Abstract
Phytophthora sojae Kaufmann and Gerdemann causes Phytophthora root rot, a destructive soybean disease worldwide. A basic helix-loop-helix (bHLH) transcription factor is thought to be involved in the response to P. sojae infection in soybean, as revealed by RNA sequencing (RNA-seq). However, the molecular mechanism underlying this response is currently unclear. Here, we explored the function and underlying mechanisms of a bHLH transcription factor in soybean, designated GmPIB1 (P. sojae-inducible bHLH transcription factor), during host responses to P. sojae. GmPIB1 was significantly induced by P. sojae in the resistant soybean cultivar 'L77-1863'. Analysis of transgenic soybean hairy roots with elevated or reduced expression of GmPIB1 demonstrated that GmPIB1 enhances resistance to P. sojae and reduces reactive oxygen species (ROS) accumulation. Quantitative reverse transcription PCR and chromatin immunoprecipitation-quantitative PCR assays revealed that GmPIB1 binds directly to the promoter of GmSPOD1 and represses its expression; this gene encodes a key enzyme in ROS production. Moreover, transgenic soybean hairy roots with GmSPOD1 silencing through RNA interference exhibited improved resistance to P. sojae and reduced ROS generation. These findings suggest that GmPIB1 enhances resistance to P. sojae by repressing the expression of GmSPOD1.
Highlights
Phytophthora root and stem rot caused by Phytophthora sojae is one of the most destructive soybean diseases worldwide, resulting in annual losses of $1–2 billion globally (Tyler, 2007)
The predicted three-dimensional model of GmPIB1 consists of two α-helices (Supplementary Fig. S1C).To further explore the evolutionary relationship among plant basic helix–loop–helix (bHLH) proteins, we constructed a phylogenetic tree using MEGA4.0 (Tamura et al, 2007) based on amino acid sequences
~35% of inoculated empty vector (EV) transgenic hairy roots of resistant cultivar ‘L77-1863’ and ~95% of inoculated GmPIB1-RNA interference (RNAi) transgenic hairy roots were completely dead at 5 d of inoculation with P. sojae (Fig. 1I)
Summary
Phytophthora root and stem rot caused by Phytophthora sojae is one of the most destructive soybean diseases worldwide, resulting in annual losses of $1–2 billion globally (Tyler, 2007). Several TF families play important roles in plant stress tolerance, such as basic helix–loop–helix (bHLH), DREB, ERF, WRKY, MYB, bZIP, and NAC TFs (Tran et al, 2004; Hu et al, 2006; Kim and Kim, 2006; Liao et al, 2008a,b; Zhou et al, 2008; Seo et al, 2010; Hao et al, 2011; Niu et al, 2012; Liu et al, 2014; Dong et al, 2015) These TFs separately or cooperatively affect the expression of various downstream genes and constitute gene networks for stress adaptation (Wang et al, 2015a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
