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ALTERATION OF 13 C‐ASSIMILATE PARTITIONING IN PLANTS OF PHASEOLUS VULGARIS EXPOSED TO OZONE
Author(s) -
OKANO K.,
ITO O.,
TAKEBA G.,
SHIMIZU A.,
TOTSUKA T.
Publication year - 1984
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1984.tb04119.x
Subject(s) - phaseolus , photosynthesis , chromosomal translocation , biology , botany , ozone , carbon fixation , horticulture , chemistry , biochemistry , gene , organic chemistry
S ummary A quantitative tracer experiment was conducted to elucidate the effects of continuous exposure to ozone (O 3 ) at 0.2 μl 1 −1 on the translocation and the distribution of 13 C‐labelled photosynthetic assimilates from the individual source leaves in 14‐d‐old plants of Phasealus vulgaris . The amount of labelled assimilates exported from the primary leaf, which acted as a main source of photosynthates for growth of the roots, decreased remarkably in the presence of O 3 as a result of both a considerable reduction of 13 CO 2 fixation (62%) and the inhibition of translocation. On the other hand, that from the first trifoliate leaf, which mainly nourished the immature growing leaves, was not decreased in the same way by O 3 because a smaller reduction of 13 CO 2 fixation (24%) was almost compensated by an acceleration of translocation. The pattern of assimilate distribution was altered by O 3 , so that a greater proportion of assimilates was partitioned to the growing leaves at the expense of the root and the stem. Consequently, the amount of labelled assimilates translocated to the non‐photosynthetic organs (stem and root) decreased by 53 %, while that to the photosynthetic organs (leaves) was reduced by only 28%. These results suggest that the plants might have adapted themselves to an environment containing O 3 so that the reduction of growth efficiency caused by O 3 could be minimized.