Effect of nitrates supplied with the transpiration flow on assimilate translocation

Effect of nitrates supplied with the transpiration flow on assimilate translocation Solutions of nitrates (0.5% KNO3, 0.2% NH4NO3) or urea (0.15%) were fed under the pressure of 104 Pa to 50–60-cm-long detached shoots of common flax (Linum usitatissimum L.). One hour after the start of supplying the solutions, an assimilation clip chamber was fastened to the middle part of the shoot (14C source area), and 14CO2 was blown through in the light for 2.5 min. The analysis of distribution of 14C among the labeled products of photosynthesis produced by source leaves showed that nitrates reduced the incorporation of the label into sucrose. At the same time, the ratio of labeled sucrose to labeled hexoses decreased, and the incorporation of the label into serine greatly increased. Urea did not produce such effects. The pattern of distribution of 14C within the plant 3 h after the assimilation of 14CO2 points to the suppression of assimilate efflux from the leaves of plants fed with nitrates. In plants supplied with water or urea, 17–20% of labeled carbon was found below the 14C source area of the shoot, in nitrate type of treatment, only 3–5% was found there. In plants supplied with nitrates, the cortex tissue below the source leaf contained more 14C in proteins and less in low-molecular substances. In the wood tissue, such a correlation was not observed. When the shoot was supplied with water or urea, the content of 14C in sucrose in the source leaves in 3 h declined from 55–60% to 38–42%. When the shoot was fed with nitrates, the share of label in sucrose increased from 50 to 62–73%. Autoradiography of the source leaves showed that, in plants supplied with water or urea, the label was predominantly accumulated in large vascular bundles, and in nitrate type of treatment, it was accumulated outside large bundles. Electron microscopy showed that, in nitrate plants, the companion cells of phloem endings were very much vacuolated. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Russian Journal of Plant Physiology Springer Journals

Effect of nitrates supplied with the transpiration flow on assimilate translocation

Loading next page...
 
/lp/springer_journal/effect-of-nitrates-supplied-with-the-transpiration-flow-on-assimilate-9DN0Enq9ol
Publisher
Nauka/Interperiodica
Copyright
Copyright © 2007 by Pleiades Publishing, Ltd.
Subject
Life Sciences; Plant Physiology; Plant Sciences
ISSN
1021-4437
eISSN
1608-3407
D.O.I.
10.1134/S1021443707030120
Publisher site
See Article on Publisher Site

Abstract

Solutions of nitrates (0.5% KNO3, 0.2% NH4NO3) or urea (0.15%) were fed under the pressure of 104 Pa to 50–60-cm-long detached shoots of common flax (Linum usitatissimum L.). One hour after the start of supplying the solutions, an assimilation clip chamber was fastened to the middle part of the shoot (14C source area), and 14CO2 was blown through in the light for 2.5 min. The analysis of distribution of 14C among the labeled products of photosynthesis produced by source leaves showed that nitrates reduced the incorporation of the label into sucrose. At the same time, the ratio of labeled sucrose to labeled hexoses decreased, and the incorporation of the label into serine greatly increased. Urea did not produce such effects. The pattern of distribution of 14C within the plant 3 h after the assimilation of 14CO2 points to the suppression of assimilate efflux from the leaves of plants fed with nitrates. In plants supplied with water or urea, 17–20% of labeled carbon was found below the 14C source area of the shoot, in nitrate type of treatment, only 3–5% was found there. In plants supplied with nitrates, the cortex tissue below the source leaf contained more 14C in proteins and less in low-molecular substances. In the wood tissue, such a correlation was not observed. When the shoot was supplied with water or urea, the content of 14C in sucrose in the source leaves in 3 h declined from 55–60% to 38–42%. When the shoot was fed with nitrates, the share of label in sucrose increased from 50 to 62–73%. Autoradiography of the source leaves showed that, in plants supplied with water or urea, the label was predominantly accumulated in large vascular bundles, and in nitrate type of treatment, it was accumulated outside large bundles. Electron microscopy showed that, in nitrate plants, the companion cells of phloem endings were very much vacuolated.

Journal

Russian Journal of Plant PhysiologySpringer Journals

Published: May 25, 2007

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off