3.1 Biuret injury in hydroponically grown rice seedlings
We first investigated the biuret sensitivity of wild-type rice plants.
When wild-type Nipponbare seeds were sown in culture solutions
supplemented with varying levels of biuret (0, 0.1, 0.3, and 1.0 mmol
L-1 biuret), germination was not inhibited, regardless
of the biuret levels. The plant height of 7-day-old seedlings decreased
with increasing concentrations of biuret (Figure 1a). Chlorosis was
observed in some plants exposed to 0.1 mmol L-1 biuret
and all plants exposed to 0.3 mmol L-1 biuret. It was
most markedly observed in leaf blades of the emerging third leaf. In
plants exposed to 1.0 mmol L-1 biuret, chlorosis was
less prominent, probably because of the severe reduction in the growth
(Figure 1b).