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Background Actinidia eriantha is a precious material to study the metabolism and regulation of ascorbic acid (AsA) because of its high AsA content. Although the pathway of AsA biosynthesis in kiwifruit has been identified, the mechanism of AsA metabolism and regulation is still unclear. The purpose of this experiment is to reveal the AsA metabolic characteristics of A. eriantha ‘Ganmi 6’ from the molecular level, and lay a theoretical foundation for the research on the genetic improvement of kiwifruit quality. Results We found that AsA reached the accumulation peak at S7 (110 DAF) during the process of fruit growth and development. The activity of GalDH, GalLDH, MDHAR and DHAR in fruit was similar to AsA accumulation trend, and both of them were significantly positively correlated with AsA content. It was speculated that GalDH and GalLDH were key enzymes in AsA biosynthesis, while MDHAR and DHAR were key enzymes in AsA regeneration cycle, which together regulated AsA accumulation in fruit. Also, we identified 98,656 unigenes with an average length of 932 bp from the transcriptome libraries using RNA-seq technology after data assembly. There were 50,184 (50.87%) unigenes annotations in four databases. Two thousand nine hundred forty-nine unigenes were enriched into the biosynthesis pathway of secondary metabolites, among which 133 unigenes involved in the AsA and aldehyde metabolism pathways, and 23 candidate genes related to AsA biosynthesis, cycling and degradation were screened out. Conclusions Considering gene expression levels and changes of physiological traits and related enzyme activity, we concluded that the accumulation of AsA depends mainly on the L-galactose pathway, and the D-galacturonic acid pathway and AsA recycling pathway as the secondary pathways, which co-maintain the high AsA content in fruit of A. eriantha.

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According to the investigation of wild Actinidia eriantha in Jiangxi province of China, we found that soluble solids content of fruit was lower than edible standard (14%). However, we found a high-sugar type A. eriantha line (code was ‘MM24’, test material) during investigative process at Nancheng county (E 116° 48′, N 26° 23′, 845 m). We sheared its scions to asexual reproduction in Fengxin County (rootstock was A. deliciosa ‘Miliang 1’ with 7 years old) and at the same time DUS (Distinctness, Uniformity and Stability) test was also carried out. There were uncontested differences between the two comparative genotypes according to the results of polyacrylamide gel electrophoresis, it can be judged as a new cultivar. In addition, there was great similarity on most important morphological and quality characteristics. While, there was difference on SSC, DM and TS between the two materials on ripen fruit, these indicators were much higher on test material than on control. The sugar degree assessment showed that the sugar degree of test material was strong and retention time was long. Further, no sucrose was found before DAF 135 d in test material and sucrose were significantly higher than in control only at DAF 165 d and DAF 175 d. The qRT-PCR results of sucrose-related genes showed that the relative expression levels of AcSPS1, AcSPS3, AcSPS5 and AcSUS5 genes were consistent with the sucrose accumulation trend, which was probably the main genes for the difference in sugar degree.

Abstract. The purpose of this study is to evaluate the potential synergic effect of BRAF V600E mutation and multifocality on central lymph nodes metastasis (CLNM) in the patients with unilateral papillary thyroid carcinoma (PTC). We enrolled 413 patients with unilateral PTCs who accepted prophylactic unilateral or bilateral central lymph node dissection (LND). Univariate and multivariate analyses were made to determine the association between related factors and CLNM. Then, all patients were divided into 4 groups based on their status of BRAF V600E mutation and multifocality. Relative excess risk of interaction (RERI), attributable proportion (AP) of interaction and synergy index (SI) were applied to evaluate the interactive effect of these two factors on CLNM. Results showed that BRAF V600E mutation and multifocality were independent risk factors for CLNM. A further study revealed that unilateral PTCs accompanying multifocality with BRAF V600E mutation had the highest incidence of CLNM compared with other subgroups. Besides, RERI was 4.323 (95% CI = 1.276-7.369), AP was 0.523 (95% CI = 0.364-0.682) and SI was 2.469 (95% CI = 1.607 to 3.794), indicating a significant additive interaction of BRAF V600E mutation and multifocality on CLNM. The present study has confirmed that BRAF V600E mutation and multifocality are risk factors for CLNM in unilateral PTC. Additionally, unilateral PTC patients accompanying multifocality with BRAF V600E mutation may have an increased risk of CLNM in clinically negative CLNM.