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RNA editing, a vital supplement to the central dogma, yields genetic information on RNA products that are different from their DNA templates. The conversion of C-to-U in mitochondria and plastids is the main kind of RNA editing in plants. Various factors have been demonstrated to be involved in RNA editing. In this minireview, we summarized the factors and mechanisms involved in RNA editing in plant organelles. Recently, the rapid development of deep sequencing has revealed many RNA editing events in plant organelles, and we further reviewed these events identified through deep sequencing data. Numerous studies have shown that RNA editing plays essential roles in diverse processes, such as the biogenesis of chloroplasts and mitochondria, seed development, and stress and hormone responses. Finally, we discussed the functions of RNA editing in plant organelles.

Transcriptomic analysis of the relationship between gene expression patterns and flavonoid contents in the flower buds of Lonicera japonica under light-induced conditions, especially the flavonoid pathway genes and transcription factors. Flos Lonicerae Japonicae (FLJ), the flower buds of Lonicera japonica Thunb., has been used to treat some human diseases including severe respiratory syndromes and hand-foot-and-mouth diseases owing to its putative antibacterial, and antiviral effects. Luteoloside is a flavonoid that is used by the Chinese Pharmacopoeia to evaluate the quality of FLJ. Light is an important environmental factor that affects flavonoid biosynthesis in the flower buds of L. japonica. However, how light triggers increases in flavonoid production remains unclear. To enhance our understanding of the mechanism involved in light-regulated flavonoid biosynthesis, we sequenced the transcriptomes of L. japonica exposed to three different light conditions: 100% light intensity (CK), 50% light intensity (LI50), and 25% light intensity (LI25) using an Illumina HiSeq 4000 System. A total of 77,297 unigenes with an average length of 809 bp were obtained. Among them, 43,334 unigenes (56.06%) could be matched to at least one biomolecular database. Additionally, 4188, 1545 and 1023 differentially expressed genes (DEGs) were identified by comparative transcriptomics LI25-vs-CK, LI50-vs-CK, and LI25-vs-LI50, respectively. Of note, genes known to be involved in flavonoid biosynthesis, such as 4-coumarate coenzyme A ligase (4CL), and chalcone synthase (CHS) were up-regulated. In addition, a total of 1649 transcription factors (TFs) were identified and divided into 58 TF families; 98 TFs exhibited highly dynamic changes in response to light intensity. Quantitative real-time PCR (qRT-PCR) was used to test the expression profiles of the RNA sequencing (RNA-Seq) data. This study offers insight into how transcriptional expression pattern is influenced by light in the flower buds of L. japonica, and will enhance the understanding of molecular mechanisms of flavonoid biosynthesis in response to light in L. japonica.

Soil salinity severely limits agricultural crop production worldwide. As one of the biggest plant specific transcription factor families, AP2/ERF members have been extensively studied to regulate plant growth, development and stress responses. However, the role of AP2/ERF family in maize salt tolerance remains largely unknown. In this study, we identified a maize AP2-ERF family member ZmEREB20 as a positive salinity responsive gene. Overexpression of ZmEREB20in Arabidopsis enhanced ABA sensitivity and resulted in delayed seed germination under salt stress through regulating ABA and GA related genes. ZmEREB20 overexpression lines also showed higher survival rates with elevated ROS scavenging toward high salinity. Furthermore, root hair growth inhibition by salt stress was markedly rescued in ZmEREB20 overexpression lines. Auxin transport inhibitor TIBA drastically enhanced root hair growth in ZmEREB20 overexpression Arabidopsis under salt stress, together with the increased expression of auxin-related genes, ion transporter genes and root hair growth genes by RNA-seq analysis. ZmEREB20 positively regulated salt tolerance through the molecular mechanism associated with hormone signaling, ROS scavenging and root hair plasticity, proving the potential target for crop breeding to improve salt resistance.

Plants are adapted to sense numerous stress stimuli and mount efficient defense responses by directing intricate signaling pathways. They respond to undesirable circumstances to produce stress-inducible phytochemicals that play indispensable roles in plant immunity. Extensive studies have been made to elucidate the underpinnings of defensive molecular mechanisms in various plant species. Transcriptional factors (TFs) are involved in plant defense regulations through acting as mediators by perceiving stress signals and directing downstream defense gene expression. The cross interactions of TFs and stress signaling crosstalk are decisive in determining accumulation of defense metabolites. Here, we collected the major TFs that are efficient in stress responses through regulating secondary metabolism for the direct cessation of stress factors. We focused on six major TF families including AP2/ERF, WRKY, bHLH, bZIP, MYB, and NAC. This review is the compilation of studies where researches were conducted to explore the roles of TFs in stress responses and the contribution of secondary metabolites in combating stress influences. Modulation of these TFs at transcriptional and post-transcriptional levels can facilitate molecular breeding and genetic improvement of crop plants regarding stress sensitivity and response through production of defensive compounds.

Light and gravity are two key determinants in orientating plant stems for proper growth and development. The organization and dynamics of the actin cytoskeleton are essential for cell biology and critically regulated by actin-binding proteins. However, the role of actin cytoskeleton in shoot negative gravitropism remains controversial. In this work, we report that the actin-binding protein Rice Morphology Determinant (RMD) promotes reorganization of the actin cytoskeleton in rice (Oryza sativa) shoots. The changes in actin organization are associated with the ability of the rice shoots to respond to negative gravitropism. Here, light-grown rmd mutant shoots exhibited agravitropic phenotypes. By contrast, etiolated rmd shoots displayed normal negative shoot gravitropism. Furthermore, we show that RMD maintains an actin configuration that promotes statolith mobility in gravisensing endodermal cells, and for proper auxin distribution in light-grown, but not dark-grown, shoots. RMD gene expression is diurnally controlled and directly repressed by the phytochrome-interacting factor-like protein OsPIL16. Consequently, overexpression of OsPIL16 led to gravisensing and actin patterning defects that phenocopied the rmd mutant. Our findings outline a mechanism that links light signaling and gravity perception for straight shoot growth in rice.

Mentha canadensis L. has important economic value for its abundance in essential oils. Menthol is the main component of M. canadensis essential oils, which is certainly the best-known monoterpene for its simple structure and wide applications. However, the regulation of menthol biosynthesis remains elusive in M. canadensis. In this study, transcriptome sequencing of M. canadensis with MeJA treatment was applied to illustrate the transcriptional regulation of plant secondary metabolites, especially menthol biosynthesis. Six sequencing libraries were constructed including three replicates for both control check (CK) and methyl jasmonate (MeJA) treatment and at least 8 Gb clean bases was produced for each library. After assembly, a total of 81,843 unigenes were obtained with an average length of 724 bp. Functional annotation indicated that 64.55% of unigenes could be annotated in at least one database. Additionally, 4430 differentially expressed genes (DEGs) with 2383 up-regulated and 2047 down-regulated transcripts were identified under MeJA treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment indicated that &ldquo, Monoterpenoid biosynthesis&rdquo, was one of the most significantly enriched pathways in metabolism. Subsequently, DEGs involved in JA signal transduction, transcription factors, and monoterpene biosynthesis were analyzed. 9 orthologous genes involved in menthol biosynthesis were also identified. This is the first report of a transcriptome study of M. canadensis and will facilitate the studies of monoterpene biosynthesis in the genus Mentha.