全 文 ：拟南芥叶片衰老过程中细胞溶血磷脂和膜脂不饱和度的变化*
贾艳霞1,2, 李唯奇1**
(1 中国科学院昆明植物研究所 中国西南野生生物种质资源库, 云南 昆明摇 650201;
2 中国科学院大学, 北京摇 100049)
摘要: 细胞膜的流动性和渗透性的改变是植物衰老过程中一个内在的、 具有破坏性的变化。 膜脂组成中,
溶血磷脂的出现是膜伤害的一个重要标志; 膜脂双键数目的变化是影响膜流动性的主要因素。 应用脂类组
学的方法, 检测了拟南芥野生型及其磷脂酶 D啄 (PLD啄) 缺失型突变体在离体诱导的、 脱落酸 (abscisic
acid, ABA) 和乙烯 (ethylene) 促进的衰老过程中, 溶血磷脂 ( lysophospholipids, lysoPLs) 的分子变化,
并通过计算膜脂双键指数 (double bond index, DBI) 表征了膜流动性的变化。 结果表明, 在离体诱导的衰
老过程和乙烯促进的衰老过程中, 溶血磷脂的总含量和各溶血磷脂分子的变化不显著, 而在 ABA 促进的
衰老过程中溶血磷脂总含量和部分溶血磷脂分子均显著升高; 在上述三种衰老处理下, 总膜脂的 DBI均下
降, 但是离体诱导和激素促进的的衰老过程中各类膜脂的 DBI 的变化却不同。 同时我们还发现, 抑制
PLD啄基因表达降低了 ABA促进的衰老过程中溶血磷脂的产生、 减缓了 ABA 和乙烯促进的衰老过程中总
的膜脂的 DBI的降低。
关键词: 拟南芥; 磷脂酶 D啄; 乙烯; 脱落酸; 衰老
中图分类号: Q 945摇 摇 摇 摇 摇 摇 文献标识码: A摇 摇 摇 摇 摇 摇 摇 文章编号: 2095-0845(2013)05-569-09
Changes in Lysophospholipid and Degree of Unsaturated Membrane
Lipids are Associated With Senescence in Arabidopsis Leaves
JIA Yan鄄Xia1,2, LI Wei鄄Qi1**
(1 Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany,
Chinese Academy of Sciences, Kunming 650201, China; 2 University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: Alterations of membrane fluidity and permeability are an inherent feature of deterioration associated with
senescence in plants. With regard to membrane lipid constituents, the occurrence of lysophospholipid (lysoPL) is a
signal of membrane damage, while changes in the double bond number of membrane lipids has important effects on
membrane fluidity. In the present study, a lipidomics approach was used to study changes in lysoPL molecular spe鄄
cies, and, in addition, the double bond index (DBI) of membrane lipids was calculated to indicate membrane fluid鄄
ity in wild type (WS) and a phospholipid D啄 (PLD啄) knockout mutant of Arabidopsis during detachment鄄induced,
abscisic acid (ABA)鄄 or ethylene鄄promoted senescence. The results indicated that the content of total lysoPLs and
some lysoPL molecular species increased markedly during ABA鄄promoted senescence, while no significant change
was detected during detachment鄄induced and ethylene鄄promoted senescence. The DBI of total membrane lipids de鄄
creased during three senescence treatments; however, the pattern of change for each membrane lipid class differed
between detachment鄄induced and hormone鄄promoted senescence. Suppression of PLD啄 attenuated lysoPLs accumula鄄
植 物 分 类 与 资 源 学 报摇 2013, 35 (5): 569 ~ 577
Plant Diversity and Resources摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 DOI: 10. 7677 / ynzwyj201312124
*
**
Funding: The National Basic Research Program of China (31070262), Fund of State Key Laboratory of Phytochemistry and Plant Resources
in West China (O97C0211Z1)
Author for correspondence; E鄄mail: weiqili@ mail. kib. ac. cn
Received date: 2012-10-12, Accepted date: 2013-01-15
作者简介: 贾艳霞 (1982-) 女, 博士, 工程师, 主要从事植物逆境分子生理学研究。 E鄄mail: jiayanxia@ mail. kib. ac. cn
tion during ABA鄄promoted senescence, and slowed down the decrease of DBI of the total membrane lipids during
ABA鄄 and ethylene鄄promoted senescence.
Key words: Arabidopsis; Phosphalipase D啄; Ethylene; ABA; Senescence
Abbreviations: abscisic acid (ABA); phospholipase D (PLD); Lysophospholipid ( lysoPL); double bond index
(DBI); phosphatidylcholine ( PC); phosphatidylglycerol ( PG); phosphatidylinositol ( PI); phosphatidic acid
(PA); phosphatidylserine ( PS); digalactosyldiacylglycerol ( DGDG); monogalactosyldiacylglycerol ( MGDG);
phosphatidylethanolamine (PE); electrospray ionization tandem mass spectrometry (ESI鄄MS / MS)
摇 Leaf senescence, as an integral part of plant
development, occurs in the last stage of leaf develo鄄
pment (Lim et al., 2007). The changes most close鄄
ly associated with senescence are declines in total
protein and RNA levels and chloroplast breakdown.
Under constant environmental conditions, senes鄄
cence occurs in response to aging and is relatively
constant and predictable ( Hensel et al., 1993 ).
However, certain stress such as drought or nutrient
limitation or darkness can result in premature senes鄄
cence, shortening the lifetime of individual leaves or
indeed the whole plants. Moreover, hormones also
are able to hasten or repress senescence, and ABA
and ethylene was known for accelerating leaf senes鄄
cence and inducing visible yellowing ( Oh et al.,
1996; Weaver et al., 1998).
Macromolecule degradation is likely to increase
the levels of radical species such as reactive oxygen
species (ROS) in senescing tissues ( Thompson et
al., 1998). The increased of radical species can
induce lipid peroxidation, which alter membrane flu鄄
idity and permeability ( Thompson et al., 2000).
Membrane deterioration leading to leakiness and loss
of selective permeability is an early and ubiquitous
feature of senescence (Fan et al., 1997; Lim et al.,
2005; Espinoza et al., 2007; Mart侏nez et al.,
2008). Membrane lipids (Wanner et al., 1991),
play a pivotal role by impacting membrane properties
like fluidity, permeability and active transport. Gen鄄
erally, the unsaturation degree of membrane lipids is
used to reflect membrane fluidity ( Bakht et al.,
2006 ). Galactolipids ( monogalactosyldiacylglycer鄄
ol, MGDG; digalactosyldiacylglycerol, DGDG ),
which are the dominant component of thylakoid
membranes, are main contributors to membrane un鄄
saturation because they harbor more trienoic fatty
acids than other membrane phospholipids (phosphati鄄
dylcholine, PC; phosphatidylethanolamine, PE ).
Disruption of membrane integrity is additional impor鄄
tant feature associated with senescence in plant (Fan
et al., 1997; Thompson et al., 1998). The levels
of total lipids decrease in senescing leaves and it ap鄄
pears that the membranes of the cell including the
thylakoid membranes are metabolized to provide en鄄
ergy for senescence process (Harwood et al., 1982;
Wanner et al., 1991 ). Lysophospholipids ( Lyso鄄
PLs) including lysophosphatidylcholine ( lysoPC),
lysophosphatidylglycerol ( lysoPG), and lysophos鄄
phatidylethanolamine ( lysoPE), are derived from
the hydrolysis of phospholipids at the sn鄄1 or sn鄄2
position of the glycerol backbone. In comparison
with other membrane glycerolipid, the content of ly鄄
soPLs in Arabidopsis is low but very sensitive to
stress such as freezing, heat鄄shock, and dehydra鄄
tion. Upon exposure to stress, lysoPLs usually in鄄
crease by five鄄 to 20鄄 fold within hour or even mi鄄
nutes (Welti et al., 2002; Li et al., 2008). Exoge鄄
nous application of lysoPE is purported to delay leaf
senescence in plants (Hong et al., 2009). Howev鄄
er, how the endogenous lysoPL response to leaf se鄄
nescence is unknown.
Phospholipase D啄 ( PLD啄), which is one of
twelve PLDs in Arabidopsis, has several properties
that distinguish it from other PLDs (Gardiner et al.,
2001; Wang and Wang, 2001). PLD啄 is activated
by oleic acid and is tightly associated with the plas鄄
ma membrane and microtubule cytoskeleton (Gardi鄄
ner et al., 2001; Wang and Wang, 2001). Analy鄄
075摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 植 物 分 类 与 资 源 学 报摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 第 35 卷
ses of PLD啄鄄altered Arabidopsis suggest that PLD啄
positively regulate plant tolerance to stress such as
freezing (Li et al., 2004; Li et al., 2008), and ul鄄
tra鄄violet irradiation (Zhang et al., 2003). Accord鄄
ing to our previous study, suppression of PLD啄 re鄄
tarded ABA鄄and ethylene鄄promoted senescence ( Jia
et al., 2013), while the change in lysoPLs content,
the unsaturation degree of membrane glycerolipids
and the effects of PLD啄 during such senescence
process have not been investigated.
In the present study, electrospray ionization
and tandem mass spectrometry ( ESI鄄MS / MS) was
used to examine the changes in the lysoPLs and the
unsaturation degree of membrane lipid during de鄄
tachment鄄induced leaf senescence and ABA鄄 or eth鄄
ylene鄄promoted leaf senescence in wild type (WS)
and PLD啄鄄KO mutant Arabidopsis. The results showed
that response patterns of lysoPLs were different,
while changes in DBI of membrane lipid were similar
during ABA鄄 and ethylene鄄promoted senescence.
Moreover, the association of lysoPLs and DBI of
membrane lipid with PLD啄鄄mediated retardation of
ABA鄄 and ethylene鄄promoted senescence were also
been analyzed.
1摇 Methods and materials
1. 1摇 Plant materials
A PLD啄鄄kncokout mutant was preciously isola鄄
ted from Arabidopsis Wassilewskija ecotype (WS).
The loss of PLD啄 was confirmed by the absence of
the transcript, protein, and activity of PLD啄 (Li et
al., 2008).
1. 2摇 Growth conditions and hormone treatments
Two Arabidopsis genotypes were hydroponic sys鄄
tem in a controlled growth chamber with 23 益 (day)
and 19 益 (night) and 60% relative humidity under
a 12鄄h photoperiod fluorescent lighting of 120 滋mol
·m-2·s-1 . Fully expanded leaves were collected from
6鄄week鄄old Arabidopsis plants. The detached leaves
were rinsed briefly with sterile water and placed ad鄄
axial side up in Petri dishes containing water or the
final concentration of 50 滋M ABA (Sigma鄄Aldrich,
St Louis, USA, A1049 ) or ethephon ( Sigma鄄
Aldrich, St Louis, USA, C0143). Ethephon was
chosen to treat the detached leaves, because it was
easier to control and have identical effect on the de鄄
tached leaves comparing with ethylene. The leaves
were incubated at 依 23 益 under a 12鄄h photoperiod
and light of 120 滋mol·m-2·sec-1 .
1. 3摇 Lipid extraction and ESI / MS鄄MS analysis
The process of lipid extraction, ESI鄄MS / MS a鄄
nalysis, and quantification was performed as de鄄
scribed previously with minor modification (Welti et
al., 2002; Li et al., 2008). Each sample contained
two or three detached leaves with a pooled dry weight
of 2 to 9 mg, and five replicates for each genotype
were analyzed. To inhibit lipolytic activities, leaves
were transferred immediately into 3 mL of isopropanol
with 0. 01% butylated hydroxytoluene at 75 益 and
extracted several times with chloroform / methanol
(2 颐1) with 0. 01% butylated hydroxytoluene, until
all of the remaining leaves appeared white. Automa鄄
ted ESI鄄MS / MS analysis was performed in the Kansas
Lipidomics Research Center Analytical Laboratory.
1. 4摇 Data analysis
Statistical analysis was performed using Origin
7.0 (OriginLab Corporation, Northampton, MA, USA).
Double bond index (DBI) were calculated with the
formula: DBI= [移(N伊mol% lipid)] / 100, where
N was the total number of double bonds in the two
fatty acid chains of each glycerolipid molecule
(Zheng et al., 2011). For all quantitative measure鄄
ments in present study, five replicates from each
sampling time were analyzed. The data were subjec鄄
ted to one鄄way analysis of variance (ANOVA) with
SPSS 16. 0. Statistical significance was tested by
Fisher爷s least significant difference (LSD) method.
2摇 Results and Discussion
2. 1 摇 Total lysoPLs increased significantly while
PLD啄鄄KO mutant Arabidopsis showed lower ly鄄
soPLs during ABA鄄promoted senescence
That fact that exogenous application of lysoPE
delay leaf senescence (Hong et al., 2009) urged us
1755 期摇 摇 摇 JIA and LI: Changes in Lysophospholipid and Degree of Unsaturated Membrane Lipids are Associated …摇 摇 摇
to find out how the endogenous lysoPLs (lysoPE, ly鄄
soPC and lysoPG) respond to three treatments that in鄄
duced senescence artificially. In the first, detachment鄄
induced senescence, detached Arabidopsis leaves were
floated on water. In the second and the third, de鄄
tachment鄄induced senescence was accelerated by the
addition of ABA and ethephon, respectively.
During ABA鄄promoted senescence, the content
of lysoPC, lysoPE and lysoPG increased significant鄄
ly, which increase by 180% , 250% and 200% of
initial level at day 5, respectively (Table 1). Leav鄄
es treated with water or ethylene did not show signif鄄
icant changes in total lysoPLs content comparing
with ABA treatment ( Table 1). Moreover, losing
PLD啄 activity attenuated amount of accumulated ly鄄
soPLs compared to WS during ABA鄄promoted senes鄄
cence, but not during detachment鄄induced and eth鄄
ylene鄄promoted senescence ( Table 1 ). These re鄄
sults suggested that endogenous lysoPLs only in鄄
creased during ABA鄄promoted senescence, whereas
no significant changes were detected during detach鄄
ment鄄induced or ethylene鄄promoted senescence, and
the change of lysoPLs might not be a universal
process ( such as chlorophyll content) during leaf
senescence. Thus, more evidences were needed to
verify the effect of endogenous lysoPLs on leaf senes鄄
cence.
2. 2 摇 The change patterns of lysoPLs molecular
species were different in the three senescence
treatments
The change patterns of each lysoPL molecular
species responding to senescence were also be ana鄄
lyzed. LysoPLs contain mostly 16颐0, 18颐2, and 18颐3
species, although 16 颐1 is also a significant molecular
species in lysoPE. When leaves incubated in water,
no significant changes in lysoPLs species were dis鄄
covered, except for some individual molecular spe鄄
cies, such as 16 颐0鄄, 18 颐2鄄, 18 颐3鄄lysoPE (Fig. 1A).
During ABA鄄promoted senescence, unsaturated lyso鄄
PL molecular species, such as 18 颐3鄄lysoPC, 16 颐1鄄,
18颐3鄄, and 18颐2鄄lysoPE, and saturated molecular spe鄄
cies, such as 16 颐0鄄LysoPC and 16 颐 0鄄lysoPE tended
Table 1摇 Changes in total amount of lysoPLs classes under three senescence treatments.
The dry weight is dry weight minus lipid
Lipids
classes Treatments Genotypes
Lipids (dry weight) / nmol·(mg) -1
0 day 3 days 5 days
RC / %
3 days 5 days
water WSPLD啄鄄KO
0. 02 依 0. 01a
0. 02 依 0. 01a
0. 01 依 0. 01a
0. 01 依 0. 01a
0. 01 依 0. 00a
0. 01 依 0. 00a
—
—
—
—
LysoPG ABA WSPLD啄鄄KO
0. 02 依 0. 01b
0. 02 依 0. 01a
0. 02 依 0. 00b
0. 01 依 0. 01a*
0. 06 依 0. 03a
0. 01 依 0. 00a*
—
—
200
—
ETH WSPLD啄鄄KO
0. 02 依 0. 01a
0. 02 依 0. 01a
0. 01 依 0. 00a
0. 01 依 0. 00a
0. 00 依 0. 00a
0. 01 依 0. 00a
—
—
—
—
water WSPLD啄鄄KO
0. 05 依 0. 02a
0. 05 依 0. 01a
0. 02 依 0. 01b
0. 05 依 0. 01a
0. 04 依 0. 01a
0. 04 依 0. 01a
-60
—
—
—
LysoPC ABA WSPLD啄鄄KO
0. 05 依 0. 02b
0. 05 依 0. 01c
0. 12 依 0. 02a
0. 08 依 0. 02b*
0. 14 依 0. 01a
0. 12 依 0. 03a
140
60
180
140
ETH WSPLD啄鄄KO
0. 05 依 0. 02a
0. 05 依 0. 01a
0. 06 依 0. 02a
0. 04 依 0. 02a
0. 04 依 0. 01a
0. 04 依 0. 01a
—
—
—
—
water WSPLD啄鄄KO
0. 04 依 0. 01a
0. 04 依 0. 01a
0. 02 依 0. 00b
0. 04 依 0. 01a
0. 03 依 0. 00a
0. 03 依 0. 02a
-50
—
—
—
LysoPE ABA WSPLD啄鄄KO
0. 04 依 0. 01c
0. 04 依 0. 01c
0. 10 依 0. 01b
0. 08 依 0. 01b*
0. 14 依 0. 02a
0. 11 依 0. 02a*
150
100
250
175
ETH WSPLD啄鄄KO
0. 04 依 0. 01a
0. 04 依 0. 01a
0. 06 依 0. 03a
0. 04 依 0. 01a
0. 06 依 0. 03a
0. 04 依 0. 01a
—
—
—
—
Values are means 依S. D. (n=4 or 5) . Values with different letters are significantly different (P<0. 05) . “*冶 indicates that the value is signifi鄄
cantly different from that of the WS under the same condition (P<0. 05)
275摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 植 物 分 类 与 资 源 学 报摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 第 35 卷
to increase, while there was no significant change in
other lysoPL molecular species during ABA鄄promo鄄
ted senescence ( Fig. 1B). Although ethylene also
promoted leaf senescence, the patterns of lysoPLs
molecular species change in ethylene鄄promoted se鄄
nescence was different from that in ABA鄄promoted
senescence. During ethylene鄄promoted senescence,
the content of 18 颐 2鄄lysoPC and 18 颐 2鄄lysoPE de鄄
creased to 33% and 50% of initial levels, respec鄄
tively (Fig. 1C). Ablation of PLD啄 resulted in less
increasing of 16 颐 0鄄, 18 颐 3鄄lysoPC and 16 颐 1鄄lysoPE
molecular species during ABA鄄promoted senescence
comparing with WS, while no differences in levels of
any lysoPL species were detected between WS and
PLD啄鄄KO plants during detachment鄄induced and
ethylene鄄promoted senescence (Fig. 1). The results
suggested that ABA and ethylene both promoted leaf
senescence while differed in lysoPLs molecular spe鄄
cies response. PLD啄 only involved in some lysoPLs
molecular species production during ABA鄄promoted
senescence, but more studies were needed to prove
if it contributed to the retardation of ABA鄄promoted
senescence.
2. 3摇 The change patterns of DBI were different
among lipid classes
The unsaturation degree of membrane lipid sig鄄
nificantly impacts the fluidity of the membranes.
DBI was employed to indicate the unsaturation de鄄
gree of membrane glycerolipids. The DBI is the ave鄄
rage number of double molecular species and a high
DBI indicates the presence of more unsaturated
membrane lipids, and vice versa.
The DBI of plastidic lipids MGDG was 5. 9,
which was much higher comparing to other lipid
classes, while the DBI of phosphatidylserine ( PS)
was lower than other lipids, which was only 2. 5.
The change of DBI in each membrane lipid was dif鄄
ferent between detachment鄄induced and hormone鄄
promoted senescence. During detachment鄄induced
senescence, the DBI of four kinds of lipids (MG鄄
DG, DGDG, PG, PC) decreased, while the DBI of
other lipids remained unchanged (Table 2). When
Fig. 1 摇 Changes in lysoPL molecular species in Arabidopsis as re鄄
vealed by ESI鄄MS / MS under three senescence treatments. Left panel,
lipid of wild type WS plant; right panel, lipid of PLD啄鄄knockout mu鄄
tant plant. The white bars represent nontreated leaves, and the double鄄
hatched bars represent treated for 3 days leaves, and the black bars re鄄
present for 5 days leaves. The values are the means 依SD. (n=4 or 5)
A. The change of lysoPL molecular species during detachment鄄in鄄
duced senescence; B. The change of lysoPL molecular species during
ABA鄄promoted senescence; C. The change of lysoPL molecular spe鄄
cies during ethylene鄄promoted senescence
3755 期摇 摇 摇 JIA and LI: Changes in Lysophospholipid and Degree of Unsaturated Membrane Lipids are Associated …摇 摇 摇
Table 2摇 Changes in double bond index (DBI) of each lipid classes under three senescence treatments
Lipids
classes Treatments Genotypes
Double bond index (DBI)
0 day 3 days 5 days
RC / %
3 days 5 days
water WSPLD啄鄄KO
3. 41 依 0. 02a
3. 43 依 0. 08a
3. 38 依 0. 07a
3. 38 依 0. 07a
3. 00 依 0. 07b
3. 06 依 0. 14b
—
—
-12. 02
-10. 79
PG ABA WSPLD啄鄄KO
3. 41 依 0. 02a
3. 43 依 0. 08a
3. 23 依 0. 17b
3. 27 依 0. 06b
2. 89 依 0. 14c
3. 05 依 0. 10c
-5. 28摇
-4. 66摇
-15. 25
-11. 08
ETH WSPLD啄鄄KO
3. 41 依 0. 02a
3. 43 依 0. 08a
3. 39 依 0. 11ab
3. 23 依 0. 18b
3. 26 依 0. 11b
3. 38 依 0. 05ab
—
-5. 83摇
-4. 40
—
water WSPLD啄鄄KO
3. 86 依 0. 05a
3. 88 依 0. 03a
3. 63 依 0. 06c
3. 66 依 0. 07b
3. 71 依 0. 04b
3. 71 依 0. 02b
-5. 96摇
-5. 67摇
-3. 89
-4. 38
PC ABA WSPLD啄鄄KO
3. 86 依 0. 05b
3. 88 依 0. 03b
4. 11 依 0. 05a
4. 22 依 0. 32a
4. 11 依 0. 02a
4. 09 依 0. 02a
6. 48
8. 76
6. 48
5. 41
ETH WSPLD啄鄄KO
3. 86 依 0. 05c
3. 88 依 0. 03c
4. 04 依 0. 10b
3. 98 依 0. 08b
4. 30 依 0. 10a
4. 22 依 0. 08a
4. 66
2. 58
11. 40
8. 76
water WSPLD啄鄄KO
3. 26 依 0. 03a
3. 28 依 0. 02a
3. 25 依 0. 02a
3. 27 依 0. 04a
3. 27 依 0. 03a
3. 30 依 0. 01a
—
—
—
—
PE ABA WSPLD啄鄄KO
3. 26 依 0. 03c
3. 28 依 0. 02b
3. 41 依 0. 02a
3. 38 依 0. 02a
3. 35 依 0. 02b
3. 37 依 0. 02a
4. 60
3. 05
2. 76
2. 74
ETH WSPLD啄鄄KO
3. 26 依 0. 03b
3. 28 依 0. 02b
3. 53 依 0. 06a
3. 54 依 0. 07a
3. 60 依 0. 07a
3. 53 依 0. 05a*
8. 28
7. 93
10. 43
7. 62
water WSPLD啄鄄KO
2. 74 依 0. 06a
2. 71 依 0. 04a
2. 69 依 0. 05a
2. 70 依 0. 04a
2. 70 依 0. 05a
2. 71 依 0. 04a
—
—
—
—
PI ABA WSPLD啄鄄KO
2. 74 依 0. 06b
2. 71 依 0. 04b
2. 79 依 0. 02b
2. 77 依 0. 03a
2. 83 依 0. 03a
2. 77 依 0. 05a 2. 21
3. 28
2. 21
ETH WSPLD啄鄄KO
2. 74 依 0. 06b
2. 71 依 0. 04b
2. 83 依 0. 04a
2. 85 依 0. 07a
2. 92 依 0. 08a
2. 87 依 0. 05a
3. 28
5. 17
6. 57
5. 90
water WSPLD啄鄄KO
3. 92 依 0. 80a
3. 57 依 1. 12a
3. 34 依 0. 83b
3. 19 依 0. 90b
3. 93 依 0. 49a
3. 74 依 0. 90a
-14. 79摇 摇
-10. 64摇 摇
—
—
PA ABA WSPLD啄鄄KO
3. 92 依 0. 80a
3. 57 依 1. 12a
3. 36 依 0. 36a
3. 09 依 0. 20a
3. 53 依 0. 39a
3. 43 依 0. 23a
—
—
—
—
ETH WSPLD啄鄄KO
3. 92 依 0. 80a
3. 57 依 1. 12a
3. 88 依 0. 89a
3. 49 依 0. 56a
3. 10 依 0. 82a
3. 74 依 0. 90a
—
—
—
—
water WSPLD啄鄄KO
2. 52 依 0. 18a
2. 60 依 0. 34a
2. 49 依 0. 14a
2. 63 依 0. 22a
2. 50 依 0. 22a
2. 70 依 0. 33a
—
—
—
—
PS ABA WSPLD啄鄄KO
2. 52 依 0. 18a
2. 60 依 0. 34a
2. 76 依 0. 18a
2. 56 依 0. 10a
2. 67 依 0. 29a
2. 68 依 0. 14a
—
—
—
—
ETH WSPLD啄鄄KO
2. 52 依 0. 18a
2. 60 依 0. 34a
2. 49 依 0. 14a
2. 63 依 0. 22a
2. 91 依 0. 81a
2. 70 依 0. 33a
—
—
—
—
water WSPLD啄鄄KO
5. 91 依 0. 01a
5. 91 依 0. 01a
5. 89 依 0. 01b
5. 89 依 0. 01b
5. 86 依 0. 01b
5. 86 依 0. 01b
-0. 34摇
-0. 34摇
-0. 85
-0. 85
MGDG ABA WSPLD啄鄄KO
5. 91 依 0. 01b
5. 91 依 0. 01b
5. 91 依 0. 01b
5. 92 依 0. 01ab
5. 93 依 0. 01a
5. 93 依 0. 00a
—
—
0. 34
0. 34
ETH WSPLD啄鄄KO
5. 91 依 0. 01b
5. 91 依 0. 01b
5. 93 依 0. 02ab
5. 92 依 0. 02ab
5. 95 依 0. 01a
5. 93 依 0. 01a*
—
—
0. 68
0. 34
water WSPLD啄鄄KO
5. 17 依 0. 02a
5. 15 依 0. 03a
5. 15 依 0. 04a
5. 18 依 0. 04a
4. 98 依 0. 04b
5. 02 依 0. 05b
—
—
-4. 05
-3. 09
DGDG ABA WSPLD啄鄄KO
5. 17 依 0. 02b
5. 15 依 0. 03b
5. 28 依 0. 04ab
5. 32 依 0. 03ab
5. 32 依 0. 06a
5. 32 依 0. 02a
—
—
2. 50
3. 30
ETH WSPLD啄鄄KO
5. 17 依 0. 02b
5. 15 依 0. 03b
5. 36 依 0. 10a
5. 25 依 0. 16ab
5. 36 依 0. 09a
5. 37 依 0. 01a
3. 28
—
3. 28
4. 27
Values are means 依S. D (n=4 or 5) . Values with different letters are significantly different (P<0. 05) . “*冶 indicates that the value is signifi鄄
cantly different from that of the WS under the same condition (P<0. 05) . DBI = (移[N伊mol % molecular specie]) / 100, N is the number of
double bonds in each molecular specie
475摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 植 物 分 类 与 资 源 学 报摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 第 35 卷
leaves incubated in ABA or ethylene, the DBI of
five types of lipid classes [MGDG, DGDG, PC, PE
and PI (phosphatidylinositol)] increased, while the
DBI of PG decreased, and the DBI of PA, PS main鄄
tained. During ABA鄄 and ethylene鄄promote senes鄄
cence, the DBI of plastidic lipids MGDG showed the
smallest changes among all lipid classes, which in鄄
creased to 0. 34% and 0. 68% of initial levels in
WS plants, respectively (Table 2). The change pat鄄
ters of DBI of lysoPLs were different among three se鄄
nescence treatments, although the content of Lyso鄄
PLs was minor compared to other membrane glycero鄄
lipids (Table 3). The DBI of the main membrane
lipids (MGDG, DGDG and PC) increased during
ABA鄄 and ethylene鄄promoted senescence while de鄄
creased during detachment鄄induced senescence, the
differences might be resulted from the effects of the
hormone themselves on the unsaturation of the mem鄄
brane lipids.
2. 4 摇 The DBI of total membrane lipids de鄄
creased during three senescence treatments
The DBI of total membrane lipids were ana鄄
lyzed, and the results showed that the DBI of total
membrane lipids decreased significantly during three
senescence treatments. However, what爷s interesting
was that the DBI of total membrane lipids declined
while the DBI of most lipid classes increased during
ABA鄄 and ethylene鄄promoted senescence (Tables 2-
4). The decline of DBI of total membrane lipids
might be caused by the dramatic degradation of plas鄄
tidic lipid MGDG which occupy about 77% of the
total membrane lipids (Li et al., 2008). Koiwai et
al. (1981) have reported that chloroplast lipid MG鄄
DG and DGDG degraded more rapidly than non鄄
chloroplastic lipids PE, PC, PI and PS (mainly lo鄄
cated in the membranes of non鄄photosynthetic organ鄄
elles such as endoplasmic reticulum and mitochon鄄
dria). The DBI was calculated based on the mol%
content of each lipid molecule species, so it is con鄄
ceivable that the dramatic degradation of galactolip鄄
ids might contribute to the decrease of DBI of total
membrane lipids.
Table 3摇 Changes in double bond index (DBI) of lysoPLs classes under three senescence treatments
Lipids
classes Treatments Genotypes
Double bond index (DBI)
0 day 3 days 5 days
RC / %
3 days 5 days
water WSPLD啄鄄KO
1. 83 依 0. 16a
1. 69 依 0. 13a
1. 65 依 0. 17a
1. 69 依 0. 18a
1. 71 依 0. 19a
1. 79 依 0. 84a
—
—
—
—
LysoPC ABA WSPLD啄鄄KO
1. 83 依 0. 16a
1. 69 依 0. 13b
1. 89 依 0. 04a
2. 01 依 0. 13a
1. 96 依 0. 06a
1. 96 依 0. 84ab
—
—
—
—
ETH WSPLD啄鄄KO
1. 83 依 0. 16b
1. 69 依 0. 13b
1. 83 依 0. 10b
1. 85 依 0. 19b
2. 16 依 0. 24a
1. 85 依 0. 15a*
—
—
18. 03
9. 47
water WSPLD啄鄄KO
1. 46 依 0. 04a
1. 48 依 0. 03a
1. 25 依 0. 11b
1. 42 依 0. 09a
1. 42 依 0. 09a
1. 50 依 0. 06a
-14. 38
—
—
—
LysoPG ABA WSPLD啄鄄KO
1. 46 依 0. 04a
1. 48 依 0. 03a
1. 18 依 0. 07b
1. 17 依 0. 12b
1. 12 依 0. 12b
1. 18 依 0. 08b
-19. 18
-20. 95
-23. 29
-20. 27
ETH WSPLD啄鄄KO
1. 46 依 0. 04a
1. 48 依 0. 03a
1. 26 依 0. 11b
1. 36 依 0. 22a
0. 97 依 0. 09c
0. 96 依 0. 09b
-13. 70
—
-33. 56
-35. 14
water WSPLD啄鄄KO
2. 22 依 0. 76a
2. 82 依 0. 23a
2. 40 依 0. 66a
3. 00 依 0. 00a
2. 04 依 0. 88a
1. 86 依 0. 65b
—
—
—
-34. 04
LysoPE ABA WSPLD啄鄄KO
2. 22 依 0. 76a
2. 82 依 0. 23a
2. 52 依 0. 51a
2. 48 依 0. 64ab
1. 71 依 0. 60a
1. 70 依 0. 79b
—
—
—
-39. 72
ETH WSPLD啄鄄KO
2. 22 依 0. 76a
2. 82 依 0. 23a
3. 00 依 0. 00a
2. 32 依 0. 86ab
0. 99 依 0. 41b
1. 88 依 0. 65b*
—
—
-55. 41
-33. 33
Values are means 依S. D (n=4 or 5) . Values with different letters are significantly different (P<0. 05) . “*冶 indicates that the value is signifi鄄
cantly different from that of the WS under the same condition (P<0. 05) . DBI = (移[N伊mol % molecular specie]) / 100, N is the number of
double bonds in each molecular specie
5755 期摇 摇 摇 JIA and LI: Changes in Lysophospholipid and Degree of Unsaturated Membrane Lipids are Associated …摇 摇 摇
Table 4摇 Changes in double bond index (DBI) of total membrane lipids under three senescence treatments
Treatments Genotypes
Double bond index (DBI)
0 day 3 days 5 days
RC / %
3 days 5 days
water WSPLD啄鄄KO
5. 53 依 0. 03a
5. 53 依 0. 04a
5. 44 依 0. 05b
5. 46 依 0. 02b
5. 34 依 0. 04c
5. 31 依 0. 02c
-1. 63
-1. 27
-3. 43
-3. 98
ABA WSPLD啄鄄KO
5. 53 依 0. 03a
5. 53 依 0. 04a
5. 44 依 0. 04b
5. 44 依 0. 05b
5. 12 依 0. 01c
5. 17 依 0. 01c*
-1. 63
-1. 63
-7. 41
-6. 51
ETH WSPLD啄鄄KO
5. 53 依 0. 03a
5. 53 依 0. 04a
5. 45 依 0. 05b
5. 41 依 0. 04b
5. 15 依 0. 01c
5. 28 依 0. 01c*
-1. 45
-2. 17
-6. 87
-4. 52
Values are means 依S. D (n=4 or 5) . Values with different letters are significantly different (P<0. 05) . “*冶 indicates that the value is signifi鄄
cantly different from that of the WS under the same condition (P<0. 05) . DBI = (移[N伊mol % molecular specie]) / 100, N is the number of
double bonds in each molecular specie
2. 5摇 Suppression of PLD啄 slowed down the de鄄
crease of DBI of total lipids, while no effect on
the DBI of different lipid classes
To investigate the role of unsaturation of mem鄄
brane glycerolipids in senescence, we analyzed the
DBI of membrane lipids in PLD啄鄄KO plants, in
which hormone鄄promoted senescence was delayed
relative to that in WS plants ( Tables 2 - 3). The
DBI of total membrane lipids were identical between
WS and PLD啄鄄KO plants during detachment鄄induced
senescence, while which were significantly higher in
PLD啄鄄KO leaves than in WS leaves during ABA鄄
and ethylene鄄promoted senescence at day 5 ( Table
4). However, no significant differences of DBI were
detected in each membrane lipid class between WS
and PLD啄鄄KO plants during three senescence treat鄄
ments. The data indicated that the delayed senes鄄
cence was associated with the suppression of PLD啄
correlated with a decrease in DBI of total lipids,
which also was contributed to the slower degradation
of galactolipids in PLD啄鄄KO plants. Our lipid profi鄄
ling indicated that suppressing PLD啄 retarded ABA鄄
promoted leaf senescence by attenuating lipid degra鄄
dation, and PA level was significant difference be鄄
tween WS and PLD啄鄄KO plants (Jia et al., 2013).
Here showed that suppression of PLD啄 did not affect
DBI level of PA. This suggested that PA played a
role in hormone鄄promoted senescence by exchanging
head group with other lipids but not by changing the
double bonds of its acyl groups.
In conclusion, our results suggested that the
patterns of lysoPL changes were not completely iden鄄
tical, while the unsaturation degree of membrane
lipids was similar in ABA鄄 to in ethylene鄄promoted
senescence. Suppression of PLD啄 attenuated 16 颐 0鄄
and 18 颐 3鄄lysoPC species and 16 颐 1鄄lysoPE species
production during ABA鄄promoted senescence and al鄄
so slowed down the decrease of DBI of total mem鄄
brane lipids during ABA鄄 and ethylene鄄promoted se鄄
nescence. However, many questions still remained
unclear and would be further studied in future, such
as metabolism of different lipid profiles in ABA鄄 and
ethylene鄄promoted leaf senescence, the mechanism
of suppression of PLD啄 delayed ABA鄄 and ethylene鄄
promoted senescence, and the effect of the endoge鄄
nous lysoPLs and the unsaturation degree of mem鄄
brane lipids on leaf senescence.
Acknowledgement: We thank Dr. Buzhu Yu and Dr. Hongy鄄
ing Chen for their critical reading of the paper.
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7755 期摇 摇 摇 JIA and LI: Changes in Lysophospholipid and Degree of Unsaturated Membrane Lipids are Associated …摇 摇 摇