TaDIR1-2, a Wheat Ortholog of Lipid Transfer Protein AtDIR1 Contributes to Negative Regulation of Wheat Resistance against Puccinia striiformis f. sp. tritici

Abstract

Very few LTPs have been shown to act through plasma membrane receptors or to be involved in the hypersensitive response (HR). DIR1, a new type of plant LTP interacts with lipids in vitro, moves to distant tissues during systemic acquired resistance (SAR) and therefore is thought to be involved in long-distance signaling during SAR. However, the exact functions of DIR1 orthologs in cereal species under biotic and abiotic stresses have not been thoroughly defined. In this study, a novel wheat ortholog of the DIR1 gene, TaDIR1-2, was isolated from Suwon11, a Chinese cultivar of wheat and functionally characterized. Phylogenetic analysis indicated that TaDIR1-2 is clustered within the nsLTP-Type II group and shows a closer relationship with DIR1 orthologs from monocots than from eudicots. TaDIR1-2 was localized in the cytoplasm and the cell membrane of wheat mesophyll protoplast. Transcription of TaDIR1-2 was detected in wheat roots, stems and leaves. TaDIR1-2 transcript was significantly induced during the compatible interaction of wheat with the stripe rust pathogen, Puccinia striiformis f. sp. tritici (Pst). Treatments with salicylic acid (SA) and low temperature significantly up-regulated the expression of TaDIR1-2. Transient overexpression of TaDIR1-2 did not induce cell death or suppress Bax-induced cell death in tobacco leaves. Knocking down the expression of TaDIR1-2 through virus-induced gene silencing increased wheat resistance to Pst accompanied by HR, increased accumulation of H2O2 and SA, increased expression of TaPR1, TaPR2, TaPAL, and TaNOX, and decreased expression of two reactive oxygen species (ROS) scavenging genes TaCAT and TaSOD. Our results suggest that TaDIR1-2 acts as a negative regulator in wheat resistance to Pst by modulating ROS and/or SA-induced signaling.

ABA-Induced Sugar Transporter TaSTP6 Promotes Wheat Susceptibility to Stripe Rust

“…For plasma membrane staining by FM4-64 (Thermo Fisher Scientific;Fischer-Parton et al, 2000), leaves were immersed in a phosphate-buffered saline of 5 mM of FM4-64. Wheat leaf protoplast isolation and the transient expression of pTF486-TaSTP6 constructs were performed as described by Ahmed et al (2017). Fluorescence signals were monitored 2 d later or 18-h post transformations using an FV1000 Confocal Laser Microscope (Olympus).…”

Silencing of copine genes confers common wheat enhanced resistance to powdery mildew

“…Virus-induced gene silencing (VIGS) is a useful strategy for the study of gene function in cereals. It uses a Barley stripe mosaic virus (BSMV)-based silencing system in monocot plants (Bennypaul et al, 2012;Holzberg et al, 2002), and has been successfully utilized in wheat gene function studies (Ahmed et al, 2017;Kage et al, 2017;Liu et al, 2016).…”

TaSTP13 contributes to wheat susceptibility to stripe rust possibly by increasing cytoplasmic hexose concentration

“…Leaves were immersed in PBS consisting of 5 μM FM4-64 N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino) phenyl) hexatrienyl pyridinium dibromide (Invitrogen, USA) for 10 min before visualization of the plasma membrane via staining. Wheat leaf protoplast isolation and transient expression of pTF486-TaSTP13 constructs were performed as described previouly [37]. GFP fluorescence was monitored by an Olympus FV1000 confocal laser microscope (Olympus, Tokyo, Japan) with an excitation laser at 488 nm after transformations at 18 h (protoplasts) and 2 days (leaves).…”