TITLE:
Influence of Arsenate and Phosphate on the Regulation of Growth and TCA Cycle in the Rice (Oryza sativa L.) Cultivars IR64 and Nayanmani
AUTHORS:
Jayeeta Saha, Madhushree Dutta, Asok K. Biswas
KEYWORDS:
Arsenic, Phosphate, Respiration, Rice, TCA cycle, Amelioration
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.8,
July
20,
2017
ABSTRACT: The influence of arsenate and phosphate on the
growth and respiration of 21 days old seedlings in two cultivars of rice, viz.,
IR64 and Nayanmani was studied. As arsenate and
phosphate are similar in their chemical configuration and the latter is
preferentially taken up by the phosphate transporters, it results in a competitive inhibition of arsenate uptake in presence of phosphate.
Increasing concentrations of sodium arsenate (25 μM, 50 μM and 100 μM) hindered
the growth in both the cultivars, with cv. IR64 being more severely affected
than cv. Nayanmani. There was an elevation in the levels of organic acids
measured in both the cultivars, accompanied by a reduction in the activities of
the dehydrogenases of the TCA cycle, viz., pyruvate dehydrogenase, isocitrate
dehydrogenase, succinate dehydrogenase and malate dedrogenase under arsenic
treatment alone. Also, an elevation in the activities of citrate synthase and
fumarase enzymes was noticed in both test
seedlings with increasing concentrations of arsenic. These alterations were
more prominent in cv. IR64 than in cv. Nayanmani. On joint application of
phosphate along with arsenate, amelioration of the toxic effects of arsenate was observed to some
extent, resulting in an overall revival of respiration leading to improved
growth and metabolism.