Department of Vegetable and Field Crops, Institute of Plant Sciences, Agricultural Research Organization, Volcani Institute, 68 HaMaccabim Road, P.O. Box 15159, Rishon LeZion 7505101, Israel.
Department of Postharvest Science, Institute of Postharvest and Food Sciences, Agricultural Research Organization, Volcani Institute, 68 HaMaccabim Road, P.O. Box 15159, Rishon LeZion 7505101, Israel.
Fungal Genet Biol. 2022 Jan;158:103653. doi: 10.1016/j.fgb.2021.103653. Epub 2021 Dec 14.
Previous network-based comparative genomic analysis between major lifestyles of fungal plant pathogens highlighted that HNM1, a predicted choline transporter, is part of the necrotroph core-genome's functions. In this work we have generated and characterized deletion mutants and developed complemented strains for the HNM1 homolog (Bchnm1) in the necrotrophic model fungal plant pathogen Botrytis cinerea. The Bchnm1 deletion mutants exhibited reduced conidia germination and germ tube elongation. The functional activity of the Δbchnm1 deletion mutants was illustrated by reduced necrotic colonization of B. cinerea on tomato and French bean leaves. The role of BcHnm1 in germination was also supported by qRT-PCR results that illustrated increased Bchnm1 transcript levels during the early infection stages (at 16 h post inoculation) of the WT strain on tomato plant leaves, and during conidia germination (in-vitro). In line with the predicted function of BcHnm1 in choline transport, Δbchnm1 deletion mutant showed an attenuated choline import capacity. The potential role of choline in the WT B. cinerea was further demonstrated by an increase in conidia germination (by 100%) in the presence of 1 mM exogenous choline while growth in the presence of hemicholinium-3, an inhibitor of choline transporter, showed 40% inhibition in germination. In contrast to the WT, exogenous choline and the inhibitor did not affect conidia germination in the Δbchnm1 deletion mutants. Collectively, this study shows for the first time that BcHnm1, a predicted choline transporter, is important for conidial germination, germ tube elongation, response to exogenous choline, and virulence in plant pathogenic fungi.
先前基于网络的真菌植物病原菌主要生活方式的比较基因组分析表明，预测的胆碱转运蛋白 HNM1 是坏死营养型核心基因组功能的一部分。在这项工作中，我们生成并表征了缺失突变体，并开发了互补菌株，用于研究坏死营养型模式真菌植物病原菌 Botrytis cinerea 中的 HNM1 同源物（Bchnm1）。Bchnm1 缺失突变体表现出降低的分生孢子萌发和芽管伸长。Δbchnm1 缺失突变体的功能活性通过降低 B. cinerea 在番茄和法国豆叶片上的坏死定殖来证明。BcHnm1 在萌发中的作用也得到了 qRT-PCR 结果的支持，该结果表明在 WT 菌株接种番茄叶片后的早期感染阶段（接种后 16 小时），以及在分生孢子萌发期间（体外），Bchnm1 转录本水平增加。与 BcHnm1 预测的胆碱转运功能一致，Δbchnm1 缺失突变体显示出胆碱摄取能力减弱。WT B. cinerea 中胆碱的潜在作用进一步通过在存在 1mM 外源胆碱的情况下增加分生孢子萌发（增加 100%）来证明，而在胆碱转运抑制剂 hemicholinium-3 的存在下，萌发抑制率为 40%。与 WT 相比，外源胆碱和抑制剂不会影响 Δbchnm1 缺失突变体中的分生孢子萌发。总的来说，这项研究首次表明，预测的胆碱转运蛋白 BcHnm1 对分生孢子萌发、芽管伸长、对外源胆碱的反应以及植物病原菌的毒力都很重要。
