二倍体和四倍体西瓜幼苗根系形态差异比较

Comparison of root morphology in diploid and tetraploid watermelon seedlings

多倍体植物由于染色体加倍,其形态特征与二倍体有明显差异。以二倍体和其人工诱导的同源四倍体西瓜为材料,利用根系分析仪扫描和石蜡切片的方法比较7 d和3叶1心期不同倍性西瓜幼苗的根系形态差异。结果表明,在根系发育至7 d时,四倍体西瓜幼苗根系长度不及二倍体,但是平均直径、投影面积、表面积和体积均大于其同源二倍体;在3叶1心期,四倍体西瓜幼苗的根系长度、平均直径、投影面积、表面积和体积均显著大于其同源二倍体;与二倍体西瓜相比,四倍体西瓜根部的后生木质部细胞较大,筛管和伴胞较多且大;四倍体西瓜幼苗根系鲜质量和干质量均大于其同源二倍体。因此,染色体加倍后,四倍体西瓜幼苗根系无论是细胞大小还是生物量均大于其同源二倍体,该结果可以为研究植物多倍体的形态变异和优势机理提供一定的理论依据。

The morphological characteristics of polyploid plants are significantly different from that of diploid plants due to the genome duplication.Diploid and colchicine induced autotetraploid watermelon were used in this research,the seedlings at 7 days and three-leaf stage were used to investigate the root differnece,the root system was scanned by a root scanner,the cellular structure of the root was observed by paraffin section,and the biomass of the root was measured.The results showed that after cultured for 7 days the length of the tetraploid watermelon seedlings were shorter than that of diploid plants,but the average diameter,projection area,surface area and volume were larger than those of diploid ones.The length,average diameter,projection area,surface area and volume of the tetraploid watermelon seedlings were found a significant increase than those of diploid plants at three-leaf stage.Compared with diploid watermelon,the root of tetraploid watermelon showed larger metaxylem cells,more sieve tubes and cell partners.The fresh weight and dry weight of tetraploid watermelon seedlings were greater than their homologous diploid roots.The results can provide some theoretical basis for studying the morphological variation of plant polyploids.