Search

Anthocyanin is a vital indicator for both fruit nutritional and commercial value. Anthocyanin accumulation is a surprisingly complicated process mediated by multiple networks associated with genetic, developmental, hormonal, and environmental factors. Transcriptional regulation along with epigenetic regulation constitutes the dominant molecular framework for anthocyanin biosynthesis. Here, we focus on current knowledge on regulatory mechanisms of anthocyanin accumulation, with emphasis on the latest progress in transcriptional and epigenetic regulation and the crosstalk between various signaling pathways. We present an emerging picture of how various internal and external stimuli control anthocyanin biosynthesis. Additionally, we discuss the synergistic or antagonistic effect of developmental, hormonal and environmental cues on anthocyanin accumulation in fruit.

The ATP-binding cassette (ABC) transporter family is a large and diverse protein superfamily that plays various roles in plant growth and development. Although the ABC transporters are known to aid in the transport of a wide range of substrates across biological membranes, their role in anthocyanin transport remains elusive. In this study, we identified a total of 132 putative ABC genes in the peach genome, and they were phylogenetically classified into eight subfamilies. Variations in spatial and temporal gene expression levels resulted in differential expression patterns of PpABC family members in various tissues of peach. PpABCC1 was identified as the most likely candidate gene essential for anthocyanin accumulation in peach. Transient overexpression of PpABCC1 caused a significant increase in anthocyanin accumulation in tobacco leaves and peach fruit, whereas virus-induced gene silencing of PpABCC1 in the blood-fleshed peach resulted in a significant decrease in anthocyanin accumulation. The PpABCC1 promoter contained an MYB binding cis-element, and it could be activated by anthocyanin-activator PpMYB10.1 based on yeast one-hybrid and dual luciferase assays. Thus, it seems that PpABCC1 plays a crucial role in anthocyanin accumulation in peach. Our results provide a new insight into the vacuolar transport of anthocyanins in peach.

Peach Prunus persica is an economically important fruit tree crop worldwide. Although the external color of fruit is an important aspect of fruit quality, the mechanisms underlying its formation remain elusive in peach. Here, we report an elongated hypocotyl 5-homolog gene PpHYH involved in the regulation of anthocyanin pigmentation in peach fruit peel. Anthocyanin accumulation in fruit peel is light-dependent in peach. PpHYH had no auto-activation activity and its transcription was induced by sunlight. PpHYH activated transcription of a cluster of three PpMYB10 genes in the present of a cofactor PpBBX4 encoding a B-BOX protein, leading to anthocyanin accumulation in the sun-exposed peel. However, the PpHYH activity was repressed by a negative regulator of PpCOP1 encoding constitutive photomorphogenesis protein 1 which accumulated in the nucleus under dark condition, resulting in failure of anthocyanin accumulation in the shaded peel. PpCOP1 was re-localized into the cytosol under light condition, in accordance with fruit peel pigmentation. Additionally, transport of anthocyanins from the cytoplasm to the vacuole was a rate-limiting step for anthocyanin accumulation in peach fruit peel. Our results reveal for the first time the HYH gene involved in the regulation of anthocyanin accumulation in fruits, and provide target genes for genetic manipulation of fruit coloration.

Although chlorogenic acid (CGA) is a polyphenol compound with dietary benefits, the mechanism underlying its accumulation in apple fruits remains elusive. In this study, CGA content was measured in mature fruits of 379 apple accessions. A wide variation in CGA content was observed in both cultivated and wild apples. The average CGA content was significantly higher in cultivated apples than that in wild apples. Chlorogenic acid is primarily synthesized via the p-coumaroyl-CoA and quinic acid route in apple. However, no homolog encoding quinate hydroxycinnamoyl transferase (HCGQT) was identified in the apple genome, suggesting absence of CGA formation via caffeoyl glucoside and quinic acid. Additionally, transcriptional levels of two structural genes, MdPAL3 and MdHQT, were significantly correlated with CGA contents, suggesting their crucial roles in determining CGA accumulation in apple fruits. Our results will be useful for future genetic dissection and improvement of CGA accumulation in apple fruits.

Bsaed on certificateless public cryptosystem and forward-secure, a forward-secure certificateless proxy blind signature scheme was proposed. This new scheme is forward-secure by updating secret key frequently. We can reduce the loss of the key exposure problem. And it also overcame the problem of certificate management in the certificate-based public key cryptosystem and the inherent key escrow problem in the identity-based public key cryptosystem.

Compared to color and texture, contour is closer to human vision. So contour-based image retrieval has been a hot topic. However, existing methods can't obtain object contour effectively, which makes contour description and matching more difficult. To address these problems, this paper uses KPAC (Kernel-based Parametric Active Contour) to obtain the object contour, and proposes a novel method called LICS (Local Important Contour Sequence) for feature description and matching. Experimental results demonstrate that this approach achieves state-of-the-art performance in image retrieval.