Karyotype And Banding Pattern Analysis Of Chromosome In Citrus By Software

Citrus is one of the most important fruit crops in the world with abundant genetic resources. Chromosome karyotype and banding style analysis in citrus is an imperative cytogenetical method for citrus variety identifying. In present research, investigations were carried out to study the genetic diversity of different citrus, including HB pummelo(Citrus granids cv. Hirado Buntan), 'Hongju' tangerine (C. reticulata), trifoliate orange (Poncirus trifoliata), 'Meiwa' Kumquat (Fortunella crassifolia) and Calamondin (C. mandurensis Lout). Finding out the species specific marker chromosomes will facilitate hybrid indentification and phylogenic relationship reconstruction, as well as guiding the breeding of fruit crops. Usually, citrus chromosomes are divided into 5 to 7 types, according to the variation in numbers and position of CMA+ bands. The analysis of karyotype and banding style of these five species exactly by the software of MicroMeasure and Image Pro Plus, set out the intensity variety of DAPI fluorescence along the chromosome (from short arm to long arm), gained the fluctuate graph. The main results were as follows:1. To determine the chromosome numbers, fifty division cells from the shoot apical meristems of germinated seeds were observed in each of the 5 species. The percentage of cells possessing 18 chromosomes in Calamondin, 'Meiwa' kumquat, Trifoliate orange, 'Hongju' tangerine and HB pummelo ranking 78%, 84%, 68%, 80%, 70% respectively. Chromosomes in the remnant cells were ranging from 16 to 21.2. The karyotype formula of Calamonidn is 2n=2x=lS=16m(2SAT)+2sm, except chromosome 3 is submetacentric chromosome, the others are metacentric chromosome, and a satellite is near the short arm of chromosome 1; 'Meiwa' Kumquat's formula is 2n=2x=18=18m, all chromosomes are metacentric chromosome without satellite. It is classified as 1A Karyotype according Stebbins; Trifoliate orange's karyotype formula is 2n=2x=18=16m+2sm, chromosome 6 is submetacentric, all others are metacentric chromosome, without satellite. And it is classified .as 1B style according to Stebbin; Karyotype formula in 'Hongju' tangerine is 2n=2x=18=16m(2SAT)+2sm. chromosome 2 is submetacetric chromosome, the others are metacetric, and chromosome 7 has a satellite around the short arm. It is classified as 1B karyotype. HB pummelo's karyotype formula is 2n=2x=18=16m+2sm, chromosome 7 is submetacetric chromosome, the others are metacetric, and without satellite. The karyotype is 2B. All these five species belong to the primitive species in the citrus evolution because of their symmetry character. And 'Meiwa' Kumquat' is the earlist original. The next are Red tangerine, Trifoliate orange, Calamondin, HB pummelo compliably.3. Based on the results of fluorescence fluctuant graph and naked-eye observation, banding patterns in prometaphase chromosome were analyze, and the Idiogram were drawn among the samples of Calamondin, 'Meiwa' Kumquat, Trifoliate orange, 'Hongju' tangerine and HB pummelo, and the black banding numbers are 8, 4, 5, 10, 7 respectively.4. In present research, two-dimensional imaging of chromosome was constructed. The rough figure of chromosome was observed in focus. The results resemble the photos captured by confocal microscope, which would be helpful for physical location, copy numbers determination and mapping of interesting genes to specific chromosome.