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Self-incompatibility (SI) prevents inbreeding depression in angiosperms. Camellia sinensis is an important cash crop, but breeding improvements and genetic studies of the plant are hindered by SI. However, the SI mechanism in C. sinensis remains unclear. In this study, a putative S-RNase gene (KU852488) was cloned from C. sinensis . The full-length cDNA of CsS-RNase is 1121 bp, which encodes 238 amino acids. It shares the closest relationship with an S-RNase gene (ADA67883.1), which was cloned from a self-incompatibility Citrus reticulata cultivar ‘Wuzishatangju’. The expression level of CsS-RNase in the styles were 3–259 (‘Fuding Dabaicha’) and 5.6–119 (‘Zhongcha108’) times higher than the other tissues, for example petals, pollen grains, filaments and buds. And its expression rose in self-pollinated styles with 24 h earlier than cross-pollinated styles. The genotypes of CsS-RNase in 10 cultivars and one breeding line of C. sinensis were analyzed. Totally, 11 polymorphic amino acid residues were identified. A single nucleotide polymorphism (SNP) marker of CsS-RNase was developed. Finally, the CsS-RNase was mapped onto a reference genetic linkage map of tea plant.

Selenium (Se) is a dietary essential trace element for humans and animals. Owing to Se being obtained from food or other source of supplementation, Se-enriched tea is a possible source of supplemental Se and thus has been drawing much attention. This study aimed to identify the variation of the Se concentrations among 14 elite Camellia sinensis cultivars against two-Se-levels supplementation at seedling stage. In the present study, the genetic diversity was assessed by 93 alleles revealed by 12 SSR primers in the C. sinensis accessions. Among the scored 93 alleles, 81 (87.10%) were polymorphic, and the average Nei's gene diversity ( He ) was 0.253 and average shannon information index ( I ) was 0.394, indicating a relatively high genetic variation. Significant variations were observed for the Se concentration among the accessions in both treatments ( P −1 and 0.357–0.537 mg kg −1 in control (0) and Se-supplied (4 mg kg −1 ) treatments respectively. The quality components content, tea polyphenols and amino acid, were sensitive to Se-supplement in a few of accessions, whereas soluble sugar and aqueous extract content appeared unchanged between the contrast treatments. In addition, the genetic variation among the tea plant cultivars was not well correlated with the Se concentration. Even then, the genetic variation in Se concentration across the 14 accessions indicated the possibility of utilizing tea plant accessions to develop optimized cultivars for Se-enriched tea. For the relative high Se concentration in the tea, tea plant is supposed to be a Se-enriched species. These results may enhance our understanding the genetic variation in tea plant.