生长素和模拟微重力效应对大白菜不定根形态发生的影响  

EFFECTS OF IAA AND STIMULATED MICROGRAVITY ON FORMATION OF ADVENTITIOUS ROOTS OF CHINESE CABBAGE

作　　者：李小方[1] 何玉科[1] 汤章城[1] 

机构地区：[1]中科院上海植物生理研究所,上海200032

出　　处：《实验生物学报》2000年第2期179-187,共9页Acta Biologiae Experimentalis Sinica

基　　金：国家自然科学基金(批准号:39870450)

摘　　要：在生长素诱导下,大白菜(Brassicaampestris.spp.pekinensis)的下胚轴切段显示了一定的发根能力,其中,0.4—1.0mg/L IAA显著地促进大白菜不定根的发生。在生长素诱导24h后,可借助显微切片观察到下胚轴切面明显的解剖学变化:首先是中柱鞘内靠近韧皮部的薄壁细胞的细胞质与细胞核变浓,染色加深,部分细胞分裂;随后是分裂的细胞团增大,逐渐形成根原基并分化出根冠。当下胚轴切段培养5天后,大量不定根穿破皮层,达到肉眼可见的程度。同一外植体中不定根的发育是不同步的,下胚轴不同部位的切段具有不同的发根能力;当下胚轴切段在培养基上反插时,提高外源IAA可修饰根发生的极性,提高蔗糖浓度能增强IAA的修饰作用;在模拟微重力效应条件下,不定根发生的极性没有明显变化,但是,增加了外植体对IAA诱导发根的敏感性。本结果为进一步研究不定根发生的分子机制建立了试验系统。Under the induction of indoLe-3-acetic acid (IAA) .adventitious roots were differentiated on hypocotyl segments derived from seedlings of Chinese cabbage ( Brassica campestris spp. pekinensis). IAA at concentration of 0.4-1.0 mg/L in solid MS medium incited many adventitious roots on hypocotyL segments. The earliest anatomic changes were observed on cut surface of hypocotyl segments under optical microscope 24 hours after IAA treatment; cytoplasmic and nuclear density became higher in a few of parenchytmatous cells adjacent to phloem in tissue of pericycle, followed by cell divisions. Lately, the dividing cells expanded and developed into root primordium from which root cap was differ- entiated. After five days, most roots protruded through hypocotyl cortex and appeared just below the cut surface. The rooting capacity of the segments derived from three regions of each hypocotyl was different. High level of IAA modified the polarity of root formation on segment inserted upside down and sucrose increased the function of IAA. Additionally, microgravity did not significantly change the rooting polarity under the condition of stimulated microgravity, but it increased the competence of explants to IAA treatment. The results presented here provided an experimental system for further investigation of molecular events associated with adventitious root initiation.

关 键 词：大白菜 不定根 生长素 模拟微重力效应 下胚轴 

分 类 号：S634.1[农业科学—蔬菜学]