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Piriformospora indica (P. indica) is a mutualistic endophyte that colonizes plant roots. In this study, effects of P. indica on rice resistance against rice leaffolder (Cnaphalocrocis medinalis Guenée) were investigated. Growth inhibition and leaf injury caused by leaffolder larvae infestation in P. indica-colonized rice was significantly alleviated. Moreover, growth retardation was observed in larvae which fed on P. indica-colonized plants. JA-Ile levels and trypsin inhibitor activities in leaf tissues of P. indica-colonized plants were higher than those in noncolonized plants under leaffolder-infested conditions. P. indica effects on increasing trypsin inhibitor expression and reducing larval growth were repressed by aspirin. JA signaling drives P. indica-enhanced insect resistance in rice, and trypsin inhibitors might be candidates involved in this mechanism. Changes in antioxidant enzyme activities and malondialdehyde levels in P. indica-inoculated plants were observed, and it was demonstrated that oxidative stress induced by insect infestation could be reduced in P. indica-colonized plants. [ABSTRACT FROM AUTHOR]

Sucrose is an important carbon source for plant tissue repairing and also a signal involved in defense responses to against insect herbivores. Allocation of sucrose toward to undamaged tissues is an herbivory tolerance mechanism. Sucrose transporters (SUTs) are key factors to control sucrose flow in plants. In this study, herbivory effects caused by rice leaffolder [Cnaphalocrocis medinalis (Guenée)] on OsSUT4 expressions were investigated in rice plants, and the results showed OsSUT4 expression was significantly upregulated by larvae infestation and mechanical wounding. The wounding-induced OsSUT4 expression was not systemically demonstrated in undamaged leaves. The larval chewing-induced OsSUT4 expression was obviously reduced by blocking jasmonic acid (JA) and abscisic acid (ABA) biosynthesis. In addition to JA and ABA, data showed H2O2 generated in wounded tissues also role a signal in the regulatory pathway of herbivore-induced OsSUT4 expressions. Our finding provide insights for further study in signal network of herbivory-induced sucrose translocation. [ABSTRACT FROM AUTHOR]

Rice ( Oryza sativa L.) seminal roots are the primary roots to emerge from germinated seeds. Here, we demonstrate that the photomorphology of the seminal roots was diverse among rice varieties, and the light-induced wavy roots were found mostly in indica-type rice varieties. The light-induced wavy morphology in rice seminal roots has been different with curling or coiling roots in some other specific conditions, such as high air humidity or high nitrogen nutrient. The efficiency of light-induced root waving was developmental stage dependent. The wavy root phenotype was caused by asymmetric cell growth around the stele. Using the inhibitors to block auxin polar transport and fatty acid oxygenation, the role of auxin and oxylipins in the morphogenesis of light-induced wavy roots was investigated. Expressions of genes encoded in the enzymes involved in fatty acid oxygenation in light-exposed roots were monitored by reverse transcriptase-polymerase chain reaction. Our results suggested that auxin polar transport was essential for inducing wavy seminal roots by light stimulus. In addition, the ketol oxylipins derived from allene oxide synthase (EC 4.2.1.92)-mediated fatty acid oxygenation function as intracellular signals for triggering the light-induced wavy root phenotype. [ABSTRACT FROM AUTHOR]