Seasonal Changes in Respiration, Photosynthesis, and Translocation of the 14C Labelled Products of Photosynthesis in Young Pinus strobus L. Plants

Shiroya, Tsugio; Lister, G. R.; Slankis, V.; Krotkov, G.; Nelson, C. D.

doi:10.1093/oxfordjournals.aob.a084061

Cited by 63 publications

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“…The second objective has been to determine the amouints of 1"C lost from the plants after various periods of time following "CO. photo-a,ssimilation. A third objective has been to observe the partition of retaiined 1"C between the 80 % ethanol-soluible and insoluble fractions.Thi,s study represents an extension of previous work (13,18,19) …”

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confidence: 75%

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Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

1968

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Abstract. Pinus strobus L. plants in their third year of growth were permitted to photoassimilate '4CO, for about 1 hour at monthly intervals between April and October, and the subsequent distribution of 14C in these plants was determined 8 hours, 1 month, 2 months or 4 months after photo-assimilation. In this way, the fate of 14CO2 photo-assimilated during different months of the growing season was observed.In the spring, old needles played a significant role in photo-assimilating 14CO0 and exporting current photosynthate to the developing new shoots and roots. By July, the new shoot had replaced the old shoot both as the primary photo-assimilating part of the plant and as an exporter, particularly to the root.The root received current photosynthate from the shoot throughout the entire growing season, although plant analysis only 8 hours after photo-assimilation did not always reveal this. Trarnslocation of recent photosynthate from shoot to root was particularly high in August, September, and October.The amounts of photo-astsimilated 14C lost from the plants over a 4 month interval, principally through respiration and photorespiration, were about one-half of that absorbed during photo-assimilation, with the greatest loss occurring within the first month.3 No. 6 ine 1968To gain insight into the sources of carbohydrates for growth of various parts of a tree at different times of the year, studies using defoliation, girdling, and combinations of these techniques (1, 8,9,11,16,17), as well as observations on the contributions of dififerent aged needles (10) 3 Deceased.old shoot, and new shoot. The second objective has been to determine the amouints of 1"C lost from the plants after various periods of time following "CO. photo-a,ssimilation. A third objective has been to observe the partition of retaiined 1"C between the 80 % ethanol-soluible and insoluble fractions.Thi,s study represents an extension of previous work (13,18,19)

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“…Thi,s study represents an extension of previous work (13,18,19) ternal irradiation provided from the incorporation of 400 to 500 juc of "'CO2 (22). In As seen in figure 4, 'by mid-June elongation of the new 'shoots was essentiall4y complete, and new need'le expansion abou-t one-third complete.…”

Section: No 6 Ine 1968mentioning

confidence: 88%

Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

1968

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“…There is evidence to support the idea that sucrose is the main form in which carbon compounds are translocated in plants (1,7,8,9). Swanson (10) showed that the ratio of labeled hexoses to labeled sucrose decreased with increasing distance from the fed leaf after assimilation of 14CO-.…”

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confidence: 99%

“…(8) found with white pine seedlings that a considerabhle amotunt of photosynthate was translocated upwards during the growtlh of the shoot, when downward translocation was at the lowest value of the year. The present work on sunflower plants was carried out to find: 1) what specific factors affect the rate of translocation from a fed leaf: 2) whether the mechanisms of upward and downward translocation were different: 3) whether the translocation pattern of infiltrated a C-sugars corresponded to that of 14 C-photosynthates.…”

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Comparison of Upward and Downward Translocation of ¹⁴C From a Single Leaf of Sunflower

Shiroya

1968

Plant Physiol.

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Abstract. When single leaves attached at a given node were allowed to carry on photosynthesis in 14CO2 for 30 min, younger plants showed a higher proportion of upward translocation than did older plants. Downward translocation of 14C-photosynthate was stimulated by ATP pre-treatment of the translocating leaf, while upward translocation was not affected by ATP. A similar phenomenon was observed in the translocation of 14C-sucrose infiltrated into a leaf with or without ATP. Downward translocation of photosynthate was inhibited by DNP pre-treatment of a fed leaf. Upward translocation, however, was not affected by DNP. Thirty min after infiltration of 14C-glucose into a leaf, almost all the 14C translocated upwards was found to be in the form of glucose, whi'le a great part of the 14C translocated downwards was in the form of sucrose. In the case of translocation of infiltrated 14C-suerose, 14C found both above and below the fed leaf was mainly in the form of sucrose.In our previous study (7) 2) whether the mechanisms of upward and downward translocation were different: 3) whether the translocation pattern of infiltrated a C-sugars corresponded to that of 14 C-photosynthates. Materials and MethodsSunflower (Helianthts annuus) plants were grown at 25°for 4 to 9 weeks in a growth cabinet programmed to a 13 hr photoperiod of 30,000 lux at leaf level and an 11 hr dark period. Almost all experiments were carried out with 5-week-old plants about 20 cm tall. The first or second leaf from the base of the plant at the above-mentioned stage was mainly used as the fed leaf in all the experiments. Each experiment was done with 3 plants selected both for uniformity of height and leaf size. Every datum in the tables and figures is the average value for 3 plants.Feeding. To feed 14CO2, a leaf was enclosed in a transparent photosynthetic chamber. Seventy ,uc of 14CO.) were generated and introduced into the chamber as previously described (7). The whole planit was placed under illumination of 30,000 lux for 30 min to allowv the fed leaf to fix 14CO. and at the samiie time translocate 14C-photosynthate to parts both above and below the fed leaf. 14C-sucrose or '4C-glucose was introduced into leaves by vacuum infiltration. After infiltration for 2 min, the leaf was removed from the vessel, washed with distilled water, and kept under illumination for 30 min to translocate the infiltrated 14C-sugars.Treatmnent With A TP and DNP. The ATP solution (di-potassium salt, 2 X 10-2 M in phosphate buffer, pH 6.8, 5 X 10-2 M) or DNP solution (10-4 M in phosphate buffer, pH 6.8, 5 X 10-2 M) was introduced into the fed leaf by means of vacuum infiltration. The phosphate buffer above was infiltrated into a corresponding leaf of the control plant.

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“…With few exceptions (18,22), mesophytic, ligneous stems were not capable of net photosynthesis, but bark photosynthesis did reduce the respiratory CO2 loss from the stem.…”

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Diurnal and Seasonal Patterns of Photosynthesis and Respiration by Stems of Populus tremuloides Michx.

Foote¹,

Schaedle²

1976

Plant Physiol.

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The photosynthetic and respiratory rates of 5-to 7-year-old aspen stems (Populus tremuloides Michx.) were monitored in the field for 1 year to determine the seasonal patterns. The stem was not capable of net photosynthesis, but the respiratory CO2 loss from the stem was reduced by 0 to 100% depending on the time of year and the level of illummination as a result of bark photosynthesis. The monthly dark respiratory rate ranged from 0.24 mg COdm2 hr in January to a maximum 7.4 mg COdm2-hr in June. Individual measurements ranged from 0.02 mg COSdm2 -hr in Februay to 12.3 mg COdm22* hr in June. Gross photosynthesis followed a pattern similar to the dark respiratory rate. The mean montily rate was highest in June (1.65 mg COdm2 hr) and lowest in December (0.02 mg C02/dm2-hr). Individual measurements ranged from 0.0 mg COJdm2 hr in winter to 5.5 mg COdm2 hr in July.Winter studies showed that stem respiration continued down to -11 C, the coldest temperature during this study. Upon warming to -3 C, the dark respiratory rate showed a sudden sharp increase (7-to 12-fold) which required many hours to return to normal levels. No measurable photosynthesis occurred below -3 C. Between -3 and 0 C, the maximal photosynthetic rate was reduced to less than 50% of the respiratory rate, but increased to 89% between 5 to 10 C. On a yearly basis, bark photosynthesis in P. tremuloides reduced the stem respiratory CO2 loss by 28.7% on a daytime basis and an estimated 16 to 18% on a 24-hour basis.Bark photosynthesis has been demonstrated in twigs and stems in a variety of species (12,15,17,20). With few exceptions (18, 22), mesophytic, ligneous stems were not capable of net photosynthesis, but bark photosynthesis did reduce the respiratory CO2 loss from the stem.No information is available on the day-to-day field performance of bark photosynthesis. This investigation determined diurnal and seasonal patterns of respiration and photosynthesis of young aspen stems under year-round field conditions that exist in central New York.

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Seasonal Changes in Respiration, Photosynthesis, and Translocation of the 14C Labelled Products of Photosynthesis in Young Pinus strobus L. Plants

Cited by 63 publications

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Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

Comparison of Upward and Downward Translocation of ¹⁴C From a Single Leaf of Sunflower

Diurnal and Seasonal Patterns of Photosynthesis and Respiration by Stems of Populus tremuloides Michx.

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Seasonal Changes in Respiration, Photosynthesis, and Translocation of the 14C Labelled Products of Photosynthesis in Young Pinus strobus L. Plants

Cited by 63 publications

References 0 publications

Seasonal Changes in the Distribution of Photo-assimilated 14C in Young Pine Plants

Seasonal Changes in the Distribution of Photo-assimilated 14C in Young Pine Plants

Comparison of Upward and Downward Translocation of 14C From a Single Leaf of Sunflower

Diurnal and Seasonal Patterns of Photosynthesis and Respiration by Stems of Populus tremuloides Michx.

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Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

Seasonal Changes in the Distribution of Photo-assimilated ¹⁴C in Young Pine Plants

Comparison of Upward and Downward Translocation of ¹⁴C From a Single Leaf of Sunflower