Zheng Kong^{1, 2}, Degang Zhao^{1, 3,}

This study aimed to characterize the effect of jasmonic acid (JA) on volatile compounds in grains of Kam sweet rice. Using GC-O and SPME-GC-MS, nonanal displayed the highest odor activity value (OAV) in the filling grains and increased after applicaton of jasmonic acid in the rice seedlings. The relative expression of rice OsLOX3 (rice lipoxygenase 3) and OsHPL1 (rice hydroperoxide lyase 1) was assessed by RT-PCR in Kam sweet rice Gou Cengao and the non-aromatic Kam rice Lailong rice after rice pollination. Our data showed that OsLOX3 was elevated in Gou Cengao compared with the non-aromatic rice. In agreement, lipoxygenase (OsLOX3 gene product) levels and activity were elevated in aromatic rice samples. The positive Pearson correlation (0.715) was found between JA and lipoxygenase activity (p < 0.01). Interestingly, a significant positive Pearson correlation (0.936) was found between the concentrations of endogenous JA and the relative expression of rice OsLOX3 (p < 0.01). The results suggest that the enhancing effect of JA on the biosynthetic pathway of nonanal.

Kam sweet rice, Nonanal, 2-Acetyl-1-pyrroline, Lipoxygenase activity, Jasmonic acid, OsLOX3