Molecular structures of the stem tuber anthocyanins of colored potatoes and their coloring effects on the tubers.

This paper summarized the important achievements about the general characteristics of the molecular structures of the stem tuber anthocyanins of Colored potatoes and the basic coloring effects of the anthocyanins on the tubers. The various coloration patterns of the skins and/or flesh of Colored potato tubers result from the accumulation of the anthocyanins in the periderms, phelloderms and/or peripheral cortices of the tubers, and the tuber colors are fundamentally determined by the matching profiles of the six naturally occurring anthocyanidins, i.e., cyanidin, delphinidin, malvidin, pelargonidin, peonidin and petunidin. Generally, the tuber anthocyanidins hold an O-glycosidic bond-linked rutinosyl at the C3 site, and either a glucosyl linked by an O-glycosidic bond or no substituent group may exist at the C5 site simultaneously. Furthermore, an E-monoacyl frequently exists at the C3-rutinosyls or at the C5-glucosyls of most tuber anthocyanins, and the phenolic acids acylating the tuber anthocyanins are often p-coumaric, ferulic and caffeic acids. The popular names of the p- coumaric acid derivatives of the malvidin, pelargonidin, peonidin and petunidin of the tubers are Malvanin, Pelanin, Peonanin and Petanin, respectively. This review provides a reference for the exploration of the mechanism of the tuber coloration and the identification of the molecular structures of the stem tuber anthocyanins of Colored potatoes.

Genome-wide gene responses in a transgenic rice line carrying the maize resistance gene Rxo1 to the rice bacterial streak pathogen, Xanthomonas oryzae pv. oryzicola.

BACKGROUND: Non-host resistance in rice to its bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), mediated by a maize NBS-LRR type R gene, Rxo1 shows a typical hypersensitive reaction (HR) phenotype, but the molecular mechanism(s) underlying this type of non-host resistance remain largely unknown. RESULTS: A microarray experiment was performed to reveal the molecular mechanisms underlying HR of rice to Xoc mediated by Rxo1 using a pair of transgenic and non-transgenic rice lines. Our results indicated that Rxo1 appeared to function in the very early step of the interaction between rice and Xoc, and could specifically activate large numbers of genes involved in signaling pathways leading to HR and some basal defensive pathways such as SA and ET pathways. In the former case, Rxo1 appeared to differ from the typical host R genes in that it could lead to HR without activating NDR1. In the latter cases, Rxo1 was able to induce a unique group of WRKY TF genes and a large set of genes encoding PPR and RRM proteins that share the same G-box in their promoter regions with possible functions in post-transcriptional regulation. CONCLUSIONS: In conclusion, Rxo1, like most host R genes, was able to trigger HR against Xoc in the heterologous rice plants by activating multiple defensive pathways related to HR, providing useful information on the evolution of plant resistance genes. Maize non-host resistance gene Rxo1 could trigger the pathogen-specific HR in heterologous rice, and ultimately leading to a localized programmed cell death which exhibits the characteristics consistent with those mediated by host resistance genes, but a number of genes encoding pentatricopeptide repeat and RNA recognition motif protein were found specifically up-regulated in the Rxo1 mediated disease resistance. These results add to our understanding the evolution of plant resistance genes.

[Analysis of signal peptides of the secreted proteins in Agrobacterium tumefaciens C58].

The 4554 ORFs of Agrobacterium tumefaciens C58 Cereon were used for the prediction of signal peptides by the network tools, such as SignalP3.0, LipoP1.0, TMHMM2.0 and TargetP1.01. Total 203 signal peptides with conserved amino residues are found, among them, 158 are secretary types, 9 are RR-motif types, 28 are SignalPase II types and 8 are bacteriocin-pheromone types. However, only two signal peptides from the secreted proteins, AGR-C-1878p and AGR-C-1880p have the same amino sequences, showing the signal peptides of the strain are highly variable.