Determination of anthracnose (Colletotrichum fructicola) resistance mechanism using transcriptome analysis of resistant and susceptible pear (Pyrus pyrifolia).

BACKGROUND: Anthracnose, mainly caused by Colletotrichum fructicola, leads to severe losses in pear production. However, there is limited information available regarding the molecular response to anthracnose in pears. RESULTS: In this study, the anthracnose-resistant variety 'Seli' and susceptible pear cultivar 'Cuiguan' were subjected to transcriptome analysis following C. fructicola inoculation at 6 and 24 h using RNA sequencing. A total of 3186 differentially expressed genes were detected in 'Seli' and 'Cuiguan' using Illumina sequencing technology. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that the transcriptional response of pears to C. fructicola infection included responses to reactive oxygen species, phytohormone signaling, phenylpropanoid biosynthesis, and secondary metabolite biosynthetic processes. Moreover, the mitogen-activated protein kinase (MAPK) signaling pathway and phenylpropanoid biosynthesis were involved in the defense of 'Seli'. Furthermore, the gene coexpression network data showed that genes related to plant-pathogen interactions were associated with C. fructicola resistance in 'Seli' at the early stage. CONCLUSION: Our results showed that the activation of specific genes in MAPK, calcium signaling pathways and phenylpropanoid biosynthesis was highly related to C. fructicola resistance in 'Seli' and providing several potential candidate genes for breeding anthracnose-resistant pear varieties.

Two B-box proteins, PpBBX18 and PpBBX21, antagonistically regulate anthocyanin biosynthesis via competitive association with Pyrus pyrifolia ELONGATED HYPOCOTYL 5 in the peel of pear fruit.

Light is indispensable for the accumulation of anthocyanin in the peel of red pear fruit (Pyrus pyrifolia Nakai). ELONGATED HYPOCOTYL 5 (HY5) is considered to be a critical regulator for induction of anthocyanin biosynthesis, but detailed characterization of its regulatory mechanism is needed. In this study, multiple genetic and biochemical approaches were applied to identify the roles of P. pyrifolia HY5 (PpHY5) and two B-box (BBX) proteins, PpBBX18 and PpBBX21, in the transcriptional regulation of PpMYB10. The functions of the two BBX proteins were analyzed in overexpression lines using pear calli-based approaches. On its own PpHY5 was unable to activate downstream genes. The two BBX proteins, PpBBX18 and PpBBX21, physically interacted with PpHY5 and antagonistically regulated anthocyanin biosynthesis in Arabidopsis and pear. PpBBX18 formed a heterodimer with PpHY5 via two B-box domains, in which PpHY5 bound to the G-box motif of PpMYB10 and PpBBX18 provided the trans-acting activity, thus inducing transcription of PpMYB10. PpBBX21 interacted with PpHY5 and PpBBX18 and hampered formation of the PpHY5-PpBBX18 active transcription activator complex, and subsequently repressed anthocyanin biosynthesis. The present results demonstrate the fine-tuned regulation of anthocyanin biosynthesis via transcriptional regulation of PpMYB10 by PpHY5-associated proteins and provide insights into light-induced anthocyanin biosynthesis.

Comparative effectiveness research on patients with acute ischemic stroke using Markov decision processes.

BACKGROUND: Several methodological issues with non-randomized comparative clinical studies have been raised, one of which is whether the methods used can adequately identify uncertainties that evolve dynamically with time in real-world systems. The objective of this study is to compare the effectiveness of different combinations of Traditional Chinese Medicine (TCM) treatments and combinations of TCM and Western medicine interventions in patients with acute ischemic stroke (AIS) by using Markov decision process (MDP) theory. MDP theory appears to be a promising new method for use in comparative effectiveness research. METHODS: The electronic health records (EHR) of patients with AIS hospitalized at the 2nd Affiliated Hospital of Guangzhou University of Chinese Medicine between May 2005 and July 2008 were collected. Each record was portioned into two "state-action-reward" stages divided by three time points: the first, third, and last day of hospital stay. We used the well-developed optimality technique in MDP theory with the finite horizon criterion to make the dynamic comparison of different treatment combinations. RESULTS: A total of 1504 records with a primary diagnosis of AIS were identified. Only states with more than 10 (including 10) patients' information were included, which gave 960 records to be enrolled in the MDP model. Optimal combinations were obtained for 30 types of patient condition. CONCLUSION: MDP theory makes it possible to dynamically compare the effectiveness of different combinations of treatments. However, the optimal interventions obtained by the MDP theory here require further validation in clinical practice. Further exploratory studies with MDP theory in other areas in which complex interventions are common would be worthwhile.

Characterization of sck1, a novel Castanea mollissima mutant with the extreme short catkins and decreased gibberellin.

A novel Chinese chestnut (Castanea mollissima Bl.) mutant with extreme short catkins, here was named sck1 and has been characterized in the present study. This sck1 caused 6-fold shorter than wild-type catkins. Endogenous gibberellic acids markedly decreased in the mutant, and application of exogenous GA(3) could partially restore the sck1 phenotype to the wild-type phenotype. Paclobutrazol (PP(333)), an antagonist of GAs biosynthesis, could significantly inhibit the wild-type catkins growth, and lead to a short catkins phenotype similar to the sck1. In addition, compared to the wild-type catkins, the mRNA expression level of ent-kaurenoic acid oxidase (KAO), a gibberellin biosynthesis key gene, was significantly down-regulated (P<0.01) in the sck1. Importantly, transient over-expression of a normal CmKAO gene in short catkins also could partially restore the wild-type phenotype. Real-time PCR and semi-quantitative analysis showed that the mRNA expression level of KAO was significantly up-regulated. In addition, transient RNA interference of CmKAO in wild-type catkins led the mRNA expression level of KAO decrease significantly and inhibited the wild-type catkins elongation strongly. Taken together, our results suggest that the lower gibberellic acids content that is due to decreased CmKAO expression level may contribute to the generation of the extreme short male catkins, sck1.