Genome-wide identification of papain-like cysteine proteases in <i>Citrus sinensis</i> and expression analysis in response to <i>Candidatus</i> Liberibacter asiaticus

Papain-like cysteine proteases (PLCPs) play important roles in plant-pathogen interactions. In citrus, PLCPs are targeted by effectors from Candidatus Liberibacter asiaticus (CLas), the causal agent of Huanglongbing (HLB). To study interactions between Citrus sinensis and CLas, we identified 33 candidate CsPLCP genes HMMsearch with Peptidase_C1 domain (PF00112), further confirmed them using local BLAST PLCP sequences Arabidopsis thaliana. The CsPLCPs were classified into 9 subfamilies. Analysis cis-acting elements their promoters indicated that responsive to various phytohormones stressors. Further qPCR analysis several up-regulated during CLas infection. Subcellular localization five localized cytoplasm nucleus, while CsXBCP2 was only cytoplasm. summary, this provides a sound basis for understanding Citrus-CLas interaction.