Mapping of QTL conferring leaf rust resistance in Chinese wheat lines W014204 and Fuyu 3 at adult plant stage

Wheat leaf rust is a destructive foliar disease of common wheat （Triticum aestivum L.） worldwide. The most effective, economical s to control the disease is growing resistant cultivars with adult plant resistance （APR）. The Chinese wheat tines W014204 and Fuyu 3 showed high leaf rust resistance in the field. To identify leaf rust APR genes in the two lines, two mapping populations with 215 and 163 F2：3 lines from the crosses W014204/Zhengzhou 5389 and Fuyu 3/Zhengzhou 5389, respectively, were phenotyped for leaf rust severities during the 2010-2011, 2011-2012 and 2012-2013 cropping seasons in the field at Baoding, Hebei Province, China. A total of 1 215 SSR markers were used to identify the quantitative trait loci （QTLs） for leaf rust APR in the two populations. In the W014204/Zhengzhou 5389 population, three QTLs were detected and designated as QLr.hbu-lBL.1, QLr.hbu-2BS.1 and QLr.hbu-7DS, and explained 2.9-8.4, 11.5-38.3 and 8.5-44.5% of the phenotypic variance, respectively; all the resistance alleles at these loci were derived from W014204. In the Fuyu 3/Zhengzhou 5389 population, three QTLs, QLr.hbu-lBL.2, QLr.hbu-2BS.2 and QLr.hbu-7BL, explained 12.0-19.2, 22.3-38.9 and 4.1-4.3% of the phenotypic variance, respectively, and all resistance alleles were contributed by Fuyu 3. Based on chromosome positions of closely linked markers, both QLr.hbu-lBL. 1 and QLr.hbu-lBL.2 are Lr46, and QLr.hbu-7DS is Lr34. QLr.hbu-7BL was mapped on chromosome 7BL near to Lr68 and they are likely the same gene. Based on chromosome positions, pedigree and field reactions, the two 2BS QTLs are different from all the known APR genes and are likely to be newAPR QTL for leaf rust. These QTLs and their closely linked markers are potentially useful for improving leaf rust resistance in wheat breeding.

QTL mapping of adult plant resistance to stripe rust and leaf rust in a Fuyu 3/Zhengzhou 5389 wheat population

Stripe or yellow rust(YR)and leaf rust(LR)cause large losses in wheat production worldwide.Resistant cultivars curtail the levels of losses.The present study aimed to identify quantitative trait loci(QTL)for YR and LR resistance in 147 F2:6 recombinant inbred lines(RIL)derived from the cross Fuyu 3/Zhengzhou 5389.The RIL population and parents were genotyped with the Wheat55 K single nucleotide polymorphism(SNP)array and simple sequence repeat(SSR)markers.All materials were also phenotyped for YR severity at Mianyang in Sichuan province and Baoding in Hebei province in the 2015/2016,2016/2017,and 2017/2018 cropping seasons,and LR severity at Zhoukou in Henan province and at Baoding in 2017/2018.Eleven QTL for YR resistance and five for LR resistance were detected using inclusive composite interval mapping(Ici Mapping).Four of these QTL on chromosomes 1 BL,2 BS,3 AL,and 5 AL conferred resistance to both YR and LR.The QTL on 1 BL was Lr46/Yr29,and that on 7 BL might be Lr68.The QTL on chromosome 2 BS was detected at a similar position to previously detected loci.QYr.hebau-3 AL/QLr.hebau-3 AL,QYr.hebau-5 AL/QLr.hebau-5 AL,QYr.hebau-7 DL,QYr.hebau-4 BS,QYr.hebau-6 DL,and QYr.hebau-2 AS are likely to be new.An SSR marker for QYr.hebau-7 DL was developed and validated in a diverse wheat panel from China,suggesting effectiveness in different genetic backgrounds.These QTL with closely linked SNP and SSR markers could be useful for marker-assisted selection in wheat breeding programs targeting durable resistance to both diseases.

Identification and Characterization of Lysobacter enzymogenes as a Biological Control Agent Against Some Fungal Pathogens

Strain OH11, a Gram-negative, nonspore forming, rod-shaped bacterium with powerful antagonistic activity, was isolated from rhizosphere of green pepper in Jiangsu Academy of Agricultural Sciences of China and characterized to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain OH11 belongs to the Gammaproteobacteria and had the highest degree of sequence similarity to Lysobacter enzymogenes strain C3 （AY074793） （99%）, Lysobacter enzymogenes strain N4-7 （U89965） （99%）, Lysobacter antibioticus strain （AB019582） （97%）, and Lysobacter gummosus strain （AB16136） （97%）. Chemotaxonomic data revealed that strain OHI 1 possesses a quinine system with Q-8 as the predominant compound and C15：0 iso, C17：1 iso ω9c as the predominant iso-branched fatty acids, all of which corroborated the assignment of strain OH11 to the genus Lysobacter. Results of DNA-DNA hybridization and physiological and biochemical tests clearly showed that strain OH11 was classified as Lysobacter enzymogenes. Strain OH11 could produce protease, chitinase, and β-1,3-glucanase. It showed strong in vitro antifungal activity against Rhizoctonia solani, Sclerotinia scletotiorum, and several other phytopathogenic fungi. This is the first report of identification and characterization of Lysobacter enzymogenes as a biological control agent of plant diseases in China.

Seedling and adult plant resistance to leaf rust in 46 Chinese bread wheat landraces and 39 wheat lines with known Lr genes

Wheat leaf rust,caused by Puccinia triticina(Pt),is an important foliar disease that has an important influence on wheat yield.The most economic,safe and effective way to control the disease is growing resistant cultivars.In the present study,a total of 46 wheat landraces and 34 wheat lines with known Lr(leaf rust resistance)genes were inoculated with 16Pt pathotypes for postulating seedling resistance gene(s)in the greenhouse.These cultivars and five wheat differential lines with adult plant resistance(APR)genes(Lr12,Lr22b,Lr34,Lr35 and Lr37)were also evaluated for identification of slow rusting resistance in the field trials in Baoding,Hebei Province of China in the 2014–2015 and 2015–2016 cropping seasons.Furthermore,10 functional molecular markers closely linked to 10 known Lr genes were used to detect all the wheat genotypes.Results showed that most of the landraces were susceptible to most of the Pt pathotypes at seedling stage.Nonetheless,Lr1 was detected only in Hongtangliangmai.The field experimental test of the two environments showed that 38 landraces showed slow rusting resistance.Seven cultivars possessed Lr34 but none of the landraces contained Lr37 and Lr46.Lr genes namely,Lr9,Lr19,Lr24,Lr28,Lr29,Lr47,Lr51 and Lr53 were effective at the whole plant stage.Lr18,Lr36 and Lr45 had lost resistance to part of pathotypes at the seedling stage but showed high resistance at the adult plant stage.Lr34 as a slowing rusting gene showed good resistance in the field.Four race-specific APR genes Lr12,Lr13,Lr35 and Lr37 conferred good resistance in the field experiments.Seven race-specific genes,Lr2b,Lr2c,Lr11,Lr16,Lr26,Lr33 and LrB had lost resistance.The 38 landraces showed slow rusting resistance to wheat leaf rust can be used as resistance resources for wheat resistance breeding in China.

An AFLP marker linked to the leaf rust resistanc gene LrBi16 and test of allelism with Lr14a on chromosome arm 7BL

Leaf rust(LR), caused by Puccinia triticina, is one of the most widespread diseases of common wheat(Triticum aestivum L.) worldwide. The LR resistance gene Lr Bi16 has been mapped on chromosome arm 7BL in Chinese wheat cultivar Bimai 16 and was closely linked to SSR loci Xcfa2257 and Xgwm344 with genetic distances of 2.8 c M and 2.9 c M, respectively. In the present study, a total of 304 AFLP primer pairs were used to screen Bimai 16 and Thatcher and resistant and susceptible DNA bulks. The polymorphic AFLP marker P-ATT/M-CGC173 bp was used to genotype F2 and F3populations to identify markers more closely linked to Lr Bi16. Marker P-ATT/M-CGC173 bp was tightly linked to Lr Bi16 with a genetic distance of0.5 c M. As Lr Bi16 was mapped near the Lr14 a locus, 809 F2 plants from the Bimai 16/RL6013(Lr14a) cross were inoculated with the Pt pathotype FHNQ to test the allelism of Lr14 a and Lr Bi16. All of the F2 plants were resistant to FHNQ(IT between; and 2), suggesting that Lr14 a and Lr Bi16 are allelic.

Identification of a major QTL for Hessian fly resistance in wheat cultivar‘Chokwang’

The Hessian fly(HF,Mayetiola destructor)is one of the destructive pests of wheat(Triticum aestivum L.)worldwide.Resistant cultivars can effectively minimize wheat damage due to this insect pest.To identify new quantitative trait loci(QTL)for HF resistance,a population of recombinant inbred lines(RILs)was developed from a cross between the HF-resistant wheat cultivar‘Chokwang’and susceptible wheat‘Ning 7840’,and phenotyped for responses to HF attack.A linkage map was constructed using 1147 single nucleotide polymorphism(SNP)markers generated from genotyping-by-sequencing(GBS).One major QTL,QHf.hwwg-6 BS,for HF-resistance was identified on chromosome arm 6 BS,which explained up to84.0%of the phenotypic variation and was contributed by Chokwang.Two RILs showed recombination in the candidate interval of QHf.hwwg-6 BS,which delimited QHf.hwwg-6 BS to a 4.75 Mb physical interval between 6,028,601 bp and 10,779,424 bp on chromosome arm 6 BS of IWGSC Chinese Spring reference genome Ref Seq v2.0.Seven GBS-SNPs in the candidate interval were converted into Kompetitive allele specific polymerase chain reaction(KASP)markers.Two of them,KASP-6 B112698 and KASP-6 B7901215,were validated in a U.S.winter wheat panel.KASP-6 B112698 was nearly diagnostic,thus can be used to screen QHf.hwwg-6 BS and pyramid it with other resistance genes in breeding programs.

Postulation of Leaf Rust Resistance Genes in Seven Chinese Spring Wheat Cultivars

To detect the leaf rust resistance genes in the 7 Chinese spring wheat clultivars Shenmian 99025, Shenmia 99042, Shenmian 85, Shenmian 91, Shenmian 96, Shenmian 1167 and Shenmian 962, Thatcher, Thatcher backgrounded near-isogenic lines and 15 pathotypes of P. triticina were used for gene postulate at the seedling stage, and 9 of the 15 pathotypes were used in the field tests. Molecular markers closely linked to, or co-segregated with resistance genes Lrl, Lr9, LrlO, Lrl9, Lr20, Lr21, Lr24, Lr26, Lr28, Lr29, Lr32, Lr34, Lr35, Lr37, Lr38, and Lr47 were screened to assist detection of the resistance genes. As results, 4 known resistance genes, including Lrl, Lr9, Lr26, and Lr34, and other unknown resistance genes were postulated singly or in combination in the tested cultivars. Shenmian 85, Shenmian 91, Shenmian 96, Shenmian 962, Shenmian 1167, and Shenmian 99042 are potentially useful for wheat production and breeding programs. The result suggested that combining gene postulation, molecular markers and pedigrees is effective and more accuracy method to know the resistance genes in cultivars.

Identification of genes involved in regulating MnSOD2 production and root colonization in Bacillus cereus 905

sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes involved in regulating the sod A2 expression have not been clearly elucidated in B.cereus.In this study,a genome-wide random insertion mutagenesis was constructed by using transposon TnYLB-1 to identify novel genes regulating the sodA2 expression.Seven mutants that changed the sodA2 expression at both m RNA and protein levels were finally obtained.Sequence analysis and BLAST data showed that the genes disrupted by TnYLB-1 in B.cereus 905 shared high conservations with those in the B.cereus type strain,ATCC 14579.These genes encode heat-inducible transcription repressor,chloride channel protein,recombinase A,ferrous iron transport protein,nucleoside diphosphate kinase,and histidine ammonia-lyase.Besides,we also provided the evidence that the genes regulating the sodA2 expression could influence colonization ability of B.cereus 905 on wheat roots.Specifically,those genes downregulating the sodA2 expression significantly reduced bacterial colonization on wheat roots,and mutants with increased MnSOD2 activities could enhance bacterial population densities on wheat roots to a certain degree.Our work provided information that multiple genes are involved in MnSOD2 production and wheat root colonization.The molecular regulatory pathways through which these genes modulate the sod A2 expression and root colonization need to be investigated extensively in the future.

Co-evolved plant and blast fungus ascorbate oxidases orchestrate the redox state of host apoplast to modulate rice immunity

Apoplastic ascorbate oxidases(AOs)play a critical role in reactive oxygen species(RoS)-mediated innate host immunity by regulating the apoplast redox state.To date,little is known about how apoplastic effectors of the riceblast fungus Magnaportheoryzaemodulate the apoplast redox state of rice to subvert plant immunity.In this study,we demonstrated that M.oryzae MoAo1 is an Ao that plays a role in virulence by modulating the apoplast redox status of rice cells.We showed that MoAo1 inhibits the activity of rice OsAO3and OsAO4,which also regulate the apoplast redox status and plant immunity.In addition,we found that MoAo1,OsAO3,andOsAO4 allexhibit polymorphic variations whosevaried interactions orchestrate pathogen virulence and rice immunity.Taken together,our results reveal a critical role for extracellular redox enzymes during rice blast infection and shed light on the importance of the apoplast redox state anditsregulation inplant-pathogeninteractions.

The Piks allele of the NLR immune receptor Pik breaks the recognition of AvrPik effectors of rice blast fungus

Arms race co-evolution of plant–pathogen interactions evolved sophisticated recognition mechanisms between host immune receptors and pathogen effectors. Different allelic haplotypes of an immune receptor in the host mount distinct recognition against sequence or non-sequence related effectors in pathogens. We report the molecular characterization of the Piks allele of the rice immune receptor Pik against rice blast pathogen, which requires two head-to-head arrayed nucleotide-binding sites and leucine-rich repeat proteins. Like other Pik alleles, both Piks-1 and Piks-2 are necessary and sufficient for mediating resistance. However, unlike other Pik alleles, Piks does not recognize any known AvrPik variants of Magnaporthe oryzae. Sequence analysis of the genome of an avirulent isolate V86010 further revealed that its cognate avirulence(Avr) gene most likely has no significant sequence similarity to known AvrPik variants. Piks-1 and Pikm-1 have only two amino acid differences within the integrated heavy metal-associated(HMA) domain. Pikm-HMA interacts with AvrPik-A,-D, and-E in vitro and in vivo,whereas Piks-HMA does not bind any AvrPik variants. Characterization of two amino acid residues differing Piks-1 from Pikm-1 reveal that Piks-E229Q derived from the exchange of Glu229 to Gln229 in Piks-1 gains recognition specificity against AvrPik-D but not AvrPik-A or-E, indicating that Piks-E229Q partially restores the Pikm spectrum. By contrast,Piks-A261V derived from the exchange of Ala261 to Val261 in Piks-1 retains Piks recognition specificity.We conclude that Glu229 in Piks-1 is critical for Piks breaking the canonical Pik/AvrPik recognition pattern. Intriguingly, binding activity and ectopic cell death induction is maintained between Piks-A261V and AvrPik-D, implying that positive outcomes from ectopic assays might be insufficient to deduce its immune activity against the relevant effectors in rice and rice blast interaction.

A pair of G-type lectin receptor-like kinases modulates nlp20-mediated immune responses by coupling to the RLP23 receptor complex

Plant cells recognize microbial patterns with the plasma-membrane-localized pattern-recognition receptors consisting mainly of receptor kinases(RKs) and receptor-like proteins(RLPs). RKs, such as bacterial flagellin receptor FLS2, and their downstream signaling components have been studied extensively. However, newly discovered regulatory components of RLP-mediated immune signaling, such as the nlp20 receptor RLP23, await identification. Unlike RKs, RLPs lack a cytoplasmic kinase domain, instead recruiting the receptor-like kinases(RLKs) BAK1 and SOBIR1. SOBIR1 specifically works as an adapter for RLP-mediated immunity. To identify new regulators of RLP-mediated signaling, we looked for SOBIR1-binding proteins(SBPs) in Arabidopsis thaliana using protein immunoprecipitation and mass spectrometry,identifying two G-type lectin RLKs, SBP1 and SBP2, that physically interacted with SOBIR1.SBP1 and SBP2 showed high sequence similarity,were tandemly repeated on chromosome 4, and also interacted with both RLP23 and BAK1. sbp1 sbp2 double mutants obtained via CRISPR-Cas9 gene editing showed severely impaired nlp20-induced reactive oxygen species burst, mitogenactivated protein kinase(MAPK) activation, and defense gene expression, but normal flg22-induced immune responses. We showed that SBP1 regulated nlp20-induced immunity in a kinase activityindependent manner. Furthermore, the nlp20-induced the RLP23–BAK1 interaction, although not the flg22-induced FLS2–BAK1 interaction, was significantly reduced in sbp1 sbp2. This study identified SBPs as new regulatory components in RLP23 receptor complex that may specifically modulate RLP23-mediated immunity by positively regulating the interaction between the RLP23 receptor and the BAK1 co-receptor.

Barley FASCIATED EAR genes determine inflorescence meristem size and yield traits

In flowering plants,the inflorescence meristem(IM)provides founder cells to form successive floral meristems,which are precursors of fruits and seeds.The activity and developmental progression of IM are thus critical for yield production in seed crops.In some cereals,such as rice(Oryza sativa)and maize(Zea mays),the size of undifferentiated IM,which is located at the inflorescence apex,is positively associated with yield traits such as spikelet number.However,the relationship between IM size and yieldrelated spike traits remains unknown in the Triticeae tribe.Here we report that IM size has a negative correlation with yield traits in barley(Hordeum vulgare).Three FASCIATED EAR(FEA)orthologs,HvFEA2,HvFEA3,and HvFEA4,regulate IM size and spike morphogenesis and ultimately affect yield traits.Three HvFEAs genes are highly expressed in developing spikes,and all three loss-of-function mutants exhibit enlarged IM size,shortened spikes,and reduced spikelet number,which may lead to reduced grain yield.Natural variations identified in HvFEAs indicate selection events during barley domestication.We further reveal that HvFEA4,as a transcription factor,potentially targets multiple pathways during reproductive development,including transcriptional control,phytohormone signaling,and redox status.The roles of barley FEA genes in limiting IM size and promoting spikelet formation suggest the potential of increasing yield by manipulating IM activity.

MoLrp1-mediated signaling induces nuclear accumulation of MoMsn2 to facilitate fatty acid oxidation for infectious growth of the rice blast fungus

Fatty acid b-oxidation is critical for fatty acid degradation and cellular development.In the rice blast fungus Magnaporthe oryzae,fatty acid b-oxidation is reported to be important mainly for turgor generation in the appressorium.However,the role of fatty acid b-oxidation during invasive hyphal growth is rarely documented.We demonstrated that blocking peroxisomal fatty acid b-oxidation impaired lipid droplet(LD)degradation and infectious growth of M.oryzae.We found that the key regulator of pathogenesis,MoMsn2,which we identified previously,is involved in fatty acid b-oxidation by targeting MoDCI1(encoding dienoyl-coenzyme A[CoA]isomerase),which is also important for LD degradation and infectious growth.Cytological observations revealed that MoMsn2 accumulated from the cytosol to the nucleus during early infection or upon treatment with oleate.We determined that the low-density lipoprotein receptor-related protein MoLrp1,which is also involved in fatty acid b-oxidation and infectious growth,plays a critical role in the accumulation of MoMsn2 from the cytosol to the nucleus by activating the cyclic AMP signaling pathway.Our results provide new insights into the importance of fatty acid oxidation during invasive hyphal growth,which is modulated by MoMsn2 and its related signaling pathways in M.oryzae.

CRISPR/Cas9-mediated base-editing system efficiently generates gain-of-function mutations in Arabidopsis

Dear Editor,The CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9)system is revolutionizing genome editing due to its high efficiency,low cost,design simplicity and versatility.However,introduction of a point mutation at a desired position remains a great challenge in plant genome engineering.Currently,point mutation in plants was achieved by incorporating

Small RNA Profiling Reveals Phosphorus Deficiency as a Contributing Factor in Symptom Expression for Citrus Huanglongbing Disease

Huanglongbing （HLB） is a devastating citrus disease that is associated with bacteria of the genus ＇Candidatus Liberibacter＇ （Ca. L.）. Powerful diagnostic tools and management strategies are desired to control HLB. Host small RNAs （sRNA） play a vital role in regulating host responses to pathogen infection and are used as early diagnostic markers for many human diseases, including cancers. To determine whether citrus sRNAs regulate host responses to HLB, sRNAs were profiled from Citrus sinensis 10 and 14 weeks post grafting with Ca. L. asiaticus （Las）-positive or healthy tissue. Ten new microRNAs （miRNAs）, 76 conserved miRNAs, and many small interfering RNAs （siRNAs） were discovered. Several miRNAs and siRNAs were highly induced by Las infection, and can be potentially developed into early diagnosis markers of HLB. miR399, which is induced by phosphorus starvation in other plant species, was induced specifically by infection of Las but not Spiroplasma citri that causes citrus stubborn--a disease with symptoms similar to HLB. We found a 35% reduction of phosphorus in Las-positive citrus trees compared to healthy trees. Applying phosphorus oxyanion solutions to HLB-positive sweet orange trees reduced HLB symptom severity and significantly improved fruit production during a 3-year field trial in south-west Florida. Our molecular, physiological, and field data suggest that phosphorus deficiency is linked to HLB disease symptomology.

Sporophytic control of anther development and male fertility by glucose-6-phosphate/phosphate translocator 1(OsGPT1) in rice

Coordination between the sporophytic tissue and the gametic pollen within anthers is tightly controlled to achieve the optimal pollen fitness. Glucose-6-phosphate/phosphate translocator(GPT) transports glucose-6-phosphate, a key precursor of starch and/or fatty acid biosynthesis, into plastids. Here, we report the functional characterization of Os GPT1 in the rice anther development and pollen fertility. Pollen grains from homozygous osgpt1 mutant plants fail to accumulate starch granules, resulting in pollen sterility. Genetic analyses reveal a sporophytic effect for this mutation. Os GPT1 is highly expressed in the tapetal layer of rice anther. Degeneration of the tapetum, an important process to provide cellular contents to support pollen development, is impeded in osgpt1 plants. In addition, defective intine and exine are observed in the pollen from osgpt1 plants. Expression levels of multiple genes that are important to tapetum degeneration or pollen wall formation are significantly decreased in osgpt1 anthers. Previously, we reported that At GPT1 plays a gametic function in the accumulation of lipid bodies in Arabidopsis pollen. This report highlights a sporophytic role of Os GPT1 in the tapetum degeneration and pollen development. The divergent functions of Os GPT1 and At GPT1 in pollen development might be a result of their independent evolution after monocots and dicots diverged.

The Twin-Arginine Translocation (Tat) Pathway Is Essential for Virulence,Flagellation,and Chemotaxis in Xanthomonas oryzae pv. oryzicola Strain RsGD42

Bacterial leaf streak, caused by Xanthomonas oryzae pv. oryzicola, is an important disease of rice （Oryza sativa）. Genetic determinants （tatABC genes） of the twin-arginine translocation （Tat） pathway from X. oryzae pv. oryzicola strain RsGD42 were cloned and characterized, meanwhile, a tatC disruption mutant was generated. The tatC mutant lacked detectable flagella and was highly impaired in motility and chemotaxis. Furthermore, it was observed that the tatC mutant exhibited a reduced production of extracellular polysaccharide （EPS） and a significant reduction of virulence on adult rice plants compared to wild type strain. However, the tatC mutation in X. oryzae pv. oryzieola strain RsGD42 did not affect the growth rate and the ability to induce hypersensitive response （HR） in nonhost tobacco （Nicotiana tabacum L. cv. Samsun）. In conclusion, the data indicated that the Tat pathway significantly contributed to the virulence of X. oryzae pv. oryzicola.

Versatile effectors of phytopathogenic fungi target host immunity

Phytopathogenic fungi secrete a large arsenal of effector molecules,including proteinaceous effectors,small RNAs,phytohormones and derivatives thereof.The pathogenicity of fungal pathogens is primarily determined by these effectors that are secreted into host cells to undermine innate immunity,as well as to facilitate the acquisition of nutrients for their in planta growth and proliferation.After conventional and non-conventional secretion,fungal effectors are translocated into different subcellular compartments of the host cells to interfere with various biological processes.In extracellular spaces,apoplastic effectors cope with physical and chemical barriers to break the first line of plant defenses.Intracellular effectors target essential immune components on the plasma membrane,in the cytosol,including cytosolic organelles,and in the nucleus to suppress host immunity and reprogram host physiology,favoring pathogen colonization.In this review,we comprehensively summarize the recent advances in fungal effector biology,with a focus on the versatile virulence functions of fungal effectors in promoting pathogen infection and colonization.A perspective of future research on fungal effector biology is also discussed.

Identification and Molecular Characterization of a Phytoplasma Associated with Pomegranate Fasciation Disease

To confirm phytoplasma infection,samples of pomegranate(Punica granatum L.)plants showing symptoms of fasciation were collected from an orchard located in Tai’an,Shandong Province,China.A fragment of approximately 1.2 kb was amplified with universal primers targeting the phytoplasma 16S r RNA gene from symptomatic pomegranate plants,while no fragment was obtained from healthy plants.The phytoplasma associated with the disease was designated as pomegranate fasciation(Po F).Two representative phytoplasma 16S r DNA gene sequences(Po F-Ch01 and Po F-Ch02)had 100%nucleotide sequence identity.The 16S r DNA sequence of Po F-Ch01 and Po F-Ch02 showed the highest similarity(99.6%)to that of‘P.granatum’phytoplasma isolate AY-PG,which belong to 16Sr I-B.Further phylogenetic analysis showed that Po F-Ch01 and Po F-Ch02 belonged to a cluster of 16Sr I subgroup members.In silico RFLP analysis indicated that Po F-Ch01 shared the highest similarity coefficient of 0.97 with reference strains of 16Sr I-B,M and N.Actual RFLP analysis of both enzymes Bst U I and Bfa I confirmed that of the virtual RFLP analysis.Combining these results,we concluded that Po F was a member of the‘Candidatus Phytoplasma asteris’group(16Sr I),and has very close relationship with 16Sr I-B subgroup.

Programmed sequential cutting endows Cas9 versatile base substitution capability in plants

Dear Editors,CRISPR/Cas9-mediated genome editing techniques have triggered a revolution in biology research(Jinek et al.,2012).Cas9 coupled with guide RNAs cuts DNA at precise positions,and the resulting double stranded breaks(DSB)were effectively repaired by non-homologous end joining(NHEJ)pathway in higher eukaryotic cells,including animals and plants.