Use of positron emitting tracer system for measuring the effect of salinity on temporal and spatial distribution of 11C tracer and coupling between source and sink organs.
PlantSci_175_210.pdf 1.2 MB
Nguyen, Nguyen Tran
Mohapatra, Pravat K.
Moghaieb, Reda E.
Salinity stress affects photosynthate partitioning between sources and sinks of plants, but how it affects on these systems is less understood. Because sources and sinks are closely knitted, any adverse effect under sub-optimal condition on one part is often misinterpreted for the other. Knowledge on regulation of carbon partitioning is indispensable for stress resistance and good plant growth. In the present study, alteration of carbon partitioning in tomato plants (lycopersicon esculentum L. cv. Momotarou) under saline (NaCl) environment was studied by feeding radioactive 11C and stable 13C isotopes. Pulse chases were conducted for measuring spatial and temporal distributions of 13C. 13C was measured by standard conventional technique, but 11C distribution was monitored using by PETIS. Salt stress resulted in reduced carbon translocation towards roots. Majority of the photosynthate accumulated in the leaf. We have also observed that the reduction in translocation of carbon occurred well before salt stress symptoms of reduced photosynthesis and plant growth in salt exposed plants. The effect on sink activity also showed by decrease in stem diameter and reduced photosynthetic activity. In addition, PETIS analysis of 11C translocation indicates that carbon translocation to roots was inhibited under salt conditions without direct effect of leaf Na accumulation and osmotic stress These results suggest that NaCl has direct effects on plants inhibiting carbon partitioning within few hours of salt solution exposure without inhibition of source activity.
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