Toward understanding of rice innate immunity against Magnaporthe oryzae.

The blast fungus, Magnaporthe oryzae, causes serious disease on a wide variety of grasses including rice, wheat and barley. The recognition of pathogens is an amazing ability of plants including strategies for displacing virulence effectors through the adaption of both conserved and variable pathogen elicitors. The pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) were reported as two main innate immune responses in plants, where PTI gives basal resistance and ETI confers durable resistance. The PTI consists of extracellular surface receptors that are able to recognize PAMPs. PAMPs detect microbial features such as fungal chitin that complete a vital function during the organism's life. In contrast, ETI is mediated by intracellular receptor molecules containing nucleotide-binding (NB) and leucine rich repeat (LRR) domains that specifically recognize effector proteins produced by the pathogen. To enhance crop resistance, understanding the host resistance mechanisms against pathogen infection strategies and having a deeper knowledge of innate immunity system are essential. This review summarizes the recent advances on the molecular mechanism of innate immunity systems of rice against M. oryzae. The discussion will be centered on the latest success reported in plant-pathogen interactions and integrated defense responses in rice.

Understanding the shoot apical meristem regulation: a study of the phytohormones, auxin and cytokinin, in rice.

Auxin and cytokinin regulate different critical processes involved in plant growth and environmental feedbacks. These plant hormones act either synergistically or antagonistically to control the organisation, formation and maintenance of meristem. Meristem cells can be divided to generate new tissues and organs at the locations of plant postembryonic development. The aboveground plant organs are created by the shoot apical meristem (SAM). It has been proposed that the phytohormone, cytokinin, plays a positive role in the shoot meristem function, promotes cell expansion and promotes an increasing size of the meristem in Arabidopsis, whereas it has the reverse effects in the root apical meristem (RAM). Over the last few decades, it has been believed that the apically derived auxin suppresses the shoot branching by inactivating the axillary buds. However, it has recently become clear that the mechanism of action of auxinis indirect and multifaceted. In higher plants, the regulatory mechanisms of the SAM formation and organ separation are mostly unknown. This study reviews the effects and functions of cytokinin and auxin at the shoot apical meristem. This study also highlights the merger of the transcription factor activity with the actions of cytokinin/auxin and their complex interactions with the shoot meristem in rice.