The color of fruit skin is an important quality parameter, and in many plants, it is the result of coordinative regulation of the anthocyanin pathway. To characterize the mechanism involved in fruit peel coloration of Yunnan red pear (Pyrus pyrifolia), we constructed a subtractive cDNA library using the suppression subtractive hybridization (SSH) technology. cDNA of red peel exposed to sunlight (for 2, 4, 6, and 8 days) was subtracted from that of white skin unexposed to sunlight. Over 100 differentially expressed ESTs were obtained, putatively involved in primary and secondary metabolism, stress, and defense response. Expression analysis using semiquantitative reverse transcription polymerase chain reaction (RT-PCR) for 13 genes was performed with two pear cultivars, lightskinned 'Zaobaimi' and red-skinned 'Yunhong-1', which had been bagged and then exposed to sunlight for 0, 1, 2, 3, 5, and 7 days before harvest. This analysis showed that genes encoding for a metallothionein-like protein and a NADP-malic acid enzyme were constitutively expressed, whereas other selected genes were either down-or upregulated. Semiquantitative RT-PCR analysis for 7 anthocyanin biosynthetic pathway genes and 3 putative regulatory genes was also performed. Results showed that an R2R3 MYB transcription factor PyMYB10 was up-regulated in both the less-colored pear 'Zaobaimi' and well-colored red pear Yunhong-1 after the bag was removed, but that kinetics differed between cultivars. Other anthocyanin-related genes appeared to be coordinately regulated by the MYB-bHLH-WD40 complex. DFR and ANS genes seemed to be limiting factors for the peel coloration of less-colored pear 'Zaobaimi', while all biosynthetic steps are up-regulated by 7 days after bag removal in red fruit. This study suggests the regulation of red pear coloring is via differential effects of the MYB-bHLH-WD40 complex on the pear anthocyanin pathway genes.

Cardiovascular diseases (CVDs) are a major cause of health loss in the world. Prevention and treatment of this disease by traditional Chinese medicine is a promising method. Centranthera grandiflora Benth is a high-value medicinal herb in the prevention and treatment of CVDs; its main medicinal components include iridoid glycosides, phenylethanoid glycosides, and azafrin in roots. However, biosynthetic pathways of these components and their regulatory mechanisms are unknown. Furthermore, there are no genomic resources of this herb. In this article, we provide sequence and transcript abundance data for the root, stem, and leaf transcriptome of C. grandiflora Benth obtained by the Illumina Hiseq2000. More than 438 million clean reads were obtained from root, stem, and leaf libraries, which produced 153,198 unigenes. Based on databases annotation, a total of 557, 213, and 161 unigenes were annotated to catalpol, acteoside, and azafrin biosynthetic pathways, respectively. Differentially expressed gene analysis identified 14,875 unigenes differentially enriched between leaf and root with 8,054 upregulated genes and 6,821 downregulated genes. Candidate MYB transcription factors involved in catalpol, acteoside, and azafrin biosynthesis were also predicated. This work is the first transcriptome analysis in C. grandiflora Benth which will aid the deciphering of biosynthesis pathways and regulatory mechanisms of active components.

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Gentiana rigescens is an important medicinal herb in China. The main validated medicinal component gentiopicroside is synthesized in shoots, but is mainly found in the plant’s roots. The gentiopicroside biosynthetic pathway and its regulatory control remain to be elucidated. Genome resources of gentian are limited. Next-generation sequencing (NGS) technologies can aid in supplying global gene expression profiles. In this study we present sequence and transcript abundance data for the root and leaf transcriptome of G. rigescens, obtained using the Illumina Hiseq2000. Over fifty million clean reads were obtained from leaf and root libraries. This yields 76,717 unigenes with an average length of 753 bp. Among these, 33,855 unigenes were identified as putative homologs of annotated sequences in public protein and nucleotide databases. Digital abundance analysis identified 3306 unigenes differentially enriched between leaf and root. Unigenes found in both tissues were categorized according to their putative functional categories. Of the differentially expressed genes, over 130 were annotated as related to terpenoid biosynthesis. This work is the first study of global transcriptome analyses in gentian. These sequences and putative functional data comprise a resource for future investigation of terpenoid biosynthesis in Gentianaceae species and annotation of the gentiopicroside biosynthetic pathway and its regulatory mechanisms.

SUMMARYMedicago sativa is an excellent pasture legume, but it is very sensitive to aluminium (Al) toxicity. To better understand the mechanism of M. sativa sensitivity to Al, a forward suppression subtractive hybridization (SSH) cDNA library for an Al-sensitive cultivar, M. sativa L. cv. Yumu No. 1 (YM1), under 5 μm Al stress over a 24 h period was constructed to analyse changes in its gene expression in response to Al stress. Sequence analysis for the SSH cDNA library generated 291 high-quantity expression sequence tags (ESTs). Of these, 229 were known as functional ESTs, 137 of which have already been reported as Al response genes, whereas the other 92 were potentially novel Al-associated genes. The up-regulation of known Al resistance-associated genes encoding the transcription factor sensitive to proton rhizotoxicity 1 (STOP1) and malate transporter MsALMT1 (Al-activated malate transporter) as well as genes for antioxidant enzymes was observed. Reverse transcription polymerase chain reaction analysis validated the reliability of the SSH data and confirmed the up-regulated expression of STOP1 and MsALMT1 under 5 μm Al stress. The analysis of physiological changes indicated that hydrogen peroxide (H2O2) and malondialdehyde levels were elevated rapidly under 5 μm Al stress, suggesting that severe oxidative stress occurred in the YM1 roots. The up-regulation of antioxidant-related genes might be an important protective mechanism for YM1 in response to the oxidative stress induced by 5 μm Al toxicity. Al-induced malate exudation was increased drastically during the early period after Al treatment, which might have been due to the up-regulation and function of MsALMT and STOP1. However, malate exudation from the YM1 roots declined quickly during the subsequent period, and a gradual decrease in malate content was simultaneously observed in the YM1 roots. This result is in agreement with the observation that organic acid metabolism-associated enzymes such as phosphoenolpyruvate carboxylase, citrate synthase and malate dehydrogenase were not present in the SSH library. This might be a major reason for the YM1 sensitivity to Al.

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Pectinases are a group of enzymes with broad application, including in plant fiber processing, pectic wastewater treatment, paper pulping, fruit juice extraction, and clarification. With an increasing industrial demand for these enzymes, it is useful to isolate organisms that produce large amounts of pectinase and possess wide ranges of stability factors like temperature and pH. In this study, 17 out of 29 bacteria (58.62%) from forest soil samples were pectinolytic. However, only four bacteria (S-5, S-10, S-14, and S-17) showed high pectin hydrolysis zones (ranging from 0.2 cm to 1.7 cm). These four bacteria were identified based on colony morphology, microscopic characterization, biochemical characteristics, and 16S rDNA sequencing. They were designated as Streptomyces sp. (S-5, S-14), Cellulomonas sp. (S-10), and Bacillus sp. (S-17). Interestingly, bacteria showed cellulase and xylanase activity in addition to pectinase. The quantitative assay for pectinase activity of the four isolates provided proof that they are pectinase producers and can be considered potential candidates for industrial uses. The crude enzyme extracts of these bacteria are applicable in oil and juice extraction from sesame seeds and apples, respectively.

Zhang X.D., Allan. A.C., Chen X.Q., Fan L., Chen L.M., Shu Q., Su J., Li K.Z., 2012. Coloration, anthocyanin profile and metal element content of Yunnan Red Pear (Pyrus pyrifolia). Hort. Sci. (Prague), 39: 164-171.The pigmentation response, coloration components and the metal elemental content of Yunnan Red Pear were studied. Light is indispensable for peel pigmentation. With increasing duration of illumination of fruit, the area of skin colour and colour intensity of peel increases due to accumulation of anthocyanin. The red anthocyanin component of Yunnan Red Pear skin is cyanidin-3-O-galactoside. Other phenolic compounds in pear skin are chlorogenic acid, isorhamnetin-3-Ogalactoside and isorhamnetin-3-O-6"-malonylgalactoside; or isorhamnetin-3-O-6"-malonylglucoside; or isorhamnetin-3-O-malonylgalactoside. The elements Ca, Mg and Fe are abundant in Yunnan Red Pear flesh, and Zn, Mn, Cu were also identified. These results will aid red pear breeding and pear nutrition research, as well as increase understanding of the regulatory mechanisms underlying pear fruit colouration.