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1. H3.1K27me1 loss confers Arabidopsis resistance to Geminivirus by sequestering DNA repair proteins onto host genome

   https://doi.org/10.1038/s41467-023-43311-1  

   Wang, Zhen ; Castillo-González, Claudia M. ; Zhao, Changjiang ; Tong, Chun-Yip ; Li, Changhao ; Zhong, Songxiao ; Liu, Zhiyang ; Xie, Kaili ; Zhu, Jiaying ; Wu, Zhongshou ; et al ( November 2023 , Nature Communications)

   The H3 methyltransferases ATXR5 and ATXR6 deposit H3.1K27me1 to heterochromatin to prevent genomic instability and transposon re-activation. Here, we report thatatxr5 atxr6mutants display robust resistance to Geminivirus. The viral resistance is correlated with activation of DNA repair pathways, but not with transposon re-activation or heterochromatin amplification. We identify RAD51 and RPA1A as partners of virus-encoded Rep protein. The two DNA repair proteins show increased binding to heterochromatic regions and defense-related genes inatxr5 atxr6vs wild-type plants. Consequently, the proteins have reduced binding to viral DNA in the mutant, thus hampering viral amplification. Additionally, RAD51 recruitment to the host genome arise via BRCA1, HOP2, and CYCB1;1, and this recruitment is essential for viral resistance inatxr5 atxr6. Thus, Geminiviruses adapt to healthy plants by hijacking DNA repair pathways, whereas the unstable genome, triggered by reduced H3.1K27me1, could retain DNA repairing proteins to suppress viral amplification inatxr5 atxr6.

    

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2. IPD3, a master regulator of arbuscular mycorrhizal symbiosis, affects genes for immunity and metabolism of non-host Arabidopsis when restored long after its evolutionary loss

   https://doi.org/10.1007/s11103-024-01422-3  

   Hornstein, Eli D. ; Charles, Melodi ; Franklin, Megan ; Edwards, Brianne ; Vintila, Simina ; Kleiner, Manuel ; Sederoff, Heike ( February 2024 , Plant Molecular Biology)

   Arbuscular mycorrhizal symbiosis (AM) is a beneficial trait originating with the first land plants, which has subsequently been lost by species scattered throughout the radiation of plant diversity to the present day, including the modelArabidopsis thaliana. To explore if elements of this apparently beneficial trait are still present and could be reactivated we generatedArabidopsisplants expressing a constitutively active form ofInteracting Protein of DMI3, a key transcription factor that enables AM within the Common Symbiosis Pathway, which was lost fromArabidopsisalong with the AM host trait. We characterize the transcriptomic effect of expressingIPD3inArabidopsiswith and without exposure to the AM fungus (AMF)Rhizophagus irregularis, and compare these results to the AM modelLotus japonicusand itsipd3knockout mutantcyclops-4. Despite its long history as a non-AM species, restoringIPD3in the form of its constitutively active DNA-binding domain toArabidopsisaltered expression of specific gene networks. Surprisingly, the effect of expressingIPD3inArabidopsisand knocking it out inLotuswas strongest in plants not exposed to AMF, which is revealed to be due to changes inIPD3genotype causing a transcriptional state, which partially mimics AMF exposure in non-inoculated plants. Our results indicate that molecular connections to symbiosis machinery remain in place in this nonAM species, with implications for both basic science and the prospect of engineering this trait for agriculture.

    

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3. Bacillus cereus AR156 primes induced systemic resistance by suppressing miR825/825* and activating defense-related genes in Arabidopsis: miR825/825* and AR156-primed ISR

   https://doi.org/10.1111/jipb.12446  

   Niu, Dongdong ; Xia, Jing ; Jiang, Chunhao ; Qi, Beibei ; Ling, Xiaoyu ; Lin, Siyuan ; Zhang, Weixiong ; Guo, Jianhua ; Jin, Hailing ; Zhao, Hongwei ( February 2016 , Journal of Integrative Plant Biology)
4. Overexpression of two CDPKs from wild Chinese grapevine enhances powdery mildew resistance in Vitis vinifera and Arabidopsis

   https://doi.org/10.1111/nph.17285  

   Hu, Yang ; Cheng, Yuan ; Yu, Xuena ; Liu, Jie ; Yang, Lushan ; Gao, Yurong ; Ke, Guihua ; Zhou, Min ; Mu, Bo ; Xiao, Shunyuan ; et al ( March 2021 , New Phytologist)

   Calcium‐dependent protein kinases (CDPKs) play vital roles in metabolic regulations and stimuli responses in plants. However, little is known about their function in grapevine.

   Here, we report thatVpCDPK9andVpCDPK13, two paralogousCDPKsfromVitis pseudoreticulataaccession Baihe‐35‐1, appear to positively regulate powdery mildew resistance. The transcription of them in leaves of ‘Baihe‐35‐1’ were differentially induced upon powdery mildew infection. Overexpression ofVpCDPK9‐YFPorVpCDPK13‐YFPin theV. viniferasusceptible cultivar Thompson Seedless resulted in enhanced resistance to powdery mildew (YFP, yellow fluorescent protein). This might be due to elevation of SA and ethylene production, and excess accumulation of H₂O₂and callose in penetrated epidermal cells and/or the mesophyll cells underneath.

   Ectopic expression ofVpCDPK9‐YFPin Arabidopsis resulted in varied degrees of reduced stature, pre‐mature senescence and enhanced powdery mildew resistance. However, these phenotypes were abolished inVpCDPK9‐YFPtransgenic lines impaired in SA signaling (pad4sid2) or ethylene signaling (ein2). Moreover, both of VpCDPK9 and VpCDPK13 were found to interact with and potentially phosphorylate VpMAPK3, VpMAPK6, VpACS1 and VpACS2in vivo(ACS, 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase; MAPK, mitogen‐activated protein kinase).

   These results suggest thatVpCDPK9andVpCDPK13contribute to powdery mildew resistance via positively regulating SA and ethylene signaling in grapevine.

    

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5. RPW8.1 enhances the ethylene‐signaling pathway to feedback‐attenuate its mediated cell death and disease resistance in Arabidopsis

   https://doi.org/10.1111/nph.16857  

   Zhao, Zhi‐Xue ; Feng, Qin ; Liu, Peng‐Qiang ; He, Xiao‐Rong ; Zhao, Jing‐Hao ; Xu, Yong‐Ju ; Zhang, Ling‐Li ; Huang, Yan‐Yan ; Zhao, Ji‐Qun ; Fan, Jing ; et al ( January 2021 , New Phytologist)

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