Elicitor hydrophobin Hyd1 interacts with Ubiquilin1-like to induce maize systemic resistance

Trichoderma harzianum is a plant-beneficial fungus that secretes small cysteine-rich proteins that induce plant defense responses;however, the molecular mechanism involved in this induction is largely unknown.Here, we report that the class Ⅱ hydrophobin Th Hyd1 acts as an elicitor of induced systemic resistance(ISR) in plants. Immunogold labeling and immunofluorescence revealed Th Hyd1 localized on maize(Zea mays) root cell plasma membranes. To identify host plant protein interactors of Hyd1, we screened a maize B73 root c DNA library. Th Hyd1 interacted directly with ubiquilin1-like(UBL). Furthermore, the N-terminal fragment of UBL was primarily responsible for binding with Hyd1 and the eight-cysteine amino acid of Hyd1 participated in the protein-protein interactions. Hyd1 from T. harzianum(Thhyd1) and ubl from maize were co-expressed in Arabidopsis thaliana, they synergistically promoted plant resistance against Botrytis cinerea. RNA-sequencing analysis of global gene expression in maize leaves 24 h after spraying with Curvularia lunata spore suspension showed that Thhyd1-induced systemic resistance was primarily associated with brassinosteroid signaling, likely mediated through BAK1. Jasmonate/ethylene(JA/ET)signaling was also involved to some extent in this response. Our results suggest that the Hyd1-UBL axis might play a key role in inducing systemic resistance as a result of Trichoderma-plant interactions.

Streptomyces lydicus A_(01) affects soil microbial diversity, improving growth and resilience in tomato

The actinomycete Streptomyces lydicus A_(01) promotes tomato seedling growth; however, the underlying mechanism is unclear. In this study, we investigated whether changes in soil microbial diversity, following Streptomyces lydicus A_(01) treatment, were responsible for the increased tomato seedling growth. Eukaryotic 18 S ribosomal DNA(rDNA) sequencing showed that S. lydicus A_(01)-treated and untreated soil shared 193 operational taxonomic units(OTUs), whereas bacterial 16 S rDNA sequencing identified 1,219 shared OTUs between the treated and untreated soil. Of the 42 dominant eukaryotic OTUs, eight were significantly increased and six were significantly decreased after A_(01) treatment. Of the 25 dominant bacterial OTUs, 12 were significantly increased and eight were significantly decreased after A_(01) treatment.Most of the eukaryotes and bacteria that increased in abundance exhibited growth promoting characteristics,which were mainly predicted to be associated with mineralization of nitrogen and phosphorus, phosphate solubilization, nutrient accumulation, and secretion of auxin, whereas some were related to plant protection,such as the degradation of toxic and hazardous substances. Soil composition tests showed that S. lydicus A_(01) treatment enhanced the utilization of nitrogen, phosphorus, and potassium in tomato seedlings. Thus, microbial fertilizers based on S. lydicus A_(01) may improve plant growth, without the detriment effects of chemical fertilizers.

一株新型稻瘟霉素链霉菌JZB130180的鉴定及其对桃褐腐病的生防效果评价（英文）

目的:筛选对桃褐腐病有显著防效的链霉菌并解析其生防因子。创新点:本研究筛选到一株新型稻瘟霉素链霉菌JZB130180,其对桃褐腐病具有显著防效。通过对其生防因子解析及发酵液分析,为后续分离抑菌次生代谢物奠定了基础。方法:通过对峙培养和离体实验,检测链霉菌对桃褐腐病的抑制作用。通过平皿抑菌实验,计算链霉菌发酵液的室内毒力;随后进行了发酵液的理化性质检测。通过酶活力测定等,解析链霉菌中的生防因子。结论:链霉菌JZB130180及其发酵液对桃褐腐病具有显著的抑制作用。发酵液对桃褐腐病菌的半数有效抑制浓度(EC50)为38.3μg/mL,且对酸碱、温度和紫外线都有一定的耐受能力。此外,该菌株可以分泌几丁质酶、纤维素酶、蛋白酶等重要生防因子。