The ANIP1-OsWRKY62 module regulates both basal defense and Pi9-mediated immunity against Magnaporthe oryzae in rice

During effector-triggered immunity(ETI)against the devastating rice blast pathogen Magnaporthe oryzae,Pi9 functions as an intracellular resistance protein sensing the pathogen-secreted effector AvrPi9 in rice.Importantly,the underlying recognition mechanism(s)between Pi9 and AvrPi9 remains elusive.In this study,We identified a rice ubiquitin-like domain-containing protein(UDP),AVRPI9-INTERACTING PROTEIN 1(ANP1),which is directly targeted by AvrPi9 and also binds to Pi9 in plants.Phenotypic analysis of anip1 mu-tants and plants overexpressing ANIP1 revealed that ANIP1 negatively modulates rice basal defense against M.oryzae.ANiP1 undergoes 26S proteasome-mediated degradation,which can be blocked by both AvrPi9 and Pi9.Moreover,ANIP1 physically associates with the rice WRKY transcription factor OsWRKY62,which also interacts with AvrPi9 and Pi9 in plants.In the absence of Pi9,ANIP1 negatively regulates OsWRKY62 abundance,which can be promoted by AvrPi9.Accordingly,knocking out of OsWRKY62 in a non-Pi9 back-ground decreased immunity against M.oryzae.However,we also observed that OsWRKY62 plays negative roles in defense against a compatible M.oryzae strain in Pi9-harboring rice.Pi9 binds to ANiP1 and OsWRKY62 to form a complex,which may help to keep Pi9 in an inactive state and weaken rice immunity.Furthermore,using competitive binding assays,we showed that AvrPi9 promotes Pi9 dissociation from ANiP1,which could be an important step toward ETI activation.Taken together,our results reveal an immune strategy whereby a UDP-WRKY module,targeted by a fungal effector,modulates rice immunity in distinct ways in the presence or absence of the corresponding resistance protein.

Down-regulation of HaABCC3, potentially mediated by a cis-regulatory mechanism, is involved in resistance to Cry1Ac in the cotton bollworm, Helicoverpa armigera

Evolution of resistance to Cry proteins in multiple pest insects has been threatening the sustainable use of Bacillus thuringiensis(Bt)-transgenic crops.Better understanding about the mechanism of resistance to Cry proteins in insects is needed.Our preliminary study reported that the transcription of HaABCC3 was significantly decreased in a near-isogenic line(LFC2)of a Cry1Ac-resistant strain(LF60)of the global pest Helicoverpa armigera.However,the causality between HaABCC3 downregulation and resistance to Cry1Ac remains to be verified,and the regulatory mechanism underlying the HaABCC3 downregulation is still unclear.In this study,our data showed that both HaABCC3 and HaABCC3 downregulation were genetically linked to resistance to Cry1Ac in LF60.However,no InDels were observed in the coding sequence of HaABCC3 from LF60.Furthermore,F_(1) offspring from the cross of LF60 and a HaABCC2/3-knockout mutant exhibited moderate resistance to Cry1Ac toxin;this indicated that the high resistance to CrylAc toxin in LF60 may have resulted from multiple genetic factors,including HaABCC2 missplicing and HaABCC3 downregulation.Results from luciferase reporter assays showed that promoter activity of HaABCC3 in LF60 was significantly lower than that in the susceptible strain,which indicated that HaABCC3 downregulation was likely mediated by promoter variation.Consistently,multiple variations of the GATA-or FoxA-binding sites in the promoter region of HaABCC3 were identified.Collectively,all results in this study suggested that the downregulation of HaABCC3 observed in the H.armigera LF60 strain,which is resistant to CrylAc,may be mediated by a cis-regulatory mechanism.

Adaptive evolution to the natural and anthropogenic environment in a global invasive crop pest,the cotton bollworm

The cotton bollworm,Helicoverpa armigera,is set to become the most economically devastating crop pest in the world,threatening food security and biosafety as its range expands across the globe.Key to understanding the eco-evolutionary dynamics of H.armigera,and thus its management,is an understanding of population connectivity and the adaptations that allow the pest to establish in unique environments.We assembled a chromosome-scale reference genome and re-sequenced 503 individuals spanning the species range to delineate global patterns of connectivity,uncovering a previously cryptic population structure.

Jasmonic acid carboxyl methyltransferase regulates development and herbivory-induced defense response in rice

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.

Influence of seasonal migration on evolution of insecticide resistance in Plutella xylostella

The diamondback moth,Plutella xylostella(L.),is one of the most destructive migratory pest species of cruciferous vegetables worldwide and has developed resistance to most of the insecticides used for its control.The migration regularity,migratory behavior,and relationship between flight and reproduction of P.xylostella have been widely reported.However,the effect of migration on insecticide resistance in this pest is still unclear.In this study,the effect of migration on P.xylostella resistance to seven insecticides was investigated using populations across the Bohai Sea that were collected in the early and late seasons during 2017–2019.The bioassay results showed that the early season populations of P.xylostella from south China possessed much higher resistance to insecticides because of intensive insecticide application;alternatively,the late season populations migrated from northeast China,where the insecticides were only used occasionally,showed much lower insecticide resistance.The genome re-sequencing results revealed that,among the eight mutations involved in insecticide resistance,the frequencies of two acetylcholinesterase mutations(A298S and G324A)responsible for organophosphorus insecticide resistance were significantly decreased in the late season populations.The results indicated that P.xylostella migration between tropical and temperate regions significantly delayed the development of insecticide resistance.These findings illustrated the effect of regional migration on the evolution of insecticide resistance in P.xylostella,and provided foundational information for further research on the relationship between migration and insecticide resistance development in other insects.