异质性重金属镉胁迫下克隆整合对匍匐茎草本植物积雪草生长的影响

doi:10.3724/SP.J.1258.2011.00864

摘要/Abstract

摘要：

采用盆栽试验研究了异质性重金属镉胁迫下, 克隆整合对匍匐茎草本植物积雪草(Centella asiatica)生长的影响。将远端分株(相对年幼的分株)分别置于对照和镉胁迫处理下, 并对远端分株与近端分株(相对年长的分株)之间的匍匐茎进行切断或保持连接处理。研究结果显示: 镉胁迫处理显著降低了积雪草远端分株的净光合速率(P_n)、最大光量子产量(F_v/F_m)、叶绿素含量、叶面积、分株数和生物量; 克隆整合缓解了镉胁迫对远端分株生长的不利影响; 克隆整合不仅未导致相连近端分株的损耗, 而且相连近端分株的光合效率也没有表现出补偿性增加; 克隆整合降低了远端受胁迫分株的根冠比, 从而使之减少了对土壤中重金属镉的吸收; 匍匐茎切断和镉胁迫处理对近端分株、远端分株的叶柄长没有显著的影响。结果表明: 克隆整合提高了积雪草遭受镉胁迫的远端分株的生长, 改变了其生物量分配格局, 并有助于整个克隆片段在异质性重金属胁迫下的生长。该研究对于丰富和发展异质性环境胁迫下克隆整合的生态适应对策具有重要意义。

关键词: 适应策略, 镉胁迫, 克隆整合, 光合效率, 匍匐茎切断

Abstract:

Aims A pot experiment to examine the effects of clonal integration on growth of the stoloniferous herb Centella asiaticasuffering from heterogeneous heavy metal Cd²⁺stress was conducted to address two questions: (1) does clonal integration alleviate the negative effects on growth of clonal plants suffering from heterogeneous heavy metal stress; and (2) do the ramets growing in unfavorable microhabitats incur increased photosynthetic efficiency in the connected ramets?

Methods Relatively young, distal ramets of C. asiatica were assigned to normal or Cd²⁺ stressed soil, and the stolon connections between the relatively old proximal ramets and the young distal ramets were either severed or left intact. The net photosynthetic rate (P_n), chlorophyll fluorescence (maximum quantum yield of PSII, F_v/F_m) and chlorophyll contents of distal ramets and P_n of proximal ramets were measured. The growth performance of distal and proximal ramets was investigated at the end of the experiment.

Important findings Cd²⁺stress treatment significantly decreased the P_n, F_v/F_m, chlorophyll contents and growth of distal ramets. Clonal integration significantly alleviated the negative effect of Cd²⁺stress to distal ramets in terms of P_n, F_v/F_m, chlorophyll contents and biomass of distal ramets. There was no significant cost to the connected proximal ramets, and clonal integration did not incur increased photosynthetic efficiency in the proximal ramets. In addition, clonal integration significantly decreased root to shoot ratio of distal ramets suffering from Cd²⁺stress, and reduced the uptake of the heavy metal. Petiole length of proximal and distal ramets was not significantly affected by stolon severing and Cd²⁺stress. It is suggested that clonal integration may enhance growth of clonal plants suffering from heterogeneous heavy metal stress.

Key words: adaptation strategy, Cd²⁺ stress, clonal integration, photosynthetic efficiency, stolon severing

刘富俊, 黎云祥, 廖咏梅, 陈劲松, 权秋梅, 龚新越. 异质性重金属镉胁迫下克隆整合对匍匐茎草本植物积雪草生长的影响. 植物生态学报, 2011, 35(8): 864-871. DOI: 10.3724/SP.J.1258.2011.00864

LIU Fu-Jun, LI Yun-Xiang, LIAO Yong-Mei, CHEN Jin-Song, QUAN Qiu-Mei, GONG Xin-Yue. Effects of clonal integration on growth of stoloniferous herb Centella asiaticasuffering from heterogeneous heavy metal Cd<sup>2+</sup>stress. Chinese Journal of Plant Ecology, 2011, 35(8): 864-871. DOI: 10.3724/SP.J.1258.2011.00864

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https://www.plant-ecology.com/CN/Y2011/V35/I8/864

图/表 7

图1 试验设计图解。NS-CS, 匍匐茎保持连接且对远端分株实施镉胁迫; NS||CS, 匍匐茎切断且对远端分株实施镉胁迫; NS-NS, 匍匐茎保持连接且对远端分株不实施镉胁迫; NS||NS, 匍匐茎切断且对远端分株不实施镉胁迫。

Fig. 1 Schematic representation of the experimental design. NS-CS, stolon connections left intact and distal ramets are assigned to Cd2+ stressed soil; NS||CS, stolon connections are severed and distal ramets are assigned to Cd2+ stressed soil; NS-NS, stolon connections are left intact and distal ramets are assigned to normal soil; NS||NS, stolon connections are severed and distal ramets are assigned to normal soil.

表1 匍匐茎切断(S)和镉胁迫(C)及其交互作用(S × C)对积雪草近端、远端分株和(或)整个克隆片段叶柄长、叶面积、分株数、生物量和根冠比的双因素方差分析

Table 1 Results of two-way analysis of variance on the effects of stolen severing (S), Cd2+ stress (C) and their interaction (S × C) on petiole length, leaf area, number of ramets, biomass and root to shoot ratio of the proximal, distal ramets and/or the whole clonal fragments of Centella asiatica

	叶柄长 Petiole length	叶面积 Leaf area	分株数 Number of ramets	生物量 Biomass	根冠比 Root to shoot ratio
近端分株 Proximal ramets, df(1,12)
S	0.14^ns	0.01^ns	25.00^**	0.56^ns	1.50^ns
C	0.01^ns	0.02^ns	1.00^ns	0.16^ns	2.27^ns
S × C	0.04^ns	0.08^ns	1.00^ns	1.55^ns	2.39^ns
远端分株 Distal ramets, df(1,12)
S	0.40^ns	1.84^ns	6.25^*	0.96^ns	1.83^ns
C	3.46^ns	11.01^**	20.25^**	39.38^**	9.08^*
S × C	0.08^ns	1.45^ns	2.25^ns	5.25^*	3.44^ns
克隆片段 Whole clonal fragments, df(1,16)
S	-	1.58^ns	0.00^ns	1.74^ns	-
C	-	21.66^**	10.67^*	34.70^**	-
S × C	-	3.20^ns	0.67^ns	4.95^*	-

图2 近端、远端分株和整个克隆片段的叶面积(A)、分株数(B)和生物量(C) (平均值±标准误差)。对于近端和远端分株, 相同的小写字母表示各处理间差异不显著(p = 0.05); 对于整个克隆片段, 相同的希腊字母表示各处理间差异不显著 (p = 0.05)。NS-CS, 匍匐茎保持连接且对远端分株实施镉胁迫; NS||CS, 匍匐茎切断且对远端分株实施镉胁迫; NS-NS, 匍匐茎保持连接且对远端分株不实施镉胁迫; NS||NS, 匍匐茎切断且对远端分株不实施镉胁迫。

Fig. 2 Leaf area (A), number of ramets (B) and biomass (C) of the proximal, distal ramets and the whole clonal fragments (mean ± SE). For the proximal and distal ramets, the same lowercase letters are not significantly different at p = 0.05, for the whole clonal fragments, the same Greek letters are not significantly different at p = 0.05. NS-CS, stolon connections left intact and distal ramets are assigned to Cd 2+ stressed soil; NS||CS, stolon connections are severed and distal ramets are assigned to Cd2+ stressed soil; NS-NS, stolon connections are left intact and distal ramets are assigned to normal soil; NS||NS, stolon connections are severed and distal ramets are assigned to normal soil.

图3 近端、远端分株的叶柄长(A)和根冠比(B) (平均值±标准误差)。相同小写字母表示各处理间差异不显著(p = 0.05)。NS-CS, 匍匐茎保持连接且对远端分株实施镉胁迫; NS||CS, 匍匐茎切断且对远端分株实施镉胁迫; NS-NS, 匍匐茎保持连接且对远端分株不实施镉胁迫; NS||NS, 匍匐茎切断且对远端分株不实施镉胁迫。

Fig. 3 Petiole length (A) and root to shoot ratio (B) of the proximal and distal ramets (mean ± SE). The bars with the same lowercase letters are not significantly different at p = 0.05. NS-CS, stolon connections left intact and distal ramets are assigned to Cd 2+ stressed soil; NS||CS, stolon connections are severed and distal ramets are assigned to Cd2+ stressed soil; NS-NS, stolon connections are left intact and distal ramets are assigned to normal soil; NS||NS, stolon connections are severed and distal ramets are assigned to normal soil.

表2 积雪草远端分株净光合速率(Pn)、叶绿素荧光(最大光量子产量, Fv/Fm)和叶绿素含量(SPAD values)以及近端分株的Pn的双因素重复测量方差分析, 以匍匐茎切断(S)和镉胁迫(C)作为组间因素

Table 2 Results of Two-way repeated-measure analysis of variance, with stolen severing (S) and Cd2+ stress (C) as between-subject effects, for differences in net photosynthesis rate (Pn), chlorophyll fluorescence (maximum quantum yield of photosystem II, Fv/Fm) and chlorophyll contents (SPAD values) between distal ramets and Pn between proximal ramets of Centella asiatica

	近端分株 Proximal ramets		远端分株 Distal ramets
	P_n		P_n		F_v/F_m		SPAD
	df	F	df	F	df	F	df	F
组间效应 Between-subject effects
S	1	0.03^ns	1	6.49*	1	5.71*	1	5.18*
C	1	0.54^ns	1	66.00**	1	5.89*	1	35.29**
S × C	1	0.39^ns	1	10.96 *	1	2.38^ns	1	1.80^ns
误差 Error	8		8		8		12
组内效应 Within-subject effects
次数 Time	3	0.41^ns	3	0.24^ns	2	0.84^ns	3	5.58*
切断×次数 S × time	3	0.17^ns	3	0.17^ns	2	2.20^ns	3	0.48 ^ns
镉胁迫×次数 C × time	3	0.14^ns	3	2.75^ns	2	5.17^ns	3	5.66*
切断×镉胁迫×次数 S × C × time	3	1.68^ns	3	0.14^ns	2	1.29^ns	3	0.23^ns
误差 Error	24		24		16		36

图4 远端分株(A)和近端分株(B)的净光合速率(Pn)随时间的变化(平均值±标准误差)。◆、■、▲和×分别表示匍匐茎切断且对远端分株实施镉胁迫处理、匍匐茎保持连接且对远端分株实施镉胁迫处理、匍匐茎切断且对远端分株不实施镉胁迫处理和匍匐茎保持连接且对远端分株不实施镉胁迫处理。

Fig. 4 Variations of net photosynthetic rate (Pn) of distal ramets (A) and proximal ramets (B) with time (mean ± SE). ◆, ■, ▲ and × represent stolon connections are severed and distal ramets are assigned to Cd 2+ stressed soil, stolon connections left intact and distal ramets are assigned to Cd2+ stressed soil, stolon connections are severed and distal ramets are assigned to normal soil, and stolon connections are left intact and distal ramets are assigned to normal soil treatments, respectively.

图5 远端分株的光系统II最大光量子产量(A)和叶绿素含量(B)随时间的变化(平均值±标准误差)。◆、■、▲和×分别表示匍匐茎切断且对远端分株实施镉胁迫处理、匍匐茎保持连接且对远端分株实施镉胁迫处理、匍匐茎切断且对远端分株不实施镉胁迫处理和匍匐茎保持连接且对远端分株不实施镉胁迫处理。远端分株的第6周测定的最大光量子产量数据不可用。

Fig. 5 Variations of maximum quantum yields of photosystem II (A) and chlorophyll contents (B) of distal ramets with time (mean ± SE). ◆, ■, ▲ and × represent stolon connections are severed and distal ramets are assigned to Cd 2+ stressed soil, stolon connections left intact and distal ramets are assigned to Cd2+ stressed soil, stolon connections are severed and distal ramets are assigned to normal soil, and stolon connections are left intact and distal ramets are assigned to normal soil treatments, respectively. Data on maximum quantum yields of photosystem II in distal ramets is not available at sixth week.

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