Molecular identification of sex in Hippophae rhamnoides L. using isozyme and RAPD markers

In many dioecious plants, gender affects economic value, breeding schemes and opportunities for commercial harvests. Hippophae rhamnoides L. is a dioecious plant species in which female genotypes are commercially preferred over male genotypes. Its berries have rich medicinal, nutritional and pharmaceutical properties because of their large amounts of vitamins, essential oils, proteins, fatty acids, free amino acids and flavanoids. Primary limitation for breeding H. rhamnoides L. is its dioecious nature, since gender cannot be identified by traditional methods. Therefore, some reliable and quick methods need to be developed. This commu- nication deals with the development of isozyme and RAPD markers for early sex identification in this dioecious tree. The isozyme analysis was conducted with four enzyme systems, viz. peroxidase, esterase, malate dehydrogenase and catalase. The peroxidase enzyme system produced a female specific sex marker, which successfully differentiated between the staminate and pistillate geno- types ofH. rhamnoides L. Thirty five random decamer primers were used in our study and one male sex linked marker was identified. OPD-20 （5＇-ACTTCGCCAC-3＇） displayed a band at 911 bp that expressed polymorphism between male and female genotypes. The staminate and pistillate genotypes could be distinguished using RAPD marker OPD-209n. These results revealed the immense poten- tial of peroxidase isozyme patterns and RAPD as genetic markers for sex identification in H. rhamnoides L.

Sex-Based Variation of Gene Expression in the Gonads and Fins of Russian Sturgeon (<i>Acipenser gueldenstaedtii</i>)

Russian sturgeon (Acipenser gueldenstaedtii) is a primitive freshwater fish and a source of black caviar. The genes involved in sexual determination and differentiation are still unknown and there are no molecular markers for sex identification in this species. Studying the variation of the sex-based differences in genomic sequences and in gene expression in the sturgeon may lead to markers of sex in early stages of development and advances in aquaculture, as well as provide novel insights about the evolution of reproduction, sex determination, and sexual differentiation mechanisms in vertebrates. Previous studies by our and other groups have identified differentially expressed genes in the gonads of adult female and male sturgeon. The current study aimed to test whether these genes were also differentially expressed in non-gonadal tissue, namely fins. We measured by qRT-PCR the mRNA levels of 29 known and novel sex-related genes in the gonads and fins of males (4 years old) and females (7 years old;sexual maturation is earlier in males than in females). Six genes (ATP6, IGFRM, LIA1A, S1A, NPL1A, GAPDH and SOX9) showed higher expression in female fins. However, only ATP6 mRNA levels differed in fins of males and females of the same age (4 years old). These findings underscore the impracticality of sex identification based on gene expression in non-gonadal tissue and the need for genetic sex markers in the Russian sturgeon.

Identification of novel Z/W chromosome-specific markers from the giant freshwater prawn Macrobrachium rosenbergii

The giant freshwater prawn(Macrobrachium rosenbergii)is a commercially cultured species in China.A sex chromosome-specific marker is crucial for sex identification and distinguishing sex chromosomes.Here,based on the results of reduced-representation genome sequencing and genome survey of M.rosenbergii,we identified steady sex-linked markers.Further nucleotide alignment analysis revealed 83.42%nucleotide similarity between the amplified W-and Z-chromosome fragments.qPCR confirmed that Z chromosome-specific fragments were present in males approximately twice as often compared to females.Similarly,the W chromosome-specific fragments were present in super females approximately twice as often compared to females.Our findings elucidate the ZW/ZZ sex determination type and contribute to exploring sex-related or sex-determining genes present on the sex chromosomes of M.rosenbergii.