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A Metallochaperone Gene CaHPP7 from Pepper Improves Plants Tolerance to Both Copper and Heat Stresses

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A metallochaperone protein plays important roles in plant fighting against heavy-metal stress and other abiotic stresses, such as low temperature, drought and salinity. However, the involvement of metallochaperone proteins in plant heat tolerance is rarely reported. In previous research work, a heat-induced metallochaperone protein gene CaHPP7 was isolated from pepper. By bioinformatics and quantitative analysis, an HMA domain was identified in the amino acid sequence of CaHPP7, and the expression of CaHPP7 was induced by high temperature, heavy metals Cu2+ and Cd2+, and exogenous signal substances including ABA (Abscisic acid), MeJA (Jasmonic acid methylester), and SA (Salicylic acid). In order to further clarify the function of CaHPP7 gene in plant tolerance to heat and heavy-metal stresses, gene silencing and overexpression techniques were used to change the expression level of CaHPP7. The results showed that the silenced expression of CaHPP7 reduced the tolerance to heat and copper stresses in pepper. The chlorophyll content of isolated leaf discs was significantly lower than that of unsilenced plants. While the overexpression of CaHPP7 increased Arabidopsis thaliana tolerance to these two abiotic stresses, in which under heat stress, the survival rate of seedlings was higher than that of the control, and the reduction degree of chlorophyll content of leaf discs was lower than that of the control; under copper stress, the seed germination rate was higher than that of the control, and the degree of growth inhibition of the seedlings and chlorophyll content reduction of leaf discs were lower than those of the control. Therefore, we speculate that CaHPP7 gene plays a positive role in plant dealing with the adverse effects from heat and copper stresses. These results will lay a theoretic foundation for the uncovering of the molecular mechanism of plant tolerance to abiotic stresses, and provide a reference for the breeding of crop varieties with stress-tolerance.
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分子植物育种,2021 年,
19 卷,
3期, 849858
Molecular Plant Breeding, 2021, Vol.19, No.3, 849858
研究报告
Research Report
辣椒金属伴侣蛋白基因 !"#$$% 提高植物对铜和热胁迫的抗性
刘海波 *鲁进萍 *陈涛 朱祖廷 赵芳 逯明辉 **
西北农林科技大学园艺学院,杨凌, 712100
*同等贡献作者
** 通信作者, xnjacklu@nwsuaf.edu.cn
金属伴侣蛋白在植物抵抗重金属胁迫和低温干旱高盐等非生物胁迫中发挥重要作用,但其应对
热胁迫时发挥作用的报道还很少前期研究从辣椒中分离到一个能够响应热胁迫的金属伴侣蛋白基因
!"&$$%,通过生物信息学和定量分析发现该基因的氨基酸序列含有 1HMA 结构域,且其表达受高温
Cu2+Cd2+等重金属,以及 ABA (Abscisic acid)MeJA (Jasmonic acid methylester)SA (Salicylic acid)等外源
信号物质的诱导为了进一步明确 ’"&$$% 基因在植物重金属和热胁迫抗性形成中的功能,利用基因沉默和
过表达技术改变 !"&$$% 的表达水平结果显示,基因沉默表达后,辣椒对铜和热胁迫的抗性都降低,表现为
离体叶圆片叶绿素含量下降程度显著高于未沉默植株;而基因过表达后,拟南芥对铜和热胁迫的抗性都升
高,其中热胁迫下表现为幼苗存活率高于对照,叶圆片叶绿素含量减少程度低于对照;铜胁迫下表现为种子
发芽率高于对照,幼苗生长的受抑制程度和叶圆片叶绿素含量下降程度均低于对照故推测 !"&$$% 基因在
植物应对高温和铜胁迫的过程中起正调控作用本研究结果将为进一步揭示植物抗逆性形成的分子机制提
供理论依据,也将为农作物抗逆新品种的选育提供参考
关键辣椒(!"()*+,- "..,,- L.); 金属伴侣蛋白; HPP7; 铜胁迫;热胁迫
A Metallochaperone Gene !"&$$% from Pepper Improves Plants Tolerance
to Both Copper and Heat Stresses
Liu Haibo *Lu Jinping *Chen Tao Zhu Zuting Zhao Fang Lu Minghui **
College of Horticulture, Northwest A&F University, Yangling, 712100
* These authors contributed equally to this work
** Corresponding author, xnjacklu@nwsuaf.edu.cn
DOI: 10.13271/j.mpb.019.000849
Abstract A metallochaperone protein plays important roles in plant fighting against heavy-metal stress and other
abiotic stresses, such as low temperature, drought and salinity. However, the involvement of metallochaperone
proteins in plant heat tolerance is rarely reported. In previous research work, a heat-induced metallochaperone
protein gene !"&$$% was isolated from pepper. By bioinformatics and quantitative analysis, an HMA domain was
identified in the amino acid sequence of CaHPP7, and the expression of !"&$$% was induced by high temperature,
heavy metals Cu2+ and Cd2+, and exogenous signal substances including ABA (Abscisic acid), MeJA (Jasmonic acid
methylester), and SA (Salicylic acid). In order to further clarify the function of !"&$$% gene in plant tolerance to
heat and heavy-metal stresse s, gene silencing and overexpression techniques were used to change the expression
基金项目:本研究由国家自然科学基金项目(31572114; 31872091)和陕西省重点研发计划项目(2018NY029; 2019ZDLNY0305)
共同资助
引用格式:Liu H.B., Lu J.P., Chen T., Zhu Z.T., Zhao F., and Lu M.H., 2021, A metallochaperone gene !"&$$% from pepper improves
plants tolerance to both copper and heat stresses, Fenzi Zhiwu Yuzhong (Molecular Plant Breeding), 19(3): 849-858. (刘海波,鲁进萍,
陈涛,朱祖廷,赵芳,逯明辉, 2021, 辣椒金属伴侣蛋白基因 !"&$$% 提高植物对铜和热胁迫的抗性,分子植物育种, 19(3):
849-858.)
分子植物育种
Molecular Plant Breeding
level of !"#$$%. The results showed that the silenced expression of !"&$$% reduced the tolerance to heat and
copper stresses in pepper. The chlorophyll content of isolated leaf discs was significantly lower than that of un-
silenced plants. While the overexpression of ’"&$$% increased ()"*+,-./+/ 01"2+"3" tolerance to these two abiotic
stresses, in which under heat stress, the survival rate of seedlings was higher than that of the control, and the
reduction degree of chlorophyll content of leaf discs was lower than that of the control; under copper stress, the
seed germination rate was higher than that of the control, and the degree of growth inhibition of the seedlings and
chlorophyll content reduction of leaf discs were lower than those of the control. Therefore, we speculate that
!"&$$% gene plays a positive role in plant dealing with the adverse effects from heat and copper stresses. These
results will lay a theoretic foundation for the uncovering of the molecular mechanism of plant tolerance to abiotic
stresses, and provide a reference for the breeding of crop varieties with stress-tolerance.
Keywords Pepper (!"./+456 "33556 L.); Metallochaperone; HPP7; Copper stress; Heat stress
随着全球气候变暖的加剧和工业污染物的大量
排放,高温低温干旱洪涝等极端天气频发,这些
逆境条件会导致植物细胞代谢紊乱,进而阻碍植物的
生长发育和繁殖(Zhai et al., 2016; 郭仰东等, 2018)
因此,维持细胞代谢与功能的动态平衡对保证农作
物在逆境下的正常生产具有重要意义
伴侣蛋白是正常和胁迫条件下帮助细胞蛋白质
折叠或金属离子运输的蛋白质,其中,热激蛋白主要
负责蛋白质的折叠,金属伴侣蛋白则负责金属离子
的运输热激蛋白在植物受到逆境胁迫尤其是热胁
迫时被大量诱导而当植物遭受重金属胁迫时,金属
伴侣蛋白的表达水平会明显升高(De Abreu-Neto et
al., 2013; Jacob et al., 2017)
金属伴侣蛋白含有一个或多个重金属结合结构
HMA (Heavy metal-binding associated domain)
C端是否含有异戊二烯基化位点,将其分为 HIPP
(Heavy metal-associated isoprenylated plant protein)
HPP (Heavy metal-associated plant protein) (Teh-
seen et al., 2010)金属伴侣蛋白抵抗重金属胁迫的
作用在水稻(7)89" /"0+:")小麦(;)+0+456 "</0+:56)
拟南芥(()"*+,-./+/ 01"2+"3")等植物上已被证实
量的铜镉和锰胁迫下,
7/&=$$>? 缺失的水稻突
变株系的生长情况弱于野生型(Zhang et al., 2018;
Khan et al., 2019);小麦 &=$$ 基因 ;"&=$$@ 在酵母
(A41+9-/"441")-684</ .-6*<)中过表达后显著提高了
后者在 Cu2+ 胁迫下的生长速度(Zhang et al., 2015)
而拟南芥三重突变体 B0&=$$?C/?@/?? 则表现出较强
的镉敏感性(Tehseen et al., 2010)同时,金属伴侣蛋
白也参与了植物其他非生物胁迫抗性的形成,如低温
干旱高盐等(Barth et al., 2004; 2009; De Abreu-Neto
et al., 2013),并且还在植物的免疫反应中发挥功能
(Zschiesche et al., 2015; Radakovic et al., 2018)
在植物耐热性中的作用还很少见报道
辣椒(’"./+456 "33556 L.)是一种喜温但不耐热
的蔬菜作物(Zhai et al., 2016)在前期研究中,从辣椒
中分离到了受热胁迫诱导表达的金属伴侣蛋白基因
’"#$$D在此基础上,拟通过基因沉默和过表达技
术,分析该基因在植物对热胁迫和铜胁迫抗性中的
能,为进一步阐释金属伴侣蛋白调控植物抗逆性的
子机制和有效指导作物抗逆新品种培育提供参考
1结果与分析
1.1 CaHPP7 氨基酸序列的生物信息学分析
将从辣椒基因组数据库中提取的 CaHPP7 (Ca-
pana03g002300)的氨基酸序列,用在线工具 SMART
预测后发,该序列 8~67 aa 处含有一个 HMA
结构域(1A)将此氨基酸序列提交 NCBI获得其
他植物物种的同源蛋白经同源性比对和进化树分
析后发现,Capana03g002300 与同为茄科的番茄(Sl-
HIPP39)马铃薯(StIF2)烟草(NaHIPP)同源蛋白的
亲缘关系较近,而与油橄榄(OeHIPP39)石刁柏(Ao-
HIPP39)蓖麻(RcHIPP39)毛果杨(PtHIPP39)
(AtHPP7, AtHIPP39) 同源蛋白的亲缘关系较远
(1B)由于在 Capana03g002300 氨基酸序列中没
有检测到异戊二烯基化位点,且其基序分布也和
AtHPP7 相近,而与 AtHIPP39 相差较大(1C)因此
将该基因命名为 !"&$$D
1.2 CaHPP7 基因启动子顺式作用元件分析
PlantCARE 工具分析结果表明,
!"&$$D 基因的
启动子序列(选取基因开放阅读框上游 1 500 bp 的片
)中存在多个与逆境激素调节相关的元件,主要有
热胁迫响应元件 HSE胁迫防御响应元件 TC-rich
850
repeats脱落酸响应元件 ABRE霉素调控元
GARE-motif茉莉酸响应元件 CGTCA-motif 和乙烯
响应元件 ERE,以及真菌效应子响应元件 Box-W1
(1)这些调控元件的存在说明 !"#$$% 基因受
到多种因素的调控,而且该基因的表达与热胁迫有
一定的关系
1.3 CaHPP7 基因在逆境和外源物质处理下的表达
分析
处理
!"&$$% 基因在辣椒耐热品系
R9 和热敏品 B6 中表现出不同的表达模式(2A)
R9 在处理 1 h 后表达量开始升高,2 h 达到峰值后逐
1 CaHPP7 氨基酸序列特征分析
: A: 氨基酸序列, HMA 结构域用下划线标示; B: 进化关系分析; C: 蛋白质基序分布,不同颜色方块代表不同的氨基酸基序;
B,C: SlHIPP39: 番茄(XP_010317603); StIF2: 马铃薯(XP_006353303); NaHIPP39: 烟草(XP_019226416); OeHIPP39: 油橄榄(XP_
022871694); AoHIPP39: 石刁柏(XP_020273146); RcHIPP39: (XP_002510790); PtHIPP39: 毛果杨(XP_024437693); AtHPP7,
AtHIPP39: 拟南芥(NP_568436; NP_001030928)
Figure 1 Characterization analysis of CaHPP7 amino acid sequence
Note: A: The amino acid sequence, in which the HMA domain was marked with underline; B: Phylogenetic analysis; C: Motifs distri-
bution of proteins, different colored squares represent different amino acid motifs; B,C: SlHIPP39: ’()"*+, )-.(/0123.+, (XP_
010317603); StIF2: 43.(53"*" 5"6".+, (XP_006353303); NaHIPP39: 43.(53"*" 5"6".+, (XP_019226416); OeHIPP39: 7)0" 0+1(/"0"
(XP_022871694); AoHIPP39: 82/"1"9+2 (::3.3*")32 (XP_020273146); RcHIPP39: ;3.3*+2 .(,,+*32 (XP_002510790); PtHIPP39:
$(/+)+2 5(,0*5(2" (XP_024437693); AtHPP7, AtHIPP39: 81"63<(/232 5=")3"*" (NP_568436; NP_001030928)
元件
>32-element
脱落酸响应元件
ABRE
茉莉酸响应元件
CGTCA-motif
胁迫防御响应元件
TC-rich repeats
茉莉酸响应元件
TGACG-motif
真菌效应子响应元件
Box-W1
乙烯响应元件
ERE
赤霉素响应元件
GARE-motif
热胁迫响应元件
HSE
1>"#$$% 基因启动子逆境相关元件分析
Table 1 Stress-related .32-elements in the promoter of >"#$$%
序列
Sequence
GCAACGTGTC
CGTCA
GTTTTCTTAC
ATTCTCTAAC
TGACG
TTGACC
ATTTCAAA
AAACAGA
AAAAAATTTC
AAAAAATTTC
AGAAAATTCG
元件数量
No. of .32-element
2
3
3
4
1
1
2
3
功能
Function
响应脱落酸信号
Abscisic acid responsiveness
响应茉莉酸信号
MeJA-responsiveness
响应胁迫信号
Defense and stress responsiveness
响应茉莉酸信号
MeJA-responsiveness
响应真菌效应子信号
Fungal elicitor responsiveness
响应乙烯信号
Ethylene-responsiveness
响应赤霉素信号
Gibberellin-responsiveness
响应热胁迫
Heat stress responsiveness
辣椒金属伴侣蛋白基因 >"#$$ 提高植物对铜和热胁迫的抗性
A Metallochaperone Gene >"#$$7 from Pepper Improves Plants Tolerance to Both Copper and Heat Stresses 851
分子植物育种
Molecular Plant Breeding
渐下降,在恢复 4 h 后表达量又上升到最高,为对照
5.2 B6 !"#$$% 基因的表达受到了抑制,
胁迫 1 h 时降低为对照的 22%,之后逐渐上升,
6h时为对照的 1.6 倍,随后的恢复阶段一直保持相
对稳定的水平,与对照相比没有明显差异Cu2+
Cd2+ 的重金属胁迫处理下,R9 根系!"&$$%
均表现为上调表达,其中 Cu2+ 处理上调到对照的
12.4 倍,Cd2+ 处理上调到对照的 3.0(2B)
ABAMeJA SA 3种外源信号物质均可诱
R9 叶片中 ’"&$$% 基因的表达,且都出现了两次
表达高峰(2C)ABA 处理 2 h 基因表达量达到峰
值,为对照的 2.7 倍, 4 h 时迅速降到最低,此后又
呈现上调表达趋势,于 24 h 达到对照的 1.9 倍;Me-
JA SA 处理分别在 4h2h后达到第一次表达
高峰,此后均在 24h基因表达水平达到最高,其中
MeJA 处理为对照的 5.1 倍,SA 处理为 3.1
1.4 !"#$$% 基因沉默辣椒植株的抗逆性测定
热胁迫处理后,
!"&$$% 基因沉默辣椒
TRV2:CaHPP7 和对照植株 TRV2:00 的叶圆片均出
现黄化现象,并且沉默植株的黄化程度更严重(3A)
TRV2:00 植株叶圆片的叶绿素含量下降到未经热胁
迫处理的 47.1% TRV2:CaHPP7 则下降到对照的
13.4% (3B)
类似地,铜胁迫处理后,
!"&$$% 基因沉默植株
TRV2:CaHPP7 和对照植株 TRV2:00 的叶圆片也都
出现黄化,并且沉默植株的更严重甚至完全失绿
(3C)TRV2:00 植株叶圆片的叶绿素含量下降到
未经铜胁迫处理的 62.0% TRV2:CaHPP7 则下降
29.6% (3D)
1.5 !"&$$% 基因过量表达拟南芥植株的抗逆性测定
热胁迫处理后,5 d 苗龄的拟南芥幼苗叶片发生白
2!"&$$% 基因在逆境胁迫和外源物质处理下的表达分析
: A: 热胁迫, B6 为辣椒热敏品系, R9 为耐热品系, R 表示热胁迫恢复期; B: 重金属胁迫, H2O为对照组, Cu2+, Cd2+ 为处理组;
C: 外源物质处理, ABA 为脱落酸, MeJA 为茉莉酸甲酯, SA 为水杨酸; * ** 分别表示 0.05 0.01 水平上的差异显著性
Figure 2 Expression analysis of !"&$$% gene under abiotic stresses and exogenous treatments
Note: A: The treatment with heat stress, in which B6 is the heat-sensitive pepper line, and R9 is the heat-tolerant line, and R stands for
the recovery period after heat stress; B: The treatments with heavy metals, the treatment with H2O was used as the control, and the
treatment with Cu2+ and Cd2+; C: The treatments with exogenous substances ABA (Abscisic acid), MeJA (Jasmonic acid methylester)
and SA (Salicylic acid); * and ** represents the different significances at 0.05 and 0.01 levels respectively
852
化, !"#$$% 量表达转基因株系 OE1 OE13
片的白化程度明显小于对照植株 EV WT (4A)
转基因株系的幼苗存活率也明显高于对照植株,
OE1 的存活率达到了 90% (4B)24d苗龄的拟
南芥植株的叶圆片经热胁迫处理后,EV WT 叶圆
片的失绿程度和叶绿素含量的降低幅度显著大于
OE1 OE13 (4C; 4D)
在没有铜胁迫存在的条件下生长 6 d 后,拟南芥
!"&$$% 过表达株系 OE1 OE13 与对照株系 EV
WT 的种子发芽情况并无明显差别铜胁迫处理
下,拟南芥的发芽受到抑制, OE1OE13 相比 EV
WT 均表现出较高的发芽率和子叶绿叶率(5A;
5B; 5C)7 d 苗龄的拟南芥植株在含 100 μmol/L
浓度 CuSO4MS 培养基上竖直生长 7d后,叶片
和根系的生长受阻,但 OE1OE13 的根长和幼苗鲜
重均显著高于 EV (5D; 5E; 5F)另外, 24 d
苗龄的拟南芥植株上打取叶圆片,在 200 μmol/L
CuSO4溶液中浸泡处理 48 h 4个株系的叶圆
片均出现了非常明显的褪绿(5G)但转基因株系
OE1 OE13 叶绿素含量的下降程度显著低于对照
WT EV (5H)
2讨论
随着全球气候变暖的加剧和工业污染物的大量
排放,农作物的生产受逆境胁迫的影响越来越严重
阐明植物抗逆性形成的分子机制,对采取合理的育
种与栽培途径来提高农作物的抗逆性确保农业生
产的顺利进行具有重要意义
金属伴侣蛋白可以通过与金属离子紧密结合,
将其转运到特定细胞器进行隔离或者排出细胞外,
植物体因此免受重金属毒害(Turchetto-Zolet et al.,
2013; Li et al., 2016)前期研究中,我们从辣椒里分
离到了一个受热胁迫诱导表达的金属伴侣蛋白基
因,根据其氨基酸序列(1)将其命名为 ’"&$$%
CaHPP7 氨基酸序列中包含 HMA 结构域(1A)
并且其启动子区域含有热激转录因子结合元件 HSE
(1),推测 !"&$$% 可能同时响应重金属胁迫和热
胁迫信号,基因表达分析也证实了这一点(2)
!"&$$% 确实参与了辣椒对热胁迫和重金属胁迫
的响应过程R9 !"&$$% 基因表达量在恢复 4 h
后又上升到最高,推测在植物遭受热胁迫后的恢复
阶段,
!"&$$% 基因也发挥了积极作用其他研究者
3!"&$$% 基因沉默辣椒植株的抗逆性测定
: A,B: 热胁迫, 25 !为对照组, 40 "为处理组; C,D: 铜胁迫, H2O照组, Cu2+理组; A,C: 叶圆片表型症状; B,D: 叶圆
片叶绿素含量; TRV2:00: 转空载体对照植株; TRV2:CaHPP7: !"&$$% 基因沉默植株; **: 差异极显著($(0.01)
Figure 3 Determination of the tolerance to heat and heavy-metal stresses in !"&$$% silenced pepper plants
Note: A,B: The treatment with heat stress, the treatment with 25 #was used as the control, and the treatment with 40 $was used as
the heat stress; C,D: The treatment with copper stress, the treatment with H2O was used as the control, and the treatment with Cu2+ was
used as the copper stress; A,C: The phenotype of leaf discs; B,D: The chlorophyll content of leaf discs; TRV2:00: The control with
empty vector; TRV2:CaHPP7: The !"&$$% expression-silenced plants; **: The difference is extremely significant ($(0.01)
辣椒金属伴侣蛋白基因 !"&$$ 提高植物对铜和热胁迫的抗性
A Metallochaperone Gene !"&$$7 from Pepper Improves Plants Tolerance to Both Copper and Heat Stresses 853
分子植物育种
Molecular Plant Breeding
也发现,金属伴侣蛋白基因的表达也可以响应其他逆
境胁迫信号,如小麦 !"#$%%& 可被低温和 NaCl 显著
诱导(Zhang et al., 2015)水稻 ’()$%%*+ 在冷害和干
旱胁迫后表现为上调表达(De Abreu-Neto et al., 2013)
拟南芥 ,-#.%%/0 在冷害高盐和干旱胁迫下的表达
水平明显上升(Barth et al., 2009)这些结果说明,
了重金属胁迫外,金属伴侣基因在植物对其他逆境
胁迫的抗性中也可能发挥作用
1"2%%3 基因的启动子序列中存在 ABAMeJA
和胁迫防御等响应元件(1)实时定量分析结果也
表明该基因表达受到 ABAMeJA SA 处理的明显
诱导(2C)而这些生长调节物质在植物对重金属
胁迫和其他非生物胁迫中的作用已经被证实(Asgher
et al., 2015; Verma et al., 2016)由此推测 1"2%%3
金属伴侣蛋白基因可能通过某些共有的信号途径来
响应重金属胁迫和其他逆境胁迫此外,3种物质处
理后 1"2%%3 基因均出现了两次表达高峰(2C)
由于 ABAJA SA 除了其本身直接调控外,它们
之间还存在交叉调控(Verma et al., 2016)因此 1"-
2%%3 基因表达的第 1个高峰可能是这 3种物质的
直接诱导,第 2个高峰可能是 3种物质交叉作用的
结果,具体原因以及是哪些转录因子参与了这种交
叉调控还需要进一步研究
为了进一步明确 1"2%%3 基因在植物对铜和
热胁迫抗性形成中的功能,我们利用基因沉默和过
表达技术研究了 1"2%%3 表达水平的改变对辣椒和
拟南芥关于铜和热胁迫抗性的影响结果发现,
1"-
2%%3 基因沉默表达后,辣椒对铜和热胁迫的抗性都
降低(3)
1"2%%3 基因过表达后,拟南芥对铜和
热胁迫的抗性都升高(4; 5)这些结果说明,
1"2%%3 基因表达对植物铜和热胁迫抗性的形成具
有正调控作用
铜胁迫和热胁迫都会造成叶绿素降解,从而影
响植物叶片的光合作用,因此如何保持叶绿素结构
和含量的平衡与稳定是植物铜和热胁迫抗性形成的
重要方面(Abdelrahman et al., 2017; 王阳等, 2017)
物体内很多蛋白行使功能都需要金属离子的参与,
这类蛋白称为金属蛋白正常条件下,金属伴侣蛋白
负责将金属离子准确运输到目标细胞器和目标金属
蛋白,以维持其生物学功能当细胞内金属离子的含
量超过金属伴侣蛋白的运载能力时,多余的金属离
子就会自由进入细胞器或攻击金属蛋白,置换出正
确的金属离子,使细胞器和金属蛋白的结构和功能
遭到破坏重金属胁迫抗性较强的植物物种或品种
41"2%%3 基因过表达拟南芥植株的耐热性测定
: 22 !为对照组, 46 "42 #为处理组; A,B: 5 d 苗龄幼苗; C,D: 24 d 苗龄幼苗; A,C: 热胁迫表型; B: 幼苗存活率; D: 叶圆
片叶绿素含量; WT: 野生型拟南芥; EV: 转空载体拟南芥; OE1,OE13: 1"2%%3 基因过表达株系; **: 差异极显著(%40.01)
Figure 4 Determination of heat tolerance of 1"2%%3overexpressed ,5"6789:(7( -;"<7"=" plants
Note: The treatment with 22 $was used as the control, and the treatment with 46 %and 42 &were used as the treated groups; A,B:
5day-oldseedlings; C,D: 24day-old seedlings; A,C: Phenotypes after heat stress; B: The survival rates of seedlings; D: The chloro-
phyll contents of leaf discs; WT: Wild-type ,5"6789:(7( -;"<7"="; EV: Empty vector ,5"6789:(7( -;"<7"="; OE1,OE13: The 1"2-
%%3overexpression lines; **: The difference is extremely significant (%40.01)
854
遭受过量金属离子胁迫时,金属伴侣蛋白基因表
量升高,与金属离子结合并将其限定在细胞质,
止其对细胞器和金属蛋白产生毒害(De Abreu-Neto
et al., 2013)因此,推测 !"#$$% 基因表达通过捕获
金属离子,防止其对叶绿体的攻击而提高植株对铜
胁迫的抗性
抗氧化系统的激活与稳定在植物抗逆性形成过
程中发挥重要作用,铜胁迫和热胁迫都会造成植物
体内抗氧化系统活性下降,引起活性氧(reactive oxy-
gen species, ROS)大量积累,进而引发膜质过氧化
胞功能丧失(尉晓东等, 2016; Choudhury et al., 2017)
超氧化物歧化酶(superoxide dismutase, SOD)是抗
化系统的第一道防线,属于金属蛋白,其活性需要
Cu/Zn 离子参加因此,
!"&$$% 基因能提高植物对
铜胁迫和热胁迫的抗性,可能与其可以提高抗氧化
SOD 的稳定性有关另外,拟南芥金属伴侣蛋白
AtHIPP26 通过与干旱胁迫响应的转录因子 AtHB29
发生互作而提高抗旱性(Barth et al., 2009)AtHIPP27
通过与泛素特异性蛋白酶 UBP16 互作而提高对重
金属胁迫的抗性(Zhao et al., 2013)因此, ’"&$$%
基因提高植物对重金属和热胁迫抗性的信号途径
中,是否还有其他组分发挥作用仍需深入研究
综上所述,本研究从辣椒里克隆了一个金属伴
侣蛋白基因 !"&$$%,该基因表达受高温Cu2+Cd2+
5!"&$$% 基因过量表达拟南芥植株的铜胁迫抗性测定
: H2O为对照组, Cu2+为处理组; A,B,C: 种子发芽期; D,E,F: 7 d 苗龄幼苗; G,H: 24 d 苗龄幼苗; A,D,G: 铜胁迫后的表型症状;
B: 种子发芽率; C: 发芽种子的子叶绿叶率; E: 根长; F: 幼苗鲜重; H: 叶圆片的叶绿素含量; WT: 野生型拟南芥; EV: 转空载体拟
南芥; OE1,OE13: !"&$$% 基因过表达株系; * ** 分别表示 0.05 0.01 水平上的差异显著性
Figure 5 Determination of copper tolerance of !"&$$% overexpressed ()"*+,-./+/ 01"2+"3" plants
Note: The treatment with H2O was used as the control, and the treatment with Cu2+ was used as the copper stress; A,B,C: The stage of
seed germination; D,E,F: The seedlings with 7day-old; G,H: The seedlings with 24day-old; A,D,G: The phenotypes after copper
stress; B: The germination rates; C: The cotyledon green rates of germinated seeds; E: The root length; F: The seedling fresh weight; H:
The chlorophyll contents of leaf discs; WT: Wild-type ()"*+,-./+/ 01"2+"3"; EV: Empty vector ()"*+,-./+/ 01"2+"3"; OE1,OE13: The
!"&$$%overexpression lines; * and ** represents the different significances at 0.05 and 0.01 levels respectively
辣椒金属伴侣蛋白基因 !"&$$ 提高植物对铜和热胁迫的抗性
A Metallochaperone Gene !"&$$7 from Pepper Improves Plants Tolerance to Both Copper and Heat Stresses 855
分子植物育种
Molecular Plant Breeding
等重金属,以及 ABAMeJA SA 等外源信号物质
诱导
!"#$$% 基因沉默表达降低了辣椒对热胁迫和
铜胁迫的抗性,而过表达则提高了拟南芥对两种非
生物胁迫的抗性这种正调控作用机制可能是:
!"&$$% 基因响应铜胁迫和热胁迫后表达量提高,使
CaHPP7 蛋白合成量增多,通过捕获多余的 Cu2+
减少其对细胞器结构的破坏来提高对重金属胁迫的
性,过提高 SOD 等抗氧化酶活性来提高对热胁
迫的抗性这些研究结果将为进一步揭示植物抗逆
性形成的分子机制提供理论依据,也将为农作物抗
逆新品种的选育提供参考此外,在热胁迫条件下,
’"&$$% 基因表达在辣椒耐热材料中被诱导,而在
敏材料中被抑制,说明耐热性不同的辣椒材料对
!"&$$% 基因表达的调控存在差异因此,对热胁迫
!"&$$% 基因表达调控机制的进一步研究对于揭
示辣椒耐热分子机制具有重要意义
!材料与方法
!"# 试验材料
本研究使用的植物材料为辣椒(!"()*+,- "..,-
,- L.)耐热品系 R9 (引于世界 亚洲蔬菜研发中心,
PP004251)和热敏品系 B6以及拟南芥(/0"1*23()*)
45"6*".")哥伦比亚生态型(Col0)植物的生长条件
为:光照 16 h光强 200 μmol·m2
·s1相对湿度 60%~
80%生长温度,辣椒为 25 !/20 "拟南芥为
22 #/16 $
!"$ %&’(() 氨基酸序列和启动子序列分析
从辣椒基因组数据库(https://www.sgn.cornell.edu/
organizm/capsicumannuum/genome) 中提取 CaHPP7
的氨基酸序列(Capana03g002300)用在线工具 SM-
ART (http://smart.embl-heidelberg.de/)分析 CaHPP7
保守蛋白结构域,利用 Clustal Omega 工具(https://
www.ebi .ac.uk/Tools/msa/clustalo/) CaHPP7
他植物物种的同源基因进行多序列比对,并使用
MEGA-X 工具构建其系统发育树使用 PrePS 工具
(https://mendel.imp.ac.at/sat/PrePS/index.html) 预测其
蛋白质异戊二烯结合位点通过 MEME 工具(http://
meme-suite.org/tools/meme)搜索氨基酸序列的保守
基序7"&$$8 基因的 CDS 序列与辣椒基因组数
据库对比,获得 DNA 序列,取起始密码子 ATG
游的 1 500 bp 片段作为启动子区,并用 PlantCARE
(http://bioinformatics.psb.ugent.be/webtools/plant
care/html/)分析其中可能存在的顺式作用元件
!"! !"#$$% 基因在不同胁迫处理下的表达分析
7"#$$% 基因表达分析采用 qRT-PCR ,内参
基因为 7"91*: (AY486137)并利 2
ΔΔCt
因相对表达量(Livak and Schmittgen, 2001)所用
物核苷酸序列(2)
热胁迫处理的辣椒幼苗为 5~6 叶期的耐热品系
R9 和热 B6 40 %高温处理 6 h
25 &恢复 12 h分别在热处理 00.51246 h 和恢
复后的 2412h后取样(Zhai et al., 2016)重金属胁
迫处理分别使用 200 μmol/LCdCl2CuSO4
R9 72 h清水浸泡为对照,处理结束后对
根系进行采样外源物质处理使用 100 μmol/L
ABA100 μmol/LMeJA 5 mmol/LSA
喷施 R9 幼苗叶片,在处理 024812 24 h 后采
集幼叶(Barth et al., 2009)上述所有样品收集后用液
氮速冻,存于 80 超低温冰箱备用
!"* !"&$$% 基因沉默后辣椒幼苗抗逆性分析
利用 CaHPP7VIGs-F/-R 引物对(2)R9
cDNA 中扩 ’"#$$8 基因的 312 bp 特异片
段,参照 Wang (2019)的方法构建 ’"#$$8 的瞬时
沉默表达载体 pTRV2CaHPP7转化 R9 的子叶,
性对照为空载体 TRV2:00阳性对照 pTRV2CaPDS
的辣椒幼苗出现白化新生叶后,从 pTRV2CaHPP7
TRV2:00 幼苗上打取 1.0 cm 的叶圆片进行非生
物胁迫处理热胁迫处理为将叶圆片放入清水中
40 (处理 24 h 25 )处理为对照(Zhai et al., 2017)
铜胁迫处理为将叶圆片放入 200 μmol/LCuSO4
溶液中处 48 h清水为对照处理结束后参照 Arkus
(2005)的方法测定辣椒叶圆片的叶绿素含量试验
设置 3次重复,每个重复随机选择 3株辣椒
!+, ’"&$$% 基因过表达后拟南芥植株抗逆性分析
利用 CaHPP72307F/-R 引物对(2)R9
叶片 cDNA 中扩增 ’"#$$8 基因编码区全长,参照
Wang (2019)的方法构建 ’"#$$8 的过表达载体
pVBG2307CaHPP7并利用蘸花法(Clough and Bent,
1998)转化拟南芥 Col0载体 pVBG2307 为对照,
T3代纯合转基因种子用于非生物胁迫处理对于
胁迫处理, 5 d 苗龄的拟南芥 ’"#$$8 过表达株系
(OE1, OE13)转空载体株系(EV)野生型(WT)幼苗
进行 46 *高温处理 50 min再于 22 +条件下恢复
5 d然后统计幼苗存活率24 d 苗龄的拟南芥植
856
株上打1.0 cm 叶圆片放入清水中,42 !处理 24 h
22 "处理为对照(Zhai et al., 2017)处理结束后测定
拟南芥叶圆片的叶绿素含量,试验设置 3次重复,
个重复随机选取 8个叶圆片
对于铜胁迫处理,将拟南芥 OE1OE13EV
WT 4 个株系的种子播种在含 150 μmol/L CuSO4
MS养基上,在生长 6 d 后统计发芽率和子叶绿叶
率,以不加 CuSO4MS 培养基作为对照7d
龄的 OE1OE13 EV 拟南芥幼苗移到分别含有 0
100 μmol/L CuSO4MS 培养基上,竖直培7 d
后测量根长与幼苗鲜重24 d 苗龄的拟南芥植株
上打取 1.0 cm 叶圆片放入 200 μmol/LCuSO4
处理 48 h清水处理为对照,处理结束后测定拟
南芥叶圆片的叶绿素含量,试验设置 3次重复,每个
重复随机选取 8个叶圆片
3.6 数据分析
试验数据用 Excel 2013 进行处理并作图,并采
!测验进行差异显著性检验
作者贡献
刘海波和鲁进萍是本研究的实验设计者和实验
研究的执行人刘海波和鲁进萍完成数据分析论文
初稿的写作;陈涛朱祖廷和赵芳参与实验设计
验结果分析;逯明辉是项目的构思者及负责人,指导
实验设计数据分析论文写作与修改全体作者都
阅读并同意最终的文本
致谢
本研究由国家自然科学基金项目(31572114;
31872091)和陕西省重点研发计划项目(2018NY029;
2019ZDLNY0305)共同资助
参考文献
Abdelrahman M., Elsayed M.A., Jogaiah S., Burritt D.J., and Tran
L.P., 2017, The ''STAY-GREEN'' trait and phytohormone
signaling networks in plants under heat stress, Plant Cell
Rep., 36(7): 1009-1025.
Arkus K.A.J., Cahoon E.B., and Jez J.M., 2005, Mechanistic
analysis of wheat chlorophyllase, Arch. Biochem. Biophys.,
438(2): 146-155.
Asgher M., Khan M.I., Anjum N.A., and Khan N.A., 2015, Min-
imising toxicity of cadmium in plants-role of plant growth
regulators, Protoplasma, 252(2): 399-413.
Barth O., Vogt S., Uhlemann R., Zschiesche W., and Humbeck
K., 2009, Stress induced and nuclear localized HIPP26 from
"#$%&’()*&* !+$,&$-$ interacts via its heavy metal associated
domain with the drought stress related zinc finger transcrip-
tion factor ATHB29, Plant Mol. Biol., 69(1-2): 213-226.
Barth O., Zschiesche W., Siersleben S., and Humbeck K., 2004,
Isolation of a novel barley cDNA encoding a nuclear protein
involved in stress response and leaf senescence, Physiol.
Plant., 121(2): 282-293.
Choudhury F.K., Rivero R.M., Blumwald E., and Mittler R.,
2017, Reactive oxygen species, abiotic stress and stress com-
bination, Plant J., 90(5): 856-867.
Clough S.J., and Bent A.F., 1998, Floral dip: a simplified method
for ./0(%$1!20&34-mediated transformation of .05%&’()*&*
!+$,&$-$, Plant J., 16(6): 735-743.
De Abreu-Neto J.B., Turchetto-Zolet A.C., de Oliveira L.F.,
Zanettini M.H., and Margis-Pinheiro M., 2013, Heavy met-
al-associated isoprenylated plant protein (HIPP): characteri-
zation of a family of proteins exclusive to plants, FEBS J.,
280(7): 1604-1616.
Guo Y.D., Zhang L., Li S.T., Cao Y.Y., Qi C.D., and Wang J.F.,
2018, Progresses in research on molecular biology of abiotic
stress responses in vegetable crops, Zhongguo Nongye Ke-
2试验所用引物
Table 2 Primers used for this study
引物
Primer
CaUbi3
qCaHPP7
CaHPP7VIGs
CaHPP72307
引物序列(5'3')
Primer sequence (5'3')
F: TGTCCATCTGCTCTCTGTTG
R: CACCCCAAGCACAATAAGAC
F: GAAAGTTGTAATGAAGGTGCTA
R: CTGCTGCTATTGAATCTACCC
F: GCTCTAGAATGGCTCAGCAGATGAAAGTTGT
R: CGGGATCCTTTTGGCTCTTCTTTTTTCTCTTCT
F: GCTCTAGAATGGCTCAGCAGATGAAAGTTGT
R: GGGGTACCTTTTGGCTCTTCTTTTTTCTCTTCT
说明
Explanation
实时定量
qRT-PCR
实时定量
qRT-PCR
基因沉默载体
Gene silencing vector
过表达载体
Overexpression vector
辣椒金属伴侣蛋白基因 6$788 提高植物对铜和热胁迫的抗性
A Metallochaperone Gene 9$:887 from Pepper Improves Plants Tolerance to Both Copper and Heat Stresses 857
分子植物育种
Molecular Plant Breeding
xue (Scientia Agricultura Sinica), 51 (6): 1167-1181. (
,张磊,李双,曹芸运,齐传东,王晋芳, 2018, 蔬菜作
物应答非生物逆境胁迫的分子生物学研究进展,中国农
业科学, 51(6): 1167-1181.)
Jacob P., Hirt H., and Bendahmane A., 2017, The heat-shock pro-
tein/chaperone network and multiple stress resistance, Plant
Biotechnol. J., 15(4): 405-414.
Khan I.U., Rono J.K., Zhang B.Q., Liu X.S., Wang M.Q., Wang
L.L., Wu X.C., Chen X., Cao H.W., and Yang Z.M., 2019,
Identification of novel rice (Oryza sativa)HPP and HIPP ge-
nes tolerant to heavy metal toxicity, Ecotox. Environ. Safe.,
175(3): 8-18.
Li J.R., Wei X.Z., Yu P.L., Deng X., Xu W.X., Ma M., and
Zhang H.Y., 2016, Expression of cadR enhances its specific
activity for Cd detoxification and accumulation in Arabidop-
sis, Plant Cell Physiol., 57(8): 1720-1731.
Livak K.J., and Schmittgen T.D., 2001, Analysis of relative gene
expression data using real-time quantitative PCR and the
2
!"Ctmethod, Methods, 25(4): 402-408.
Radakovic Z.S., Anjam M.S., Escobar E., Chopra D., Cabrera J.,
Silva A.C., Escobar C., Sobczak M., Grundler F.M.W., and
Siddique S., 2018, Arabidopsis HIPP27 is a host susceptibil-
ity gene for the beet cyst nematode Heterodera schachtii,
Mol. Plant Pathol., 19(8): 1917-1928.
Tehseen M., Cairns N., Sherson S., and Cobbett C.S., 2010, Met-
allochaperone-like genes in Arabidopsis thaliana, Metal-
lomics, 2(8): 556-564.
Turchetto-Zolet A.C., Pinheiro F., Salgueiro F., and Palma-Silva
C., 2013, Phylogeographical patterns shed light on evolu-
tionary process in South America, Molecular Ecology, 22
(5): 1193-1213.
Verma V., Ravindran P., and Kumar P.P., 2016, Plant hormo-
ne-mediated regulation of stress responses, BMC Plant Biol.,
16: 86.
Wang H., Niu H.H., Liang M.M., Zhai Y.F., Huang W., Ding Q.,
Du Y., and Lu M.H., 2019, A wall-associated kinase gene
CaWAKL20 from pepper negatively modulates plant ther-
motolerance by reducing the expression of ABA-responsive
genes, Front. Plant Sci., 10(5): 591.
Wang Y., Chen Y.F., Chang X.H., Wang X., Li N., and Gao Y.F.,
2017, Heterologous overexpression of PeDWF4 gene in Pop-
ulus euphratica enhance tolerance of tobacco to abiotic stress,
Jiyinzuxue yu Yingyong Shengwuxue (Genomics and Ap-
plied Biology), 36(10): 4242-4249. (王阳,陈永富,常晓涵,
王璇,李娜,高永峰, 2017, 异源过表达胡杨 PeDWF4 基因
提高烟草对非生物胁迫的耐性,基因组学与应用生物学,
36(10): 4242-4249.)
Yu X.D., Luo W.Q., Li F., Xie D.Y., Yu X.J., LüJ.P., and Fu M.
H., 2016, The impact of Cu, Zn, Ag on the antioxidant activ-
ity of Lactuca sativa var. capitata L., Jiyinzuxue yu Yingy-
ong Shengwuxue (Genomics and Applied Biology), 35(12):
3521-3526. (尉晓东,罗文倩,李芬,谢东瑜,余晓洁,
,傅明辉, 2016, 银对结球生菜抗氧化活性的影
,基因组学与应用生物学, 35(12): 3521-3526.)
Zhai Y.F., Guo M., Wang H., Lu J.H., Liu J.P., Zhang C., Gong
Z.H., and Lu M.H., 2016, Autophagy, a conserved mecha-
nism for protein degradation, responds to heat, and other
abiotic stresses in Capsicum annuum L., Front. Plant Sci., 7
(2): 131.
Zhai Y.F., Wang H., Liang M.M., and Lu M.H., 2017, Both si-
lencing- and over-expression of pepper CaATG8c gene com-
promise plant tolerance to heat and salt stress, Environ. Exp.
Bot., 141(1): 10-18.
Zhang X.M., Feng H., Feng C.X., Xu H., Huang X.L., Wang Q.L.,
Duan X.Y., Wang X.J., Wei G.R., Huang L.L., and Kang Z.
S., 2015, Isolation and characterization of cDNA encoding a
wheat heavy metal-associated isoprenylated protein involved
in stress responses, Plant Biol., 17(6): 1176-1186.
Zhang Y.Y., Chen K., Zhao F.J., Sun C.J., Jin C., Shi Y.H., Sun
Y.Y., Li Y., Yang M., Jing X.Y., Luo J., and Lian X.M.,
2018, OsATX1 interacts with heavy metal P1B-type ATPas-
es and affects copper transport and distribution, Plant Physi-
ol., 178(1): 329-344.
Zhao J.F., Zhou H.P., and Li X.Y., 2013, Ubiquitin-specific pro-
tease16 interacts with a heavy metal associated isoprenylat-
ed plant protein27 and modulates cadmium tolerance, Plant
Signal. Behav., 8(10): 25680.
Zschiesche W., Barth O., Daniel K., B#hme S., Rausche J., and
Humbeck K., 2015, The zinc-binding nuclear protein HIPP3
acts as an upstream regulator of the salicylate-dependent
plant immunity pathway and of flowering time in Arabidop-
sis thaliana, New Phytol., 207(4): 1084-1096.
858
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