Photosynthesis-related factors play a crucial role in plant metabolism and could be involved in defense
against pathogens. To investigate the interaction between photosynthesis and defense response,
hydroponic experiments with Fusarium oxysporum f. sp. cubense (FOC) infection or without the pathogen
were conducted in greenhouse. During the early stage of disease development (after 8 days infection),
Fusarium-infected banana seedlings exhibited decreases in photosynthesis rate and stomatal
conductance without damage to Photosystem II (PSII). As disease progressed (after 10 days infection),
the maximum quantum efficiency of PSII photochemistry decreased. Simultaneously, decreases in the
maximum carboxylation efficiency and the chlorophyll content of infected plants were observed. In
addition, an increased photorespiration rate and defense reactions were detected in banana plants at the
same infection stage. Also, the activity of defense enzymes increased notably, which was associated with
the accumulation of phenolic acid and lignin. H2O2 and malate, peaked following FOC infection. A
decreased photorespiration rate following exposure to weak light was probably related to the earlier
chlorosis of infected plants. Our results demonstrate that early FOC infection induced a decrease in net
photosynthetic rate, which mainly resulted from stomatal limitation, and the damage to chloroplasts also
contributed to the reduction in the photosynthetic capacity of banana plants in the later stages of
infection. The increased photorespiration rate was possibly involved in the resistance of banana plants in
the later stages of infection, suggesting an interaction between host plant resistance and the pathogen
associated with photosynthesis.
Photosynthesis-related factors play a crucial role in plant metabolism and could be involved in defenseagainst pathogens. To investigate the interaction between photosynthesis and defense response,hydroponic experiments with Fusarium oxysporum f. sp. cubense (FOC) infection or without the pathogenwere conducted in greenhouse. During the early stage of disease development (after 8 days infection),Fusarium-infected banana seedlings exhibited decreases in photosynthesis rate and stomatalconductance without damage to Photosystem II (PSII). As disease progressed (after 10 days infection),the maximum quantum efficiency of PSII photochemistry decreased. Simultaneously, decreases in themaximum carboxylation efficiency and the chlorophyll content of infected plants were observed. Inaddition, an increased photorespiration rate and defense reactions were detected in banana plants at thesame infection stage. Also, the activity of defense enzymes increased notably, which was associated withthe accumulation of phenolic acid and lignin. H2O2 and malate, peaked following FOC infection. Adecreased photorespiration rate following exposure to weak light was probably related to the earlierchlorosis of infected plants. Our results demonstrate that early FOC infection induced a decrease in netphotosynthetic rate, which mainly resulted from stomatal limitation, and the damage to chloroplasts alsocontributed to the reduction in the photosynthetic capacity of banana plants in the later stages ofinfection. The increased photorespiration rate was possibly involved in the resistance of banana plants inthe later stages of infection, suggesting an interaction between host plant resistance and the pathogenassociated with photosynthesis.
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