甘蓝型油菜根系突变体lrn1、prl1和野生型根系显微结构的差异

油菜外源细胞分裂素不敏感突变体lrn1和prl1表现为磷高效。营养液培养0.2μmol/L细胞分裂素(6-BA)处理,与甘蓝型油菜野生型‘宁油7号’(WT)相比,突变体lrn1侧根较多,prl1主根较长。本研究利用体式显微技术、非切片压片法以及石蜡切片等技术,对3个基因型在ddH2O和0.2μmol/L 6-BA处理下的根毛、根表皮细胞分化及根尖解剖结构的差异进行了观察,结果表明:ddH2O处理,种子发芽后第1、3、6、9 d,lrn1、prl1和WT根尖成熟区根毛较少。0.2μmol/L 6-BA处理,种子发芽后第3 d,lrn1、prl1和WT根尖形成大量根毛,其中WT根毛最多、密度最大;prl1根毛最少,密度也最小;lrn1处于两者之间。种子发芽后第6 d,lrn1、prl1和WT分生区和伸长区明显缩短,lrn1和prl1分生区面积无显著差异,但两者均显著大于WT;lrn1和prl1根冠细胞结构较正常,而WT根冠细胞结构畸形;lrn1皮层原细胞之间排列较WT和prl1紧密。种子发芽后第9 d,lrn1已有4条侧根,但prl1与WT无侧根形成。6-BA处理,prl1主根较长,与其根尖分生区面积较大密切相关;lrn1侧根较多,可能与中柱原细胞排列密度较高密切相关。

Differences in Root Microscopic Structure of Root Mutants lrn1, prl1 and Wild Type in Oilseed Rape (Brassica napus L.)

Both lrn1 and prl1, two Brassica napus root mutants insensitive to exogenous cytokinin, show phosphorus efficiency. Compared with‘Ningyou 7’(WT) plants, lrn1 produces more lateral roots and prl1 has longer primary roots under 0.2 μmol/L cytokinins (6-BA) treatment by hydroponics. In this study, differences in root hair, differentiation of epidermal cells and anatomical structure of the root tip of all three genotypes under ddH₂O and 0.2 μmol/L 6-BA were studied with stereomicroscopy, non-sliced squash method and paraffin sectioning. Results showed that the root hair number at the zone of maturation in lrn1, prl1 and WT at ddH₂O was significantly less than that under 0.2 μmol/L 6-BA treatment. Under 0.2 μmol/L 6-BA treatment, the root hair length and density of WT was the longest and highest, while that of prl1 was the shortest and lowest, and that of lrn1 was between WT and prl1 3 days after germination (DAG3). The zone of cell division and cell elongation of lrn1, prl1 and WT were shortened under 0.2 μmol/L 6-BA DAG6. The meristem areas of lrn1 and prl1 were greater than that of WT, and there were no differences between these two mutants. Moreover, cell structure of the root cap of lrn1 and prl1 were normal, whereas, that of WT was abnormal. Periblem cell arrangements of lrn1 were closer than that of WT and prl1. Under 0.2 μmol/L 6-BA DAG9, lrn1 had four lateral roots, whereas prl1 and WT had no lateral roots. Longer primary root length of prl1 was closely related to its larger meristem area; and more lateral roots in lrn1 under 0.2 μmol/L 6-BA treatment were due to higher cell density in the plerome in the zone of cell division.