Salicylic acid-related ribosomal protein CaSLP improves drought and Pst.DC3000 tolerance in pepper

The ribosomal protein contains complex structures that belong to polypeptide glycoprotein family, which are involved in plant growth and responses to various stresses. In this study, we found that capsicum annuum 40S ribosomal protein SA-like (CaSLP) was extensively accumulated in the cell nucleus and cell membrane, and the expression level of CaSLP was up-regulated by Salicylic acid (SA) and drought treatment. Significantly fewer peppers plants could withstand drought stress after CaSLP gene knockout. The transient expression of CaSLP leads to drought tolerance in pepper, and Arabidopsis's ability to withstand drought stress was greatly improved by overexpressing the CaSLP gene. Exogenous application of SA during spraying season enhanced drought tolerance. CaSLP-knockdown pepper plants demonstrated a decreased resistance of Pseudomonas syringae PV.tomato (Pst) DC3000 (Pst.DC3000), whereas ectopic expression of CaSLP increased the Pst.DC3000 stress resistance in Arabidopsis. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) results showed that CaNAC035 physically interacts with CaSLP in the cell nucleus. CaNAC035 was identified as an upstream partner of the CaPR1 promoter and activated transcription. Collectively the findings demonstrated that CaSLP plays an essential role in the regulation of drought and Pst.DC3000 stress resistance.