Fig. 4

The content of NH₄ ⁺ and transcriptional levels of OsGS1;1, OsGS1;2 and OsGS1;3 in rice spikelets. The apical spikelets on the primary branches at the positions from the first (top) to the fifth were harvested during the ripening period from 7 to 35 days after flowering. NH4+ concentration was measured (a). The detection of transcript for OsGS1;1 (filled square), OsGS1;2 (opened circle) and OSGS1;3 (opened triangle) was conducted in spikelets using quantitative real-time PCR (b). Quantitative real-time PCR analyses were performed using gene-specific primers for OsGS1;1, OsGS1;2, OsGS1;3 and actin, respectively, as described in Table 1. The relative contents of these transcripts were normalized against actin transcript. Means of four independent samples and standard error values (n = 4) are indicated