Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice, secretes several cell wall degrading enzymes including cellulase (ClsA) and lipase/esterase (LipA). Prior treatment of rice leaves with purified cell wall degrading enzymes such as LipA can confer enhanced resistance against subsequent X. oryzae pv. oryzae infection. To understand LipA-induced rice defense responses, microarray analysis was performed 12 h after enzyme treatment of rice leaves. This reveals that 867 (720 upregulated and 147 downregulated) genes are differentially regulated (≥2-fold). A number of genes involved in defense, stress, signal transduction, and catabolic processes were upregulated while a number of genes involved in photosynthesis and anabolic processes were downregulated. The microarray data also suggested upregulation of jasmonic acid (JA) biosynthetic and JA-responsive genes. Estimation of various phytohormones in LipA-treated rice leaves demonstrated a significant increase in the level of JA-Ile (a known active form of JA) while the levels of other phytohormones were not changed significantly with respect to buffer-treated control. This suggests a role for JA-Ile in cell wall damage induced innate immunity. Furthermore, a comparative analysis of ClsA- and LipA-induced rice genes has identified key rice functions that might be involved in elaboration of damage-associated molecular pattern (DAMP)-induced innate immunity.
Bibliographical noteFunding Information:
We thank Michael Reichelt (Biochemistry Department, MPI-CE, Jena, Germany) for support in phytohormone estimation. We thank M. B. Madhavi for help in using microarray facility. AR was supported by a senior research fellowship from the Council of Scientific and Industrial Research, Government of India. This work was supported, in part, by a grant to RVS from the Department of Biotechnology, Government of India and by the Plant-Microbe and Soil Interactions project of the Council of Scientific and Industrial Research. No conflict of interest is declared for the other authors.
© 2014, Springer-Verlag Berlin Heidelberg.
- Cell wall degrading enzyme
- Damage-associated molecular patterns (DAMPs)
- Jasmonic acid
- Plant defense responses
- Xanthomonas oryzae