Influence of the nitrogen source on the tolerance of Actinidia chinensis to Pseudomonas syringae pv. actinidiae

ISHS Secretariat
Influence of the nitrogen source on the tolerance of Actinidia chinensis to Pseudomonas syringae pv. actinidiae

Marta Nunes da Silva is a biologist by training. She obtained her PhD in Agronomical Sciences in April 2021, from the University of Porto, Portugal. Her research interests include the study of plant-pathogens interactions, through physiological, genomic and metabolomic approaches, and plant nutrition, focusing on the effect of environmental contamination and distinct cultural practices on plant fitness and productivity. Marta’s PhD study focused on unravelling the regulatory mechanisms underpinning kiwifruit plant tolerance to the pandemic bacterium Pseudomonas syringae pv. actinidiae (Psa) through integrated approaches. Marta used micro- and mesocosm settings to evaluate plant genotypic variability to Psa and develop sustainable disease mitigation strategies. Her study showed that the green-fleshed kiwifruit (Actinidia chinensis var. deliciosa) consistently showed higher endophytic bacterial density than the kiwi berry (A. arguta), being accompanied by a greater extent of disease symptoms, decreased total chlorophylls, increased lipid peroxidation and an upregulation of the ammonia assimilation cycle. In contrast, in A. arguta bacterial colonization was lower, resulting in limited impairments in plant metabolism. Her results suggest that the abscisic acid pathway and the differential expression of specific defence-related genes play key roles in the distinct tolerance of A. chinensis and A. arguta to Psa. Moreover, NH4+ seems to be unfavourable to A. chinensis defence mechanisms by increasing N accumulation in plant tissues (which favours Psa growth), and by promoting the jasmonic acid and ethylene pathways (which negatively affect plant defences). An evaluation of the antimicrobial potential of six plant essential oils (PEOs) (anise, basil, cardamom, cumin, fennel, and laurel) also revealed that cumin was effective in decreasing Psa endophytic population after foliar application. Overall, Marta’s findings provided innovative knowledge on the regulatory pathways triggered by Psa infection in Actinidia. It demonstrated the relevance of N nutrition in kiwifruit plants’ susceptibility to the pathogen, and highlighted the contribution of PEOs and elicitors to more successful and sustainable disease management. So far, her PhD work resulted in four publications in peer-reviewed international journals, including the eJHS (European Journal of Horticultural Science).

Marta Nunes da Silva won the ISHS Young Minds Award for the best oral presentation at the X International Symposium on Kiwifruit, which was held virtually in Turkey in September 2021.

Marta Nunes da Silva, Escola Superior de Biotecnologia da Universidade Católica Portuguesa, Rua de Diogo Botelho 1327, 4169-005 Porto, Portugal, e-mail:

The article is available in Chronica Horticulturae

actinidia chinensis
pseudomonas syringae
Young Minds Award Winners