Responses to combined abiotic and biotic stress in tomato are governed by stress intensity and resistance mechanism

Abstract

HighlightSalt stress severity differentially affected partial powdery mildew resistance. Stress combination uniquely resulted in accelerated senescence. mlo-based and R-gene-mediated resistance maintained robustness across salt treatments.

Ethylene and Abscisic Acid Signaling Pathways Differentially Influence Tomato Resistance to Combined Powdery Mildew and Salt Stress

“…As shown previously (Kissoudis et al, 2016), NIL-ol-2 exhibited increased callose deposits compared to NIL-Ol-1 and MM upon PM infection, and additional salt stress decreased callose deposits in all genotypes ( Figure 5 ). Under only PM infection, the epi mutation resulted in a near complete absence of callose deposits in the crosses with Ol-1 and ol-2 .…”

“…These lines were studied in more detail under control conditions, salt stress (50 mM), PM inoculation, and combined salt stress and PM inoculation, allowing an assessment of growth performance costs under the different stress conditions. These Ol -gene and mutant combinations are particularly interesting as ABA is the major hormone orchestrating abiotic stress responses in plants (Yoshida et al, 2014), while ET signaling was shown to be crucial for plant susceptibility and senescence responses under combined stress (Kissoudis et al, 2016). …”

“…Ion content, and especially Na + and Cl - concentration was shown to impact PM susceptibility (Kissoudis et al, 2016). Both the epi and not crosses with NIL-Ol-1 and NIL-ol-2 accumulated a higher amount of Na + and Cl - under salt stress compared to the parental NILs ( Supplementary Figure S2 ).…”

“…Combined stress impacted plant performance significantly more than the individual stresses, which was manifested by accelerated senescence and leaf abscission. However, this response was strongly conditioned by the type of resistance to PM, as indicated by the examination of near-isogenic lines (NILs) carrying the resistance loci Ol-1, ol-2 , and Ol-4 (Kissoudis et al, 2016). The dominant locus Ol-1 enhances basal defence by inducing delayed cell death (DCD) in the late stages of pathogen infection (Li et al, 2007; Seifi, 2011).…”

“…The dominant locus Ol-4 is an NBS-LRR gene homologous to Mi-1 (Seifi et al, 2011), and triggers a hypersensitivity response (HR) to prevent the PM colonization after formation of primary haustoria (Bai et al, 2003; Li et al, 2006). Expression analysis of selected pathway marker genes indicated a significant role of ET and JA, which were uniquely highly upregulated in the tomato susceptible genotypes under combined stress (Kissoudis et al, 2016). …”