Natural rubber is usually synthesized in the rubber particles present in the latex of rubber-producing plants such as the Pará rubber tree (Hevea brasiliensis) and rubber dandelion (Taraxacum kok-saghyz). Since the detailed lipid compositions of fresh latex and rubber particles of the plants are poorly known, the present study reports detailed compound lipid composition, focusing on phospholipids and galactolipids in the latex and rubber particles of the plants. In the fresh latex and rubber particles of both plants, phospholipids were much more dominant (85–99%) compared to galactolipids. Among the nine classes of phospholipids, phosphatidylcholines (PCs) were most abundant, at ~80%, in both plants. Among PCs, PC (36:4) and PC (34:2) were most abundant in the rubber tree and rubber dandelion, respectively. Two classes of galactolipids, monogalactosyl diacylglycerol and digalactosyl diacylglycerol, were detected as 12% and 1%, respectively, of total compound lipids in rubber tree, whereas their percentages in the rubber dandelion were negligible (< 1%). Overall, the compound lipid composition differed only slightly between the fresh latex and the rubber particles of both rubber plants. These results provide fundamental data on the lipid composition of rubber particles in two rubber-producing plants, which can serve as a basis for artificial rubber particle production in the future.

Sorghum (Sorghum bicolor (L.)) Moench is an important food for humans and feed for livestock. Sorghum contains dhurrin which can be degraded into toxic hydrogen cyanide. Here, we report the expression patterns of 14 candidate genes related to dhurrin ((S)-4-Hydroxymandelnitrile-β-D-glucopyranoside) metabolism and the effects of the gene expression on specific metabolite content in selected sorghum accessions. Dhurrin-related metabolism is vigorous in the early stages of development of sorghum. The dhurrin contents of most accessions tested were in the range of approximately 6–22 μg mg⁻¹ fresh leaf tissue throughout growth. The p-hydroxybenzaldehyde (pHB) contents were high at seedling stages, but almost nonexistent at adult stages. The contents of p-hydroxyphenylacetic acid (pHPAAc) were relatively low throughout growth compared to those of dhurrin or pHB. Generally, the expression of the candidate genes was higher at seedling stage than at other stages and decreased gradually as plants grew. In addition, we identified significant SNPs, and six of them were potentially associated with non-synonymous changes in CAS1. Our results may provide the basis for choosing breeding materials to regulate cyanide contents in sorghum varieties to prevent HCN toxicity of livestock or to promote drought tolerance or pathogen resistance.