R2R3 MYB‐dependent auxin signalling regulates trichome formation, and increased trichome density confers spider mite tolerance on tomato

Abstract

Unicellular and multicellular tomato trichomes function as mechanical and chemical barriers against herbivores. Auxin treatment increased the formation of II, V and VI type trichomes in tomato leaves. The auxin response factor gene SlARF4, which was highly expressed in II, V and VI type trichomes, positively regulated the auxin-induced formation of II, V and VI type trichomes in the tomato leaves. SlARF4 overexpression plants with high densities of these trichomes exhibited tolerance to spider mites. Two R2R3 MYB genes, SlTHM1 and SlMYB52, were directly targeted and inhibited by SlARF4. SlTHM1 was specifically expressed in II and VI type trichomes and negatively regulated the auxin-induced formation of II and VI type trichomes in the tomato leaves. SlTHM1 down-regulation plants with high densities of II and VI type trichomes also showed tolerance to spider mites. SlMYB52 was specifically expressed in V type trichomes and negatively regulated the auxin-induced formation of V type trichome in the tomato leaves. The regulation of SlARF4 on the formation of II, V and VI type trichomes depended on SlTHM1 and SlMYB52, which directly targeted cyclin gene SlCycB2 and increased its expression. In conclusion, our data indicates that the R2R3 MYB-dependent auxin signalling pathway regulates the formation of II, V and VI type trichomes in tomato leaves. Our study provides an effective method for improving the tolerance of tomato to spider mites.

Chronic Gamma Irradiation Changes Phenotype and Gene Expression Partially Transmitted to Next-Generation Tomato Seedlings

“…Hase et al [17,63] showed that the frequency of DNA mutations, including single-substitutions, small InDels, and DNA structural variation, increased when irradiation was applied at higher doses. Trichomes are specialized cells that undergo differentiation from the epidermis of plants and play an essential role in conferring protection to plants against various biotic and abiotic stresses [64][65][66]. We detected a decrease in the density of type VI trichomes on leaves when gamma rays were used for chronic irradiation at a dose of 100-200 Gy for 4 weeks.…”

Phytohormone-Based Regulation of Trichome Development

“…The GLABRA 1 (GL1)-GLABRA 3 (GL3)/ENHANCER OF GLABRA 3 (EGL3)-TRANSPARENT TESTA GLABRA 1 (TTG1) trichome development complex has been well studied ( Zhao et al, 2008 ); however, knowledge of the interaction between this complex and phytohormones is limited. Sweet wormwood ( Artemisia annua ), tomato ( Solanum lycopersicum ), and cucumber ( Cucumis sativus ) are the main plant species used as models for studying glandular trichome development ( Lv et al, 2017 ; Du et al, 2020 ; Xiong et al, 2020 ), and many studies have indicated that trichome development involves phytohormones ( Yan et al, 2017 ; Chen et al, 2020 ; Yuan et al, 2021 ).…”

H and HL synergistically regulate jasmonate-triggered trichome formation in tomato

“…In tomato, THM1, a R2R3 MYB transcription factor, acts as a negative regulator of long trichomes [ 74 ]. To explore the relationship between THM1 and H/HL, we examined the transcriptional level of THM1 in mutants of h , hl , and h / hl h .…”

“…In addition, JAZ2 can block the activity of H and HL in the repression of THM1 expression. THM1 has been shown by previous studies to regulate auxin-induced trichome formation [ 74 ]. In the Y2H assay, H/HL could interact with multiple JAZ proteins ( Fig.…”