Many Camellia oleifera germplasm resources were collected from Guizhou Province, but the fruit morphological variation and genetic diversity of C. oleifera germplasm resources remain unclear. The genetic diversity of C. oleifera germplasms resources in Guizhou was studied based on fruit traits and simple sequence repeat (SSR) molecular markers to build a core collection. This paper aims to provide a scientific basis for the collection, management, development, and utilization of C. oleifera resources in Guizhou province. The variation coefficients among and within varieties of seven fruit phenotypic traits of C. oleifera ranged from 11.79% to 61.76% and from 8.15% to 42.31%, respectively, showing rich phenotypic variation. Furthermore, 12 SSR markers were used to analyze the genetic diversity. These primers generated 214 polymorphic bands, and the average number was 17.833. The average number of effective alleles (Ne), Shannon’s information index (I), observed heterozygosity (Ho), expected heterozygosity (He), polymorphic information content (PIC), and major allele frequency (MAF) were 8.999, 2.301, 0.965, 0.50, 0.836, and 0.238, respectively. The results showed that 12 SSR markers had high polymorphism, and the genetic diversity of 167 C. oleifera germplasm resources was high. Based on SSR molecular marker information and fruit traits clustering, 167 C. oleifera germplasm resources were divided into three groups. When constructing core collections based on fruit traits and molecular marker information, the PowerCore-25 of core collections greatly preserves fruit traits and improves genetic diversity. This paper can provide a reference for the genetic diversity and fruit traits variation of C. camellia germplasm resources in Guizhou Province. It is significant for establishing a core collection, thus promoting germplasm innovation and the development of the oil tea industry in Guizhou.

Plant anthocyanin is a secondary metabolite widely distributed in the roots, stems, leaves, flowers and fruits of plants, and its synthesis is significantly affected by light intensity. To reveal the physiological response mechanism of anthocyanin synthesis in blueberry leaves at different light intensities, four light intensities (100% (CK), 75%, 50% and 25%) were set for the ‘O’Neal’ southern highbush blueberry as the experimental material in our study. The relationship between endogenous hormone contents, key enzyme activities, and variations in the anthocyanin content in blueberry leaves under various light intensities during the white fruit stage (S1), purple fruit stage (S2) and blue fruit stage (S3) of fruit development were studied. The results showed that the anthocyanin content of blueberry leaves increased first and then decreased, and decreased first and then increased with the increase in light intensity and development stage, respectively. The appropriate light intensity could significantly promote the synthesis of anthocyanin, and the anthocyanin content in leaves treated with 75% light intensity was 1.09~4.08 times that of other light intensity treatments. The content or activities of gibberellin (GA₃), indoleacetic acid (IAA), jasmonic acid (JA), abscisic acid (ABA), ethylene (ETH), phenylalanine ammonia lyase (PAL), chalcone isomerase (CHI), dihydroflavonol reductase (DFR) and UDP-glucose: flavonoid 3-glucosyltransferase (UFGT) were significantly or extremely significantly correlated with the content of anthocyanin in leaves. This indicated that light intensity significantly promoted anthocyanin synthesis in blueberry leaves by affecting endogenous hormone contents and key enzyme activities in the anthocyanin synthesis pathway. This study lays a foundation for further research on the molecular mechanism of light intensity regulating anthocyanin synthesis in blueberry leaves.

Dark septate endophytes (DSE) and ericoid mycorrhizal fungi (ERMF) are employed to augment the abiotic stress resistance of fruits. However, their potential functions in enhancing the drought resistance of blueberry, an economically important fruit, remain unclear. Thus, this study aims to identify optimal inoculation combinations to enhance the drought resistance of blueberry seedlings. Specifically, the effects of single and dual inoculations with DSE (Cladosporium cladosporioides, D79) and ERMF (Oidiodendron citrinum, N12) on seedling physiology and metabolism were explored under varying drought conditions. The results showed that dual inoculation significantly improved leaf physiological characteristics. Under severe drought stress, the 1:2 DSE:ERMF ratio (D1N2) notably increased leaf relative water content (RWC) and reduced electrolyte leakage by up to 42.1% compared with the non-inoculated control. Dual inoculation also significantly decreased malondialdehyde (MDA) content, with the smallest increase observed in D1N2. Regarding antioxidant enzymes, dual inoculation sustained higher superoxide dismutase (SOD) activity under moderate drought and minimized the decline in SOD activity under severe drought (the lowest decrease was 36.4% in D1N2 versus 56.7% in CK). Moreover, the antioxidant losses under drought stress were reduced by upregulating various metabolic processes, especially the biosynthesis of phenylalanine, tyrosine, and tryptophan. A comprehensive evaluation suggested that inoculation with a 1:2 mixture of DSE and ERMF most effectively improved blueberry drought resistance, primarily by enhancing water and metabolite supply and stimulating the antioxidant defenses.