Changes in the acquisition and partitioning of carbon and nitrogen in the gibberellin‐deficient mutants A70 and W335 of tomato (Solanum lycopersicum L.)

Abstract

Even though the growth-promoting effects of gibberellins (GAs) in plants are well established, little is known about GA action on carbon metabolism and the available reports seem contradictory. We studied the effects of GA deficiency in mutants of tomato ( Solanum lycopersicum L.) on rates of carbon acquisition and the allocation of acquired carbon to growth and respiration of leaves, stems and roots. Carbon budgets were calculated from 24 h measurements of photosynthesis and respiration. The partitioning of nitrogen compounds to leaves, stems and roots, which strongly influences carbon budgets, was also studied. The GAdeficient mutants acquired less carbon per unit plant mass per day than did the wild type and used a larger fraction of it for root growth and root respiration. To find out to what extent these changes were just consequences of restriction of growth, the experiment was repeated at a low exponential nitrate addition rate, which forced all genotypes to grow at the same rate. Under these conditions, the low-GA mutants still photosynthesized and respired faster and partitioned more carbon to root growth than the wild type did. The reasons for the observed differences in carbon economies between the wild type and the low-GA mutants are discussed.

Impact of Altered Gibberellin Metabolism on Biomass Accumulation, Lignin Biosynthesis, and Photosynthesis in Transgenic Tobacco Plants

“…These results were in agreement with earlier GA application experiments showing a stimulation of xylem fiber elongation and cambial activity (Wareing, 1958;Digby and Wareing, 1966;Ridoutt et al, 1996). However, remarkably little is known about how GAs affect photosynthesis, which supplies carbon skeletons and energy for growth (Nagel and Lambers, 2002). The few available reports reveal contradictory results showing that application of GA 3 either stimulates (Yuan and Xu, 2001;Ashraf et al, 2002) or reduces the photosynthetic rate (Dijkstra et al, 1990).…”

“…No significant differences in photosynthetic rates were found between a GA-deficient tomato mutant and wildtype plants (Cramer et al, 1995). Different ways of measuring and calculating photosynthesis as well as the different experimental systems used (application of GA or GA inhibitors, use of mutants) were thought to be the reason for these contradictory results (Nagel and Lambers, 2002). The latter authors investigated the interrelationship between photosynthesis, respiration and growth using tomato GA mutants.…”

“…The latter authors investigated the interrelationship between photosynthesis, respiration and growth using tomato GA mutants. For this purpose, CO 2 exchange of intact plants was followed over 24 h and used to calculate the carbon budget (Nagel and Lambers, 2002). Although photosynthesis per unit leaf area was unaffected in the GA-deficient mutant, carbon assimilation per unit plant mass was reduced compared to wild type, which was brought about by the lower specific leaf area.…”

Comparative Productivity and Seed Nutrition of Cotton by Plant Growth Regulation under Deficient and Adequate Boron Conditions

“…Some studies have provided the ground basis that exogenously applied PGRs improve crop productivity and the nutritional quality of crop plants through improved photosynthesis and nutrient uptake and through accumulation within the plant body (Nagel and Lambers, 2002;Agegnehu and Taye, 2004;Niu et al, 2016).…”

Control de la floración en el género prunus. Factores climáticos y nutricionales

“…Nevertheless, little information is available about the effects of GAs on photosynthesis. Moreover, it is not clear if there is any relationship between GA concentrations and the rates of photosynthesis, growth and respiration (Nagel and Lambers, 2002). The few available reports reveal contradictory results, concluding that application of GA 3 both stimulates and reduces the photosynthetic rate (Dijkstra et al, 1990;Ashraf et al, 2002;Biemelt et al, 2004).…”