Wheat susceptibility to blast is enhanced by a photosynthetic inhibitor

Abstract

Considering blast, caused by Pyricularia oryzae, as a critical threat to wheat yield and the importance of photosynthesis as the source of energy used by plants to activate their mechanisms of defence to counteract pathogen infections, this study aimed to investigate whether wheat plants compromised in their photosynthetic process by using an inhibitor of photosynthesis could become more susceptible to blast. Plants from cultivars BRS 220 (moderately resistant) and BRS Guamirim (susceptible) were non‐sprayed (‐DCMU plants) or sprayed (+DCMU plants) with a solution (10 μM) of 3‐([3,4‐dichlorophenyl]‐1,1‐dimethylurea) (DCMU) at 24 hr before inoculation with P. oryzae. Blast progressed much faster on the leaves of +DCMU plants from cultivars BRS 220 and BRS Guamirim in comparison with ‐DCMU plants of these cultivars. Increased susceptibility of plants from the two cultivars to blast caused by DCMU was associated with its negative effect on the photosynthetic apparatus, decreasing phenylalanine ammonia‐lyase activity and reducing the concentration of total soluble phenolics. Chitinase activity for the infected plants from the two cultivars was lower compared with non‐inoculated ‐DCMU plants but was greater for inoculated +DCMU plants. Distinctly, β‐1,3‐glucanases activity was kept stable for inoculated +DCMU plants. In conclusion, manipulation of the photosynthetic process of wheat plants by using DCMU allowed to understand their response to P. oryzae infection at the physiological level and reinforced the concept that photosynthesis was important for wheat resistance to blast.

Chlorophyll a Fluorescence: A Method of Biotic Stress Detection

“…As known, studies demonstrated that pathogens secret their effectors for linking to receptor specifics in chloroplasts looking for a reduction drastic in the ROS controlling the plant defense mechanisms, suggesting the crucial role of the photosynthetic machinery in the basal plant resistance against pathogen infection [69]. In this sense, the manipulation of photosynthetic activity using photosynthesis inhibitor-specific (DCMU) in wheat cultivars with differential basal resistance to Pyricularia oryzae showed increases in the blast severity in both cultivars as a consequence of a low photosynthetic activity affecting the enzymatic responses related to plant resistance such as phenylalanine ammonia-lyase (PAL) and reinforced the concept that photosynthesis was important for wheat resistance to blast [70].…”

Pinus thunbergii Parl. Somatic Plants’ Resistance to Bursaphelenchus xylophilus Depends on Pathogen-Induced Differential Transcriptomic Responses

“…We hypothesized that the high expression of these photosynthetic genes in resistant trees helped to inhibit PWN infestation and delay the development of PWD in resistant P. thunbergii. For host-pathogen interactions, photosynthetic regulation was developed as an approach to seek to correlate functional manipulation of PS I and PS II with host defense responses derived from primary metabolism [43]. After PWN infestation, photosynthesisregulated genes responded first, followed by significant modifications in the circadian rhythm-plant pathway (p < 0.001).…”