Apoptotic‑like PCD inducing HRC gene when silenced enhances multiple disease resistance in plants

Programmed cell death (PCD) plays an important role in plant environmental stress and has the potential to be manipulated to enhance disease resistance. Plants have innate immunity and, following pathogen perception, the host induces a Hypersensitive Response PCD (HR-PCD), leading to pattern (PTI) or effector triggered immunity (ETI). Here we report a non-HR type or Apoptotic-Like PCD (AL-PCD) in pathogen infected wheat and potato based on apoptotic-like DNA fragmentation. A deletion mutation in the gene encoding histidine rich calcium binding protein (TaHRC) in FHB-resistant wheat (R-NIL) failed to induce AL-PCD. Similarly, the CRISPR-Cas9 based silencing of StHRC gene in Russet Burbank potato failed to induce apoptotic-like DNA fragmentation, proved based on DNA laddering and TUNEL assays. The absence of AL-PCD in wheat R-NIL reduced pathogen biomass and mycotoxins, increasing the accumulation of resistance metabolites and FHB-resistance, and in potato it enhanced resistance to multiple pathogens. In addition, the reduced expressions of metacaspase (StMC7) and Ca2+ dependent endonuclease 2 (StCaN2) genes in potato with Sthrc indicated an involvement of a hierarchy of genes in the induction of AL-PCD. The HRC in commercial varieties of different crops, if functional, can be silenced by genome editing possibly to enhance resistance to multiple pathogens

Identification of late blight resistance-related metabolites and genes in potato through nontargeted metabolomics

Late blight of potato (Solanum tuberosum) caused by Phytophthora infestans significantly reduces the productivity of potato around theworld. Resistance to late blight in potato is either qualitative or quantitative. Qualitative resistance governed by race-specific single R genes is well characterized and gives complete resistance, but is not durable. Quantitative resistance governed by polygenes gives partial resistance, but is durable in nature. However, the quantitative resistance mechanisms are poorly studied and are not efficiently exploited in potato breeding. A nontargeted metabolic profiling of resistant (F06037) and susceptible (Shepody) potato cultivars, using high-resolution liquid chromatography–mass spectrometry, was applied to elucidate the quantitative resistance mechanisms against P. infestans (US-8 genotype). The hydroxycinnamic acid amides (HCAAs) of the shunt phenylpropanoid pathway were highly induced following pathogen inoculation in F06037. In parallel, the transcript abundances of genes that catalyze the biosynthesis of these metabolites, such as 4- coumarate:CoA ligase, tyrosine decarboxylase, ornithine decarboxylase, tyramine hydroxycinnamoyl transferase, and putrescine hydroxycinnamoyl transferase, were also higher in the resistant genotype. Sequencing of the coding genes of these enzymes revealed single-nucleotide polymorphisms between resistant and susceptible genotypes, and the amino acid changes caused missense mutations altering protein functions. HCAAs deposited at host cell walls inhibit pathogen colonization, thus reducing lesion expansion. In addition, these also act as phytoalexins, leading to the reduced biomass of the pathogen. Following validation, the HCAAs can be used as biomarker metabolites for late blight resistance. The putative candidate genes can be either used to develop allele-specific markers for marker-assisted breeding programs or suitably stacked into elite cultivars through cisgenic approaches, following validation.Doddaraju Pushpa, Kalenahalli N. Yogendra, Raghavendra Gunnaiah, Ajjamada C. Kushalappa, Agnes Murph

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Not AvailableThe identification of marker tightly linked to male sterility will greatly facilitate for marker assisted selection (MAS) breeding through accurate selection of parental lines in hybrid production. In the present study, to assess the efficiency of previously reported SCAR 4 marker for marker assisted selection was validated by screening the marker in a total of 226 F2 mapping population derived from a cross between male sterile (IIHR10521AB) and a male fertile pure line (IIHRMY7) maintained at IIHR along with bulk segregant analysis. The results showed that the marker segregated in the F2 population showing that it is linked to sterility locus. The marker was also validated by screening 12 different apetalloid male sterile lines maintained at IIHR, the results of amplification gave clear and similar band size amplicons present in parents in all the apetalloid sterile lines confirming that it is linked to male sterility and hence this study is significantly useful and can offer a powerful tool for the efficient selection in MAS breeding programmes in marigold.Not Availabl

Identification and validation of SSR markers for Xanthomonas axonopodis pv. punicae an incitant of bacterial blight of pomegranate

This study reports genome wide characterization and development of first set of microsatellite markers through in silico analysis of eight sequenced Xanthomonas axonopodis pv. punicae strains available in the public database. SSR survey resulted in identification of ~ 4638 perfect SSRs, with mean marker frequency 901 SSRs/Mb and densitiy of 11,006 bp/Mb aross the eight genomes. Frequency distribution graphs revealed hexa-nucleotide repeats were more prominent fowllowed by tri-, tetra-, di- and penta-nucleotides in the analysed genomes. We desinged 2927 SSR primers that are specific to the strain LMG 859 and ePCR confirmed on seven other Xap genomes. This resulted in identification of 542 informative SSRs that are producing single amplicons, from which 66 primers were successfully validated through wet lab experiments on eight Xap isolates of pomegranate. Furthermore, utility of these SSRs were demostrated by analysing molecular diversity among 22 Xap isolates using 20 Xap_SSR primers. SSRs revealed moderate genetic diversity among Xap isolates (61%) and grouped 11 isolates that are repersenting six different states into one cluster. This proved the earlier evidence of wider spread of ST3 type Xap acoss India using Multi locus Sequence Typing (MLST) technique. In summary, Xap_SSR will serve as powerful genomics tools that would helps in monitoring of population dynamics, taxonomy, epidomology and quarantine aspects in bacterial blight pathogen through development of microsatellite based Multilocus Variable number of Tandem repeat analysis (MLVA) in future

Differentially expressed proteins associated with fusarium head blight resistance in wheat

Citation: Zhang, Xianghui, Jianming Fu, Yasuaki Hiromasa, Hongyu Pan, and Guihua Bai. “Differentially Expressed Proteins Associated with Fusarium Head Blight Resistance in Wheat.” PLOS ONE 8, no. 12 (December 20, 2013): e82079. https://doi.org/10.1371/journal.pone.0082079.Background: Fusarium head blight (FHB), mainly caused by Fusarium graminearum, substantially reduces wheat grain yield and quality worldwide. Proteins play important roles in defense against the fungal infection. This study characterized differentially expressed proteins between near-isogenic lines (NILs) contrasting in alleles of Fhb1, a major FHB resistance gene in wheat, to identify proteins underlining FHB resistance of Fhb1. Methods: The two-dimensional protein profiles were compared between the Fusarium-inoculated spikes of the two NILs collected 72 h after inoculation. The protein profiles of mock- and Fusarium-inoculated Fhb1+NIL were also compared to identify pathogen-responsive proteins. Results: Eight proteins were either induced or upregulated in inoculated Fhb1+NIL when compared with mock-inoculated Fhb1+NIL; nine proteins were either induced or upregulated in the Fusarium-inoculated Fhb1+NIL when compared with Fusarium-inoculated Fhb1−NIL. Proteins that were differentially expressed in the Fhb1+NIL, not in the Fhb1−NIL, after Fusarium inoculation included wheat proteins for defending fungal penetration, photosynthesis, energy metabolism, and detoxification. Conclusions: Coordinated expression of the identified proteins resulted in FHB resistance in Fhb1+NIL. The results provide insight into the pathway of Fhb1-mediated FHB resistance