Jasmonate and salicylatemediated signaling pathways play significant roles in induced plant defenses, but there is no sufficient evidence for their roles in monocots against aphids. We exogenously applied methyl jasmo...Jasmonate and salicylatemediated signaling pathways play significant roles in induced plant defenses, but there is no sufficient evidence for their roles in monocots against aphids. We exogenously applied methyl jasmonate （MeJA） and salicylic acid （SA） on wheat seedlings and examined biochemical responses in wheat and effects on the grain aphid, Sitobion avenae （Fab.）. Application of MeJA significantly increased levels of wheat＇s polyphenol oxidase, peroxidase and proteinase inhibitor 1, 2 and 6 days after treatment. In twochoice tests, adult aphids preferred control wheat leaves to MeJA or SA treated leaves. Electrical penetration graph （EPG） recordings of aphid probing behavior revealed that on MeJAtreated plants, the duration of aphid＇s first probe was significantly shorter and number of probes was significantly higher than those on control plants. Also total duration of probing on MeJAtreated plants was significantly shorter than on control plants. Total duration of salivation period on SAtreated plants was significantly longer, while mean phloem ingestion period was significantly shorter than on control plants. However, no significant difference in total duration of phloem sap ingestion period was observed among treatments. The EPG data suggest that MeJAdependent resistance factors might be due to feeding deterrents in mesophyll, whereas the SAmediated resistance may be phloembased. We did not observe any significant difference of MeJA and SA application on aphid development, daily fecundity, intrinsic growth rate and population growth. The results indicate that both MeJA and SAinduced defenses in wheat deterred S. avenae colonization processes and feeding behavior, but had no significant effects on its performance.展开更多
Jasmonic acid（JA） and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase（JMT） may be involved in plant defense and development by methylating JA to methyl jasmonate（Me...Jasmonic acid（JA） and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase（JMT） may be involved in plant defense and development by methylating JA to methyl jasmonate（Me JA） and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene,Os JMT1, whose encoding protein was localized in the cytosol, we found that the recombinant Os JMT1 protein catalyzed JA to Me JA. Os JMT1 is up-regulated in response to infestation with the brown planthopper（BPH; Nilaparvata lugens）. Plants in which Os JMT1 had been overexpressed（oeJMT plants） showed reduced height and yield. These oe-JMT plants also exhibited increased Me JA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine（JAIle）. The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs,probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H_2O_2 and Me JA in oe-JMT plants. These results indicate that Os JMT1,by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice.展开更多
文摘Jasmonate and salicylatemediated signaling pathways play significant roles in induced plant defenses, but there is no sufficient evidence for their roles in monocots against aphids. We exogenously applied methyl jasmonate （MeJA） and salicylic acid （SA） on wheat seedlings and examined biochemical responses in wheat and effects on the grain aphid, Sitobion avenae （Fab.）. Application of MeJA significantly increased levels of wheat＇s polyphenol oxidase, peroxidase and proteinase inhibitor 1, 2 and 6 days after treatment. In twochoice tests, adult aphids preferred control wheat leaves to MeJA or SA treated leaves. Electrical penetration graph （EPG） recordings of aphid probing behavior revealed that on MeJAtreated plants, the duration of aphid＇s first probe was significantly shorter and number of probes was significantly higher than those on control plants. Also total duration of probing on MeJAtreated plants was significantly shorter than on control plants. Total duration of salivation period on SAtreated plants was significantly longer, while mean phloem ingestion period was significantly shorter than on control plants. However, no significant difference in total duration of phloem sap ingestion period was observed among treatments. The EPG data suggest that MeJAdependent resistance factors might be due to feeding deterrents in mesophyll, whereas the SAmediated resistance may be phloembased. We did not observe any significant difference of MeJA and SA application on aphid development, daily fecundity, intrinsic growth rate and population growth. The results indicate that both MeJA and SAinduced defenses in wheat deterred S. avenae colonization processes and feeding behavior, but had no significant effects on its performance.
基金sponsored by the Special Fund for Agro-scientific Research in the Public Interest (201403030)the China Agriculture Research System (CARS01-21)the National Program of Transgenic Variety Development of China (2011ZX08009-003-001)
文摘Jasmonic acid（JA） and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase（JMT） may be involved in plant defense and development by methylating JA to methyl jasmonate（Me JA） and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene,Os JMT1, whose encoding protein was localized in the cytosol, we found that the recombinant Os JMT1 protein catalyzed JA to Me JA. Os JMT1 is up-regulated in response to infestation with the brown planthopper（BPH; Nilaparvata lugens）. Plants in which Os JMT1 had been overexpressed（oeJMT plants） showed reduced height and yield. These oe-JMT plants also exhibited increased Me JA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine（JAIle）. The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs,probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H_2O_2 and Me JA in oe-JMT plants. These results indicate that Os JMT1,by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice.
