查看更多>>摘要：Root nodule symbiosis(RNS)between legumes and rhizobia is a major source of nitrogen in agricultural systems.Effective symbiosis requires precise regulation of plant defense responses.The role of the de-fense hormone jasmonic acid(JA)in the immune response has been extensively studied.Current research shows that JA can play either a positive or negative regulatory role in RNS depending on its concentration,but the molecular mechanisms remain to be elucidated.In this study,we found that inoc-ulation with the rhizobia Sm1021 induces the JA pathway in Medicago truncatula,and blocking the JA pathway significantly reduces the number of infection threads.Mutations in the MtMYC2 gene,which encodes a JA signaling master transcription factor,significantly inhibited rhizobia infection,terminal dif-ferentiation,and symbiotic cell formation.Combining RNA sequencing and chromatin immunoprecipita-tion sequencing,we discovered that MtMYC2 regulates the expression of nodule-specific MtDNF2,MtNAD1,and MtSymCRK to suppress host defense,while it activates MtDNF1 expression to regulate the maturation of MtNCRs,which in turn promotes bacteroid formation.More importantly,MtMYC2 par-ticipates in symbiotic signal transduction by promoting the expression of MtIPD3.Notably,the MtMYC2-MtIPD3 transcriptional regulatory module is specifically present in legumes,and the Mtmyc2 mutants are susceptible to the infection by the pathogen Rhizoctonia solani.Collectively,these findings reveal the molecular mechanisms of how the JA pathway regulates RNS,broadening our understanding of the roles of JA in plant-microbe interactions.
Pedro de los ReyesGloria Serrano-BuenoFrancisco J.Romero-CamperoHe Gao...
1204-1220页
查看更多>>摘要：Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment.Among these processes,the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks.The photoperiodic pathway,which controls plant response to day length,is one of the most important pathways controlling flowering.In Ara-bidopsis photoperiodic flowering,CONSTANS(CO)is the central gene activating the expression of the florigen FLOWERING LOCUS T(FT)in the leaves at the end of a long day.The circadian clock strongly reg-ulates CO expression.However,to date,no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock.Using transcriptional networks,we have identified rele-vant network motifs regulating the interplay between the circadian clock and the photoperiod pathway.Gene expression,chromatin immunoprecipitation experiments,and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock.Plants with altered CO expression showed a different in-ternal clock period,measured by daily leaf rhythmic movements.We showed that CO upregulates the expression of key genes related to the circadian clock,such as CCA 1,LHY,PRR5,and GI,at the end of a long day by binding to specific sites on their promoters.Moreover,a high number of PRR5-repressed target genes are upregulated by CO,and this could explain the phase transition promoted by CO.The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes.Taken together,our results indicate that there may be a feedback loop in which CO com-municates back to the circadian clock,providing seasonal information to the circadian system.
查看更多>>摘要：Xenia,the phenomenon in which the pollen genotype directly affects the phenotypic characteristics of maternal tissues(i.e.,fruit ripening),has applications in crop production and breeding.However,the under-lying molecular mechanism has yet to be elucidated.Here,we investigated whether mobile mRNAs from the pollen affect the ripening and quality-related characteristics of the fruit using cross-pollination between distinct Malus domestica(apple)cultivars.We demonstrated that hundreds of mobile mRNAs originating from the seeds are delivered to the fruit.We found that the movement of one of these mRNAs,ACC oxidase 3(MdACO3),is coordinated with fruit ripening.Salicylic acid treatment,which can cause plasmodesmal closure,blocks MdACO3 movement,indicating that MdACO3 transcripts may move through the plasmo-desmata.To assess the role of mobile MdACO3 transcripts in apple fruit,we created MdACO3-GFP-ex-pressing apple seeds using MdACO3-GFP-overexpressing pollen for pollination and showed that MdACO3 transcripts in the transgenic seeds move to the flesh,where they promote fruit ripening.Furthermore,we demonstrated that MdACO3 can be transported from the seeds to fruit in the fleshy-fruited species tomato and strawberry.These results underscore the potential of mobile mRNAs from seeds to influence fruit characteristics,providing an explanation for the xenia phenomenon.Notably,our findings highlight the feasibility of leveraging diverse pollen genomic resources,without resorting to genome editing,to improve fruit quality.
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