Arsenic (As) is toxic to organisms, and elevated As accumulation in rice
(Oryza sativa) grain poses a significant health risk to humans. The
predominant form of As in soil under aerobic conditions is As(V). Rice roots
take up As(V) by phosphate (Pi) transporters, such as OsPT1 and OsPT8. Ying
Ye from Huazhong Agricultural University in China investigated the
contribution of OsPT4 on rice As(V) uptake and transport.
Ying's team determined that the mRNA amounts of OsPTs in rice seedlings, and
expressions of OsPT1, OsPT4, and OsPT8 were upregulated under As(V)
conditions. OsPT4-overexpressing plants were obtained to examine the As(V)
transport activity in rice. The transgenic rice showed sensitivity to As(V)
stress with aboveground parts showing delayed growth and the roots stunted.
The team also used CRISPR-Cas9 and targeted the OsPT4 gene, developing
knockout lines. The knockout lines showed the opposite phenotype compared to
the overexpressing lines.
The study indicates that OsPT4 is involved in As(V) uptake and transport and
could be a good candidate gene to generate low As-accumulating rice.