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Coffee is one of the most economically important agricultural commodities in the world. Labeling accuracy and conservation efficiency are essential for coffee germplasm management and for the exchange and utilization in breeding new varieties. However, due to its homogenous genetic background, accurate identification of Coffea arabica germplasm has not been fully achieved. Specifically, data comparison across different laboratories and genotyping platforms has not been available. Here, we report the screening of 672 candidate SNPs using Nano-Fluidic Array genotyping. Based on call rate, Minor Allele Frequency and Linkage Disequilibrium, a set of 96 SNPs were selected for genotyping C. arabica. This validated panel is suitable for use in coffee germplasm conservation and crop improvement, including varietal identification, seeds and nursery accreditation, and coffee bean authentication.

Soil erosion and deposition dramatically affect the biogeochemical cycle of terrestrial ecosystem, while how the microbial communities and soil multiple functions responds to soil erosion, particularly following deposition, are rarely addressed. Such knowledge gap hinders our comprehensively understanding about biogeochemistry cycling, the development of sustainable soil management practices and the restoration of degraded lands in an eroding environment. Herein, we compared the bacterial communities in the eroding, depositional, and adjacent non-eroding forest zones in the China’s Loess Plateau to explore how erosion and deposition alter soil bacterial communities and multifunctionality. We used the 16S rRNA gene amplicon sequencing to assess bacterial richness and community composition and analyzed co-occurrence networks to elucidate the associations among microbes. We also measured a series of soil functional parameters to assess soil multifunctionality and analyzed the relationship between soil multifunctionality and bacterial community structures. While erosion significantly reduced soil bacterial richness and multifunctionality, much of this loss was recovered in the depositional zone, with greater values in depositional zone than eroding zone. Soil erosion and subsequent deposition significantly decreased the complexity and connectivity of bacterial co-occurrence network compared with the forest. Soil multifunctionality was regulated by bacterial richness, community compositions and network complexity. Random forest modeling showed specific ecological clusters were the optimal predictors of multifunctionality, which was positively affected by Acidobacteria dominated network module but negatively affected by Actinobacteria dominated network module. This study suggests deposition can alleviate negative impacts of erosion on bacterial community richness and soil multifunctionality, and thus would be helpful for developing sustainable soil management and restoring degraded lands in eroding environments.

Proanthocyanidins (PAs) are secondary metabolites that contribute to important plant traits like fruit astringency. Persimmon (Diospyros kaki Thunb.) is unique for accumulating abundant PAs in its fruit flesh. Two non-astringent-type mutants, namely, Japanese pollination-constant and non-astringent (J-PCNA) and Chinese PCNA (C-PCNA), were unable to accumulate PA naturally on the tree before harvest. It was clear that the decreased expression profile of a Myb transcription factor (TF) DkMyb4 in persimmon fruits results in the PCNA trait in J-PCNA mutant. However, the mechanism leading to the PCNA trait in C-PCNA mutant remains unclear. In this study, with the purpose of figuring out whether or not there was a certain Myb TF resulting in PCNA trait in C-PCNA mutant, a gene homologous to DkMyb4 was isolated from C-PCNA cultivar ‘Luotian-tianshi’, named DkPA1. Bioinformatics analysis showed that DkPA1 shared high similarity to DkMyb4 in amino acid level, and that DkPA1 was phylogenetically closer to PA-related Myb TFs. Expression pattern of DkPA1 coincided with expression of PA pathway genes, also consistent with PA accumulation model in both C-PCNA and non-PCNA fruit during fruit development. Though being absent in J-PCNA, we found there were MYBCORE cis-motifs in promoter of PA pathway Leucoanthocyanidin reductase (DkLAR) gene isolated from C-PCNA and non-PCNA, which was reported as a key cis-element for PA biosynthesis and target of Myb TFs. These results suggested that DkLAR was regulated by DkPA1 in C-PCNA and non-PCNA, it played much more important role in C-PCNA and non-PCNA PA biosynthesis than that in J-PCNA.

Persimmon (Diospyros kaki Thunb.) fruits accumulate abundant proanthocyanidins (PAs) which can protect plants against herbivore and UV irradiation, contribute to the taste of many fruits, and act as antioxidants that are beneficial to human health. Previous studies indicated that, basic Helix–Loop–Helix (bHLH) transcription factors, such as AtTT8 and VvMYC1, regulated PA biosynthesis in Arabidopsis and grape respectively. Here, we had cloned and characterized a bHLH gene (DkMYC1) from ‘Luotian-tianshi’ persimmon. Phylogenetic analysis of the DkMYC1 protein sequence showed it shared high similarity with AtTT8 and VvMYC1. The expression profile of DkMYC1 was analyzed in two pollination-constant non-astringent (PCNA) type persimmon cultivar fruits with different molecular mechanisms for PA accumulation, and one astringent (non-PCNA) type persimmon by quantitative real-time PCR (qRT-PCR) analysis during fruits development. Results showed the expression pattern of DkMYC1 was correlated with PA accumulation in the two PCNA and the non-PCNA cultivars during fruits development and the expression of biosynthetic genes which were involved in PA biosynthesis. These results indicated that DkMYC1 may be an important bHLH transcription factor regulating PA biosynthesis in persimmon. This is the first report of a bHLH transcription factor gene involved in PA biosynthesis in persimmon.