Comparative study of the effect of salt stress, Alternaria alternata attack or combined stress on the Cakile maritima growth and physiological performance

Abstract

Cakile maritima is a halophytic plant model that is well known by its ability to tolerate high salt concentrations. Salinity was reported to improve the tolerance of halophytes to several abiotic stresses; however, the involvement of salt in the tolerance to biotic stress is still scant. In the present work, the effect of salt on C. maritima responses towards the pathogenic Alternaria alternata was investigated. For that, C. maritima seeds were germinated for four weeks. Plants were then divided into four groups: i) Plants irrigated with salt (200mM NaCl); ii) Plants infested by fungus; iii) Plants irrigated with salt and infested by fungus and finally control plants (0mM NaCl, without inoculation). Our results showed that upon salt stress or fungal attack, plants reduced biomass production, hydration status and photosynthetic performance which were associated with a decrease in the gas exchange and chlorophyll fluorescence parameters, with a more pronounced effect upon fungal attack. However, under combined stress, a significant increase of these parameters was noticed, with a level close to that of control. Concerning nutrient contents, K, Zn, Fe, Cu and Mg decreased in the C. maritima leaves exposed to both stresses applied individually. In contrast, all these nutrients were increased in plants grown under combined stress. Taken together, we can conclude that plants grown under combined stresses had better growth rate and physiological performance compared to all other treated plants, and that salt may be the key in improving the C. maritima ability to tolerate fungal attack.

A metabolomic view on local climate adaptation: Latitudinal divergence of heat and drought responses in a coastal plant

“…The genus Alternaria has been shown to excrete substantial amounts of this compound to promote the growth of its host plants (Wang et al, 2022). Given that Cakile is well known to associate with fungi of the genus Alternaria (Chalbi et al, 2021), our findings are indicative of a higher abundance and more severe heat-stress induced disruption of such beneficial interactions in plants from Northern European origins.…”

Synergic Effects of Salinity and Rhizoctonia solani (Kuhn) Infection on Growth and Yield Attributes of Rice (Oryza sativa L.)

“…The findings of this study discovered a notable retardation in the aforementioned growth parameters, particularly when plants are subjected to the dual stressors of high salt concentrations and the presence of sheath blight disease. Hence, the observed retardation of these parameters, especially under the influence of salt stress and sheath blight disease, is in harmony with Chalbi et al (2021).…”

Fungal and Fungal-like Diseases of Halophytes in the Mediterranean Basin: A State-of-the-Art Review

“…infections, as four different species are described on this host (A. arborescens, A. alternata, A. brassicicola, and A. mali). The Alternaria spp.-C. maritima pathosystems have been extensively investigated [67][68][69][70]. The best-known and most widely investigated species associated with this halophyte is Alternaria brassicicola (Pleosporales) which causes black necrotic lesions on many parts of the host.…”

“…In artificial inoculation trials in saline conditions, the presence of salt (200 mM NaCl) was associated with a lower susceptibility to A. alternata infection [69]. This is the sole study where a pathosystem involving a halophytic species was investigated in the presence of salt.…”

“…Interestingly, when both saline and biotic stress were applied, plants exhibited a higher growth rate and photosynthesis compared to single-stress application. The key to the alleviation of salt stress over fungal attack might reside in the intrinsic ability of halophytes to tolerate salinity and hence, after exposure to the stress, the defense mechanisms implemented by the plants (e.g., improved scavenging of reactive oxygen species) might act towards other stresses [69]. On the other hand, the susceptibility to salinity of fungal and fungal-like species must be considered as some species can tolerate this stress better than others (see Section 6 for a discussion of salt stress in fungal and fungal-like organisms).…”