Abstract:
Growing ecological evidence indicates that roots are critical contributors towards securing whole-plant immunity, including leaf defense. However, the molecular mechanisms underlying these effects remain largely uncharacterized. Previously, we have found that cellulose-deficient mutants in KORRIGAN1 (KOR1) exhibit constitutive activation of the Jasmonate (JA) pathway specifically in roots. JA is essential to protect plants against chewing herbivores, necrotrophic pathogens, RNA viruses as well as abiotic stresses such mechanical wounding, drought and elevated salinity. Yet, very little is known about the physiological relevance of JA production in roots. While constitutive root JA signalling in kor1 did not impact root growth, we found increased defense responses in kor1 shoots against the generalist herbivore Spodoptera littoralis. As JA signalling is not induced in kor1 shoots, we hypothesized that a JA-Ile-dependent root-derived mobile signal relocates to and activates shoot defence responses. A multi-omics approach corroborated a root-derived JA-dependent increase of shoot Glucosinolates impacting insect defense. These findings can be recapitulated in wild-type plants, and represent a fundamental opportunity to understand and harness inter-organ coordination for improving plant environmental resilience.

Roots as Key Regulators of Whole-Plant Immunity: A Jasmonate-Driven Defense Cascade

Emerging ecological evidence underscores the pivotal role of roots in orchestrating whole-plant immunity, extending their influence beyond the rhizosphere to aboveground tissues such as leaves. Despite this growing recognition, the molecular mechanisms mediating root-to-shoot immune signaling remain largely elusive.

Our previous work identified that cellulose-deficient mutants in KORRIGAN1 (KOR1) exhibit constitutive activation of the Jasmonate (JA) signaling pathway specifically in roots. JA is a central phytohormone involved in plant defense against a broad spectrum of biotic threats—including chewing herbivores, necrotrophic pathogens, and RNA viruses—as well as abiotic stresses such as mechanical wounding, drought, and salinity. However, the physiological significance of JA biosynthesis in roots has not been fully elucidated.

Interestingly, although kor1 mutants show persistent JA signaling in roots without affecting root growth, we observed a marked enhancement of defense responses in the shoots against the generalist herbivore Spodoptera littoralis. Notably, JA signaling is not activated in kor1 shoots, suggesting the existence of a JA-Ile-dependent mobile signal originating in the roots that translocates to aerial tissues to trigger defense mechanisms.

Using a multi-omics approach, we confirmed that this root-derived JA signal leads to an upregulation of Glucosinolates in shoots—key metabolites known to deter insect herbivory.

Importantly, this inter-organ signaling cascade can be recapitulated in wild-type plants, highlighting a conserved mechanism of systemic defense coordination.

These findings open new avenues for understanding and leveraging root-shoot communication to enhance plant resilience under environmental stress, offering promising strategies for crop protection and sustainable agriculture.

Bio:
2016 - present Research group leader Leibniz Institute of Plant Biochemistry, Halle, Germany Jasmonate signalling group

2010-2015 Postdoctoral scientist and Junior lecturer in Plant molecular biology (Ted Farmer lab) University of Lausanne, Switzerland The Arabidopsis thaliana wound response

2010 PhD in Crop Genetics (Simon Griffiths lab) John Innes Centre, Norwich, UK Determination of height variation in bread wheat

2004 & 2006 BSc in Biology and MSc in Functional Genomics University of Trieste, Italy Allelic diversity of Coffea arabica fertility genes