全 文 :谷子转录因子 SiNF-YA5通过ABA非依赖途径提高转基因拟南芥耐盐
性
黄 锁 1,** 胡利芹 1,** 徐东北 1,2 李微微 1,3 徐兆师 1 李连城 1
周永斌 1,2 刁现民 1 贾冠清 1 马有志 1 陈 明 1,*
1 中国农业科学院作物科学研究所 / 农作物基因资源与基因改良国家重大科学工程 / 农业部麦类生物学与遗传育种重点实验室, 北京
100081; 2 西北农林科技大学农学院 / 旱区作物逆境生物学国家重点实验室, 陕西杨凌 712100; 3 哈尔滨师范大学生命科学与技术学院 / 黑
龙江省分子细胞遗传与遗传育种重点实验室, 黑龙江哈尔滨 150025
摘 要:核转录因子 Y(nuclear transcription factor Y,NF-Y)类转录因子在植物生长发育和非生物胁迫响应基因表达调控中发
挥重要的作用,NF-Y 由 3 种亚基(NF-YA、NF-YB、NF-YC)组成。本研究从抗逆性强的谷子品种龙谷 25 中克隆 1 个新的
NF-Y类转录因子基因 SiNF-YA5。该基因序列为 924 bp,编码 307个氨基酸,分子量为 33.76 kD,等电点 pI为 9.19。SiNF-YA5
在 149~210位氨基酸之间含有 CBF保守结构域。亚细胞定位分析表明,SiNF-YA5定位于细胞膜和细胞核。基因功能分析显
示,在不同浓度高盐处理下,和野生型拟南芥(WT)相比 SiNF-YA5 转基因拟南芥种子萌发率更高;苗期 SiNF-YA5 转基因拟
南芥根表面积和植株鲜重显著高于 WT,证明过表达 SiNF-YA5 基因可以显著提高植物耐盐性。基因表达分析结果显示,在
SiNF-YA5 转基因拟南芥中参与盐胁迫响应的基因 NHX1 和 LEA7 的表达量明显高于 WT。另一方面,SiNF-YA5 转基因拟南
芥与WT相比对于 ABA的敏感性差异不显著,以上结果证明 SiNF-YA5主要通过 ABA非依赖途径提高转基因植物对高盐胁
迫的耐性。
关键词:谷子;NF-Y类转录因子;高盐胁迫;ABA非依赖途径 1
Transcription Factor SiNF-YA5 from Foxtail Millet (Setaria italica) Conferred
Tolerance to High-salt Stress through ABA-independent Pathway in Transgenic
Arabidopsis
HUANG Suo1,**, HU Li-Qin1,**, XU Dong-Bei1,2, LI Wei-Wei1,3, XU Zhao-Shi1, LI Lian-Cheng1, ZHOU
Yong-Bin1,2, DIAO Xian-Min1, JIA Guan-Qing1, MA You-Zhi1, and CHEN Ming1,*
1 Institute of Crop Science, Chinese Academy of Agricultural Sciences / National Key Facility For Crop Gene Resource and Genetic Improvement / Key
Laboratory of Biology and Genetic Improvement of Triticeae Crop, Ministry of Agriculture, Beijing 100081, China;2 College of Agronomy, Northwest A&F
University / State Key Laboratory of Arid Region Crop Adversity Biology, Yangling 712100, China; 3 College of Life Science and Technology, Harbin Normal
University / Key Laboratory of Molecular Cytogenetics and Genetic Breeding of Heilongjiang Province, Harbin 150025, China
Abstract: Nuclear transcription factor Y (NF-Y) consistsing of three subunits, NF-YA, NF-YB, and NF-YC, plays an essential role
in many biologic processes, including growth, development, and abiotic stress response. In this study, a NF-Y like transcription factor
gene SiNF-YA5 was isolated from foxtail millet variety Longgu 25. The full-length sequence of SiNF-YA5 gene is 924 bp, encoding
本研究由国家转基因新品种生物培育科技重大专项(2016ZX08002-002)和中国农业科学院创新工程资助。
This work was funded by the National Key Project for Research on Transgenic Biology (2014ZX08002-002) and the Innovation Project of Chinese Academy of
Agricultural Sciences.
* 通讯作者(Corresponding author): 陈明, E-mail: chenming02@caas.cn, Tel: 13683360891 **同等贡献(Contributed equally to this work)
第一作者联系方式:E-mail: hnndhs@126.com, Tel: 17701300735
Received(收稿日期): 2016-03-06; Accepted(接受日期): 2016-06-20; Published online(网络出版日期):
URL:
1
网络出版时间:2016-07-04 08:26:27
网络出版地址:http://www.cnki.net/kcms/detail/11.1809.S.20160704.0826.014.html
307 amino acids. Molecular weight and isoelectric point of SiNF-YA5 protein are 33.76 kD and 9.19, respectively. There is a
conserved CBF domain from the 149th to the 210th amino acids of SiNF-YA5. According to the subcellular localization analysis,
SiNF-YA5 was mainly localized and expressed on the plasma membrane and nucleus in plant cell. Gene functional analysis showed
that under different NaCl concentration treatments, the germination rate of SiNF-YA5 transgenic Arabidopsis was significantly higher
than that of wild-type (WT) Arabidopsis during seed germination stage; root surface area and fresh weight of SiNF-YA5 transgenic
Arabidopsis remarkably increased compared with WT during seedling stage. Those results indicated that the overexpression of
SiNF-YA5 in transgenic plants could enhance tolerance to high salt. Gene expression analysis showed that the expressions of two salt
stress related genes, namely NHX1 and LEA7, increased significantly in SiNF-YA5 transgenic plants. On the other hand, there was no
obvious difference in sensitivity to ABA between SiNF-YA5 transgenic Arabidopsis and WT showed during seed germination and
seedling stages indicating that SiNF-YA5 could enhance salt tolerance through ABA-independent pathway in transgenic plants.
Keywords: Foxtail millet (Setaria italic); NF-Y like transcription factor; High salt stress; ABA independent signaling pathway
干旱、盐碱和低温等非生物胁迫严重影响作物的生长发育及产量[1]。植物在长期的进化过程中逐渐形
成一套复杂的逆境应答机制,以抵御不良环境对植物的损害[2-3]。大量研究证明,植物细胞在染色体水平、
转录水平以及转录后水平精确调控一系列胁迫应答基因的表达,其中,一些功能蛋白包括胚胎发育后期丰
富蛋白(LEA蛋白)、渗透调节蛋白、离子区域化和水通道蛋白、脯氨酸及果聚糖合成酶及甜菜碱合成酶等
直接发挥功能增强植物细胞抗逆性 [4]。另外一些调控蛋白包括感应和传导胁迫信号的蛋白激酶(例如
CDPK,cadium dependent phospholylation kinase;MAPK,mitogen-activated protein kinases )以及参与调控
基因表达的转录因子(包括 Bzip, basic leucine zipper类;NAC, nascent polypeptide-associated complex类;
DREB, dehydration responsive element binding protein类;NF-Y, nuclear transcription factor Y类等)在植物胁
迫应答过程中也发挥重要的基因表达调控作用[5]。近年来,研究证明 NF-Y类、NAC类、DREB类等转录
因子参与多种逆境信号转导途径[6]。ABA (abscisic acid)是调控植物非生物胁迫响应的主要激素[7]。植物调
控非生物胁迫响应的信号途径主要被分为 ABA依赖性和 ABA非依赖性信号途径[2-3]。DREB1A转录因子
主要参与 ABA非依赖的逆境信号途径,过表达 DREB1A提高植物对低温的抗性[8];而 MYBR/C (MYB/C
recognition site)和 ABRE (ABA responsive element)作为 ABA依赖性信号途径中的一类重要的顺式作用元
件,能够调节干旱响应基因的表达[9],过表达 MYC类转录因子 AtMYC2和 MYB 类转录因子 AtMtYB2基
因可以提高植物对 ABA的敏感性和对脱水逆境的耐受性[10]。
植物 NF-Y类转录因子是一类重要的逆境调节因子,由 NF-YA、NF-YB和 NF-YC亚基组成。在行使
功能时,NF-YB亚基和 NF-YC亚基先在细胞质中形成异源二聚体,然后迁移到细胞核中和 NF-YA亚基结
合形成有活性的异源三聚体[11-13]。NF-Y异源三聚体具有保守的 CCAAT-box位点结合特性,而 CCAAT-box
顺式调控元件存在于真核生物约 25%基因的启动子区域,说明 NF-Y转录因子在调控真核生物细胞内基因
表达方面具有重要作用[14-16]。NF-Y转录因子普遍存在于拟南芥[17]、水稻[18]、玉米[19]、大豆[20]、小麦[21-22]
等作物中,参与细胞增殖[23]、叶绿体形成[24]、胚胎发育、种子成熟[25]、光合作用[26-27]、固氮成分的合成[28-29]、
花发育[30]等生长发育过程。除此之外,一些 NF-YA类转录因子在 ABA信号途径中发挥重要作用。基因芯
片分析结果显示诱导启动 NF-YA2、NFYA3、NF-YA7 和 NF-YA10 基因的表达可以下调 PYR1/PYL/RCAR、
PP2C和 SnRK2等 ABA信号途径相关基因的转录[31]。除此之外,一些 NF-YA类基因的拟南芥突变体和过
表达植株在萌发期或者干旱条件下也表现与 ABA有关的表型。拟南芥 AtNF-YA5基因通过依赖 ABA信号
途径调控干旱胁迫[32],并且在萌发期,NF-YA5突变体也表现出对 ABA高度敏感[33]。同时定量分析显示过
表达 NF-YA1、NF-YA2、NF-YA3、NF-YA7、NF-YA9 和 NF-YA10 均可导致拟南芥对 ABA 高度敏感[25]。这
些研究结果都说明 NF-Y转录因子调控植物抗逆反应依赖 ABA信号途径,关于 NF-Y转录因子通过 ABA
非依赖途径调控植物抗逆反应未见报道。
谷子具有抗旱、耐贫瘠等特点,是研究作物抗逆的理想材料[34]。本研究通过克隆并分析高盐胁迫响
应 NF-Y类转录因子 SiNF-YA5基因的特性和生物学功能,旨在为 NF-Y类转录因子调控植物抗逆性的信号
2
途径提供证据,同时也为作物耐盐遗传改良提供新的遗传资源。
1 材料与方法
1.1 试验材料
1.1.1 植物材料 拟南芥野生型(Columbia生态型,WT)由本实验室保存,谷子品种龙谷 25由中国农业
科学院作物科学研究所刁现民课题组提供。
1.1.2 载体和菌株 大肠杆菌、农杆菌 GV3101、pBI121载体、GFP载体都由本实验室保存,pZeroBack
载体购于北京天根公司。
1.1.3 试剂 限制性内切酶、T4 DNA连接酶购于 Promega公司;in-Fusion克隆试剂盒购于 TaRaKa公
司;RT-PCR试剂盒购于全式金生物技术有限公司:质粒提取试剂盒、RNA提取试剂盒、DNA凝胶回收试
剂盒、qRT-PCR试剂盒购于天根公司;引物合成和测序由奥科生物技术科技有限公司完成;其他化学药品
为国产分析纯试剂。
1.2 谷子 SiNF-YA5基因的生物信息学分析
谷子数据来源于 Phytozome 数据库 (http://www.phytozome.net/search.php),利用 SMART 数据库
(http://smart.embl-heidelberg.de/)在线工具分析谷子 SiNF-YA5蛋白的保守结构域。
1.3 SiNF-YA5基因的克隆及载体构建
根据谷子基因 SiNF-YA5 的 CDS 序列设计基因引物 A5-F1 和 A5-R1(表 1),用 RNA 提取试剂盒
(TIANGEN, 北京)提取龙谷 25植株总 RNA,用 TransScript II一步法反转录试剂盒(TransGen, 北京)反转录
成 cDNA,以 cDNA 为模板扩增 SiNF-YA5,并将其回收纯化,采用 in-Fusion 试剂盒(TaKaRa)将其连接到
pZeroBack载体上。以 pZeroBack-SiNF-YA5质粒为模板,引物为A5-F2和A5-R2 (表 1)扩增 SiNF-YA5,BamH
I 酶切 GFP 表达载体,利用 in-Fusion 技术构建载体 16318hGFP-SiNF-YA5。同样以 pZeroBack-SiNF-YA5
质粒为模板,引物为 A5-F3和 A5-R3 (表 1)扩增 SiNF-YA5,Sma I酶切 pBI121表达载体, 利用 in-Fusion技
术构建载体 pBI121-SiNF-YA5。
1.4 SiNF-YA5的亚细胞定位
参考 Yoo等[35]的方法制备谷子原生质体,将融合表达的重组质粒 p16318hGFP-SiNF-YA5和 GFP空载
体质粒作为对照分别转化原生质体,黑暗培养 16 h以上,并在激光共聚焦显微镜(Zeiss LSM700)下观察定
位情况。
1.5 拟南芥转化
参考 Clough等[36]方法进行 SiNF-YA5基因的遗传转化,将收获的 T0代种子种于含卡那霉素(50 mg L-1)
的MS0培养基上,筛选、扩繁获得 T3代的纯合转基因株系 OE1、OE2和 OE3,进一步分析其功能。
1.6 RNA提取及 SiNF-YA5的表达谱分析
将谷子幼苗在营养土中正常生长(温度 22℃、相对湿度 65%、光照周期 16 h光照/8 h黑暗)3周后分别
移至干旱(6% PEG-6000)、ABA (100 μmol L–1)、NaCl (100 mmol L–1)、低氮(0.2 mmol L–1)的水培营养液中
胁迫处理,于处理后 0、1、6和 24 h分别取样,用 RNA提取试剂盒(TianGen,天根)提取谷子植株总 RNA。
另外取 NaCl(MS0 +125 mmol L–1)处理的拟南芥转基因和WT植株,提取总 RNA,–80℃保存备用。分别用
4 种胁迫下的谷子总 RNA 和 NaCl 处理下的拟南芥转基因和 WT 植株 RNA 反转录产物作为模板,以
TransScriptII一步法反转录试剂盒(TransGen, 北京)反转录成 cDNA,以 SYBR Green染料法,在 ABI Prism
7500上进行实时荧光定量 PCR。RT-PCR反应体系含:2×SuperReal PreMix Plus (含荧光染料)(天根公司)12.5
μL、10 μmol L–1正向引物和反向引物各 0.5 μL、50×ROX Reference Dye∆ 0.5 μL、RNase-free ddH2O 9.5 μL。
反应条件为 95℃预变性 10 min;95℃变性 15 s,60℃退火 20 s,72℃延伸 30 s, 并收集荧光信号,35个循
环,用 2–∆∆Ct 法计算该基因表达量。谷子 SiNF-YA5 基因 qRT-PCR 引物为 A5-F4 和 A5-R4,内参基因
(Si001873m.g)引物为 SiActin-F和 SiActin-R (表 1);拟南芥下游基因 qRT-PCR引物为 NHX1-F和 NHX1-R、
3
LEA7-F和 LEA7-R,内参基因(AT3G15260)引物为 AtActin-F和 AtActin-R (表 1)。
表 1 SiNF-YA5基因克隆和 Real-time PCR分析所用引物
Table 1 Primers used for gene cloning and real-time PCR analysis
名称
Primer
序列
Primer sequence (5′–3′)
用途
Function
退火温度
Temperature (℃)
A5-F1
A5-R1
ATGCTTCTGCGAGAAATGGA
TCATGACGGGGTGCGGTGGC
基因克隆
Gene cloning
55
A5-F2
A5-R2
TATCTCTAGAGGATCCATGCTTCTGCGAGAAATG
TGCTCACCATGGATCCTCATGACGGGGTGCGGTG
构建 GFP载体
Vector construction of GFP
63
A5-F3
A5-R3
CTCTAGAGGATCCCCGGGATGCTTCTGCGAGAA
ACTAGTGGATCCCCCGGGTCATGACGGGGTGCG
构建 pBI121载体
Vector construction of pBI121
65
A5-F4
A5-R4
CGTTCCATACCATGCCCAAC
CCACAACTATCATTGTTTTCGGAT
实时定量 PCR
Real-time PCR
55
SiActin-F
SiActin-R
GGCAAACAGGGAGAAGATGA
GAGGTTGTCGGTAAGGTCACG
谷子内参基因
Internal control gene in millet
58
NHX1-F
NHX1-R
AGCCTTCAGGGAACCACAAT
CTCCAAAGACGGGTCGCATG
下游基因检测
Testing of downstream gene
60
LEA7-F
LEA7-R
GGACAAAACTCAAGAGACAG
CATCGTGTGCCTTGTTCTTGAT
下游基因检测
Testing of downstream gene
60
AtActin-F
AtActin-R
TGTTCCCATCAGAACCGTGA
CACCTGTCTTTGGGTCAACAA
拟南芥内参基因
Internal control gene in Arabidopsis
60
1.7 转 SiNF-YA5基因拟南芥的抗盐性分析
将WT和转 SiNF-YA5基因株系 OE1、OE2、OE3的种子经 70%酒精处理 3 min,无菌水清洗 3次,每
次 1 min左右;用 0.5%~0.8%的次氯酸钠处理 15 min,无菌水清洗 3次,每次 1 min;4℃春化 3 d,再将种
子分别点播至MS0、MS0 +75 mmol L–1 NaCl、MS0 +100 mmol L–1 NaCl和MS0 +125 mmol L–1 NaCl的培养
基上,每种材料 64粒种子,重复 3次。在 22℃、相对湿度 65%、光照周期 16 h光照/8 h黑暗条件下萌发
种子,统计萌发率,从第 1天开始统计,连续统计 4 d;同时,将MS0培养基上正常生长 7 d的拟南芥幼
苗转移至MS0、MS0+100 mmol L–1 NaCl、MS0 +125 mmol L–1 NaCl和MS0 +150 mmol L–1 NaCl培养基上,
垂直培养 7 d,统计不同浓度处理下 SiNF-YA5过表达株系和WT植株鲜重,使用根系扫描仪(WINRHIZO
proLA2400)分析根长,试验重复 3次,运用方差分析软件分析转基因株系与野生型之间的差异。
1.8 转 SiNF-YA5基因拟南芥对 ABA敏感性分析
方法同 1.7。萌发试验的 ABA处理浓度为 0.5 μmol L–1和 1 μmol L–1,苗期敏感性试验的 ABA处理浓
度为 30 μmol L–1和 40 μmol L–1。
2 结果与分析
2.1 SiNF-YA5基因的特性分析
前期工作对谷子干旱胁迫转录组分析发现 1 个在干旱处理下表达上调的 NF-YA 类转录因子基因
SiNF-YA5。在谷子基因组数据库(http://www.phytozome.net/)搜索 SiNF-YA5 全长序列,发现 SiNF-YA5 基因
编码序列为 924 bp,有 6个外显子,5个内含子,编码 307个氨基酸,分子量为 33.76 kD。SiNF-YA5在
149~210位氨基酸之间含有 CBF保守域,属于 CCAAT结合蛋白家族。
2.2 SiNF-YA5基因的表达模式分析
利用 qRT-PCR分别检测结果(图 1),在 NaCl处理下,SiNF-YA5的表达量逐渐上升并在 24 h达到最
大,表达量是处理前的 13倍;在 PEG处理下,SiNF-YA5的表达量逐渐上升,在 24 h达最高值,表达量提
高了 4倍;在低氮处理下,SiNF-YA5的表达量也呈上升趋势,在 12 h达最高值,表达量提升了 6倍左右。
在 ABA处理下,SiNF-YA5的表达量在 1 h有所上升,但相比处理前仅提高 1.5倍。
4
图 1 SiNF-YA5在不同处理下的表达模式
Fig. 1 Expression patterns of the SiNF-YA5 gene under various treatments
2.3 SiNF-YA5蛋白亚细胞定位分析
将融合表达的重组质粒p16318hGFP-SiNF-YA5和GFP空载体质粒作为对照分别转化制备的原生质体,
激光共聚焦显微镜下观察结果显示,对照 GFP 蛋白在细胞核、细胞质、细胞膜中均有表达;而转入
16318hGFP-SiNF-YA5融合载体的原生质体在细胞核和细胞膜上都能观察到绿色荧光信号,表明 SiNF-YA5
定位在细胞膜和细胞核中(图 2)。
图 2 16318hGFP-SiNF-YA5蛋白的亚细胞定位分析结果
Fig. 2 Subcellular localization of 16318hGFPSiNF-YA5 protein
2.4 高盐条件下 SiNF-YA5转基因拟南芥种子萌发率分析
从第 1天观察WT和 SiNF-YA5转基因拟南芥株系 OE-1、OE-2和 OE-3, 连续 4 d统计萌发率。结果显
示,在MS0培养基中的 SiNF-YA5转基因拟南芥和WT种子萌发率基本保持一致,在 24 h以后萌发率维持
在 95%左右(图 3, 图 4-A);在 75 mmol L–1 NaCl的培养基中,在 24 hWT不萌发,SiNF-YA5转基因拟南芥
少量萌发,在 48 h,两者的萌发率相差最大,WT为 26.3%,SiNF-YA5转基因拟南芥为 84.5%,72 h以后
SiNF-YA5转基因拟南芥萌发率接近 100%,两者差异逐渐减小(图 3, 图 4-A);在 100 mmol L–1 NaCl和 125
mmol L–1 NaCl的培养基中,分别在 36 h及 48 h,SiNF-YA5转基因拟南芥和WT的萌发率才开始出现差异,
SiNF-YA5 转基因拟南芥的萌发率始终显著高于 WT (图 3, 图 4-A)。以上结果表明,高盐处理条件下,
SiNF-YA5转基因拟南芥的萌发率明显高于WT,随着 NaCl浓度的增加,WT和 SiNF-YA5转基因拟南芥的
萌发速率都减慢,但 SiNF-YA5 转基因拟南芥的萌发率始终显著高于 WT。另外,在萌发第 5 天统计,在
100 mmol L–1 NaCl和 125 mmol L–1 NaCl处理条件下,SiNF-YA5转基因拟南芥绿苗数高于WT,并达到极
显著水平(图 4-B)。说明在拟南芥中过表达 SiNF-YA5 基因提高了拟南芥萌发期对高盐胁迫的耐受性,
SiNF-YA5正向调节植物对高盐胁迫的耐性。
5
图 3 高盐处理下 SiNF-YA5转基因拟南芥和WT种子萌发情况
Fig.3 Seed germination situation of SiNF-YA5 transgenic Arabidopsis and WT under high salt stress condition
6
图4 高盐处理下SiNF-YA5转基因拟南芥和WT种子的萌发率和绿苗率
Fig. 4 Seed germination rates and green plantlet rates of SiNF-YA5 transgenic Arabidopsis and WT under high salt stress
A:高盐处理下的种子萌发率;B:高盐处理下的绿苗率;采用单因素方差分析法对数据进行统计分析,柱上不同的小写字母代表柱值在 0.05水平上
差异显著,不同大写字母代表柱值在 0.01水平上差异显著。
A: seed germination rate under high salt treatment; B: green plantlet frequency under high salt treatment; Data statically analysis was made by the means of
one-way ANOVA. The values marked with different lower-case letters on the columns are significantly different at the 0.05 level; The values marked with
different upper case letters on the columns are significantly different at the 0.01 level.
2.5 SiNF-YA5转基因拟南芥苗期耐盐性鉴定
垂直培养 7 d后显示,在正常MS0培养基上,SiNF-YA5转基因拟南芥根表面积和植株鲜重与WT比较
没有明显差别(图 5,6-A),而在 100 mmol L–1、125 mmol L–1 NaCl胁迫处理下,与WT相比,SiNF-YA5
转基因拟南芥的根表面积及植株鲜重增加,在 125 mmol L–1 NaCl处理下的根表面积差异达到极显著水平
(图 6-A),转基因株系的鲜重与WT相比差异达到显著水平(图 6-B)。以上结果表明在植物中过表达 SiNF-YA5
基因可以显著提高转基因拟南芥苗期耐盐性。在 150 mmol L–1 NaCl处理条件下,转基因拟南芥及WT都
趋向于死亡,差异不显著(图 5)。
7
图 5 高盐处理下 SiNF-YA5转基因拟南芥和WT苗期表型
Fig. 5 Phenotype of SiNF-YA5 transgenic Arabidopsis and WT seedlings under high salt stress
图 6 高盐处理下 SiNF-YA5转基因拟南芥和WT苗期根表面积和鲜重
Fig. 6 Root surfaces(A) and fresh weights(B) of SiNF-YA5 transgenic Arabidopsis and WT seedlings under high salt stress
A:高盐处理下的根表面积;B:高盐处理下植株鲜重。采用单因素方差分析法对数据进行统计分析,柱上不同的小写字母代表柱值在 0.05水平上差
异显著,不同大写字母代表柱值在 0.01水平上差异显著。
A: root surface under high salt treatment.; B: fresh weight under high salt treatment. Data statically analysis was made using method of one-way ANOVA. The
values marked with different lower-case letters on the columns are significantly different at the 0.05 level; The values marked with different upper case letters
on the columns are significantly different at the 0.01 level.
2.6 高盐胁迫响应相关基因的表达分析
图 7显示,在盐胁迫下,盐胁迫响应相关基因 Na+/H+转运蛋白基因(NHX1)和种子胚胎发育后期富集的
脱水保护蛋白基因(LEA7)在 SiNF-YA5转基因拟南芥中的表达明显高于WT,说明 SiNF-YA5可能通过控制
拟南芥中盐胁迫相关基因 NHX1和 LEA7的表达来提高植物耐盐性。
8
图 7 NaCl处理下 SiNF-YA5转基因拟南芥中盐胁迫相关基因表达水平
Fig. 7 Expression levels of two stress-tolerant genes in SiNF-YA5 transgenic Arabidopsis under NaCl treatment
2.7 SiNF-YA5转基因植株对 ABA敏感性分析
在 ABA处理下,WT和 SiNF-YA5转基因株系萌发率无差异(图 8-A,图 9)。取上述MS0培养基上正常
生长 7 d的WT和 SiNF-YA5转基因拟南芥幼苗,分别转接到正常MS0和含有 30 μmol L–1和 40 μmol L–1 ABA
的MS0培养基上照光,垂直培养 7 d,结果显示,WT和转基因拟南芥在地上部分和地下部分无显著差异(图
8-B)。说明无论在萌发期还是苗期,SiNF-YA5 转基因拟南芥与 WT 相比对 ABA 敏感性没有差异,证明
SiNF-YA5不参与 ABA信号途径,它通过 ABA非依赖途径调控植物的耐盐性。
图 8 SiNF-YA5转基因拟南芥和WT对 ABA敏感性
Fig. 8 Sensitivity analysis of SiNF-YA5 transgenic Arabidopsis and WT under ABA treatment
A:SiNF-YA5转基因拟南芥和WT种子在含有 0.5 μmol L–1和 1 μmol L–1 ABA的培养基上萌发情况;B:SiNF-YA5转基因拟南芥幼苗和WT幼苗在含
有 30 μmol L–1和 40 μmol L–1 ABA的培养基上对 ABA敏感性。
A: seed germination situation of SiNF-YA5 transgenic Arabidopsis and WT under 0.5 μmol L–1 and 1 μmol L–1 ABA treatment; B: sensitivity analysis of
SiNF-YA5 transgenic Arabidopsis seedlings under 30 μmol L–1 and 40 μmol L–1 ABA treatment.
9
图 9 ABA处理下SiNF-YA5转基因拟南芥和WT种子的萌发率
Fig. 9 Seed germination rates of SiNF-YA5 transgenic Arabidopsis and WT under ABA treatment
3 讨论
NF-Y转录因子是一类重要的逆境调控因子,它由 3类亚基构成,NF-YA亚基可进一步被分为 7个亚
族。本研究从谷子中克隆 1个 NF-YA类基因 SiNF-YA5, 根据已经发表的谷子 NF-YA类转录因子进化树分
析结果显示 SiNF-YA5属于第 III亚族[37],与水稻 NF-YA蛋白(OsHAP2E)进化关系最近,而与拟南芥 NF-YA
蛋白进化关系较远。目前,已经报道许多 NF-Y类转录因子依赖 ABA信号途径参与干旱、耐盐胁迫反应。
大豆 GmNF-YA3受 ABA和 NaCl胁迫诱导表达,在拟南芥中过表达 GmNF-YA3能够提高植物的抗旱性。
在正常条件下,在 GmNF-YA3 过表达拟南芥中,ABA 合成及信号传导相关基因和胁迫相关基因转录水平
提高[20]。拟南芥 AtNF-YA1基因依赖 ABA信号途径负向调控植物盐胁迫耐性,抑制幼苗的生长。在苗期,
过表达 AtNF-YA1基因的转基因拟南芥提高了植物对盐和 ABA的敏感性,当 ABA抑制剂存在时,过表达
AtNF-YA1 拟南芥对盐敏感的表型恢复[38]。谷子 SiNF-YA1 (Si037045m)和 SiNF-YB8 (Si032469m)基因通过
ABA 信号途径激活胁迫相关基因表达,改善植物生理特性从而正向调节植物耐盐性和耐旱性[37]。同时发
现 SiNF-YA5与拟南芥 AtNF-YA1、谷子 SiNF-YA1和 SiNF-YB8均不在同一亚族,推测 SiNF-YA5可能通过与
上述基因不同的其他途径调控耐盐和抗旱性。本文研究结果表明,在高盐处理条件下,SiNF-YA5转基因拟
南芥在萌发期的萌发率显著高于WT (图 4);在苗期,SiNF-YA5转基因拟南芥的根系比WT发达,鲜重显
著大于WT (图 6)。然而,与 SiNF-YA1和 SiNF-YB8基因不同,SiNF-YA5转基因拟南芥在萌发期和苗期对
ABA均不敏感(图 8),所以推测 SiNF-YA5通过 ABA非依赖途径提高植物对 NaCl胁迫的耐性。Chamindika
创建拟南芥 NF-YA类转录因子的 10个过表达材料,观察 ABA调节的种子萌发和植物生长发育的情况,结
果发现所有的材料生长发育受到抑制,但萌发期对 ABA敏感性存在差异。在 ABA不敏感的过表达材料中
进行基因表达检测发现 ABA 信号途径相关基因下调[39]。同样,NF-YC 类转录因子在种子萌发期对 ABA
的反应也不完全相同,种子萌发期 NF-YC4突变体对 ABA敏感,而 NF-YC3 和 NF-YC9突变体则不敏感[40]。
这些研究结果都表明 NF-Y类转录因子调控耐盐的途径存在差异,同时存在着 ABA依赖型和 ABA非依赖
型的耐盐信号调控途径。
在 SiNF-YA5转基因株系中,我们检测到参与盐胁迫响应基因 NHX1和 LEA7的表达量较WT都显著提
高(图 7)。同时,分别分析 NHX1和 LEA7基因的启动子区域,发现两者均有 4个 CAATT-box结构域(NF-Y
类转录因子结合元件),因此推测 SiNF-YA5可能主要通过ABA非依赖途径直接激活下游基因NHX1和 LEA7
基因表达完成植物的耐盐调控。NHX1 是第 1 个在拟南芥中发现的 Na+/H+ 转运蛋白,能够促进钠离子在
液泡中的积累 [41]。盐胁迫环境下构建及分析 SOS 转录调控网络时发现拟南芥 bZIP类转录因子At5g65210
首先通过 ABA 非依赖途径接收细胞膜上感受器传递的外界 Na+信号,然后调控液泡膜上的 Na+/H+转运基
因 NHX1[42]。NHX1主要利用液泡膜的 H+-ATPase和液泡膜 H+-PPase产生的跨膜质子梯度将胞质中的 Na+
逆浓度梯度运入液泡中降低 Na+对植物细胞的毒害作用[43]。LEA蛋白是一类参与细胞抗逆保护的蛋白质,
广泛存在于植物的种子中,能够在干旱胁迫时保护膜系统以及生物大分子免受脱水伤害。植物遭受干旱、
10
盐渍及低温等胁迫时,体内 LEA 基因的表达会增加。已有研究报道 LEA 基因可以增加转基因水稻耐盐和
抗旱性[44]。关于 SiNF-YA5 提高转基因植物对高盐胁迫耐性的信号途径还需要进一步分析,本研究初步阐
明了谷子 SiNF-YA5在调节高盐胁迫响应中的 ABA非依赖型信号途径,为进一步了解谷子抗逆机制提供了
新的依据。
4 结论
从谷子中分离出 NF-Y类转录因子基因 SiNF-YA5。SiNF-YA5被定位于细胞核及细胞膜。SiNF-YA5受
低氮、干旱、高盐等胁迫的诱导表达。在植物中过表达 SiNF-YA5 可以显著提高植物在萌发期及苗期的耐
盐性。SiNF-YA5转基因植物对 ABA的敏感性与WT差异不显著,证明 SiNF-YA5通过 ABA非依赖途径调
控植物的耐盐性。
References
[1] Boyer J S. Plant productivity and environment. Science, 1982, 218: 443–448
[2] Xiong L M, Schumaker K S, Zhu J K. Cell signaling during cold, drought, and salt stress. Plant Cell, 2002, 14: S165–S183
[3] Zhu J K. Salt and drought stress signal transduction in plants. Annu Rev Plant Biol, 2002, 53: 247–273
[4] The Arabidopsis Genome Initiative. Analysis of the genome sequence of the flowering plant Arabidopsis thaliana. Nature, 2000, 408: 796–815
[5] Riechmann J L, Ratcliffe O J. A genomic perspective on plant transcription factors. Curr Opin Plant Biol, 2000, 3: 423–434
[6] Kasuga M, Liu Q, Miura S, Yamaguchi-Shinozaki K, Shinozaki K. Improving plant drought, salt and freezing tolerance by gene transfer of a single
stress-inducible transcription factor. Nat Biotechnol, 1999, 17: 287–291
[7] Yamaguchi-Shinozaki K, Shinozaki K. Transcriptional regulatory networks in cellular responses and tolerance to dehydration and cold stresses. Annu Rev
Plant Biol, 2006, 57: 781–803
[8] Jiang C, Iu B, Singh J. Requirement of a CCGAC cis-acting element for cold induction of the BN115 gene from winter Brassica napus. Plant Mol Biol,
1996, 30: 679–684
[9] Uno Y, Furihata T, Abe H, Yoshida R, Shinozaki K, Yamaguchi-Shinozaki K. Arabidopsis basic leucine zipper transcription factors involved in an abscisic
acid-dependent signal transduction pathway under drought and high-salinity conditions. Proc Natl Acad Sci USA, 2000, 97: 11632–11637
[10] Abe H, Urao T, Ito T, Seki M, Shinozaki K, Yamaguchi-Shinozaki K. Arabidopsis AtMYC2 (bHLH) and AtMYB2 (MYB) function as transcriptional
activators in abscisic acid signaling. Plant Cell, 2003, 15: 63–78
[11] Mantovani R, Li X Y, Pessara U, Hooft van Huisjduijnen R, Benoist C, Mathis D. Dominant negative analogs of NF-YA. J Biolog Chem, 1994, 32:
20340–20346
[12] Frontini M, Imbriano C, Manni I, Mantovani R. Cell cycle regulation of NF-YC nuclear localization. Cell Cycle, 2004, 3: 217–222
[13] Kahle J, Baake M, Doenecke D, Albig W. Subunits of the heterotrimeric transcription factor NF-Y are imported into the nucleus by distinct pathways
involving importin beta and importin 13. Mol Cell Biol, 2005, 25: 5339–5354
[14] Steidl S, Tuncher A, Goda H, Guder C, Papadopoulou N, Kobayashi T, Tsukagoshi N, Kato M, Brakhage A. A single subunit of a heterotrimeric
CCAAT-binding complex carries a nuclear localization signal: Piggy back transport of the pre-assembled complex to the nucleus. J Mol Biol, 2004, 342:
515–524
[15] Ceribelli, M, Dolfini, D, Merico D, Gatta R, Vigano A M., Pavesi G, Mantovani R. The histone-like NF-Y is a bifunctional transcription factor. Mol Cell
Biol, 2008, 28: 2047–2058
[16] Maity S N, de Crombrugghe B. Role of the CCAAT-binding protein CBF/NF-Y in transcription. Trends Biochem Sci, 1998, 23: 174–178
[17] Siefers N, Dang K K, Kumimoto R W, Bynum W E, Tayrose G, Holt B F. Tissue-specific expression patterns of Arabidopsis NF-Y transcription factors
suggest potential for extensive combinatorial complexity. Plant Physiol, 2009, 149: 625–641
[18] Thirumurugan T, Ito Y, Kubo T, Serizawa A, Kurata N. Identification, characterization and interaction of HAP family genes in rice. Mol Genet Genomics,
2008, 279: 279–289
11
[19] Nelson D E, Repetti PP, Adams T R, Creelman R A, Wu J, Warner D C, Anstrom D C, Bensen R J, Castiglioni P P, Donnarummo M G, Hinchey B S,
Kumimoto R W, Maszle D R, Canales R D, Krolikowski K A, Dotson S B, Gutterson N, Ratcliffe O J, Heard J E. Plant nuclear factor Y (NF-Y) B subunits
confer drought tolerance and lead to improved corn yields on water-limited acres. Proc Natl Acad Sci USA, 2007, 104: 16450–16455
[20] Ni, Z Y, Hu Z, Jiang Q Y, Zhang H. GmNFYA3, a target gene of miR169, is a positive regulator of plant tolerance to drought stress. Plant Mol Biol, 2013,
82: 113–129
[21] Qu B, He X, Wang J, Zhao Y, Teng W, Shao A, Zhao X, Ma W, Li B, Li Z, Tong Y. A wheat CCAAT box-binding transcription factor increases the grain
yield of wheat with less fertilizer input. Plant Physiol, 2014; 167: 411–423
[22] Stephenson T J, McIntyre C L, Collet C, Xue G P. Genome-wide identification and expression analysis of the NF-Y family of transcription factors in
Triticum aestivum. Plant Mol Biol, 2007, 65: 77–92
[23] Sun X C, Ling S, Lu Z H, Ouyang Y D, Liu S S, Yao J. OsNF-YB1, a rice endosperm-specific gene, is essential for cell proliferation in endosperm
development. Gene, 2014, 551: 214–221
[24] Miyoshi K, Ito Y, Serizawa A, Kurata N. OsHAP3 genes regulate chloroplast biogenesis in rice. Plant J, 2003, 36: 532–540
[25] Mu J, Tan H, Hong S, Liang Y, Zuo J. Arabidopsis transcription factor genes NF-YA1, 5, 6, and 9 play redundant roles in male gametogenesis,
embryogenesis, and seed development. Mol Plant, 2013, 6: 188–201
[26] Alam M M, Tanaka T, Nakamura H, Ichikawa H, Kobayashi K, Yaeno T, Yamaoka N, Shimomoto K, Takayama K, Nishina H, Nishiguchi M.
Overexpression of a rice heme activator protein gene (OsHAP2E) confers resistance to pathogens, salinity and drought, and increases photosynthesis and
tiller number. Plant Biotechnol J, 2015, 13: 85–96
[27] Stephenson T J., McIntyre C L, Collet C, Xue G P. TaNF-YB3 is involved in the regulation of photosynthesis genes in Triticum aestivum. Funct Integr
Genomics, 2011, 11: 327–340
[28] Combier J P, Frugier F, de Billy F, Boualem A, El-Yahyaoui F, Moreau S, Vernie T, Ott T, Gamas P, Crespi M, Niebel A. MtHAP2-1 is a key transcriptional
regulator of symbiotic nodule development regulated by microRNA169 in Medicago truncatula. Genes Dev, 2006, 20: 3084–3088
[29] Zanetti M E, Blanco F A, Beker M P, Battaglia M, Aguilar O M. A C subunit of the plant nuclear factor NF-Y required for rhizobial infection and nodule
development affects partner selection in the common bean-Rhizobium etli Symbiosis. Plant Cell, 2010, 22: 4142–4157
[30] Hackenberg D, Keetman U, Grimm B. Homologous NF-YC2 subunit from Arabidopsis and tobacco is activated by photooxidative stress and induces
flowering. Int J Mol Sci, 2012, 13: 3458–3477
[31] Leyva-Gonzalez M A, Ibarra-Laclette E, Cruz-Ramirez A, HerreraEstrella L. Functional and transcriptome analysis reveals an acclimatization strategy for
abiotic stress tolerance mediated by Arabidopsis NF-YA family members. 2012, PLoS One, 7: e48138
[32] Li W X, Oono Y, Zhu J, He X J, Wu J M, Iida K, Lu X Y, Cui X P, Jin H L, Zhu J K. The Arabidopsis NFYA5 transcription factor is regulated
transcriptionally and posttranscriptionally to promote drought resistance. Plant Cell, 2008, 20: 2238–2251
[33] Warpeha K M, Upadhyay S, Yeh J, Adamiak J, Hawkins S I, Lapik Y R, Anderson M B, Kaufman L S. The GCR1, GPA1, PRN1, NFY signal chain
mediates both blue light and abscisic acid responsesin Arabidopsis. Plant Physiol, 2007, 143: 1590–1600
[34] 刘敬科, 刁现民. 我国谷子产业现状与加工发展方向. 农业工程技术: 农产品加工业, 2013, (12): 15–17
Liu J K, Diao X M. Foxtail millet processing industry status and development trend in our country. Agriculture Engineering Technology(Agricultural
Product Processing), 2013, (12): 15–17 (in Chinese)
[35] Yoo S D, Cho Y H, Sheen J. Arabidopsis mesophyll protoplasts: a versatile cell system for transient gene expression analysis. Nat Protoc, 2007, 2:
1565–1572
[36] Beehtold N, Ellis J, Pelletier G. In plant Agrobacterium mediated gene transfer by infiltration of adult Arabidopsis thaliana plants. Life Sci, 1993, 316:
1194–1199
[37] Feng Z J, He G H, Zheng W J, Lu P P, Chen M, Gong Y M, Ma Y Z, Xu Z S. Foxtail Millet NF-Y Families: Genome-Wide Survey and Evolution Analyses
Identified Two Functional Genes Important in Abiotic Stresses. Front Plant Sci, 2015, 6
[38] Li Y J, Fang Y, Fu Y R, Huang J G, Wu C A, Zheng C C. NFYA1 Is Involved in Regulation of Postgermination Growth Arrest Under Salt Stress in
Arabidopsis. PLoS One, 2013, 8(4): e61289
[39] Siriwardana C L, Kumimoto R W, Jones D S, Holt B F. Gene Family Analysis of the Arabidopsis NF-YA Transcription Factors Reveals Opposing Abscisic
12
Acid Responses During Seed Germination. Plant MolBiol Rep, 2014, 32: 971–986
[40] Kumimoto R W, Siriwardana C L, Gayler K K, Risinger J R, Siefers N, Holt B F. NUCLEAR FACTOR Y transcription factors have both opposing and
additive roles in ABA-mediated seed germination, PLoS One, 2013, 8: e59481
[41] Gaxiola R A, Rao R, Sherman A, Grisafi P, Alper S L, Fink G R. The Arabidopsis thaliana proton transporters, AtNHX1 and Avpl, can function in cation
detoxification in yeast. Proc Natl Acad Sci USA, 1999, 96: 1480–1485
[42] 谢崇波, 金谷雷, 徐海明, 朱军. 拟南芥在盐胁迫环境下 SOS转录调控网络的构建及分析. 遗传, 2010, 6: 639–646
Xie C B, Jing G L, Xu H M, Zhu J. Construction and analysis of SOS pathway-related transcriptiona regulatory network underlying salt stress response in
Arabidopsis. Hereditas, 2010, 6: 639–646 (in Chinese with English abstract)
[43] Wu Y Y, Chen Q J, Chen M, Chen J, Wang X C. Salt-tolerant transgenic perennial ryegrass (Lolium perenne L.) obtained by Agrobacterium
tumefaciens-mediated transformation of the vacuolar Na+/H+ antiporter gene. Plant Sci, 2005, 169: 65–73
[44] Babu R C, Zhang J X, Blum A, Ho T H D, Wu R, Nguyen H T. HVA1, a LEA gene from barley confers dehydration tolerance in transgenic rice (Oryza
sativa L.) via cell membrane protection. Plant Sci, 2004, 166: 855–862
13