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14 C‐Photosynthate Translocation in C 3 and C 4 Plants as Related to Leaf Anatomy 1
Author(s) -
Gallaher R. N.,
Ashley D. A.,
Brown R. H.
Publication year - 1975
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1975.0011183x001500010016x
Subject(s) - phloem , chromosomal translocation , biology , spots , panicum , botany , photosynthesis , apex (geometry) , genetics , gene
This study was performed to investigate the relationship between 14 C photosynthate translocation and phloem cross‐sectional area in C 3 and C 4 plants. Spots 5 mm in diameter were labeled by 14 CO 2 exposure on fully expanded leaves of two monocots ( Panicum maximum Jacq., a C 4 species and Panicum milioides Nees ex. Trin., a C 3 species) and two dicots ( Amaranthus retroflexus L., a C 4 species and Glycine max Merrill, a C 3 species). The spots were removed after 3 hours of translocation and equally divided. Half of the spots were used for 14 C analysis and half for anatomical study of cross sectional areas of phloem and other tissues. In all cases percent translocation from and cross‐sectional area of phloem tissue in labeled spots were higher in C 4 than in C 3 plants. P. maximum had 100% greater translocation out of and 96% more phloem tissue in the labeled spots than P. milioides . A. retroflexus translocated 48, 91, and 45% more 14 C out of spots over the midvein, secondary, and tertiary veins, respectively, than G. max . A. retrollexus had 5, 92, and 66% more phloem tissue in the above respective spots than G. max . Photosynthesis rates were higher in C 4 than in C 3 plants, but differences were not as great as those in translocation. Data from this study indicate that C 4 plants have both a greater translocation capacity and larger cross‐sectional area of phloem than C 3 plants.