Camellia species are ancient oilseed plants with a history of cultivation over two thousand years. Prior to oil extraction, natural seed drying is often practiced, a process affecting fatty acid quality and quantity. MicroRNAs (miRNA) of lipid metabolism associated with camellia seed natural drying are unexplored. To obtain insight into the function of miRNAs in lipid metabolism during natural drying, Illumina sequencing of C. oleifera and C. meiocarpa small-RNA was conducted. A total of 274 candidate miRNAs were identified and 3733 target unigenes were annotated by performing a BLASTX. Through integrated GO and KEGG function annotation, 23 miRNA regulating 131 target genes were identified as lipid metabolism, regulating fatty acid biosynthesis, accumulation and catabolism. We observed one, two, and four miRNAs of lipid metabolism which were specially expressed in C. Meiocarpa, C. oleifera, and the two species collectively, respectively. At 30% moisture contents, C. meiocarpa and C. oleifer produced nine and eight significant differentially expressed miRNAs, respectively, with high fatty acid synthesis and accumulation activities. Across the two species, 12 significant differentially expressed miRNAs were identified at the 50% moisture content. Sequencing of small-RNA revealed the presence of 23 miRNAs regulating lipid metabolism in camellia seed during natural drying and permitted comparative miRNA profiles between C. Meiocarpa and C. oleifera. Furthermore, this study successfully identified the best drying environment at which the quantity and quality of lipid in camellia seed are at its maximum.

To elucidate chloroplast genome evolution within neotropical-paleotropical bamboos, we fully characterized the chloroplast genome of the woody bamboo Guadua angustifolia. This genome is 135,331 bp long and comprises of an 82,839-bp large single-copy (LSC) region, a 12,898-bp small single-copy (SSC) region, and a pair of 19,797-bp inverted repeats (IRs). Comparative analyses revealed marked conservation of gene content and sequence evolutionary rates between neotropical and paleotropical woody bamboos. The neotropical herbaceous bamboo Cryptochloa strictiflora differs from woody bamboos in IR/SSC boundaries in that it exhibits slightly contracted IRs and a faster substitution rate. The G. angustifolia chloroplast genome is similar in size to that of neotropical herbaceous bamboos but is ~3 kb smaller than that of paleotropical woody bamboos. Dissimilarities in genome size are correlated with differences in the lengths of intergenic spacers, which are caused by large-fragment insertion and deletion. Phylogenomic analyses of 62 taxa yielded a tree topology identical to that found in preceding studies. Divergence time estimation suggested that most bamboo genera diverged after the Miocene and that speciation events of extant species occurred during or after the Pliocene.

Marker-assisted selection (MAS) is implemented to improve Camellia oleifera yield and fruit attributes for meeting China’s increased demand for new varieties development. We conducted three-generational (G₀, G₁, and G₂) hybridization (diallel mating) and selection experiment and used Sequence-Related Amplified Polymorphism (SRAP). SRAP markers to investigate their utility in a MAS framework. The utilized SRAP markers were instrumental in hybrid authenticity and the identification of matroclinal or patroclinal inheritance presence, thus guiding mating pair selection and direction (their role as male or females). Across the studied 3 generations, estimates of genetic diversity parameters showed steady increase with percentage increase of ((G₀ to G₁ and G₁ to G₂) 9.25 and 9.05: observed number of alleles; 3.12 and 7.80: means effective number of alleles; 12.35 and 22.34: Nei‘s gene diversity; and 14.21 and 21.77: Shannon‘s index), indicating lack of diversity reduction associated with selection. Estimates of genetic distance and their correlation with heterosis were useful in guiding selection of mating pairs for achieving the desired yield and fruit attributes (fruit diameter, height, weight, and index, peel thickness, number of seeds per fruit, seed weight per fruit, and seed rate). Most yield and fruit attributes exhibited high broad-sense heritability with increasing trend over generation intervals, indicating the increased potential of hybrid breeding for this species.

The molecular mechanisms of fatty acid biosynthesis and accumulation duringCamellia meiocarpa andCamellia oleifera seed natural drying are characterized through transcriptome analyses.