Comprehensive Genomic Survey, Structural Classification, and Expression Analysis of WRKY Transcription Factor  Family in Rhododendron simsii

(1) Rhododendron is one of the top ten traditional flowers in China, with both high ornamental and economic values. However, with the change of the environment, Rhododendron suffers from various biological stresses. The WRKY transcription factor is a member of the most crucial transcription factor families, which plays an essential regulatory role in a variety of physiological processes and developmental stresses. (2) In this study, 57 RsWRKYs were identified using genome data and found to be randomly distributed on 13 chromosomes. Based on gene structure and phylogenetic relationships, 57 proteins were divided into three groups: I, II, and III. Multiple alignments of RsWRKYs with Arabidopsis thaliana homologous genes revealed that WRKY domains in different groups had different conserved sites. RsWRKYs have a highly conserved domain, WRKYGQK, with three variants, WRKYGKK, WRKYGEK, and WRKYGRK. Furthermore, cis-acting elements analysis revealed that all of the RsWRKYs had stress and plant hormone cis-elements, with figures varying by group. Finally, the expression patterns of nine WRKY genes treated with gibberellin acid (GA), methyl jasmonate (MeJA), heat, and drought in Rhododendron were also measured using quantitative real-time PCR (qRT-PCR). The results showed that the expression levels of the majority of RsWRKY genes changed in response to multiple phytohormones and abiotic stressors. (3) This current study establishes a theoretical basis for future studies on the response of RsWRKY transcription factors to various hormone and abiotic stresses as well as a significant foundation for the breeding of new stress-tolerant Rhododendron varieties

Genome-Wide Identification of Petunia <i>HSF</i> Genes and Potential Function of <i>PhHSF19</i> in Benzenoid/Phenylpropanoid Biosynthesis

Volatile benzenoids/phenylpropanoids are the main flower scent compounds in petunia (Petunia hybrida). Heat shock factors (HSFs), well known as the main regulator of heat stress response, have been found to be involved in the biosynthesis of benzenoid/phenylpropanoid and other secondary metabolites. In order to figure out the potential function of HSFs in the regulation of floral scent in petunia, we systematically identified the genome-wide petunia HSF genes and analyzed their expression and then the interaction between the key petunia HSF gene with target gene involved in benzenoid/phenylpropanoid biosynthesis. The results revealed that 34 HSF gene family members were obtained in petunia, and most petunia HSFs contained one intron. The phylogenetic analysis showed that 23 petunia HSFs were grouped into the largest subfamily HSFA, while only two petunia HSFs were in HSFC subfamily. The DBD domain and NLS motif were well conserved in most petunia HSFs. Most petunia HSF genes’ promoters contained STRE motifs, the highest number of cis-acting element. PhHSF19 is highly expressed in petal tubes, followed by peduncles and petal limbs. During flower development, the expression level of PhHSF19 was dramatically higher at earlier flower opening stages than that at the bud stage, suggesting that PhHSF19 may have potential roles in regulating benzenoid/phenylpropanoid biosynthesis. The expression pattern of PhHSF19 is positively related with PhPAL2, which catalyzes the first committed step in the phenylpropanoid pathway. In addition, there are three STRE elements in the promoter of PhPAL2. PhHSF19 was proven to positively regulate the expression of PhPAL2 according to the yeast one hybrid and dual luciferase assays. These results lay a theoretical foundation for further studies of the regulation of HSFs on plant flower scent biosynthesis

Chemical and size characterization of particles emitted from the burning of coal and wood in rural households in Guizhou, China

International audienceField measurements were conducted to determine indoor air particulate pollutant emissions from the burning of coal and wood, two major household fuels, in rural households in Guizhou, China. Chemical composition, particle mass and particle size distribution as well as number concentration were measured in this study. Chemical composition analysis indicates that the carbonaceous particle is dominant in the PM2.5 mass, accounting for about 41% for wood and 55% for coal. The OC/EC ratio was 10.8 for wood and 7.6 for coal. Most of the water-soluble ions were found in the 0.4–2.1 μm size fractions and dominated by ammonium and sulfate. Particle mass concentrations inversely correlate with particle total number concentrations during the sampling period. Obvious differences were observed in the evolution of particle number concentrations and size distributions between coal combustion and wood burning. Particles emitted from coal combustion were characterized by unimodal size distribution, with average peak values ranging from 70.3 to 75.7 nm during the flaming stage of the burning cycle. Particles from wood burning were characterized by a transition from a bimodal size distribution to a unimodal distribution during the same period. Average peak values in the bimodal mode were 10–20 nm (nucleation mode) and 40–50 nm (Aitken mode), whereas the average peak value in the unimodal mode was about 63 nm