Propagula and shoots of Syntrichia pagorum (Pottiaceae) exhibit different ecological strategies of desiccation tolerance
Propagula and shoots of Syntrichia pagorum (Pottiaceae) exhibit different ecological strategies of desiccation tolerance
复制标题
DOI：
10.1639/0007-2745-119.2.181
复制
发表时间：
2016-07
期刊：
影响因子：
--
通讯作者：
L. Stark;J. Brinda;Joshua Greenwood
中科院分区：
文献类型：
--
作者：
L. Stark;J. Brinda;Joshua Greenwood
摘要我们提出了两个问题：(1)在繁殖期、幼苗期和成苗期，苔藓的脱水耐性(DT)的生态策略是什么？以及(2)在这三个生命阶段，哪个干燥因素、干燥速度或平衡相对湿度对植物存活和健康的影响更大？取自美国西南部的标本室标本，继代培养，去除田间效应，在原沙培养皿中培养6个月，依次产生幼芽、成株和繁殖苗。幼枝表现为诱导脱水耐性(IDT)的生态策略，繁殖枝和成体枝条主要表现为结构性脱水耐性(CDT)策略。这一结论是在两种干燥速率(20min和48h)和两种平衡相对湿度(RH分别为50%和1%)下进行的，并监测了复水后的发芽率(繁殖体)、视觉叶片损伤和叶绿素荧光(繁殖体和新梢)。我们首次发现：(1)苔藓植物培养、脱硬的成体枝条和繁殖体在平衡相对湿度为50%时具有固有的CDT；(2)干燥速率对复水植物健康的影响大于平衡相对湿度；(3)苔藓植物枝条在正常发育过程中可以从一种耐脱水的生态策略过渡到另一种策略。
Abstract We posed two questions regarding the desiccation tolerance (DT) of the moss Syntrichia pagorum: (1) What is the ecological strategy of DT in three available life phases (propagula, juvenile and adult shoots)? and (2) which desiccating factor, rate of drying or equilibrating relative humidity, has the greater effect on plant survival and health in these three life phases? Plants of S. pagorum were regenerated from an herbarium specimen collected from the American southwest, subcultured to remove field effects, and grown in Petri dishes on native sand for up to 6 months, producing in sequence juvenile shoots, adult shoots and propagula. Whereas juvenile shoots exhibited an ecological strategy of inducible desiccation tolerance (IDT), the propagula and adult shoots largely exhibited the strategy of constitutive desiccation tolerance (CDT). This conclusion was reached by subjecting each life phase to two rates of drying (20 min and 48 hours at subturgor) in combination with two equilibrating relative humidities (RH, 50% and <1%), and monitoring germination rate (propagula), visual leaf damage, and chlorophyll fluorescence (propagula and shoots) upon rehydration. We show for the first time that (1) cultured, dehardened adult shoots and propagula of a bryophyte are inherently CDT at an equilibrating RH of 50%, (2) rate of drying has a greater effect on rehydrated plant health than equilibrating RH, and (3) a bryophyte shoot can transition during normal development from one ecological strategy of desiccation tolerance to the alternative strategy.