Abstract
Pb inhibits plant growth. To study Pb tolerance in rice (Oryza sativa), we screened 229 varieties for Pb tolerance or sensitivity. Three-day-old seedlings were treated for 12 d with 20 microM Pb solution. Based on the dry weight of the root, three Pb-tolerant (var CH-55, var KH-2J, var Kumnung) and three Pb-sensitive (var Aixueru, var C-9491, var Milyang23) rice varieties were selected. The root biomasses of the tolerant varieties were approximately 10-fold higher than those of the sensitive ones. The greatest morphological difference between the two groups was in the growth of the adventitious roots, as tolerant lines were able to develop adventitious roots after 6 d of Pb treatment, whereas sensitive ones did not develop any even after 15 d. The growth of adventitious roots in the tolerant varieties was dependent on a mechanism, whereby Pb was altered to a form that cannot be taken up by the tissue, because (a) the solution in which the tolerant varieties of rice had grown still contained Pb but nevertheless did not affect the root growth of new rice seedlings, and (b) the adventitious roots of tolerant seedlings developed in Pb solution contained little Pb. The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties, whereas the opposite was observed for the sensitive ones. Oxalate added to the growth solution ameliorated the inhibition of root growth by Pb. These results suggest that compounds such as oxalate secreted from the root may reduce the bio-availability of Pb, and that this may constitute an important Pb tolerance mechanism in the tolerant rice varieties studied here.
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Claims 11
Claim · model-written summary
Three rice varieties were selected as Pb tolerant.
Oryza sativaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“three Pb-tolerant (var CH-55, var KH-2J, var Kumnung)”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Three rice varieties were selected as Pb sensitive.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“three Pb-sensitive (var Aixueru, var C-9491, var Milyang23)”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Root biomass in tolerant varieties was approximately tenfold that in sensitive varieties.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The root biomasses of the tolerant varieties were approximately 10-fold higher than those of the sensitive ones”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Tolerant lines developed adventitious roots after six days of Pb treatment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Sensitive lines lacked adventitious roots even after fifteen days of Pb treatment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sensitive ones did not develop any even after 15 d”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Pb solution used to grow tolerant varieties did not impair root growth in new rice seedlings.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the solution in which the tolerant varieties of rice had grown still contained Pb but nevertheless did not affect the root growth of new rice seedlings”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Adventitious roots of tolerant seedlings grown in Pb solution contained little Pb.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the adventitious roots of tolerant seedlings developed in Pb solution contained little Pb”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Pb treatment increased root and exudate oxalate content in tolerant varieties.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Pb treatment decreased root and exudate oxalate content in sensitive varieties.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas the opposite was observed for the sensitive ones”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Added oxalate ameliorated Pb inhibition of rice root growth.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxalate added to the growth solution ameliorated the inhibition of root growth by Pb”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
Claim · model-written summary
Root secreted compounds such as oxalate may reduce Pb bioavailability and mediate tolerance.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“compounds such as oxalate secreted from the root may reduce the bio-availability of Pb, and that this may constitute an important Pb tolerance mechanism”
t0“Rice”
e1“rice (Oryza sativa)”
e2“tolerant lines were able to develop adventitious roots after 6 d of Pb treatment”
e3“The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties”
The same questions in other papers
lead atom · molecular: metabolites · Oryza sativa (rice)Results agree
2 papers in the same direction as this paper
- positive
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.