Expression and promoter analysis of the OsHSP16.9C gene in rice

The role of walnut bZIP genes in explant browning

BACKGROUND

Basic leucine zipper (bZIP) proteins are important transcription factors in plants. To study the role of bZIP transcription factors in walnut explant browning, this study used bioinformatics software to analyze walnut bZIP gene family members, along with their transcript levels in different walnut tissues, to evaluate the transcriptional expression of this gene family during the primary culture of walnut explants and to reveal the mechanism of action of walnut bZIP genes in walnut explant browning.

RESULTS

The results identified 65 JrbZIP genes in the walnut genome, which were divided into 8 subfamilies and distributed on 16 chromosomes. The results of transcriptome data analysis showed that there were significant differences in the expression of four genes, namely, JrbZIP55, JrbZIP70, JrbZIP72, and JrbZIP88, under both vermiculite and agar culture conditions. There were multiple hormone (salicylic acid, abscisic acid, auxin, and gibberellin) signaling and regulatory elements that are responsive to stress (low temperature, stress, and defense) located in the promoter regions of JrbZIP55, JrbZIP70, JrbZIP72, and JrbZIP88. The walnut JrbZIP55 protein and Arabidopsis bZIP42 protein are highly homologous, and the proteins interacting with Arabidopsis bZIP42 include the AT2G19940 oxidoreductases, which act on aldehyde or oxygen-containing donors.

CONCLUSION

It is speculated that JrbZIP55 may participate in the regulation of browning in walnut explants.

Functional characterization of the Pinellia ternata cytoplasmic class II small heat shock protein gene PtsHSP17.2 via promoter analysis and overexpression in tobacco

High temperature is one of the main abiotic factors limiting agricultural production, particularly for heat-sensitive plant species. Small heat-shock proteins contribute substantially to alleviating damage to plants caused by heat stress. In the present study, the heat shock protein gene PtsHSP17.2 from Pinellia ternata was functionally characterized through promoter analysis and its overexpression in tobacco. Respectively, relative expression using real-time RT-PCR and ex situ promoter activity assay indicated that PtsHSP17.2 is strongly inducible under heat stress, and in silico promoter analysis discovered multiple stress-related cis elements including heat shock element. When overexpressing PtsHSP17.2 in tobacco, the thermotolerance of transgenic plants was markedly enhanced. Furthermore, the transgenic tobacco plants exhibited less variation in chlorophyll content, relative electrolyte leakage, and malondialdehyde content under heat stress compared with wild-type (WT) plants. The activities of antioxidant enzymes and content of proline were significantly enhanced under heat stress in transgenic plants relative to WT plants. Transgenic plants also had enhanced water retention and increased antioxidative capacity. Further, the expression levels of genes encoding antioxidant enzymes were more highly induced by heat stress in transgenic lines than WT. These results enrich the current understanding of thermal adaptation of heat-sensitive plant species and encourage further genetic improvement.

Characterization and expression profiles of small heat shock proteins in the marine red alga Pyropia yezoensis

Small heat shock proteins (sHSPs) are found in all three domains of life (Bacteria, Archaea, and Eukarya) and play a critical role in protecting organisms from a range of environmental stresses. However, little is known about their physiological functions in red algae. Therefore, we characterized the sHSPs (PysHSPs) in the red macroalga Pyropia yezoensis, which inhabits the upper intertidal zone where it experiences fluctuating stressful environmental conditions on a daily and seasonal basis, and examined their expression profiles at different developmental stages and under varying environmental conditions. We identified five PysHSPs (PysHSP18.8, 19.1, 19.2, 19.5, and 25.8). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that expression of the genes PysHSP18.8, PysHSP19.5, and PysHSP25.8 was repressed at all the developmental stages under normal conditions, whereas PysHSP19.1 and PysHSP19.2 were overexpressed in mature gametophytes and sporophytes. Exposure of the gametophytes to high temperature, oxidative stress, or copper significantly increased the mRNA transcript levels of all the five genes, while exogenous application of the ethylene precursor 1-aminocylopropane-1-carboxylic acid (ACC) significantly increased the expression levels of PysHSP19.2, PysHSP19.5, and PysHSP25.8. These findings will help to further our understanding of the role of PysHSP genes and provide clues about how Pyropia species can adapt to the stressful conditions encountered in the upper intertidal zone during their life cycle.