Hayashi Adriana Hissae, Appezzato-da-Glória Beatriz
Seção de Anatomia e Morfologia, Instituto de Botânica, C.P. 3005, 01061-970, São Paulo, São Paulo, Brazil.
Rev Biol Trop. 2009 Sep;57(3):789-800. doi: 10.15517/rbt.v57i3.5493.
Previous studies pointed out that species richness and high density values within the Leguminosae in Brazilian forest fragments affected by fire could be due, at least partially, to the high incidence of root sprouting in this family. However, there are few studies of the factors that induce root sprouting in woody plants after disturbance. We investigated the bud formation on root cuttings, and considered a man-made disturbance that isolates the root from the shoot apical dominance of three Leguminosae (Bauhinia forficata Link., Centrolobium tomentosum Guill. ex Benth, and Inga laurina (Sw.) Willd) and one Rutaceae (Esenbeckia febrifuga (St. Hil.) Juss. ex Mart.). All these species resprout frequently after fire. We also attempted to induce bud formation on root systems by removing the main trunk, girdling or sectioning the shallow lateral roots from forest tree species Esenbeckia febrifuga and Hymenaea courbaril L. We identified the origin of shoot primordia and their early development by fixing the samples in Karnovsky solution, dehydrating in ethyl alcohol series and embedding in plastic resin. Serial sections were cut on a rotary microtome and stained with toluidine blue O. Permanent slides were mounted in synthetic resin. We observed different modes of bud origin on root cuttings: close to the vascular cambium (C. tomentosum), from the callus (B. forficata and E. febrifuga) and from the phloematic parenchyma proliferation (I. laurina). Fragments of B. forficata root bark were also capable of forming reparative buds from healing phellogen formed in callus in the bark's inner side. In the attempt of bud induction on root systems, Hymenaea courbaril did not respond to any of the induction tests, probably because of plant age. However, Esenbeckia febrifuga roots formed suckers when the main trunk was removed or their roots were sectioned and isolated from the original plant. We experimentally demonstrated the ability of four tree species to resprout from roots after disturbance. Our results suggest that the release of apical dominance enables root resprouting in the studied species.
先前的研究指出，在受火灾影响的巴西森林片段中，豆科植物内的物种丰富度和高密度值可能至少部分归因于该科植物根萌蘖的高发生率。然而，关于干扰后诱导木本植物根萌蘖的因素的研究很少。我们研究了根插条上的芽形成，并考虑了一种人为干扰，即隔离三种豆科植物（紫叶羊蹄甲Link.、绒毛合轴荚豆Guill. ex Benth和月桂英格（Sw.）Willd）以及一种芸香科植物（退热艾森柏（St. Hil.）Juss. ex Mart.）的根与茎尖优势。所有这些物种在火灾后都频繁萌蘖。我们还试图通过去除主干、环剥或切断森林树种退热艾森柏和孪叶豆的浅侧根来诱导根系上的芽形成。我们通过将样品固定在卡诺夫斯基溶液中、在乙醇系列中脱水并包埋在塑料树脂中来确定芽原基的起源及其早期发育。在旋转切片机上切取连续切片，并用甲苯胺蓝O染色。将永久切片安装在合成树脂中。我们观察到根插条上芽起源的不同模式：靠近维管形成层（绒毛合轴荚豆）、来自愈伤组织（紫叶羊蹄甲和退热艾森柏）以及来自韧皮薄壁组织增殖（月桂英格）。紫叶羊蹄甲根皮的碎片也能够从树皮内侧愈伤组织中形成的愈合木栓形成层形成修复芽。在对根系进行芽诱导的尝试中，孪叶豆对任何诱导试验都没有反应，可能是因为植株年龄。然而，当去除退热艾森柏的主干或切断其根系并与原植株分离时，其根系会形成吸根。我们通过实验证明了四种树种在干扰后从根萌蘖的能力。我们的结果表明，顶端优势的解除使所研究的物种能够从根上重新萌发生长。
