The Arabidopsis R2R3 MYB Transcription Factor MYB15 Is a Key Regulator of Lignin Biosynthesis in Effector-Triggered Immunity
FRONTIERS IN PLANT SCIENCE
Authors: Kim, Seu Ha; Lam, Pui Ying; Lee, Myoung-Hoon; Jeon, Hwi Seong; Tobimatsu, Yuki; Park, Ohkmae K.
Abstract
Lignin, a major component of the secondary cell wall, is important for plant growth and development. Moreover, lignin plays a pivotal role in plant innate immunity. Lignin is readily deposited upon pathogen infection and functions as a physical barrier that limits the spread of pathogens. In this study, we show that an Arabidopsis MYB transcription factor MYB15 is required for the activation of lignin biosynthesis genes such asPAL,C4H,4CL,HCT,C3 ' H,COMT, andCAD, and consequently lignin formation during effector-triggered immune responses. Upon challenge with the avirulent bacterial pathogenPstDC3000 (AvrRpm1), lignin deposition and disease resistance were reduced inmyb15mutant plants. Furthermore, whereas invading pathogens, together with hypersensitive cell death, were restricted to the infection site in wild-type leaves, they spread beyond the infected area inmyb15mutants. The exogenous supply of the lignin monomer coniferyl alcohol restored lignin production and rescued immune defects inmyb15plants. These results demonstrate that regulation at the transcriptional level is key to pathogen-induced lignification and that MYB15 plays a central role in this process.
Association between the presence of distolingual root in mandibular first molars and the presence of C-shaped mandibular second molars: a CBCT study in a Taiwanese population
QUINTESSENCE INTERNATIONAL
Authors: Wu, Yu-Chiao; Su, Wen-Song; Mau, Lian-Ping; Cheng, Wan-Chien; Weng, Pei-Wei; Tsai, Yi-Wen Cathy; Su, Chi-Chun; Chiang, Ho-Sheng; Lin, Jarshen; Shieh, Yi-Shing; Huang, Ren-Yeong
Abstract
Objectives:The purpose of this study was to assess the prevalence of C-shaped canals in permanent mandibular second molars (SMs) and to determine whether its appearance was associated with the presence of distolingual root (DLR) in permanent mandibular first molars (FMs). Method and materials: Three hundred and eighty patients were qualified for evaluation of their FMs and SMs using cone beam computed tomography.The prevalence, distribution pattern, external root morphology, and the internal root canal anatomy of the examined molars were recorded and analyzed. Furthermore, the association between the root canal configurations of SMs and the appearance of DLR in FMs was also assessed. Results: The prevalence of SMs with C-shaped root canals was 44.7%. The most common root canal configuration type of the one-rooted SMs with C-shaped anatomy was C3 (45.6%), followed by C2 and C1.The frequency of C-shaped canals in SMs was 45.4%in Non-DLR group, 52.6% in unilateral DLR group, and 33.9% in bilateral DLR group, respectively. Moreover, the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was significantly lowered. Conclusion:The association between the presence of DLR in FMs and C-shaped canal configurations in neighboring SMs was surveyed, and the prevalence of C-shaped root canals in SMs with the presence of bilateral DLRs in FMs was found to be significantly lowered.