Study On Technique Of Anther Culture Of Carrot (Daucus Carota L.) And Obtain Of Special Carrot Germplasm

Carrot is commercially one of the important vegetables, so it has become the object of intensive research aiming to obtain new cultivars. Carrot breeding has been dominated by the method based on heterosis. The process of obtaining parental lines in order to derive hybrids is time– consuming and very expensive. Moreover, a strong depression observed in the breeding within related plants has always been a big problem. The lack of complete homozygosity in parental lines leads to limited application of the potentials of the hybrid technique. One of the methods to obtain true homozygous lines is based on anther culture.The embryoid formation and plant regeneration in anther cultures of 42 genetypes were investigated. Direct embryogenesis was induced in 6 genetypes respectively on B5 medium. The efficiency was the highest in 60090—3.89 embryos per 100 anthers, which is in accord with the data reported in literatures. Embryogenic calli were induced in 29 genetypes on B5 medium. The efficiency was the highest in 600Q6—36.70 calli per 100 anthers, 5.9 percentage points higher than reference data. The parent with high or even moderate frequency of embryoid formation in anther culture could lead to the effective production of green plants from the F1 hybrid, F2 generation and F3 generation for breeding purposes. 7 of 11 F2 plants produced embryos and 1 of 9 F3 plants produced embryos. 70Q50-4 exhibied the higher frequency of embryo formation in anther culture, 2.4 percentage points higher than the data reported in literatures. It is an effective way to produce the genetypes with higher induction frequency in anther culture by the breeding of easy induction species and difficult induction species. The better medium is MS medium, and the higher frequency of embryos showed in the treatment of 0.5 mg/L2, 4-D+0.2 NAA. The result was showed that 8 mg/LAgNO3 in B5 medium can enhanced the ratio of embryos obtaimed per 100 anthers for some genetypes.Cytochemical features of embryo development during anther culture in carrot have been followed. The division of cultured microspores distined to become embryos is either generally symmetrical (B pathway and D pathway) or asymmetrical (E pathway). Some microspores with two or more nuclei were observed during anther culture. Chromosome doubling is thought to occur by nuclear fusion. Using embryoids as explants, regerated plants were obtained. The ploidy identification of 109 regeneration plants was conducted. The results indicated that the percentage of the diploids, triploids and tetraploids were 93.39%, 1.65% and 1.65%, respectively. And the result of DNA flow cytometry showed that the percentage of the diploids was 94.59%. The high frequency of regeneration plant with 2n=18, 2n=27 and 2n=36 can indicate that the extensive exist of fusing of cell nuclei.Embryoids induction during carrot anther culture have been observed. Embryoids and embrygenic calli located anther chamber that showed generation plantlets derived from carrot microspore. Identification of haploid cells showed regenerated plants originated from the microspores. H1 generation showed genetic diversity and the same line of H2 generation maintained the relative genetic stability. In this research, some special carrot germplasms were obtained, such as DH lines of resistant/susceptible of black spot disease, DH lines which bolting time is earlier, autotriploid and autotetraploid carrot and so on. Thus can enrich the genetic diversity, and also occupy germplasm for further breeding program and related studies.