Table 3.

Chemicals and heat activate citrus defense response.

Agent types	Name	Mechanisms against CLas	References
Chemicals	Salicylic acid	Induction of expression of PR-1 and PR-2 genes	Hu et al., 2018
	Acibenzolar-S-methyl	Induction of expression of PR-1 and PR-2 genes	Hu et al., 2018
	Oxalic acid	Induction of PR-2 gene expression	Hu et al., 2018
	Potassium phosphate	Induction of PR-15 gene expression	Hu et al., 2018
	β-Aminobutyric acid	Involving in SA-depend pathway	Li et al., 2016
	2,1,3-Benzothiadiazole	Functional analogs of SA	Li et al., 2016
	2,6-Dichloroisonicotinic acid	Functional analogs of SA	Li et al., 2016
	Ascorbic acid	Interfering with biosynthesis of plant hormones and the signaling process	Li et al., 2016
	24-Epibrassinolide	Induction of some plant defense genes such as glutathione peroxidase, Jasmonate acid	Canales et al., 2016
	Sulfadimethoxine sodium	Induction of genes related to the metabolism of jasmonates, brassinosteroids, reactive oxygen species (ROS), and secondary metabolites	Yang et al., 2020b
Heat	Solar thermotherapy	Many genes involved in plant-bacterium interactions being upregulated post treatment, which may be contributed to host defense against CLas	Doud et al., 2017
	Heat treatment (40°C)	A strong upregulation of chaperones involved in reversing the effects of CLas infection in citrus plants	Nwugo et al., 2016