Abstract
Among species that perform CAM photosynthesis, members of the genus Kalanchoë have been studied frequently to investigate the effect of environmental factors on the magnitude of CAM activity. In particular, different nitrogen sources have been shown to influence the rate of nocturnal CO2 fixation and organic‐acid accumulation in several species of Kalanchoë. However, there has been little investigation of the interrelationship between nitrogen source (nitrate versus ammonium), concentration and the activity of the vacuolar proton pumps responsible for driving nocturnal organic‐acid accumulation in these species. In the present study with Kalanchoë laxiflora and Kalanchoë delagoensis cultivated on different nitrogen sources, both species were found to show highest total nocturnal organic‐acid accumulation and highest rates of ATP‐ and PPi‐dependent vacuolar proton transport on 2.5 mM nitrate, whereas plants cultivated on 5.0 mM ammonium showed the lowest values. In both species malate was the principal organic‐acid accumulated during the night, but the second‐most accumulated organic‐acid was fumarate for K. laxiflora and citrate for K. delagoensis. Higher ATP‐ and PPi‐dependent vacuolar proton transport rates and greater nocturnal acid accumulation were observed in K. delagoensis compared with K. laxiflora. These results show that the effect of nitrogen source on CAM activity in Kalanchoë species is reflected in corresponding differences in activity of the tonoplast proton pumps responsible for driving sequestration of these acids in the vacuole of CAM‐performing cells.
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Claims 9
Claim · model-written summary
Both species had the highest nocturnal organic acid accumulation on 2.5 mM nitrate.
Verbatim
e0“In the present study with Kalanchoë laxiflora and Kalanchoë delagoensis cultivated on different nitrogen sources, both species were found to show highest total nocturnal organic‐acid accumulation and highest rates of ATP‐ and PPi‐dependent vacuolar proton transport on 2.5 mM nitrate, whereas plants cultivated on 5.0 mM ammonium showed the lowest values.”
Claim · model-written summary
Both species had the highest ATP and PPi dependent vacuolar proton transport rates on 2.5 mM nitrate.
Verbatim
e0“In the present study with Kalanchoë laxiflora and Kalanchoë delagoensis cultivated on different nitrogen sources, both species were found to show highest total nocturnal organic‐acid accumulation and highest rates of ATP‐ and PPi‐dependent vacuolar proton transport on 2.5 mM nitrate, whereas plants cultivated on 5.0 mM ammonium showed the lowest values.”
Claim · model-written summary
Both species had the lowest nocturnal organic acid accumulation on 5.0 mM ammonium.
Verbatim
e0“In the present study with Kalanchoë laxiflora and Kalanchoë delagoensis cultivated on different nitrogen sources, both species were found to show highest total nocturnal organic‐acid accumulation and highest rates of ATP‐ and PPi‐dependent vacuolar proton transport on 2.5 mM nitrate, whereas plants cultivated on 5.0 mM ammonium showed the lowest values.”
Claim · model-written summary
Both species had the lowest vacuolar proton transport rates on 5.0 mM ammonium.
Verbatim
e0“In the present study with Kalanchoë laxiflora and Kalanchoë delagoensis cultivated on different nitrogen sources, both species were found to show highest total nocturnal organic‐acid accumulation and highest rates of ATP‐ and PPi‐dependent vacuolar proton transport on 2.5 mM nitrate, whereas plants cultivated on 5.0 mM ammonium showed the lowest values.”
Claim · model-written summary
Malate was the principal nocturnally accumulated organic acid in both species.
Not reportedDirection
Verbatim
e0“In both species malate was the principal organic‐acid accumulated during the night”
t0“two Kalanchoë species”
Claim · model-written summary
Fumarate was the second most accumulated organic acid in K. laxiflora.
Not reportedDirection
Verbatim
e0“the second‐most accumulated organic‐acid was fumarate for K. laxiflora and citrate for K. delagoensis”
Claim · model-written summary
Citrate was the second most accumulated organic acid in K. delagoensis.
Not reportedDirection
Verbatim
e0“the second‐most accumulated organic‐acid was fumarate for K. laxiflora and citrate for K. delagoensis”
Claim · model-written summary
K. delagoensis had higher ATP and PPi dependent vacuolar proton transport rates than K. laxiflora.
Verbatim
e0“Higher ATP‐ and PPi‐dependent vacuolar proton transport rates and greater nocturnal acid accumulation were observed in K. delagoensis compared with K. laxiflora.”
Claim · model-written summary
K. delagoensis had greater nocturnal acid accumulation than K. laxiflora.
Verbatim
e0“Higher ATP‐ and PPi‐dependent vacuolar proton transport rates and greater nocturnal acid accumulation were observed in K. delagoensis compared with K. laxiflora.”