Akebia trifoliata (Thunb.) Koidz is an important Chinese medicinal and economic crop. Its seeds, which are rich in fatty acids, are usually discarded. As of now, A. trifoliata lipid biosynthesis pathways and genes have not been clearly described. In this work, we found that seed and fruit development of A. trifoliata were not synchronized, and that when the fruit was ripe, seed oil content was not at its highest. As seeds developed, linoleic and oleic acid content was found to decrease and increase, respectively. RNA sequencing yielded 108.45 GB of clean reads from 15 cDNA libraries, containing 8756 differentially expressed genes. We identified 65 unigenes associated with lipid biosynthesis, including fatty acid and triacylglycerol biosynthesis. The 65 unigenes were mapped to the A. trifoliata lipid synthesis pathway. There were 20 AtrFAD family members in A. trifoliata, which could be divided into four sub-groups with the highest number of AtrSADs. Our study revealed the dynamic changes in A. trifoliata seed oil content and composition during its growth period and provides large-scale and comprehensive transcriptome data of A. trifoliata seeds. These findings provide a basis for the improvement of A. trifoliata seed oil yield and quality.

Citrus aurantium L. (sour orange) is a significant Chinese medicinal and fruit crop rich in flavonoids. However, the pathways and genes involved in flavonoid biosynthesis at the key developmental stages of Citrus aurantium L. are not fully understood. This study found that the total flavonoid concentration gradually decreased as the fruit developed. Additionally, it showed that neohesperidin was the main flavonoid in the early stages of sour orange fruit development. However, as the development stage progressed, naringin content increased rapidly and emerged as the main flavonoid component. From 27 cDNA libraries, RNA sequencing yielded 16.64 billion clean bases, including 8989 differentially expressed genes. We identified 74 flavonoid related unigenes mapped to the phenylalanine, tyrosine, and phenylpropanoid biosynthesis pathways. A total of 152 UDP-glucuronosyltransferase genes (UGTs) were identified from C. aurantium L. transcriptome database, in which 22 key flavonoid-correlated UGTs were divided into five main AtGT groups: E, G, I, L, M. We observed that the ethylene responsive factors (ERF) and myeloblastosis (MYB) family mainly regulated the key genes involved in flavonoid biosynthesis. Overall, our study generated extensive and detailed transcriptome data on the development of C. aurantium L. and characterized the flavonoid biosynthesis pattern during its fruit developmental stages. These results will benefit genetic modification or selection to increase the flavonoid content in sour oranges.

• Feasibility of using A. trifoliata seed oil (ASO) as an edible oil was studied. • A partial least squares regression model for the ASO content was established. • The PLS model was well suited for the determination of ASO and UFA content. • Based on the study, High ASO content germplasm could be used in A. trifoliata breeding.

Citrus (Citrus reticulata) is one of the world’s most widely planted and highest-yielding fruit trees. Citrus fruits are rich in a variety of nutrients. The content of citric acid plays a decisive role in the flavor quality of the fruit. There is a high organic acid content in early-maturing and extra-precocious citrus varieties. Reducing the amount of organic acid after fruit ripening is significant to the citrus industry. In this study, we selected a low-acid variety, “DF4”, and a high-acid variety, “WZ”, as research materials. Through WGCNA analysis, two differentially expressed genes, citrate synthase (CS) and ATP citrate-pro-S-lyase (ACL), were screened out, which related to the changing citric acid. The two differentially expressed genes were preliminarily verified by constructing a virus-induced gene-silencing (VIGS) vector. The VIGS results showed that the citric acid content was negatively correlated with CS expression and positively correlated with ACL expression, while CS and ACL oppositely control citric acid and inversely regulate each other. These results provide a theoretical basis for promoting the breeding of early-maturing and low-acid citrus varieties.

Simple sequence repeats (SSRs) and sequence-related amplified polymorphism (SRAP) were employed to assess the genetic diversity and relationship among 108 ramie cultivars, which were collected from China, Japan, Indonesia and Myanmar. A total of 183 polymorphic bands were produced by using 21 SSR and 20 SRAP primer pairs. The genetic similarity matrix was obtained by using the similarity for qualitative data (SIMQUAL) subroutine of the Numerical Taxonomy and Multivariate Analysis System (NTSYS-pc) software statistical package, based on Jaccard's algorithms. The results showed that the similarity coefficient among the 108 ramie germplasms ranged from 0.22 to 0.89. By using principal components analysis (PCA) and unweighted pair-group method with arithmetic means (UPGMA), the 108 ramie germplasms were clustered into two categories. Shanon diversity index (SDI) was 1.1 and Nei's gene diversity index (NGDI) was 0.58 in the present study. When comparing their indexes, the genetic diversity in the different provinces was as follows: Guizhou (SDI 1.14, NGDI 0.61) > Jiangxi (SDI 1.11, NGDI 0.60) > Guangxi (SDI 1.05, NGDI 0.59) > Hunan (SDI 1.04, NGDI 0.58) > Hubei (SDI 1.02, NGDI 0.58) > Chongqing (SDI 0.96, NGDI 0.54). There was an abundant genetic diversity in ramie accessions growing in the China's Changsha field GenBank of ramie. Guizhou province had the highest genetic diversity and thus may be the origin centre of ramie's genetic diversity. The relationship between germplasms and geographic distribution was poor.