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Pentatricopeptide repeat (PPR) proteins are a large family in land plants that play a role in organellular RNA processing, editing, and splicing. Here, we identify an Arabidopsis thaliana mutant, gend1-1, which exhibits a short root phenotype with reduced meristem size and cell numbers. Positional cloning of GEND1 revealed that it encodes a PPR protein, and functional analysis showed that GEND1 can bind and edit mitochondrial ccmFn-1 mRNA, causing gend1 mutants to have decreased levels of cytochrome C. GEND1 was up-regulated by high temperature conditions, to which gend1 mutants were hypersensitive. Analysis of a set of PPR mutants under high temperature showed that mutants with defects in cytochrome C had comparable temperature sensitivity to gend1. Collectively, these results suggest that cytochrome C plays an important role in root development and high temperature response in Arabidopsis.

Lamina joint inclination or leaf angle (the angle between the leaf blade and vertical culm) is a major trait of rice plant architecture. The plant hormone brassinosteroid (BR) is the main regulator of this trait, while other plant hormones, including ethylene, gibberellin, and auxin, also influence leaf angle. In this study, we found that methyl jasmonate (MeJA) also participates in regulating lamina joint inclination. MeJA decreased lamina joint inclination and inhibited the BR-induced increase in lamina joint inclination. Furthermore, addition of a BR synthesis inhibitor increased the extent of change in lamina joint inclination in response to treatment with a low concentration of MeJA (0.05 or 0.5mgL(-1)), but it did not alter the lamina joint inclination of plants treated with a high concentration of MeJA (5mgL(-1)). Further studies showed that MeJA treatment significantly repressed the expression of BR biosynthesis-related genes and decreased endogenous BRs levels. In addition, the lamina joint inclination in the OsBRI1 mutant d61-1 was less sensitive to MeJA compared with its wild type counterpart, and lithium chloride-induced inactivation of GSK3-like kinase, a negative regulator of BR signaling, partly rescued the MeJA-induced reduction in lamina joint inclination. Further studies showed that MeJA treatment reduced the mRNA levels of BR signaling and target genes. These results indicate that MeJA-inhibition of lamina joint inclination may depend on BR biosynthesis and the BR signaling pathway.

Multiple surface envelope proteins are involved in the human herpes simplex virus type 1 entry and fusion. Among them, glycoprotein D (gD) has an important role by binding to the host receptors such as herpes virus entry mediator and nectin-1. Although the complex structure of gD with herpes virus entry mediator has been established, the binding mode of gD with the nectin-1 is elusive. Nectin-1 is a member of the immunoglobulin (Ig)-like (three Ig-like domains) cell adhesion molecules and is believed to form a homodimer to exert its functions. Here we report the complex structure of gD and nectin-1 (three Ig domains), revealing that gD binds the first Ig domain of nectin-1 in a similar mode to the nectin-1 homodimer interaction. The key amino acids responsible for nectin-1 dimerization are also used for gD/nectin-1 binding. This result indicates that binding of gD to nectin-1 would preclude the nectin-1 dimerization, consequently abolishing its cell adhesion function.