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Photosynthetic Capacities and Growth Characteristics of Nicotiana tabacum (cv. Xanthi) Cell Suspension Cultures
Author(s) -
NATO A.,
BAZETOUX S.,
MATHIEU Y.
Publication year - 1977
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1977.tb05541.x
Subject(s) - nicotiana tabacum , photosynthesis , carbon fixation , rubisco , biology , phosphoenolpyruvate carboxylase , ribulose , botany , biochemistry , chlorophyll , exponential growth , mathematical analysis , mathematics , gene
Photoheterotrophic growth of cell suspensions of Nicotiana tabacum L. (cv. Xanthi) in organic culture medium enriched in sucrose (30 g per liter) showed a classical sigmoid growth curve. The cells developed functional chloroplast structures during the exponential growth phase, when their chlorophyll content increased steadily. A limited drop (30%) in the chlorophyll amount and structural changes of the plastids (starch accumulation) were observed during the lag phase. The measurements of photosynthetic capacities (O 2 evolution and CO 2 fixation) during the growth cycle revealed changes in the photosynthetic ratio (O 2 /CO 2 ), which was near 1 during the lag and stationary phases and near 2 during exponential growth. During exponential growth there was also a rapid NO 3 − uptake. Analysis of label distribution among the products of 14 CO 2 fixation showed that both CO 2 assimilation pathways, linked to the ribulose‐biphosphate carboxylase (the autotrophic pathway) and to phosphoenolpyruvate carboxylase (the non‐autotrophic pathway) were operative with an important increase of the capacity of the latter during the exponential growth phase. Maximum rate of oxygen evolution, either endogenous or with p ‐benzoquinone as Hill reagent, as well as the increased CO 2 Fixation capacity via the non‐autotrophic pathway during the exponential phase were concomitant with a high cyanide inhibited O 2 uptake.