers during the favorable warm season (20-25°C) only. Secondly, the seedlings that finally establish themselves exhibit ''hypocotyl dormancy'' or ''pseudomonocotyly'' (Purohit and Nautiyal 1986;Kharkwal et al 2004). This is a phenomenon wherein the long tubulate parts of the two cotyledonary leaves of the newly emerged seedlings fuse to form a sheathing base that covers the plumule or epicotyl (Terabayashi 1987).…”

Section: Introductionmentioning

confidence: 99%

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Temperature-dependent growth and emergence of functional leaves: an adaptive mechanism in the seedlings of the western Himalayan plant Podophyllum hexandrum

et al. 2008

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As an adaptive mechanism, hypocotyl dormancy delays emergence of functional leaf until favorable season of growth in Podophyllum hexandrum, an endangered medicinal plant of the western Himalayas. However, upon exposure of the freshly germinated seedlings to favorable temperature (25 degrees C), functional leaves emerged within 20 days. Therefore, we examined regulation mechanisms of growth and development of this alpine plant by temperature under laboratory conditions. The seedlings were exposed to (1) 25 degrees C (temperature prevailing at the time of maximum vegetative growth), (2) 4 degrees C (mean temperature at the onset of winter in its natural habitat), and (3) 10 degrees C (an intermediate temperature). Slackened growth at 4 degrees C was followed by senescence of aerial parts and quiescence of roots and predetermined leaf primordia. Rapid development of leaf primordia at 25 degrees C was associated with increased starch hydrolysis. This was evident from higher alpha-amylase activity and reducing sugars. These parameters decreased on sudden exposure to 4 degrees C. In contrast, the roots (perennating organs) showed a slight increase (1.36-fold) in alpha-amylase activity. Growth and development in seedlings growing at 10 degrees C (temperature less adverse than 4 degrees C) were comparatively faster. The content of reducing sugars and alpha-amylase activity were also higher in all the seedling parts at 10 degrees C as compared to 4 degrees C. This indicated larger requirements for sugar by the seedlings at 10 degrees C. Irrespective of temperature, maximum changes in nitrate and nitrate reductase occurred during the initial 10 days, i.e., when the readily available form of sugars (reducing sugar) was highest. This indicated that a temperature-dependent availability of carbon, but not temperature itself, was an important regulator of uptake and reduction of nitrogen.

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Section: Introductionmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Temperature-dependent growth and emergence of functional leaves: an adaptive mechanism in the seedlings of the western Himalayan plant Podophyllum hexandrum

et al. 2008

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“…Dormancy, if any, probably ensued only in the after-ripened seeds, as in a vast majority of alpine seeds [26]. This could be true because Badhwar and Sharma [16] reported seed dormancy of few months to several years in this plant, and most of the subsequent work further emphasized this phenomenon [27]. The secondary or enforced dormancy that generally sets in a number of seeds is known to exist for prolonged periods, until commencement of a favorable environment [28].…”

Section: Discussionmentioning

confidence: 99%

“…Hypocotyl dormancy is another major constraint that has been reported to hinder large-scale seedling establishment [27,29]. Under natural conditions, true leaves have been reported to emerge only after 11-12 months, i.e., only in the growing season following seed germination [27].…”

Section: Discussionmentioning

confidence: 99%

An efficient method of propagation of Podophyllum hexandrum: an endangered medicinal plant of the Western Himalayas under ex situ conditions

et al. 2008

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This study shows an effective but simple method of conserving characterized populations and elite clones through vegetative propagation and genetic diversity through seeds in Podophyllum hexandrum (family Berberidaceae). Seed dormancy has been considered to be a major constraint in these seeds and most of the earlier reports recommended dormancy-breaking pretreatments such as chilling, gibberellic acid (GA(3)), etc. However, seeds of the 14 accessions that we tested exhibited no dormancy and hence did not require any pretreatments. Besides accession, collection of seeds with high moisture content could be one of the reasons for lack of dormancy. Thus, we propose germination of seeds (while they still retained moisture) in sand at 25 degrees C for high and reproducible results within a shorter period of time compared with earlier reports. Hypocotyl dormancy is known to considerably delay plant establishment and hence en masse propagation by preventing the emergence of functional leaves for up to 11-12 months. Manual removal of cotyledonary leaves, being labor and time intensive, is not a feasible method for large-scale seedling establishment. However, in this study, we showed that GA(3) at 200 ppm can alleviate hypocotyl dormancy besides reducing the time taken for true or functional leaf emergence. Treatment of cotyledonary leaves of 1 week-old-seedlings with 200 ppm GA(3 )resulted in true or functional leaf emergence within 7 days, and the resultant plants were also more vigorous than the ones obtained from manual removal of cotyledonary leaves. The study helped advance the establishment of seedlings by one growing season (almost 1 year).

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“…Having to survive the frequent but sudden snow falls and the extreme drought conditions associated with freezing temperatures, the seedlings of P. hexandrum exhibit prolonged hypocotyl dormancy followed by senescence of aerial parts. As a result vegetative growth is delayed until the following favorable season of growth (Purohit and Nautiyal 1986). However, since GA 3 is known to hasten vegetative growth in plants (Maksymowych et al 1976) including P. hexandrum (Kharkwal et al 2004), an attempt was made in the present study to understand the histological and biochemical changes that were affected by GA 3 in order to bring about this hastening of vegetative growth under ex situ conditions.…”

Section: Introductionmentioning

confidence: 99%

GA3 induced changes in slow growing endangered Himalayan plant Podophyllum hexandrum and hastening of vegetative growth

et al. 2007

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The endangered Himalayan plant Podophyllum hexandrum syn. P. emodi is inherently slow growing. The plants exhibit delayed emergence of functional leaves or hypocotyl dormancy. However, on GA 3 treatment the functional leaves were found to emerge at a favorable temperature of 25°C in a higher percentage of seedlings and in a shorter time. Functional leaves emerged even at 10°C, a temperature when hypocotyl dormancy generally prevails. A considerable increase in the biochemical parameters related to carbon and nitrogen metabolism [starch, sugars and soluble nitrates, a-amylase and nitrate reductase (NR) activity], respiration and total dehydrogenase activity in all the seedling parts also indicated an enhancement of metabolic processes as influenced by GA 3 , for further growth and development. Specific leaf area of the green cotyledonary leaves increased at 25°C, probably to meet the carbon and nitrogen requirements for new structure formation. Higher activity of enzymes involved in carbon and nitrogen metabolism, i.e., NR and a-amylase especially at Hbn, the region of leaf meristematic activity, was further indicative of higher metabolism for earlier initiation of rapid vegetative growth. Initiation of reserve accumulation was also observed at 25°C.

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Inhibitory effect of cotyledons on plumule development in two alpine rosettes

Cited by 7 publications

References 0 publications

Temperature-dependent growth and emergence of functional leaves: an adaptive mechanism in the seedlings of the western Himalayan plant Podophyllum hexandrum

Temperature-dependent growth and emergence of functional leaves: an adaptive mechanism in the seedlings of the western Himalayan plant Podophyllum hexandrum

An efficient method of propagation of Podophyllum hexandrum: an endangered medicinal plant of the Western Himalayas under ex situ conditions

GA3 induced changes in slow growing endangered Himalayan plant Podophyllum hexandrum and hastening of vegetative growth

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