Floodwater Oxygen Content, Ethylene Production and Lenticel Hypertrophy in Flooded Mango (Mangifera indica L.) Trees

A system was developed to test the effects of floodwater O₂concentration on ethylene evolution and stem lenticel hypertrophy,and the effects of exogenous ethylene on stem lenticel hypertrophyin mango (Mangifera indica L.) trees. Dissolved O₂ concentrationsof 1–7x10^–9 m³ m^–3 generally resulted in hypertrophyof stem lenticels within about 6 d of flooding, whereas floodwaterO₂ concentrations of 13–15 x 10^–9 m³ m^–3 delayedhypertrophy until about day 9. After 14d of flooding, therewere more than twice the number of hypertrophied lenticels pertree with floodwater O₂ concentrations of 1–7 x 10^–9m³ m^–3 than with floodwater O₂ concentrations of 15 x10^–9 m³ m^–3. Ethylene evolution from stem tissueimmediately above the floodline increased 4- to 8-fold in treesexposed to floodwater O₂ concentrations of 1–2 x 10^–9m³ m^–3, increased 2-fold for trees exposed to floodwaterO₂ concentrations of 6–7 x 10^–9 m³ m^–3, butremained constant with floodwater O₂ concentrations of 13–15x 10^–9 m³ m^–3. Plants maintained in highly oxygenatedfloodwater (13–15 x 10^–9 m³ m^–3), and givenexogenous ethylene developed many hypertrophied lenticels, whereasplants in highly oxygenated water and not given ethylene developedfewer or nohypertrophied lenticels. These data suggest thatethylene plays a role in promotion of stem lenticel hypertrophyin flooded mango trees, and that floodwater dissolved oxygenconcentration can regulate stem lenticel hypertrophy and ethyleneevolution in this species. Key words: Flooding, hypoxia, hypertrophic cell swelling     

用分子标记研究禾本科赖草属植物可溶性碳水化合物、色素积累和生长特性之间的遗传相关性

在低温条件下,冷季草的可溶性碳水化合物通常与紫色素的积累、生长的缓慢性及对寒冷的适应性具有相关性.Vrn-1基因对一年生冬性禾本科物种的春化、生长和可溶性碳水化合物的积累有重要作用.本研究以Leymus cinereus×L. triticoides的杂种F1开放授粉获得的F2群体为材料,用204个未定位的AFLP分子标记和几个基因组特定的与 vrn-1相连锁的DNA标记检测了控制可溶性碳水化合物的积累、紫色素的积累和生长特性等几个数量性状的QTL.根据生长特性和适应性可将 Leymus cinereus和L. triticoides区分开来.研究表明可溶性碳水化合物与紫色素的积累呈正相关,而且有关基因对这两种性状具有多效性.与之相类似,分蘖、叶发育、叶生长、草被剪后的再生长和地下茎的蔓延性这些性状之间也呈正相关,控制这些性状的基因具有多效性.但是可溶性碳水化合物的积累与生长的缓慢性无相关性.有几个分子标记包括与vrn-Xm1 邻近的一个分子标记对叶可溶性碳水化合物的浓度和低温生长具有正效应.而与vrn-Ns1邻近的一个DNA标记对分蘖具有更加特别的效应.我们推测vrn-1对多年生赖草低温下叶可溶性碳水化合物的积累及生长习性具有数量效应.发现几个DNA标记对可溶性碳水化合物的积累及多个生长特性有较强的作用.研究结果暗示在赖草中紫色素的积累可作为可溶性碳水化合物积累的形态标记.