Biology subjects

Guerra, T.

Publications and source records attributed to Guerra, T..

3 recordsLinked to original sources

bioRxiv2026

Drought alters volatile profiles in European beech saplings across genetically diverse backgrounds

O_LIEuropean beech (Fagus sylvatica L.) is a widely distributed, ecologically and economically important deciduous tree species in European forests, but is increasingly threatened by drought stress. Volatile organic compounds (VOCs) are ubiquitous plant metabolites that may serve as non-invasive biomarkers of drought stress, yet they have rarely been studied in European beech. C_LIO_LIIn this study, we examined VOC responses of European beech to experimental drought across diverse genetic backgrounds in a common garden. The 72 four-year-old beech saplings represented three genetic clusters, seven provenances (geographic seed sources), and 12 maternal seed families. Half of the saplings were assigned to the drought treatment and received no water for 14 days, while the remaining saplings served as controls and were watered as required. VOC profiles, quantified as peak heights of mass spectral features, were measured for all individuals during pre-drought, drought, and rewatering periods. C_LIO_LIWe found that pre-drought VOC profiles, in particular monoterpenes, varied significantly among genetic backgrounds. Experimental drought significantly altered VOC profiles, characterized by increased green leaf volatiles and decreased monoterpenes, oxidized terpenoid derivatives, and other fatty acid derivatives. Reductions in monoterpenes persisted after rewatering, indicating a drought legacy effect. Drought responses were largely conserved across genetic backgrounds, with significant seed family-specific responses detected for only three VOC features. C_LIO_LIOur findings suggest that VOC profiles are genetically structured yet highly plastic under drought and highlight their potential as non-invasive biomarkers for monitoring drought stress in European beech under climate change. C_LI

ecology↗

bioRxiv2021

The Xanthomonas type-III effector protein XopS stabilizes CaWRKY40a to regulate defense hormone responses and preinvasion immunity in pepper (Capsicum annuum)

A critical component of plant immunity against invading pathogens is the rapid transcriptional reprogramming of the attacked cell to minimize virulence. Many adapted plant bacterial pathogens use type III effector (T3E) proteins to interfere with plant defense responses, including the induction of immunity genes. The elucidation of effector function is essential to understanding bacterial pathogenesis. Here, we show that XopS, a T3E of Xanthomonas campestris pv. vesicatoria (Xcv), interacts with and inhibits the proteasomal degradation of the transcriptional regulator of defense gene expression WRKY40. Virus-induced gene silencing of WRKY40 in pepper enhanced plant tolerance towards Xcv infection, indicating it represses immunity. Stabilization of WRKY40 by XopS reduces the expression of its targets including salicylic acid (SA)-responsive genes and the jasmonic acid (JA) signaling repressor JAZ8. Xcv bacteria lacking XopS display significantly reduced virulence when surface inoculated onto susceptible pepper leaves. XopS delivery by Xcv, as well as ectopic expression of XopS in Arabidopsis or Nicotiana benthamiana prevented stomatal closure in response to bacteria and biotic elicitors in a WRKY40 dependent manner. This suggests that XopS interferes with preinvasion as well as with apoplastic defense by manipulating WRKY40 stability and gene expression eventually altering phytohormone crosstalk to promote pathogen proliferation.

plant biology↗

bioRxiv2019

Calcium-dependent protein kinase 5 links calcium-signaling with SARD1-dependent immune memory in systemic acquired resistance

- Systemic acquired resistance (SAR) prepares infected plants for faster and stronger defense activation upon subsequent attacks. SAR requires an information relay from primary infection to distal tissue and the initiation and maintenance of a self-maintaining phytohormone salicylic acid (SA)-defense loop. - In spatial and temporal resolution we show that calcium-dependent protein kinase CPK5 contributes to immunity and SAR. In local basal resistance CPK5 functions upstream of SA-synthesis, -perception, and -signaling. In systemic tissue, enhanced CPK5 signaling leads to an accumulation of SAR marker genes including transcription factor Systemic Acquired Resistance Deficient 1 (SARD1). - Plants of enhanced CPK5-, but not CPK6-, signaling display a super-priming phenotype of enhanced resistance toward a secondary bacterial infection. In sard1 background, CPK5-mediated basal resistance is still mounted but systemic super-priming is lost. - The biochemical analysis determines CPK5 half maximal kinase activity for calcium K50 [Ca2+] to [~]100 nM close to the cytoplasmic resting level. This low activation threshold uniquely qualifies CPK5 to decode subtle changes in calcium prerequisite to immune signal relay and to onset and maintenance of priming at later time points in distal tissue. Our data explain why CPK5 functions as a hub in basal and systemic plant immunity.

plant biology↗