Disentangling the resistant mechanism of Fusarium wilt TR4 interactions with different cultivars and its elicitor application

Abstract

Fusarium wilt of banana, especially Tropical Race 4 (TR4) is a major factor restricting banana production. Developing a resistant cultivar and inducing plant defenses by elicitor application are currently two of the best options to control this disease. Isotianil is a monocarboxylic acid amide that has been used as a fungicide to control rice blast and could potentially induce systemic acquired resistance in plants. To determine the control effect of elicitor isotianil on TR4 in different resistant cultivars, a greenhouse pot experiment was conducted and its results showed that isotianil could significantly alleviate the symptoms of TR4, provide enhanced disease control on the cultivars ‘Baxi’ and ‘Yunjiao No.1’ with control effect 50.14% and 56.14%, respectively. We compared the infection processes in ‘Baxi’ (susceptible cultivars) and ‘Yunjiao No.1’ (resistant cultivars) two cultivars inoculated with pathogen TR4. The results showed that TR4 hyphae could rapidly penetrate the cortex into the root vascular bundle for colonization, and the colonization capacity in ‘Baxi’ was significantly higher than that in ‘Yunjiao No.1’. The accumulation of a large number of starch grains was observed in corms cells, and further analysis showed that the starch content in ‘Yunjiao No. 1’ as resistant cultivar was significantly higher than that in ‘Baxi’ as susceptible cultivar, and isotianil application could significantly increase the starch content in ‘Baxi’. Besides, a mass of tyloses were observed in the roots and corms and these tyloses increased after application with isotianil. Furthermore, the total starch and tyloses contents and the control effect in the corms of ‘Yunjiao No.1’ was higher than that in the ‘Baxi’. Moreover, the expression levels of key genes for plant resistance induction and starch synthesis were analyzed, and the results suggested that these genes were significantly upregulated at different time points after the application of isotianil. These results suggest that there are significant differences between cultivars in response to TR4 invasion and plant reactions with respect to starch accumulation, tyloses formation and the expression of plant resistance induction and starch synthesis related genes. Results also indicate that isotianil application may contribute to disease control by inducing host plant defense against TR4 infection and could be potentially used together with resistant cultivar as integrated approach to manage this destructive disease. Further research under field conditions should be included in the next phases of study.

Biological control of the native endophytic fungus Pochonia chlamydosporia from the root nodule of Dolichos lablab on Fusarium wilt of banana TR4

“…At 4 time points after inoculation with TR4, the DNA extracted from different banana roots and corms was subjected to real-time fluorescence quantitative PCR. At 4 time points after inoculation with GFP-TR4, the roots and corms of banana plants were selected and sliced to observe GFP-TR4 infection using the confocal laser microscope based on the protocol outlined by Zhou et al ( 2023 ).…”

“…To detect TR4 content changes in banana roots and corms after TR4 infection, on 1 day, 7 days,14 days and 45 days after inoculating GFP-TR4, the banana roots and corms were sampled for extracting plant tissue DNA (Zhou et al, 2023 ). The treatment without inoculated TR4 was used as the control.…”

“…Using the real-time fluorescence quantitative measurement, the number of genomic quantification of gene copy was carried out. Additionally, a specific protocol and a method were referred from Zhou et al ( 2023 ) and a standard curve was established for data analysis (efficiency, 90%−110%; correlation coefficient, R2 > 0.99).…”

A smooth vetch (Vicia villosa var.) strain endogenous to the broad-spectrum antagonist Bacillus siamensis JSZ06 alleviates banana wilt disease

“…Forty-five days after inoculation, the infection of banana leaves and bulbs was observed and recorded separately. The disease index and control effect of each group were computed following the methods of Fan et al (2021) and Zhou et al (2023). The following standards for assessing leaf diseases were applied: grade 0: no indications; grade 1: no more than 50% of the whole area with wilting of true leaves and cotyledons; grade 2: more than 50% of the whole area with wilting of true leaves and cotyledons; grade 3: just the growth tips remained, with the leaves withered or dead; grade 4: the whole plant seemed very withered or dead.…”

“…It holds the distinction of being one of the most produced, traded, and consumed fruits globally ( FAO, 2023 ). Following rice, wheat, and maize, bananas have ascended to become the fourth major food crop in developing nations ( Aguilar-Hawod et al., 2019 ; Zhou et al., 2023 ). China holds the position of the largest global importer and the second-largest manufacturer of bananas.…”