Identification and effective regulation of scarb1 gene involved in pigmentation change in autotetraploid Carassius auratus

The autotetraploid Carassius auratus(4nRR,4n=200,RRRR)is derived from whole-genome duplication of Carassius auratus red var.(RCC,2n=100,RR).In the current study,we demonstrated that chromatophores and pigment changes directly caused the coloration and variation of 4nRR skin(red in RCC,brownish-yellow in4nRR).To further explore the molecular mechanisms underlying coloration formation and variation in 4nRR,we performed transcriptome profiling and molecular functional verification in RCC and 4nRR.Results revealed that scarb1,associated with carotenoid metabolism,underwent significant down-regulation in 4nRR.Efficient editing of this candidate pigment gene provided clear evidence of its significant role in RCC coloration.Subsequently,we identified four divergent scarb1 homeologs in 4nRR:two original scarb1 homeologs from RCC and two duplicated ones.Notably,three of these homeologs possessed two highly conserved alleles,exhibiting biased and allelespecific expression in the skin.Remarkably,after precise editing of both the original and duplicated scarb1homeologs and/or alleles,4nRR individuals,whether singly or multiply mutated,displayed a transition from brownishyellow skin to a cyan-gray phenotype.Concurrently,the proportional areas of the cyan-gray regions displayed a gene-dose correlation.These findings illustrate the subfunctionalization of duplicated scarb1,with all scarb1genes synergistically and equally contributing to the pigmentation of 4nRR.This is the first report concerning the functional differentiation of duplicated homeologs in an autopolyploidfish,substantiallyenrichingour understanding of coloration formation and change within this group of organisms.

In Vivo Fast Induction of Homogeneous Autopolyploids via Callus in Sour Jujube(Ziziphus acidojujuba Cheng et Liu)

Polyploidization has been demonstrated as a very effective approach in fruit tree improvement.Sour jujube(Ziziphus acidojujuba Cheng et Liu) is a promising diploid wild,traditional fruit species(2n = 2x = 24) that is rich in vitamin C,which is the main rootstock of Chinese jujube(Z.jujuba Mill.).The novel method we developed for rapid in vivo induction of homogeneous autopolyploids(IVIHA) via callus in Chinese jujube was first applied and further optimized in sour jujube.Under optimized conditions,an average of one pure autotetraploid shoot could be regenerated from one treated branch,thereby indicating a relatively high efficiency rate.A total of 9 pure autotetraploid genotypes were created,and one of these was released as a new cultivar named ‘Zhuguang' in 2015.Moreover,unexpected octoploids and hexaploids were also simultaneously created and detected.The leaves of tetraploids were thicker,broader,and darker in color than those of the original diploids,whereas the leaf sizes of octoploids were much smaller compared to that of diploids.However,stoma size increased with the occurrence of ploidy,mainly from diploid to octoploid.The well grown ploidies of jujube included diploids,triploids,and tetraploids.Anatomical observation indicated that adventitious buds/shoots emerged from the callus that formed on the cut,which was then followed by the development of connective vascular tissues between the adventitious bud and the stock plant tissue.This study demonstrates the universality of the IVIHA method that was initially developed in Chinese jujube,as well as provides a foundation for high-efficiency pure polyploid induction in sour jujube.

Comparison Between a Tetraploid Turnip and Its Diploid Progenitor(Brassica rapa L.):The Adaptation to Salinity Stress

Polyploidy is pursued in plant breeding programs due mainly to its ability to yield larger vegetative or reproductive organs. In controlled growth chamber experiments, a tetraploid turnip （cv. Aijiaohuang, 4n） and its diploid progenitor （cv. Aijiaohuang, 2n） were evaluated for their tolerance to salinity stress via investigations on a group of physiological parameters. The results indicate that the tetraploid turnip exhibit better adaptation to a high concentration salt medium （200 mmol L-1）, as evidenced by a less-affected germination rate and a healthier morphological appearance at the seedling stage. Furthermore, an extension of salinity stress up to a certain period of time at the 5-7-leaf stage shows differences between the tetraploid turnip and its diploid progenitor. The former had a higher K＋/Na＋ ratio in the roots, higher glutathione concentration and antioxidant activities in the leaves, and smaller reductions in photosynthetic capacity in terms of leaf chlorophyll content. Studies on the differences between an autopolyploid and its respective relative, from which the autopolyploid originated, in terms of their tolerance to salinity and/or other abiotic stresses, have remained rather limited. The comparison is interesting due to a homogenous genetic background.

Natural and artificial polyploids in aquaculture

Genome polyploidy has been revealed to result in evolutionary advantages and novelties,and therefore,polyploid aquatic animals may possess excellent traits of economic interest including rapid growth,extensive adaptability and disease resistance.For this reason,numerous species of natural polyploid fishes,such as common carp,gibel carp,crucian carp,salmon,and sturgeon,were chosen as important target species for aquaculture.Many artificial polyploids have been commercially utilized for aquaculture and most of them were created from natural polyploid fishes of the Cyprinidae and Salmonidae.Thanks to the easy mass production and better economic traits in growth and flesh quality,the synthetized autopolyploids or allopolyploids from natural polyploid species in cyprinid fishes have been extensively applied to aquaculture throughout China.This review outlines polyploidy advantages and innovative opportunities,lists natural polyploid species used in aquaculture,and summarizes artificial polyploids that have been induced or synthetized,and used in aquaculture.Moreover,some main research trends on polyploid utilization and ploidy manipulation of aquaculture animals are also introduced and discussed in the review.

Morphological and chemical studies of artificial Andrographis paniculata polyploids

Andrographis paniculata(Burm. f.) Nees(AP) is commonly used for the treatment of many infectious diseases and has been cultivated widely in Asian countries, and has been included in United States Pharmacopoeia as a dietary supplement, but the cultivars of A. paniculata are not abundant due to its self-pollinated. With the aims to enrich AP resources and provide materials for after breeding we explored the polyploidy induction. Different explants, colchicine concentration, and treatment time were tested. After identification by flow cytometry, eleven polyploid plants with different morphologic traits were obtained. The agronomic traits and andrographolide concentration of the polyploids were improved greatly. One of the polyploids(serial 3-7) was chosen for further study. The traits of the second and third generation polyploids(serial 3-7) were stable. Compared with the normal plants, the seeds(2 nd generation) weight increased by 31%, and the andrographolide concentration of the leaves increased by 14%(2 nd) and 28%(3 rd). In conclusion, AP autopolyploids with different morphologic traits were established successfully for the first time, and the polyploids induction might be effective for crop improvement of AP.