Red fruits are popular and widely accepted by consumers because of an enhanced appearance and enriched anthocyanins. The molecular mechanism of anthocyanin regulation in red-skinned pear (Pyrus) has been studied, and the genes encoding the biosynthetic steps and several transcription factors (TFs) have been characterized. In this study, a candidate R2R3 MYB TF, PyMYB114, was identified by linkage to the quantitative trait loci (QTL) for red skin color on linkage group 5 in a population of Chinese pear (Pyrus bretschneideri). The function of PyMYB114 was verified by transient transformation in tobacco (Nicotinana tabacum) leaves and strawberry (Fragaria) and pear fruits, resulting in the biosynthesis of anthocyanin. Suppression of PyMYB114 could inhibit anthocyanin biosynthesis in red-skinned pears. The ERF/AP2 TF PyERF3 was found to interact with PyMYB114 and its partner PybHLH3 to co-regulate anthocyanin biosynthesis, as shown by a dual luciferase reporter system and a yeast two-hybrid assay. In addition, the transcript abundance of PyMYB114 and PyMYB10 were correlated, and co-transformation of these two genes into tobacco and strawberry led to enhanced anthocyanin biosynthesis. This interaction network provides insight into the coloration of fruits and the interaction of different TFs to regulate anthocyanin biosynthesis.

Accumulating evidence shows that hydrogen sulfide (H(2)S) plays various physiological roles in plants, such as seed germination, root organogenesis, abiotic stress tolerance, and senescence of cut flowers. However, whether H(2)S participates in the regulation of ripening and senescence in postharvest fruits remains unknown. In the present study, the effect of H(2)S on postharvest shelf life and antioxidant metabolism in strawberry fruits was investigated. Fumigation with H(2)S gas released from the H(2)S donor NaHS prolonged postharvest shelf life of strawberry fruits in a dose-dependent manner. Strawberry fruits fumigated with various concentrations of H(2)S sustained significantly lower rot index, higher fruit firmness, and kept lower respiration intensity and polygalacturonase activities than controls. Further investigation showed that H(2)S treatment maintained higher activities of catalase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase and lower activities of lipoxygenase relative to untreated controls. H(2)S also reduced malondialdehyde, hydrogen peroxide, and superoxide anion to levels below control fruits during storage. Moreover, H(2)S treatment maintained higher contents of reducing sugars, soluble proteins, free amino acid, and endogenous H(2)S in fruits. We interpret these data as indicating that H(2)S plays an antioxidative role in prolonging postharvest shelf life of strawberry fruits.

Multiple chromatographically separable complexes containing the TATA binding protein (TBP), which exhibit different functional properties, exist in HeLa cells. At least three distinct subpopulations of such complexes can be functionally defined as TFIID since they function with RNA polymerase II. Using a partially reconstituted HeLa cell in vitro transcription system and immunoprecipitation with a monoclonal antibody directed against TBP, we show that stimulation of transcription by the chimeric activators GAL‐VP16, GAL‐TEF‐1 and GAL‐ER(EF) requires the presence of factors which are tightly associated with these TFIID complexes. Moreover, the activity of GAL‐TEF‐1 appears to be mediated by at least two chromatographically distinct populations of TFIID. The factor(s) associated with one of these populations is also required for the activity of GAL‐ER (EF) and GAL‐VP16, while the factor(s) associated with the other population functions selectively with GAL‐TEF‐1. These two TFIID populations are composed of both common and unique TBP associated factors (TAFs).

The action of the chimeric acidic transcriptional activator GAL‐VP16 has been investigated by performing a series of kinetic experiments using the detergent Sarkosyl as well as monoclonal antibodies which specifically inhibit GAL‐VP16 DNA binding and transcriptional activation. GAL‐VP16 binds to recognition site rapidly, remains bound after transcriptional initiation and is required to maintain stimulated levels of reinitiation. GAL‐VP16 action, which appears to result in an increase in the number of preinitiation complexes formed, occurs after the formation of template‐committed complexes composed of promoter‐bound TFIIA (STF) and a partially purified TFIID fraction conferring GAL‐VP16 responsiveness on a reconstituted basal transcription system. This TFIID fraction cannot be replaced by TFIIB or cloned TFIID. Our results suggest that GAL‐VP16 activates step(s) in preinitiation complex assembly occurring after TFIID has bound.