Spraying calcium chloride helps to enhance the resistance of kidney bean plants to western flower thrips.

BACKGROUND: The western flower thrips (WFT), Frankliniella occidentalis (Thysanoptera: Thripidae), is a significant pest in horticulture and ornamental agriculture. While exogenous calcium (Ca) has been shown to confer plant immune responses against thrips, the detailed mechanisms of this interaction remain to be elucidated for improved thrips management strategies. This study aimed to assess the impact of exogenous Ca on WFT feeding behavior and to explore its role in enhancing the defense mechanisms of kidney bean plants against WFT attacks. We compared WFT feeding preferences and efficiency on kidney bean plants treated with H2O or Ca, and examined whether exogenous Ca improves plant defense responses to thrips attack.

RESULTS: WFT exhibited less preference for feeding on Ca-treated plants over H2O-treated ones. The total duration of WFT's long-ingestion probes was significantly reduced on Ca-treated plants, indicating impaired feeding efficiency. Furthermore, WFT infestation activated both jasmonic acid (JA) and salicylic acid (SA) signaling pathways in kidney bean plants, and exogenous Ca application led to elevated levels of endogenous Ca2+ and CaM, up-regulation of genes associated with JA and SA pathways (LOX, AOS, PAL, and β-1,3-glucanase), and increased accumulation of JA, SA, flavonoids, and alkaloids.

CONCLUSION: Our findings demonstrate that the application of exogenous Ca enhances endogenous Ca2+, JA, and SA signaling pathways in kidney bean plants. This enhancement results in an up-regulation of the biosynthesis of flavonoid and alkaloid, thereby equipping the plants with an enhanced defense against WFT infestation. © 2024 Society of Chemical Industry.