[CiteSpace knowledge map of research hotspots and frontiers of Polygalae Radix].

In this study, the Web of Science and China National Knowledge Infrastructure(CNKI) were searched comprehensively for the literature about the research on Polygalae Radix. After manual screening, 1 207 Chinese articles and 263 English articles were included in this study. Excel was used to draw the line chart of the annual number of relevant publications. CiteSpace 6.1.R3 was used for the visual analysis of author cooperation, publishing institutions, keyword co-occurrence, keyword clustering, and bursts in the research on Polygalae Radix. The results showed that the number of articles published in Chinese and English increased linearly, which indicated the rising research popularity of Polygalae Radix. WANG J and LIU X were the authors publishing the most articles in Chinese and English, respectively. Shanxi University of Chinese Medicine and Chinese Academy of Medical Sciences were the research institutions with the largest number of Chinese and English publications in this field, respectively. The institutions publishing the relevant articles in English formed a system with the Chinese Academy of Medical Sciences as the core. According to the keywords, the research hotspots of Polygalae Radix included variety selection and breeding, quality standard, extraction and identification of active chemical components, prescription compatibility, processing, clinical medication rules, and pharmacological mechanism. The research frontiers were the molecular mechanisms of Polygalae Radix and its active components in exerting the protective effect on brain nerve, regulating receptor pathways, alleviating anxiety and Alzheimer's disease, as well as data mining and clinical medication summary. This study has reference significance for the topic selection and frontier identification of the future research on Polygalae Radix.

Global Survey and Expressions of the Phosphate Transporter Gene Families in Brassica napus and Their Roles in Phosphorus Response.

Phosphate (Pi) transporters play critical roles in Pi acquisition and homeostasis. However, currently little is known about these genes in oil crops. In this study, we aimed to characterize the five Pi transporter gene families (PHT1-5) in allotetraploid Brassica napus. We identified and characterized 81 putative PHT genes in B. napus (BnaPHTs), including 45 genes in PHT1 family (BnaPHT1s), four BnaPHT2s, 10 BnaPHT3s, 13 BnaPHT4s and nine BnaPHT5s. Phylogenetic analyses showed that the largest PHT1 family could be divided into two groups (Group I and II), while PHT4 may be classified into five, Groups I-V. Gene structure analysis revealed that the exon-intron pattern was conservative within the same family or group. The sequence characteristics of these five families were quite different, which may contribute to their functional divergence. Transcription factor (TF) binding network analyses identified many potential TF binding sites in the promoter regions of candidates, implying their possible regulating patterns. Collinearity analysis demonstrated that most BnaPHTs were derived from an allopolyploidization event (~40.7%) between Brassica rapa and Brassica oleracea ancestors, and small-scale segmental duplication events (~39.5%) in the descendant. RNA-Seq analyses proved that many BnaPHTs were preferentially expressed in leaf and flower tissues. The expression profiles of most colinearity-pairs in B. napus are highly correlated, implying functional redundancy, while a few pairs may have undergone neo-functionalization or sub-functionalization during evolution. The expression levels of many BnaPHTs tend to be up-regulated by different hormones inductions, especially for IAA, ABA and 6-BA treatments. qRT-PCR assay demonstrated that six BnaPHT1s (BnaPHT1.11, BnaPHT1.14, BnaPHT1.20, BnaPHT1.35, BnaPHT1.41, BnaPHT1.44) were significantly up-regulated under low- and/or rich- Pi conditions in B. napus roots. This work analyzes the evolution and expression of the PHT family in Brassica napus, which will help further research on their role in Pi transport.