Combined and single effects of elevated CO₂ and temperatures on rice bakanae disease under controlled conditions in phytotrons

Abstract

Bakanae disease, caused by Fusarium fujikuroi, was investigated under different CO2 and temperature environments in order to simulate climate changes in the F. fujikuroi–rice pathosystem. F. fujikuroi‐infected plants were grown under six phytotron conditions: low (18/22 °C night/day), medium (22/26 °C), and high (26/30 °C) temperature, at either ambient (450 ppm) or elevated (850 ppm) CO2 concentrations. Bakanae disease index (DI), seedling death incidence, fungal DNA quantity, and chlorophyll and carbohydrate contents varied significantly in infected plants as a consequence of changes in both CO2 and temperature. Plant height and dry weight were only influenced by single factors (temperature for height, and temperature or CO2 for dry weight), and not by the CO2 × temperature interaction. Medium and high temperatures (irrespective of the CO2 level) increased the DI significantly (range from 67.5% to 95.8%) compared to low temperatures (range from 45.8% to 47.5%). Under elevated CO2 levels, noticeable differences in the expression of four rice defence‐related genes and fungal DNA quantity were observed between those plants grown at higher temperatures and those at lower temperatures. Overall, combined and single effects of elevated CO2 and high temperatures seem to be favourable for bakanae disease development in the Mediterranean basin.

A Review of the Most Common and Economically Important Diseases That Undermine the Cultivation of Tomato Crop in the Mediterranean Basin

“…Recent reports have shown increasing disease severity associated with climate change for necrotrophic plant pathogens, such as A. alternata, Cercospora sp., Colletotrichum gloeosporioides, F. equiseti, F. fujikuroi, and F. oxysporum f. sp. conglutinans [334][335][336]. Regarding this review, seven of the tomato plant necrogenic pathogens described, i.e., Bc, Forl, Vd, TSWV, ToMV, PepMV, and PSTVd, have been also reported for their increased pathogenicity or enhanced transmission rates, [19,20,61,63] while up to now, no reports are available for ToBRFV and PMoV.…”

Past and Future Epidemiological Perspectives and Integrated Management of Rice Bakanae in Korea

“…Recently, the combined effect of CO 2 with temperature on the incidence of bakanae was evaluated. Matić et al (2021) reported that the disease index and death incidence of rice inoculated with the pathogen were elevated under high temperature and CO 2 concentration, with solid support from genetic analysis showing the specific conditions favorable for disease progression. In the disease cycle of bakanae ( Fig.…”

“…1 ). Given that the causal agent of bakanae, Fusarium fujikuroi , favors warm and humid climates ( Manandhar, 1999 ; Matić et al, 2021 ), the variable incidences since 2012 were likely to be affected by weather variabilities during the cropping seasons. Moreover, from 2022, the Korea Seed & Variety Service distributes only rice seeds that are not disinfected but promotes the hot water immersion method.…”

“…Based on the comprehensive review of previous studies, weather conditions during the flowering stage are expected to have a significant effect on rice bakanae infection ( Bashyal, 2018 ; Bashyal et al, 2014 ; Manandhar, 1999 ; Matić et al, 2017 , 2021 ; Piombo et al, 2020 ; Singh et al, 2019 ). Considering that rice grains infected during the rice flowering stage determine the initial incidence level of bakanae in the following year, a prediction model can be developed for simulating bakanae infection based on meteorological information during the flowering stage.…”

“…2 ), seeds that were infected from the previous cropping season transmit the disease at the following season, indicating that the grain infection taking place at the flowering or maturing stage, and further the climatic conditions affecting the infection during that stage, is very critical ( Desjardins et al, 1997 ). Because bakanae is a rice disease favoring high temperature, humidity, and CO 2 concentration, there is a high possibility that it increases with the warm and humid conditions prevailing under climate change ( Manandhar, 1999 ; Matić et al, 2021 ; Piombo et al, 2020 ). According to Bashyal (2018) , the optimal temperatures for the infection and development of bakanae is 27–30°C and 35°C, respectively, which are warmer than the optimal temperatures (approximately 29 °C) for the development of rice bacterial leaf blight, a well-known thermophilic disease ( Horino et al, 1982 ).…”