海南省儋州市本地黄皮是著名的热带水果,但存在核大、可食率低、品质不一等问题,为选育无(少)核黄皮新品种,开展儋州本地黄皮核型分析和多倍体诱导试验,对供试黄皮露白种子分别采用0.25％、0.5％、1％秋水仙素和浸泡24、36、48 h 2个因素3个水平共9个处理诱导多倍体,取幼苗根尖进行染色体计数,剥取叶片下表面观测气孔大小和密度,取幼嫩叶片采用流氏细胞仪鉴定倍性,筛选较优的秋水仙素和时间处理后,添加0.05％、0.10％、0.20％二甲基亚砜(DM-SO)和5、10、15 mg/L萘乙酸(NAA)优化多倍体诱导方式.结果表明,儋州本地黄皮体细胞染色体数量2n=18,核型公式是2n=2x=18=12m+6sm,相对长度组成是2n=1s+4M1+4M2,2B型,核型不对称性高,进化程度高.0.50％秋水仙碱浸泡36 h处理的下胚轴膨大率最高,为35.53％,多倍体和同源四倍体诱导率最高,分别为4.82％和2.07％,表型变异株中多倍体和同源四倍体占比分别为13.62％和5.83％,为多倍体诱导较优处理.该处理优化以0.10％DMSO+10 mg/L NAA处理最优,多倍体和同源四倍体诱导率最高,分别为18.18％和8.74％,除了 0.20％DMSO+10 mg/L NAA外,极显著高于其他处理(p＜0.01).
Karyotype analysis and autopolyploid induction of Danzhou local Clausena lansium
Danzhou local Clausena lansium is a famous tropical fruit,but with problems of big seed,low edible rate and variable quality.To select seedless or small seed C.lansium,karyotype analysis and polyploid induc-tion experiment of local C.lansium was carried out.Germinated seeds of Danzhou local C.lansium were soaked in different concentrations of colchicine(0.25％,0.50％,1.0％)for different length of time(24 h,36 h,48 h)to induce polyploidy.The root tips of seedlings were used for chromosome counting.The lower sur-face of the leaf was peeled off to observe the size and density of stomata.The ploidy was identified by flow cy-tometer with young leaves.Polyploid induction system was optimized by adding DMSO(0.05％,0.10％and 0.20％)and NAA(5,10,15 mg/L after screening out the optimal concentration and treatment time of colchi-cine.The results showed that the number of somatic chromosomes of Danzhou local Clausena lansium was 2n=18,and the karyotype formula was 2n=2x=18=12m+6sm with the relative length composition of 2n=ls+4Ml+4M2.The karyotype was type 2B with high asymmetry and high degree of evolution.The germinated seeds soaked in 0.5％colchicine for 36 h had the highest hypocotyl swollen rate of 35.53％with the highest induction rate of poly-ploid and autotetraploid of 4.82％and 2.07％,respectively.The proportion of polyploid and autotetraploid in pheno-typic variants was 13.62％and 5.83％,respectively.Soaked in 0.5％colchicine for 36 h was a better treatment for polyploidy induction.The optimal polyploidy induction system was 0.5％colchicine+0.1％DMSO+10 mg/L NAA for 36 h,with the highest induction rate of polyploid and autotetraploid of 18.18％and 8.74％,respectively,extremely significant higher that of other treatments except 0.20％DMSO+10 mg/L NAA.
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