A MAP kinase cascade broadly regulates the lifestyle of Sclerotinia sclerotiorum and can be targeted by HIGS for disease control.

Sclerotinia sclerotiorum causes white mold or stem rot in a wide range of economically important plants, bringing significant yield losses worldwide. Control of this pathogen is difficult as its resting structure sclerotia can survive in soil for years, and no Resistance genes have been identified in S. sclerotiorum hosts. Host-induced gene silencing (HIGS) has shown promising effects in controlling many fungal pathogens, including S. sclerotiorum. However, better molecular genetic understanding of signaling pathways involved in its development and pathogenicity is needed to provide effective HIGS gene targets. Here, by employing a forward genetic screen, we characterized an evolutionarily conserved mitogen-activated protein kinase (MAPK) cascade in S. sclerotiorum, consisting of SsSte50-SsSte11-SsSte7-Smk1, which controls mycelial growth, sclerotia development, compound appressoria formation, virulence, and hyphal fusion. Moreover, disruption of the putative downstream transcription factor SsSte12 led to normal sclerotia but deformed appressoria and attenuated host penetration, as well as impaired apothecia formation, suggestive of diverged regulation downstream of the MAPK cascade. Most importantly, targeting SsSte50 using host-expressed double-stranded RNA resulted in largely reduced virulence of S. sclerotiorum on both Nicotiana benthamiana leaves and transgenic Arabidopsis thaliana plants. Therefore, this MAPK signaling cascade is generally needed for its growth, development, and pathogenesis and can serve as ideal HIGS targets for mitigating economic damages caused by S. sclerotiorum infection.

Immune receptor mimicking hormone receptors: a new guarding strategy.

Plant intracellular nucleotide-binding domain leucine-rich repeat (NLR) receptors play crucial roles in immune responses against pathogens. How diverse NLRs recognize different pathogen effectors remains a significant question. A recent study published in Nature uncovered how pepper NLR Tsw detects phytohormone receptors' interference caused by tomato spotted wilt virus (TSWV) effector, triggering a robust immune response, showcasing a new manner of NLR guarding.

Plant immune signaling network mediated by helper NLRs.

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) are intracellular immune receptors for pathogen recognition and signaling. They include sensor NLRs (sNLRs) that detect pathogens, and helper NLRs, which transduce downstream immune signals. During immune responses, both membrane-localized pattern recognition receptors (PRRs) and sNLRs rely on helper NLRs for signal transduction. The Arabidopsis helper NLRs, ADR1s and NRG1s, along with their interacting lipase-like protein dimers, are differentially required by sNLRs. Recent structural and biochemical analyses suggest that they assemble into oligomeric resistosomes with lipase-like protein dimers upon perception of small molecules produced from enzymatic activities of upstream TIR-type sNLRs. As a result, ADR1s and NRG1s form membrane calcium channels to induce immune responses and cell death. In contrast, Solanaceous NRC clade helper NLRs transduce signals from many sNLRs and some PRRs. Here, we summarize the recent advances in plant helper NLR research, with a focus on their structural and biochemical mechanisms in immune signaling.

The Devastating Rice Blast Airborne Pathogen Magnaporthe oryzae-A Review on Genes Studied with Mutant Analysis.

Magnaporthe oryzae is one of the most devastating pathogenic fungi that affects a wide range of cereal plants, especially rice. Rice blast disease causes substantial economic losses around the globe. The M. oryzae genome was first sequenced at the beginning of this century and was recently updated with improved annotation and completeness. In this review, key molecular findings on the fungal development and pathogenicity mechanisms of M. oryzae are summarized, focusing on fully characterized genes based on mutant analysis. These include genes involved in the various biological processes of this pathogen, such as vegetative growth, conidia development, appressoria formation and penetration, and pathogenicity. In addition, our syntheses also highlight gaps in our current understanding of M. oryzae development and virulence. We hope this review will serve to improve a comprehensive understanding of M. oryzae and assist disease control strategy designs in the future.

Application of System Dynamics to Inform a Model of Adolescent SBIRT Implementation in Primary Care Settings.

System dynamics (SD) modeling is used to compare and contrast strategies for effective implementation of an evidence-based adolescent behavioral health treatment in primary care settings. With qualitative and quantitative data from an on-going cluster-randomized trial in 7 federally qualified health center sites, two implementation conditions were compared: generalist vs. specialist. In the generalist approach, the primary care provider (PCP) delivered brief intervention (BI) for substance misuse (n = 4 clinics). In the specialist approach, BIs were delivered by behavioral health counselors (BHCs) (n = 3 clinics). The resultant SD model compared 'basecase' dynamics to strategic approaches to deploying continuous technical assistance (TA) and performance feedback reporting (PFR). The basecase effectively represented the SBIRT intervention, which reflected actual monthly volume of adolescent primary care visits (N = 9639), screenings (N = 5937), positive screenings (N = 246), and brief interventions (BIs; N = 50) over the 20-month implementation period. Insights gained suggest that implementation outcomes are sensitive to frequency of PFR, with bimonthly events generating the most rapid and sustained screening results. Simulated trends indicated that availability of the BHC directly impacts success of the specialist model. Similarly, understanding PCPs' perception of severity of need for intervention is key to outcomes in either condition.