Most research on plant amino acid transporters was conducted in Arabidopsis,
thus limiting understanding of their roles in rice. OsLHT1 (Lysine/Histidine
transporter) was found to function as a histidine transporter in yeast, but
its substrate profile and actual function in living plants remain unclear.
Thus, scientists from Guangxi University analyzed the substrate selectivity
of OsLHT1 and influence of its disruption on rice growth and fecundity. The
findings are published in BMC Plant Biology.

Using two-electrode voltage clamp, the researchers analyzed the substrate
selectivity of OsLHT1 in frog oocytes. This showed that OsLHT1 could
transport a wide array of amino acids such as basic, neutral, and acidic
amino acids, and showed a preference for neutral and acidic amino acids.
Using CRISPR-Cas9, two oslht1 mutants were generated leading to loss of
function of OsLHT1, inhibiting rice root and shoot growth, which
consequently led to reducing grain yields. Further analysis showed that
OsLHT1 was expressed in different rice organs, including root, stem, flag
leaf, flag leaf sheath, and young panicle. Temporary expression in rice
protoplast showed that OsLHT1 was localized to the plasma membrane, which is
consistent with its function as an amino acid transporter.

Based on the results, OsLHT1 is an amino acid transporter with wide
substrate specificity and with preference for neutral and acidic amino
acids, and disruption of OsLHT1 function inhibited rice growth and
fecundity.

[bmcplantbiol.biomedcentral.com]