Soil Inoculated with <i>Streptomyces rochei</i> D74 Invokes the Defense Mechanism of <i>Helianthus annuus</i> Against <i>Orobanche cumana</i>

Soil Inoculated with <i>Streptomyces rochei</i> D74 Invokes the Defense Mechanism of <i>Helianthus annuus</i> Against <i>Orobanche cumana</i>

<i>Orobanche cumana</i> Wallr. is a root parasitic plant that causes considerable yield losses of up to 50% in sunflower <i>Helianthus annuus</i> plantations. The holoparasite fulfills its entire demand for water, minerals, and organic nutrients from the host’s vascular syste...

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Main Authors: Jiao Xi, Tengqi Xu, Zanbo Ding, Chongsen Li, Siqi Han, Ruina Liang, Yongqing Ma, Quanhong Xue, Yanbing Lin
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Agriculture
Subjects:
<i>Streptomyces rochei</i>
sunflower
<i>O. cumana</i>
system resistance
microbiome
Online Access:https://www.mdpi.com/2077-0472/15/14/1492
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Summary:<i>Orobanche cumana</i> Wallr. is a root parasitic plant that causes considerable yield losses of up to 50% in sunflower <i>Helianthus annuus</i> plantations. The holoparasite fulfills its entire demand for water, minerals, and organic nutrients from the host’s vascular system. Agronomic practices alone are not effective in controlling this pest. This study investigated the mechanism of a verified plant growth-promoting strain, <i>Streptomyces rochei</i> D74, on the inhibition of the parasitism of <i>O. cumana</i> in a co-culture experiment. We conducted potted and sterile co-culture experiments using sunflower, <i>O. cumana</i>, and <i>S. rochei</i> D74. Our results suggest that the inoculated bacteria invoked the sunflower systemic resistance (SAR and ISR) by increasing the activity of resistance-related enzymes (SOD, POD, PPO, and PAL), the gene expression of systemic resistance marker genes (<i>PR-1</i> and <i>NPR1</i>), ethylene synthesis genes (<i>HACS. 1</i> and <i>ACCO1</i>), and JA synthesis genes (<i>pin2</i> and <i>lox</i>). The expression levels of ISR marker genes (lox, <i>HACS. 1</i>, <i>ACCO1</i>, and <i>pin2</i>) increased by 1.66–7.91-fold in the seedling stage. Simultaneously, <i>S. rochei</i> D74 formed a protective layer on the sunflower root surface, preventing <i>O. cumana</i> from connecting to the vascular system of the sunflower roots. In addition, <i>S. rochei</i> D74 reduced 5DS synthesis of the strigol precursor substance, resulting in a reduction in <i>O. cumana</i> germination. These results demonstrated that the <i>S. rochei</i> D74 strain improved systemic resistance and decreased seed germination to prevent <i>O. cumana</i> parasitism.
ISSN:2077-0472

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