Defence‐related pathways, phytohormones and primary metabolism are key players in kiwifruit plant tolerance to Pseudomonas syringae pv. actinidiae

Abstract

The reasons underlying the differential tolerance of Actinidia spp. to the pandemic pathogen Pseudomonas syringae pv. actinidiae (Psa) have not yet been elucidated. We hypothesized that differential plant‐defence strategies linked to transcriptome regulation, phytohormones and primary metabolism might be key and that Actinidia chinensis susceptibility results from an inefficient activation of defensive mechanisms and metabolic impairments shortly following infection. Here, 48 h postinoculation bacterial density was 10‐fold higher in A. chinensis var. deliciosa than in Actinidia arguta, accompanied by significant increases in glutamine, ornithine, jasmonic acid (JA) and salicylic acid (SA) (up to 3.2‐fold). Actinidia arguta showed decreased abscisic acid (ABA) (0.7‐fold), no changes in primary metabolites, and 20 defence‐related genes that were only differentially expressed in this species. These include GLOX1, FOX1, SN2 and RBOHA, which may contribute to its higher tolerance. Results suggest that A. chinensis' higher susceptibility to Psa is due to an inefficient activation of plant defences, with the involvement of ABA, JA and SA, leading to impairments in primary metabolism, particularly the ammonia assimilation cycle. A schematic overview on the interaction between Psa and genotypes with distinct tolerance is provided, highlighting the key transcriptomic and metabolomic aspects contributing to the different plant phenotypes after infection.

BdGUCD1 and Cyclic GMP Are Required for Responses of Brachypodium distachyon to Fusarium pseudograminearum in the Mechanism Involving Jasmonate

“…Moreover, there is still much missing information and gaps in the understanding of the interactions between cGMP and hormones in response to pathogen infection. There is evidence that cGMP, GCs [ 4 , 5 , 14 ], and hormones are involved in the plant response to pathogen infection [ 15 , 16 , 17 , 18 ]. Therefore, it is worth exploring whether and how these molecules cooperate.…”

Role of Promising Secondary Metabolites to Confer Resistance Against Environmental Stresses in Crop Plants: Current Scenario and Future Perspectives

“…Furthermore, various phytohormones, including as JA, SA, and ABA, interact to establish a defense network against environmental challenges ( Kumudini et al, 2018 ). Understanding the interactions between phytohormones and defense signaling pathways might lead to the discovery of novel targets for establishing host resistance mechanisms ( Kumudini et al, 2018 ; Nunes da Silva et al, 2022 ; Table 2 ).…”

Interplay between phytohormone signalling pathways in plant defence – other than salicylic acid and jasmonic acid

“…This was further supported by hormone profiling of resistant and susceptible kiwifruit during challenge with P. syringae . ABA concentration was significantly reduced in resistant kiwifruit due to down-regulation of biosynthesis genes and up-regulation of ABA catabolism genes [ 66 ]. Concomitantly, JA and SA levels remained unchanged in resistant kiwifruit but were significantly increased in susceptible plants where ABA remained stable [ 66 ].…”

“…ABA concentration was significantly reduced in resistant kiwifruit due to down-regulation of biosynthesis genes and up-regulation of ABA catabolism genes [ 66 ]. Concomitantly, JA and SA levels remained unchanged in resistant kiwifruit but were significantly increased in susceptible plants where ABA remained stable [ 66 ]. The ability of bacterial and fungal pathogens to generate ABA, which can negatively affect plant defences, indicates that pathogens can utilize ABA as an effector to modulate immunity.…”