SlMYB1 regulates the accumulation of lycopene, fruit shape, and resistance to Botrytis cinerea in tomato

Fruit lycopene,shape,and resistance are essential traits in vegetables whose final product is fruit,and they are also closely related to and strictly regulated by multiple transcription factors.Lycopene,which cannot be synthesized by the human body and can only be ingested from the outside,was important in maintaining human health.During fruit ripening and post-harvest,tomato plants face a variety of biotic or abiotic stresses,which might inf lict great damage to fruit quality due to its f lat shape and pointed tip during storage and transportation.Therefore,there is an urgent need for key molecular switches to simultaneously improve fruit lycopene and resistance to biotic stress during ripening.Here,we identified the MYB transcription factor SlMYB1 in tomato plants which could bind to the promoters of lycopene synthesis-related genes,SlLCY1,SlPSY2,and the pathogen-related gene SlPR5 directly,to regulate the fruit lycopene and resistance to Botrytis cinerea in tomato.In addition to regulating lycopene synthesis,SlMYB1 also regulates the content of soluble sugar,soluble protein and f lavonoid in tomato.What’s more,SlMYB1 could regulate the tomato fruit shape,making it smoother or f latter to prevent skin damage caused by vibration on fruits.RNA sequencing(RNA-seq)further showed that SlMYB1 fruit-specific expression lines had multiple differentially expressed genes compared with those from wild-type plants,suggesting that SlMYB1 might have multiple roles in fruit nutritional quality control and resistance to stresses,which is a rare occurrence in previous studies.In summary,our results revealed that SlMYB1 was an essential multi-functional transcription factor that could regulate the lycopene and resistance to Botrytis cinerea,and change the shape of fruit in tomato plants.

Recognition of the inducible,secretory small protein OsSSP1 by the membrane receptor OsSSR1 and the co-receptor OsBAK1 confers rice resistance to the blast fungus

The plant apoplast,which serves as the frontline battleground for long-term host–pathogen interactions,harbors a wealth of disease resistance resources.However,the identification of the disease resistance proteins in the apoplast is relatively lacking.In this study,we identified and characterized the rice secretory protein OsSSP1(Oryza sativa secretory small protein 1).OsSSP1 can be secreted into the plant apoplast,and either in vitro treatment of recombinant OsSSP1 or overexpression of OsSSP1 in rice could trigger plant immune response.The expression of OsSSP1 is suppressed significantly during Magnaporthe oryzae infection in the susceptible rice variety Taibei 309,and OsSSP1-overexpressing lines all show strong resistance to M.oryzae.Combining the knockout and overexpression results,we found that OsSSP1 positively regulates plant immunity in response to fungal infection.Moreover,the recognition and immune response triggered by OsSSP1 depend on an uncharacterized transmembrane OsSSR1(secretory small protein receptor 1)and the key co-receptor OsBAK1,since most of the induced immune response and resistance are lost in the absence of OsSSR1 or OsBAK1.Intriguingly,the OsSSP1 protein is relatively stable and can still induce plant resistance after 1 week of storage in the open environment,and exogenous OsSSP1 treatment for a 2-week period did not affect rice yield.Collectively,our study reveals that OsSSP1 can be secreted into the apoplast and percepted by OsSSR1 and OsBAK1 during fungal infection,thereby triggering the immune response to enhance plant resistance to M.oryzae.These findings provide novel resources and potential strategies for crop breeding and disease control.

OsBGLU19 and OsBGLU23 regulate disease resistance to bacterial leaf streak in rice

β-Glucosidase belongs to the glycoside hydrolase I family,which is widely present in multiple species and responds to various biotic and abiotic stresses.In rice,whetherβ-glucosidase is involved in the interaction between plants and microorganisms is not clear.In this study,we found that the expression of several genes encodingβ-glucosidases,including OsBGLU19 and OsBGLU23,were upregulated after inoculation with Xanthomonas oryzae pv.oryzicola(Xoc)and downregulated after inoculation with X.oryzae pv.oryzae(Xoo).The respective insertion mutants of OsBGLU19 and OsBGLU23,bglu19 and bglu23,were more susceptible to Xoc infection.The expression of OsAOS2,a key gene in the jasmonic acid signal pathway,was dramatically downregulated after inoculation with Xoc in the bglu19 and bglu23 mutants.Simultaneously,the expression of downstream disease resistance-related genes,such as OsPR1a,OsPR5 and a key transcription factors OsWRKY72 were obviously downregulated.The resistance mediated by OsBGLU19 and OsBGLU23 to bacterial leaf streak is related to disease resistance-related genes above mentioned.

ASF1 regulates asexual and sexual reproduction in Stemphylium eturmiunum by DJ-1 stimulation of the PI3K/AKT signaling pathway

Most fungi display a mixed mating system with both asexual and sexual reproduction.The timing of the two modes of reproduction must be carefully coordinated through signal perception and coordination in the cell along with chromatin modification.Here,we investigated coordination of reproductive output by investigating the function of the histone chaper-one anti-silencing factor 1(ASF1)in a fungal species amenable to characterization of both asexual and sexual reproduction.We used knockout approach to show that SeASF1 influenced asexual and sexual reproduction in Stemphylium eturmiunum.SeASF1-deleted strains failed to produce pseudothecia,but produce abnormal conidia and showed an irregular distribution of nuclei in mycelium.Transcriptome sequencing was then used to identify genes with altered expression in the SeASF1-deleted strains.The transcriptional expression of the identified SeDJ-1 was strongly regulated by SeASF1.The interaction of SeDJ-1 and SeASF1 was confirmed using Y2H,Co-IP,and pull-down.Due to some components of phosphatidylinositol 3-kinase/protein kinase B(PI3K/AKT)signaling pathway were known to interact with DJ-1 in mammals,we verified SePI3K,an element of PI3K/AKT signaling pathway in S.eturmiunum,was directly linked to SeDJ-1 and then these two proteins were defined as a coordinator of reproduction.However,knockout of SeDJ-1 or SePI3K altered the asexual and sexual repro-duction,but SePI3K recovered the asexual and sexual development of∆Sedj-1.The SeDJ-1-M6 segment of SeDJ-1 was essential for its interaction with SePI3K and played a critical role in restoring sexual reproduction in the∆Sepi3k,providing a deep understanding of the regulatory mechanism of SeDJ-1 in S.eturmiunum development.Summarily,SeASF1 is able to trigger SeDJ-1 and SeDJ-1can also activate SePI3K,which is orchestrally involved in asexual and sexual reproduction in S.eturmiunum.All these results reveal that SeASF1 manipulates asexual and sexual reproduction in S.eturmiunum by SeDJ-1 perception of PI3K/AKT signaling pathway.These data highlight the deep similarities in coordinating asexual and sexual processes in both fungi and eukaryotes in general.

Multiple forms of vitamin B_(6) regulate salt tolerance by balancing ROS and abscisic acid levels in maize root

Salt stress causes osmotic stress,ion toxicity and oxidative stress,inducing the accumulation of abscisic acid(ABA)and excessive reactive oxygen species(ROS)production,which further damage cell structure and inhibit the development of roots in plants.Previous study showed that vitamin B_(6)(VB_(6))plays a role in plant responses to salt stress,however,the regulatory relationship between ROS,VB_(6) and ABA under salt stress remains unclear yet in plants.In our study,we found that salt stress-induced ABA accumulation requires ROS production,in addition,salt stress also promoted VB_(6)(including pyridoxamine(PM),pyridoxal(PL),pyridoxine(PN),and pyridoxal 5′-phosphate(PLP))accumulation,which involved in ROS scavenging and ABA biosynthesis.Furthermore,VB_(6)-deficient maize mutant small kernel2(smk2)heterozygous is more susceptible to salt stress,and which failed to scavenge excessive ROS effectively or induce ABA accumulation in maize root under salt stress,interestingly,which can be restored by exogenous PN and PLP,respec-tively.According to these results,we proposed that PN and PLP play an essential role in balancing ROS and ABA levels under salt stress,respectively,it laid a foundation for VB_(6) to be better applied in crop salt resistance than ABA.

Plant immune inducer ZNC promotes rutin accumulation and enhances resistance to Botrytis cinerea in tomato

Gray mold is a destructive disease caused by Botrytis cinerea,a pervasive plant pathogen,which poses a threat to both tomato growth and postharvest storage.The utilization of induced resistance presents a potential strategy for combating plant pathogenic attacks.ZNC(zhinengcong),an extract derived from the endophytic fungus Paecilo-myces variotii,has been discovered to play a vital role in preventing diverse forms of bacterial infections.Nevertheless,the precise mechanism behind its ability to enhance tomato resistance to fungi remains unclear.In this study,we found that the exogenous spraying of ZNC could significantly improve the resistance of tomato plants to B.cinerea.The results of both the metabolomic analysis and high-performance liquid chromatography(HPLC)demonstrated that tomato plants responded to ZNC treatment by accumulating high levels of rutin.Additional transcriptome analysis uncovered that rutin enhances tomato resistance possible by initiating the generation of reactive oxygen species(ROS)and phosphorylation of mitogen-activated protein kinases(MPKs)related genes expression during the initial phase of invasion by B.cinerea.In addition,we also found that rutin might activate plant immunity by eliciting ethylene(ET)and jasmonic acid(JA)-mediated pathways.Therefore,plant immune inducer ZNC and rutin has bright application prospects and high utilization value to control gray mold.

The bacterial effector AvrRxo1 inhibits vitamin B6 biosynthesis to promote infection in rice

Xanthomonas oryzae pv.oryzicola(Xoc),which causes rice bacterial leaf streak,invades leaves mainly through stomata,which are often closed as a plant immune response against pathogen invasion.How Xoc overcomes stomatal immunity is unclear.Here,we show that the effector protein AvrRxo1,an ATPdependent protease,enhances Xoc virulence and inhibits stomatal immunity by targeting and degrading rice OsPDX1(pyridoxal phosphate synthase),thereby reducing vitamin B6(VB6)levels in rice.VB6 is required for the activity of aldehyde oxidase,which catalyzes the last step of abscisic acid(ABA)biosynthesis,and ABA positively regulates rice stomatal immunity against Xoc.Thus,we provide evidence supporting a model in which a major bacterial pathogen inhibits plant stomatal immunity by directly targeting VB6 biosynthesis and consequently inhibiting the biosynthesis of ABA in guard cells to open stomata.Moreover,AvrRxo1-mediated VB6 targeting also explains the poor nutritional quality,including low VB6 levels,of Xoc-infected rice grains.