Comprehensive Analysis of Subcellular Localization, Immune Function and Role in Bacterial wilt Disease Resistance of Solanum lycopersicum Linn. ROP Family Small GTPases

Abstract

ROPs (Rho-like GTPases from plants) belong to the Rho-GTPase subfamily and serve as molecular switches for regulating diverse cellular events, including morphogenesis and stress responses. However, the immune functions of ROPs in Solanum lycopersicum Linn. (tomato) is still largely unclear. The tomato genome contains nine genes encoding ROP-type small GTPase family proteins (namely SlRop1–9) that fall into five distinct groups as revealed by phylogenetic tree. We studied the subcellular localization and immune response induction of nine SlRops by using a transient overexpression system in Nicotiana benthamiana Domin. Except for SlRop1 and SlRop3, which are solely localized at the plasma membrane, most of the remaining ROPs have additional nuclear and/or cytoplasmic distributions. We also revealed that the number of basic residues in the polybasic region of ROPs tends to be correlated with their membrane accumulation. Though nine SlRops are highly conserved at the RHO (Ras Homology) domains, only seven constitutively active forms of SlRops were able to trigger hypersensitive responses. Furthermore, we analyzed the tissue-specific expression patterns of nine ROPs and found that the expression levels of SlRop3, 4 and 6 were generally high in different tissues. The expression levels of SlRop1, 2 and 7 significantly decreased in tomato seedlings after infection with Ralstonia solanacearum (E.F. Smith) Yabuuchi et al. (GMI1000); the others did not respond. Infection assays among nine ROPs showed that SlRop3 and SlRop4 might be positive regulators of tomato bacterial wilt disease resistance, whereas the rest of the ROPs may not contribute to defense. Our study provides systematic evidence of tomato Rho-related small GTPases for localization, immune response, and disease resistance.

Null mutants of a tomato Rho of plants exhibit enhanced water use efficiency without a penalty to yield

“…S1 A ). Previously referred to as ROP3 ( 37 ) and incorrectly categorized as a type-I ROP ( 38 ), we have now designated Solyc03g114070.3 as SlROP9 ( ROP9 ) to ensure clarity and alignment with the established Arabidopsis nomenclature. It is worth noting that tomato has a total of nine ROPs, and this specific nomenclature facilitates a more straightforward comparison.…”

Rho of plant GTPases with geranylgeranylation motif modulate monoterpene indole alkaloid biosynthesis inCatharanthus roseus

“…The fact that CrROP3 and CrROP5 interact with CrPGGT-I, get geranylgeranylated, localize to the nucleus, and positively affect MIA biosynthesis indicates that the modulation of gene expression and MIA accumulation occurs in the nucleus. Recently, several tomato ROPs have been shown to be localized in the nucleus; however, their exact roles have not been determined (Wang et al, 2022). Taking cues from these observations, as well as results from this study, we checked the interaction of CrROP3 and CrROP5 with TFs related to MIA biosynthesis that were affected in CrROP3 and CrROP5 silencing and overexpression backgrounds.…”