Rice blast disease caused by Magnaporthe oryzae is the most devastating disease of rice. Previous studies have identified a terpene synthase gene, OsTPS19, as a candidate defense gene. The team of Xujun Chen from China Agricultural University studied OsTPS19, which was found to be upregulated by M. oryzae infection.

The team found that overexpression of the OsTPS19 gene in rice plants enhanced the plants' resistance against rice blast. On the other hand, OsTPS19 RNAi-silenced lines were found more susceptible to the disease. Further analysis also revealed that the production of a monoterpene (S)-limonene was increased in OsTPS19-overexpressing lines while it decreased in RNAi lines.

This indicates that OsTPS19 functions as an (S)-limonene synthase in rice and plays a partial role in defense against M. oryzae.

For more information, read the article in Plant Biotechnology Journal.

Figure 1: Expression of OsTPS19 was increased in the OsWRKY89 overexpression line and was induced by the rice blast fungus. (a) Expression of OsTPS19 and OsTPS20 in the OsWRKY89 overexpression rice line (OW89‐S13). (b) Induction of OsTPS19 and OsTPS20 transcription by inoculation of the virulent rice blast fungus M. oryzae SZ (SZ). The transcription level of each gene was normalized with rice ubiquitin gene (UBQ). WT represents the wild‐type control plants; Mock represents the control treatments. Values presented are the means ± SD of three separate analyses for each RNA template; similar results were obtained from each duplicate. Asterisks indicate statistically significant differences (Student's t test; *P < 0.05 and **P < 0.01).