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What is the fate of xylem‐transported CO 2 in Kranz‐type C 4 plants?
Author(s) -
Stutz Samantha S.,
Hanson David T.
Publication year - 2019
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/nph.15908
Subject(s) - xylem , amaranthus hypochondriacus , photosynthesis , botany , transpiration , petiole (insect anatomy) , transpiration stream , aerenchyma , herbaceous plant , biology , chemistry , agronomy , amaranth , hymenoptera
Summary High concentrations of dissolved inorganic carbon in stems of herbaceous and woody C 3 plants exit leaves in the dark. In the light, C 3 species use a small portion of xylem‐transported CO 2 for leaf photosynthesis. However, it is not known if xylem‐transported CO 2 will exit leaves in the dark or be used for photosynthesis in the light in Kranz‐type C 4 plants. Cut leaves of Amaranthus hypochondriacus were placed in one of three solutions of [NaH 13 CO 3 ] dissolved in KCl water to measure the efflux of xylem‐transported CO 2 exiting the leaf in the dark or rates of assimilation of xylem‐transported CO 2 * in the light, in real‐time, using a tunable diode laser absorption spectroscope. In the dark, the efflux of xylem‐transported CO 2 increased with increasing rates of transpiration and [ 13 CO 2 *]; however, rates of 13 C efflux in A. hypochondriacus were lower compared to C 3 species. In the light, A. hypochondriacus fixed nearly 75% of the xylem‐transported CO 2 supplied to the leaf. Kranz anatomy and biochemistry likely influence the efflux of xylem‐transported CO 2 out of cut leaves of A. hypochondriacus in the dark, as well as the use of xylem‐transported CO 2 * for photosynthesis in the light. Thus increasing the carbon use efficiency of Kranz‐type C 4 species over C 3 species.