第七章 植物的抗性生理
胁迫 (Stress),对植物生长的不良环境因子。
逆境,胁迫的总称。
? 生物胁迫,
病、虫、杂草,动物、人为因素等。
? 非生物胁迫,
? 水分 （旱、涝） ；
? 盐；
? 温度 （热、冷、冻） ；
? 辐射 （可见、紫外） ；
? 化学物质 （杀虫剂、重金属、空气污染）。
地球上可用于农业耕作土地的分配
胁迫引起作物大幅度减产
植物响应胁迫的方式,
抗逆性 ———— 存活 或生长；
感逆性 ———— 死亡。
植物抵抗胁迫（抗逆性）的机制,
避逆 (avoidance)机制 —— 物种进化形成的 组
成性 的适应。
耐逆 (tolerance)机制 —— 调整生理反应机
制 （驯化） 以适应胁迫。
植物驯化过程通过改变基因表达方式
来形成抗逆性的生理反应机制
第一节 低温胁迫和植物抗寒性
一、冷害 (Chilling stress)
主要零上低温所引起。
冷害引起的生理反应,
降低原生质的流动性；
原生质膜透性增大，胞内内容物外渗；
光合作用受抑制；
呼吸紊乱；
改变基因表达和蛋白质的合成方式；
Exposure of chilling-
sensitive plants such
as cucumber to 2° C
for 1d cause severe
injury,The plant on
the right was kept at
25 ° C
冷伤害的主要机理,
低温 — → 膜相变 （液晶相 → 凝胶相）
凝胶相,膜收缩，透性增大,胞内内容物外渗；
膜结合蛋白活性下降，代谢紊乱。
膜相变在一定温度范围内是可逆的。
? Thermal transition from the
gel phase (L?) to liquid
crystalline phase (L?) in a
pure phosphatidylcholine
bilayer (low panel),
? At low temperatures,motion
of fatty acid chains is limited
by Van der Waals forces,As
the temperature is raised
through the phase transition,
heat is absorbed and Van
der Waals forces are
disrupted to form a bilayer
with melted fatty acid chains,
膜脂中不饱和脂肪酸的含量,决定膜相变温度
? 不饱和脂肪酸含量越高，引起 膜相变的温度越低。
? 含不饱和脂肪酸越多的物种和品种，抗冷性越强。
例：粳稻 > 籼稻
?Ratio of unsaturated and saturated fatty
acids of membrane lipids of mitochondria
isolated from chilling-sensitive and chilling-
resistant tissues
?Chilling-sensitive tissues,
? Bean shoot 2.8
? Sweet potato tuber 1.7
? Maize shoot 2.1
? Tomato green fruit 2.8
?Chilling-resistant tissues,
? Cauliflower buds 3.2
? Turnip root 3.9
? Pea shoot 3.8
Three different chilling responses
in lipid mutants of Arabidopsis,? (A) Compared with WT-type (left),the fad6
(right) becomes
chlorotic after 3
weeks at 5° C;
(B) fad2 die after 7
weeks at 6° C;
? (C) Compared with
WT-type (left),the fab1
(right) unaffected by
up to 1 week at 2° C;
(D) After 4 weeks at
2° C,however,fab1
(right) show clear
symptoms of
chlorosis and reduced
growth,
二、冻害（ Freezing stress）,主要由零下低温
使植物组织结冰所引起。
1、胞外结冰,
环境温度缓慢下降，质外体（细胞间隙）结冰，
引起胞质水分亏缺；
2、胞内结冰,
环境温度骤然下降，质外体与共质体均结冰，冰
在形成或融化过程中对亚细胞精细结构的机械伤害。
植物耐受冻害的生理机制
1,膜稳定性,改变膜脂的构成（脂肪酸不饱和
度、膜固醇和脑苷脂的丰度、膜蛋白的性质）；
2,基因表达改变,COR15a gene,转基因拟南芥
表现强抗冻性；
3,抗冻蛋白 (AFPs,antifreeze proteins)
在低温驯化期间形成，专一分泌并累积与细
胞间隙；
AFPs 以大表面寡聚复合体覆盖于冰晶表面，
抑制冰晶的增大；
AFPs 存在于真菌、昆虫、鱼与植物（尤其
为过冬植物）中。
A,Crystal growth in water;
B,Water plus a purified AFP,a glucanase,from
winter rye;
C,Water plus a crude extract of apoplastic
proteins from cold-acclimated winter rye leaves,
三、低温锻炼（ Cold hardening）,预先以适当、
安全的低温给予植物一定时间的处理。
提高植物耐寒性的有效措施
? Leakage of electrolytes from mature Arabidopsis leaves before
and after acclimation at 4° C for 7d,
? During freezing
stress,changes in
plasma membrane
morphology
determine death or
survive of the cell,
Cold acclimation allows plants to survive freezing
? The Arabidopsis plants on the right were incubated at 4 ° C
for 4d to acclimate the plants,after which both pots were
kept at -5 ° C for 4d,and then transferred to growth
conditions at 23 ° C for 10d,
第二节 高温胁迫和植物抗热性
高温引起的生理反应,
细胞结构的损伤（细胞器和细胞骨架）；
膜功能受损
基因表达改变
蛋白质的合成改变（正常蛋白合成受阻，诱导 HSPs合成）
? 主要的热激蛋白及其功能（数字,MW)
HSP family Probable function
HSP110 Unknown
HSP90 Protecting receptor proteins
HSP70 ATP-dependent protein assembly or
disassembly
reactions; preventing proteins from
denaturation
HSP60 Molecular chaperone,directing the proper
assembly
of multi-subunit proteins
LMW HSPs Function largely unknown (17-28kDa)
Ubiquitin An 8 kDa protein involved in targeting
other proteins
for proteolytic degration
热锻炼能提高植物的耐热性
? Induced thermo-tolerance in soybean seedlings,
? Left,Grown at 28° C;
? Center,2h at 40 ° C before 2h at 45 ° C,then
28° C;
? Right,2h at 45 ° C,then 28° C,
第三节 水分 (亏缺 )胁迫
(water deficit stress)
及植物的抗旱性
? 包括 干旱 (drought)胁迫 （由自然环境缺
水引起）和 脱水 (desiccation)胁迫 （实
验室人为脱水引起）；
? 为 盐 (salt)胁迫 和 渗透 (osmotic)胁迫 的
组成部分。
旱生植物,
生长于极端干旱地区，如沙漠；
形态、功能上特殊机制，能抗极度脱水；
复水后, 起死回生,
中生植物,
耐受一定范围内的脱水，产生相应的生理反应；
大部分高等植物。
? Craterostigma plantagineum plants,(A) Fully turgid
plant,(B) Desiccated plant (unwatered for 7d),(C)
Plant rehydrated for 6h,
中生植物的生理变化与耐旱性,
1、地上部生长延缓，乃至部分叶片脱落。降
低失水；
2,根系纵向生长加快，增加吸水；根 /冠 (R/T)
增大
3、气孔关闭，光合作用下降；
4,ABA上升；
5,渗透调节物质大量合成；
6,水分 胁迫诱导的基因表达。
? Movement of H2O into & out of a cell depends on the
water potential gradient across the plasma membrane,
ABA在植物中起传递旱情的信号,
? Accumulation of ABA in maize roots and in xylem
sap as a result of soil drying,
? Effect of manipulating ABA concentration in
xylem sap on stomatal conductance of leaves
(abaxial epidermis) in maize,
渗透调节物质 (osmolyte),
高度水溶性、不干预细胞代谢的有机化合物。
? The chemical structures
of some important cellular
compatible osmolytes,
渗透调节作用 (osmotic adjustment)
? Osmotic adjustment occurs when the concentration of solutes
within a plant cell increase to maintain a positive turgor pressure
within the cell,
水分胁迫响应基因的表达与抗胁迫
? Expression of MIP-related genes in roots of Mesembryanthemum
crystallinum,Declining transcript abundance in response to
osmotic stress correlates with loss of turgor,Transcript
concentrations increase as turgor is restored,
? MIP (major intrinsic protein),a aquaporin ecoded by RD28 gene,
水分胁迫响应基因亦受 ABA诱导
? Accumulation of RAB18 & LT178 mRNA in Arabidopsis
thaliana,
通过 抗旱锻炼 能提高植物的抗旱性
抗性锻炼,植物经过一段时间的自然或人工的
非致死胁迫后，往往增强了对该胁迫的抗性。
“蹲苗”：适度干旱措施
第四节 涝害 (flooding)与植物的抗涝性
Plants vary in ability to tolerate flooding
Wetland plants Flood-tolerant plants Flood-sensitive plants
Sweet flag Arabidopsis thaliana Soybean
Rice grass Barnyard grass Tomato
Barnyard grass Oat Pea
Coral tree Potato
Golden dock Wheat
Rice Corn
Wild rice
A flooded maize field,
Flooding in the US
Midwest in 1993
resulted in an estimated
33% reduction in yield
compared with 1992,
Wetland plants posses diverse anatomical,morphological
and physiological features that permit survival in aquatic
environments or waterlogged soils
Survival strategies of a freshwater weed,(A) Hydrilla verticillata (L.f.)
Royle,a monocotyledous native of Asia,is an invasive submerged
weed in freshwater ecosystems in the southern US,(B) Hydrilla
develops as a dense mat of stems and leaves near the surface of the
water,These plants now threaten waterways in Florida and other
Southeastern states,
Aerenchyma,continuous,columnar intracellular
spaces formed in root cortical tissues
Aerenchyma development in root cortex of maize after oxygen
deprivation,(A) under aerobic conditions,(B) under 72h of hypoxia
Lenticels,openings in the periderm that allow gas
exchange
? Adventitious roots and prominent lenticels on the stem
of young ash after flooding,The black arrow indicates
the water depth during flooding,
Pneumatophores,shallow roots that grow with
negative geotrophy out of the aquatic environment,
? Pneumatophores of mangrove develop from roots
submerged in estuarine mud
Internodal stem elongation,enables stems and leaves
to be established above the aquatic environment,
(A) Diagram illustrating growth response of seedlings deepwater rice to
flooding,Submerge promotes rapid internodal elongation and
development of adventitious roots,Once the flood waters recede,the
adventitious roots grow into the soil and aerial portions of the plant
grow upward,
(B) Photographs comparing internode elongation in aerobic (left) and
submerged (right) plants,Arrows indicate positions of nodes,
During short-term acclimation to anoxic conditions,plants
generate ATP through glycolysis and fermentation
Major fermentation products
of carbohydrate
metabolism in flooded
roots
Impact of oxygen deprivation on
respiratory metabolism
Oxygen status Effect on metabolism
Normoxic (aerobic) Aerobic respiration proceeds normally,Almost all ATP
production results from oxidative phosphorylation,
Hypoxic The partial pressure of O2 limits ATP production by oxi-
dative phosphorylation,Glycolysis accounts for a larger
percentage of ATP yield than under normoxic condition,
Metabolic and developmental changes are stimulated
that result in adaptation to a low-oxygen environment,
Anoxic (anaerobic) ATP is produced by way of glycolysis,Cells exhibit low
ATP contents,diminished protein synthesis,and
impaired division and elongation,If anoxic conditions
persist,many plant cells die,
Effects of hypoxic pretreatment and acclimation on
survival of anoxia,avoidance of cytoplasmic acidosis
by lactate efflux,
Flooding typically results in hypoxia,followed by anoxia,Exposure of
maize seedlings to hypoxia for several hours before being transferred to
anoxia increases the ability of roots for lactate efflux and prolongs
survival,
Ethylene promotes long-term acclimative responses,
including formation of aerenchyma and stem
elongation
Treatment Action Effect on aerenchyma
develpment
Hypoxia Stimulates ETH production Promoted
Hypoxia + Ag+ Inhibits ETH action Reduced
Hypoxia + AVG Inhibits ETH synthesis Reduced
Hypoxia + EGTA Chelates Ca2+ Reduced
Normoxia + ethylene Induces ETH response Promoted
Normoxia + caffeine Increase cytosolic Ca2+ Promoted
Role of ethylene in promotion of long-term
acclimative responses
(A) Formation of aerenchyma is stimulated by
hypoxia but not by anoxia,
Transduction of low O2 signal in maize leads to PCD during
the formation of lysigenous aerenchyma,Chemicals that
increase the cytosolic Ca2+ concentration under aerobic
conditions promote aerenchyma formation,whereas
compounds that block Ca2+ movement under anoxia inhibit
aerenchyma formation,
第五节 盐害 (salt stress)与植物的抗盐性
Areas of greatest aquifer depletion,saltwater intrusion
and groundwater contamination in US,
High salt concentrations in the rhizosphere generate
stress through water deficits and ion toxicity,
Exclusion of salt and osmotic adjustment both play
major roles in tolerance of high salt environments,
? Areas with high salinity,
Coastal salt-marshes;
Island deserts;
Near the shores of island lakes ;
Crop fields with extensive irrigation,
? In China,more than 7 million hectares are
classified as saline,much of this resulting from
centuries of irrigation,
A New England salt marsh is one highly productive estuarine
habitat,The primary producers are phytoplankton,algae,and
salt-tolerant plants such as marsh grass (Spartina),Chesapeake
Bay,Mobile Bay,and San Francisco Bay are broad,shallow
estuaries,In tropical regions,mangrove swamps function much
like salt marshes in estuarine ecology,
Consequences of Heavy Irrigation ----- salinization
? Irrigated crops in the Sahara
Desert,in Algeria,
? Extensive irrigation leads to
significant increase in the salt
content of agricultural soils,
Halophytes,plants that grow in high-salt soils
Idealized growth responses of
halophytes,salt-tolerant
nonhalophytes,and sensitive
nonhalophytes to salt
concentration,
滨藜（海马齿）：生活于
欧洲、地中海、北非与南
非等海边的盐生植物
Role of osmotic adjustment in salt tolerance
Osmotic adjustment in a mesophyll cell of a salt-stressed spinach leaf,Na+ & Cl-,which can disrupt cytosolic metabolism,
are concentrated in the vacuole,In contrast,concentrations of
glycine betaine are high in the chloroplasts (data not shown) and
cytoplasm but low in the vacuole,
? The hydration shells of macromolecules are not disrupted
by compatible solutes,Depicted is a protein with a hydration
shell surrounded by ordered H2O molecules,Ions such as Na+ and
Cl- can penetrate these shells to destroy the structure of the
protein,Unlike ions,compatible solutes such as proline and
betaine do not penetrate the proteins’ hydration shell,so protein
and solutes do not come into direct contact,
第六节 氧化胁迫 (oxidative stress)---活性
氧（ reactive oxygen species,ROS）生理
Environmental factors that increase the concentrations
of reactive oxygen species (ROS) in plant cells
Production of ROS
? Molecular structure of ROS active in plants,
Antioxidant defense systems in plants,
include nonenzymatic and enzymatic antioxidants
Subcellular locations of antioxidants
Ascorbate (Vitamin C) Apoplast,cytosol,plastid,vacuole,
?-Carotene Plastid,
Glutathione,reduced Cytosol,mitochondrion,plastid,
(GSH)
Polyamines Cytosol,mitochondrion,plastid,nucleus
?-Tocopherol Cell membranes
(Vitamin E)
Zeaxanthin Chloroplst
Subcellular locations of antioxidant enzymes
? Ascorbate peroxidase (APX) Cytosol,plastid,root nodules,
? Catalase (CAT) Cytosol,glyoxysome,peroxisome,
? Dehydroascorbate Cytosol,plastid,root nodules,
? reductase (DHAR)
? Glutathione reductase (GR) Cytosol,mitochondrion,plastid,root
nodules,
? Monodehydroascorbate Plastid,root nodules,
? reductase (MDHAR)
? Superoxide dismutase
? (grouped by metal cofactor)
? Cu/Zn SOD Cytosol,peroxisome,plastid,root nodules,
? Mn SOD Mitochondrion
? Fe SOD Plastid
Tropospheric ozone is linked to oxidative stress
The stratospheric consumption
and atmospheric generation
of O3,Stratospheric O3 (90%)
beneficially decreases the
penetration of solar radiation
to the troposphere,
Anthropomorphic release of
chlorofluoro-Carbons (CFCs)
leads to depletion of
stratospheric O3,especially
over polar regions,The
burning of fossil fuels
increases the production of
carbon compounds that react
in sunlight with O2 to form
O3 in the troposphere,
Ozone causes oxidative damage to biomolecules
O3 action and plant
responses,O3 is polar
and hydrophilic,poorly
penetrate leaf cuticle and
plasma membrane,O3
entry into the periplasmic
space can be dimished by
stomatal closure,Damage
from O3 occurs mainly as
a result of peroxidation of
plasma membrane lipids
and stimulation of ROS
production,Exposure to
O3 activates the defense
mechanism within the cell,
Whether the defenses are
successful or not depends
on the concentration of
O3,the duration of the
exposure,the age of the
plant,and the genotype,
Relationship between O3 exposure
parameters and plant responses
Exposure type O3 exposure Response
Acute High,brief Cell death;
visible injury;
Loss of membrane integrity;
Little or no antioxidant defense response;
Dramatically reduced rates of photosynthesis,
Chronic Low to Some visible injury;
moderate,Antioxidant defense response;
lengthy Reduced rates of photosynthesis;
Chlorophyll loss;
Premature senescence,
Repeated Low to Little or no injury;
moderate,Acclimation (hardening);
periodic Improved antioxidant defense response;
Higher rates of photosynthesis,
Improved yield relative to chronic exposure,
第七节 植物对非生物胁迫的适应机理
? 各种胁迫对植物的影响相互关联；植物对各种
胁迫的适应性也相互联系
? 交叉适应（ Cross adaptation; Cross protection),
植物在适应了一种胁迫环境后，增强了对另一
种胁迫因子的抗性现象
? 交叉适应现象反应了植物对各种胁迫的适应性
有着共同的机理
1、膜脂
低温诱导膜脂由液晶态向凝胶态转变 (固化 )，导致膜透
性增大，物质外渗。
膜脂的 不饱和脂肪酸含量 (不饱和度 )越高，膜的 流动
性 越大, 抗冷性 越强。
2、自由基
自由基
清除系统, 酶类 (SOD,POX,GSG-PX)；
非酶类（ Vit E,谷胱甘肽、抗坏血酸等）。
正常条件：体内自由基产生和清除系统处于平衡,
自由基水平极低；
逆境条件：清除系统降低，自由基上升，膜受伤害。
3、胁迫蛋白
逆境抑制细胞内正常的蛋白合成，但诱导出一些新的蛋
白质，即胁迫蛋白。如,
高温诱导热激蛋白、低温诱导冷驯化蛋白、盐渍诱导
渗压素
胁迫蛋白的产生往往增强植物的抗胁迫能力；
不同胁迫条件诱导的胁迫蛋白常常相同或相似，如,
缺水、盐渍亦可诱导热激蛋白等
对胁迫蛋白基因的研究可望从根本上提高植物的抗逆性。
4,ABA的调节
? ABA是植物适应各种胁迫条件的重要调节物
质,
各种胁迫调节均诱导内源 ABA水平升高；
外源 ABA处理，可以提高植物对各种胁迫
的抗性。
? ABA诱导抗性的原因,
诱导 ABA响应基因表达出响应蛋白，类似与
胁迫蛋白；
诱导渗透调节物质产生,
诱导休眠、生长延缓及气孔 关闭等
5、渗透调节
植物通过合成 渗透调节物质 来抵抗各种逆
境。
主要渗透调节物质,脯氨酸、甜菜碱、甘
露醇等
渗透调节物质的作用,
I 降低细胞水势，防止水分散失，即保
持原生质与环境之间的水分平衡
II 增强结构蛋白的水合结构和稳定性，
保护膜结构完整
胁迫 (Stress),对植物生长的不良环境因子。
逆境,胁迫的总称。
? 生物胁迫,
病、虫、杂草,动物、人为因素等。
? 非生物胁迫,
? 水分 （旱、涝） ；
? 盐；
? 温度 （热、冷、冻） ；
? 辐射 （可见、紫外） ；
? 化学物质 （杀虫剂、重金属、空气污染）。
地球上可用于农业耕作土地的分配
胁迫引起作物大幅度减产
植物响应胁迫的方式,
抗逆性 ———— 存活 或生长；
感逆性 ———— 死亡。
植物抵抗胁迫（抗逆性）的机制,
避逆 (avoidance)机制 —— 物种进化形成的 组
成性 的适应。
耐逆 (tolerance)机制 —— 调整生理反应机
制 （驯化） 以适应胁迫。
植物驯化过程通过改变基因表达方式
来形成抗逆性的生理反应机制
第一节 低温胁迫和植物抗寒性
一、冷害 (Chilling stress)
主要零上低温所引起。
冷害引起的生理反应,
降低原生质的流动性；
原生质膜透性增大，胞内内容物外渗；
光合作用受抑制；
呼吸紊乱；
改变基因表达和蛋白质的合成方式；
Exposure of chilling-
sensitive plants such
as cucumber to 2° C
for 1d cause severe
injury,The plant on
the right was kept at
25 ° C
冷伤害的主要机理,
低温 — → 膜相变 （液晶相 → 凝胶相）
凝胶相,膜收缩，透性增大,胞内内容物外渗；
膜结合蛋白活性下降，代谢紊乱。
膜相变在一定温度范围内是可逆的。
? Thermal transition from the
gel phase (L?) to liquid
crystalline phase (L?) in a
pure phosphatidylcholine
bilayer (low panel),
? At low temperatures,motion
of fatty acid chains is limited
by Van der Waals forces,As
the temperature is raised
through the phase transition,
heat is absorbed and Van
der Waals forces are
disrupted to form a bilayer
with melted fatty acid chains,
膜脂中不饱和脂肪酸的含量,决定膜相变温度
? 不饱和脂肪酸含量越高，引起 膜相变的温度越低。
? 含不饱和脂肪酸越多的物种和品种，抗冷性越强。
例：粳稻 > 籼稻
?Ratio of unsaturated and saturated fatty
acids of membrane lipids of mitochondria
isolated from chilling-sensitive and chilling-
resistant tissues
?Chilling-sensitive tissues,
? Bean shoot 2.8
? Sweet potato tuber 1.7
? Maize shoot 2.1
? Tomato green fruit 2.8
?Chilling-resistant tissues,
? Cauliflower buds 3.2
? Turnip root 3.9
? Pea shoot 3.8
Three different chilling responses
in lipid mutants of Arabidopsis,? (A) Compared with WT-type (left),the fad6
(right) becomes
chlorotic after 3
weeks at 5° C;
(B) fad2 die after 7
weeks at 6° C;
? (C) Compared with
WT-type (left),the fab1
(right) unaffected by
up to 1 week at 2° C;
(D) After 4 weeks at
2° C,however,fab1
(right) show clear
symptoms of
chlorosis and reduced
growth,
二、冻害（ Freezing stress）,主要由零下低温
使植物组织结冰所引起。
1、胞外结冰,
环境温度缓慢下降，质外体（细胞间隙）结冰，
引起胞质水分亏缺；
2、胞内结冰,
环境温度骤然下降，质外体与共质体均结冰，冰
在形成或融化过程中对亚细胞精细结构的机械伤害。
植物耐受冻害的生理机制
1,膜稳定性,改变膜脂的构成（脂肪酸不饱和
度、膜固醇和脑苷脂的丰度、膜蛋白的性质）；
2,基因表达改变,COR15a gene,转基因拟南芥
表现强抗冻性；
3,抗冻蛋白 (AFPs,antifreeze proteins)
在低温驯化期间形成，专一分泌并累积与细
胞间隙；
AFPs 以大表面寡聚复合体覆盖于冰晶表面，
抑制冰晶的增大；
AFPs 存在于真菌、昆虫、鱼与植物（尤其
为过冬植物）中。
A,Crystal growth in water;
B,Water plus a purified AFP,a glucanase,from
winter rye;
C,Water plus a crude extract of apoplastic
proteins from cold-acclimated winter rye leaves,
三、低温锻炼（ Cold hardening）,预先以适当、
安全的低温给予植物一定时间的处理。
提高植物耐寒性的有效措施
? Leakage of electrolytes from mature Arabidopsis leaves before
and after acclimation at 4° C for 7d,
? During freezing
stress,changes in
plasma membrane
morphology
determine death or
survive of the cell,
Cold acclimation allows plants to survive freezing
? The Arabidopsis plants on the right were incubated at 4 ° C
for 4d to acclimate the plants,after which both pots were
kept at -5 ° C for 4d,and then transferred to growth
conditions at 23 ° C for 10d,
第二节 高温胁迫和植物抗热性
高温引起的生理反应,
细胞结构的损伤（细胞器和细胞骨架）；
膜功能受损
基因表达改变
蛋白质的合成改变（正常蛋白合成受阻，诱导 HSPs合成）
? 主要的热激蛋白及其功能（数字,MW)
HSP family Probable function
HSP110 Unknown
HSP90 Protecting receptor proteins
HSP70 ATP-dependent protein assembly or
disassembly
reactions; preventing proteins from
denaturation
HSP60 Molecular chaperone,directing the proper
assembly
of multi-subunit proteins
LMW HSPs Function largely unknown (17-28kDa)
Ubiquitin An 8 kDa protein involved in targeting
other proteins
for proteolytic degration
热锻炼能提高植物的耐热性
? Induced thermo-tolerance in soybean seedlings,
? Left,Grown at 28° C;
? Center,2h at 40 ° C before 2h at 45 ° C,then
28° C;
? Right,2h at 45 ° C,then 28° C,
第三节 水分 (亏缺 )胁迫
(water deficit stress)
及植物的抗旱性
? 包括 干旱 (drought)胁迫 （由自然环境缺
水引起）和 脱水 (desiccation)胁迫 （实
验室人为脱水引起）；
? 为 盐 (salt)胁迫 和 渗透 (osmotic)胁迫 的
组成部分。
旱生植物,
生长于极端干旱地区，如沙漠；
形态、功能上特殊机制，能抗极度脱水；
复水后, 起死回生,
中生植物,
耐受一定范围内的脱水，产生相应的生理反应；
大部分高等植物。
? Craterostigma plantagineum plants,(A) Fully turgid
plant,(B) Desiccated plant (unwatered for 7d),(C)
Plant rehydrated for 6h,
中生植物的生理变化与耐旱性,
1、地上部生长延缓，乃至部分叶片脱落。降
低失水；
2,根系纵向生长加快，增加吸水；根 /冠 (R/T)
增大
3、气孔关闭，光合作用下降；
4,ABA上升；
5,渗透调节物质大量合成；
6,水分 胁迫诱导的基因表达。
? Movement of H2O into & out of a cell depends on the
water potential gradient across the plasma membrane,
ABA在植物中起传递旱情的信号,
? Accumulation of ABA in maize roots and in xylem
sap as a result of soil drying,
? Effect of manipulating ABA concentration in
xylem sap on stomatal conductance of leaves
(abaxial epidermis) in maize,
渗透调节物质 (osmolyte),
高度水溶性、不干预细胞代谢的有机化合物。
? The chemical structures
of some important cellular
compatible osmolytes,
渗透调节作用 (osmotic adjustment)
? Osmotic adjustment occurs when the concentration of solutes
within a plant cell increase to maintain a positive turgor pressure
within the cell,
水分胁迫响应基因的表达与抗胁迫
? Expression of MIP-related genes in roots of Mesembryanthemum
crystallinum,Declining transcript abundance in response to
osmotic stress correlates with loss of turgor,Transcript
concentrations increase as turgor is restored,
? MIP (major intrinsic protein),a aquaporin ecoded by RD28 gene,
水分胁迫响应基因亦受 ABA诱导
? Accumulation of RAB18 & LT178 mRNA in Arabidopsis
thaliana,
通过 抗旱锻炼 能提高植物的抗旱性
抗性锻炼,植物经过一段时间的自然或人工的
非致死胁迫后，往往增强了对该胁迫的抗性。
“蹲苗”：适度干旱措施
第四节 涝害 (flooding)与植物的抗涝性
Plants vary in ability to tolerate flooding
Wetland plants Flood-tolerant plants Flood-sensitive plants
Sweet flag Arabidopsis thaliana Soybean
Rice grass Barnyard grass Tomato
Barnyard grass Oat Pea
Coral tree Potato
Golden dock Wheat
Rice Corn
Wild rice
A flooded maize field,
Flooding in the US
Midwest in 1993
resulted in an estimated
33% reduction in yield
compared with 1992,
Wetland plants posses diverse anatomical,morphological
and physiological features that permit survival in aquatic
environments or waterlogged soils
Survival strategies of a freshwater weed,(A) Hydrilla verticillata (L.f.)
Royle,a monocotyledous native of Asia,is an invasive submerged
weed in freshwater ecosystems in the southern US,(B) Hydrilla
develops as a dense mat of stems and leaves near the surface of the
water,These plants now threaten waterways in Florida and other
Southeastern states,
Aerenchyma,continuous,columnar intracellular
spaces formed in root cortical tissues
Aerenchyma development in root cortex of maize after oxygen
deprivation,(A) under aerobic conditions,(B) under 72h of hypoxia
Lenticels,openings in the periderm that allow gas
exchange
? Adventitious roots and prominent lenticels on the stem
of young ash after flooding,The black arrow indicates
the water depth during flooding,
Pneumatophores,shallow roots that grow with
negative geotrophy out of the aquatic environment,
? Pneumatophores of mangrove develop from roots
submerged in estuarine mud
Internodal stem elongation,enables stems and leaves
to be established above the aquatic environment,
(A) Diagram illustrating growth response of seedlings deepwater rice to
flooding,Submerge promotes rapid internodal elongation and
development of adventitious roots,Once the flood waters recede,the
adventitious roots grow into the soil and aerial portions of the plant
grow upward,
(B) Photographs comparing internode elongation in aerobic (left) and
submerged (right) plants,Arrows indicate positions of nodes,
During short-term acclimation to anoxic conditions,plants
generate ATP through glycolysis and fermentation
Major fermentation products
of carbohydrate
metabolism in flooded
roots
Impact of oxygen deprivation on
respiratory metabolism
Oxygen status Effect on metabolism
Normoxic (aerobic) Aerobic respiration proceeds normally,Almost all ATP
production results from oxidative phosphorylation,
Hypoxic The partial pressure of O2 limits ATP production by oxi-
dative phosphorylation,Glycolysis accounts for a larger
percentage of ATP yield than under normoxic condition,
Metabolic and developmental changes are stimulated
that result in adaptation to a low-oxygen environment,
Anoxic (anaerobic) ATP is produced by way of glycolysis,Cells exhibit low
ATP contents,diminished protein synthesis,and
impaired division and elongation,If anoxic conditions
persist,many plant cells die,
Effects of hypoxic pretreatment and acclimation on
survival of anoxia,avoidance of cytoplasmic acidosis
by lactate efflux,
Flooding typically results in hypoxia,followed by anoxia,Exposure of
maize seedlings to hypoxia for several hours before being transferred to
anoxia increases the ability of roots for lactate efflux and prolongs
survival,
Ethylene promotes long-term acclimative responses,
including formation of aerenchyma and stem
elongation
Treatment Action Effect on aerenchyma
develpment
Hypoxia Stimulates ETH production Promoted
Hypoxia + Ag+ Inhibits ETH action Reduced
Hypoxia + AVG Inhibits ETH synthesis Reduced
Hypoxia + EGTA Chelates Ca2+ Reduced
Normoxia + ethylene Induces ETH response Promoted
Normoxia + caffeine Increase cytosolic Ca2+ Promoted
Role of ethylene in promotion of long-term
acclimative responses
(A) Formation of aerenchyma is stimulated by
hypoxia but not by anoxia,
Transduction of low O2 signal in maize leads to PCD during
the formation of lysigenous aerenchyma,Chemicals that
increase the cytosolic Ca2+ concentration under aerobic
conditions promote aerenchyma formation,whereas
compounds that block Ca2+ movement under anoxia inhibit
aerenchyma formation,
第五节 盐害 (salt stress)与植物的抗盐性
Areas of greatest aquifer depletion,saltwater intrusion
and groundwater contamination in US,
High salt concentrations in the rhizosphere generate
stress through water deficits and ion toxicity,
Exclusion of salt and osmotic adjustment both play
major roles in tolerance of high salt environments,
? Areas with high salinity,
Coastal salt-marshes;
Island deserts;
Near the shores of island lakes ;
Crop fields with extensive irrigation,
? In China,more than 7 million hectares are
classified as saline,much of this resulting from
centuries of irrigation,
A New England salt marsh is one highly productive estuarine
habitat,The primary producers are phytoplankton,algae,and
salt-tolerant plants such as marsh grass (Spartina),Chesapeake
Bay,Mobile Bay,and San Francisco Bay are broad,shallow
estuaries,In tropical regions,mangrove swamps function much
like salt marshes in estuarine ecology,
Consequences of Heavy Irrigation ----- salinization
? Irrigated crops in the Sahara
Desert,in Algeria,
? Extensive irrigation leads to
significant increase in the salt
content of agricultural soils,
Halophytes,plants that grow in high-salt soils
Idealized growth responses of
halophytes,salt-tolerant
nonhalophytes,and sensitive
nonhalophytes to salt
concentration,
滨藜（海马齿）：生活于
欧洲、地中海、北非与南
非等海边的盐生植物
Role of osmotic adjustment in salt tolerance
Osmotic adjustment in a mesophyll cell of a salt-stressed spinach leaf,Na+ & Cl-,which can disrupt cytosolic metabolism,
are concentrated in the vacuole,In contrast,concentrations of
glycine betaine are high in the chloroplasts (data not shown) and
cytoplasm but low in the vacuole,
? The hydration shells of macromolecules are not disrupted
by compatible solutes,Depicted is a protein with a hydration
shell surrounded by ordered H2O molecules,Ions such as Na+ and
Cl- can penetrate these shells to destroy the structure of the
protein,Unlike ions,compatible solutes such as proline and
betaine do not penetrate the proteins’ hydration shell,so protein
and solutes do not come into direct contact,
第六节 氧化胁迫 (oxidative stress)---活性
氧（ reactive oxygen species,ROS）生理
Environmental factors that increase the concentrations
of reactive oxygen species (ROS) in plant cells
Production of ROS
? Molecular structure of ROS active in plants,
Antioxidant defense systems in plants,
include nonenzymatic and enzymatic antioxidants
Subcellular locations of antioxidants
Ascorbate (Vitamin C) Apoplast,cytosol,plastid,vacuole,
?-Carotene Plastid,
Glutathione,reduced Cytosol,mitochondrion,plastid,
(GSH)
Polyamines Cytosol,mitochondrion,plastid,nucleus
?-Tocopherol Cell membranes
(Vitamin E)
Zeaxanthin Chloroplst
Subcellular locations of antioxidant enzymes
? Ascorbate peroxidase (APX) Cytosol,plastid,root nodules,
? Catalase (CAT) Cytosol,glyoxysome,peroxisome,
? Dehydroascorbate Cytosol,plastid,root nodules,
? reductase (DHAR)
? Glutathione reductase (GR) Cytosol,mitochondrion,plastid,root
nodules,
? Monodehydroascorbate Plastid,root nodules,
? reductase (MDHAR)
? Superoxide dismutase
? (grouped by metal cofactor)
? Cu/Zn SOD Cytosol,peroxisome,plastid,root nodules,
? Mn SOD Mitochondrion
? Fe SOD Plastid
Tropospheric ozone is linked to oxidative stress
The stratospheric consumption
and atmospheric generation
of O3,Stratospheric O3 (90%)
beneficially decreases the
penetration of solar radiation
to the troposphere,
Anthropomorphic release of
chlorofluoro-Carbons (CFCs)
leads to depletion of
stratospheric O3,especially
over polar regions,The
burning of fossil fuels
increases the production of
carbon compounds that react
in sunlight with O2 to form
O3 in the troposphere,
Ozone causes oxidative damage to biomolecules
O3 action and plant
responses,O3 is polar
and hydrophilic,poorly
penetrate leaf cuticle and
plasma membrane,O3
entry into the periplasmic
space can be dimished by
stomatal closure,Damage
from O3 occurs mainly as
a result of peroxidation of
plasma membrane lipids
and stimulation of ROS
production,Exposure to
O3 activates the defense
mechanism within the cell,
Whether the defenses are
successful or not depends
on the concentration of
O3,the duration of the
exposure,the age of the
plant,and the genotype,
Relationship between O3 exposure
parameters and plant responses
Exposure type O3 exposure Response
Acute High,brief Cell death;
visible injury;
Loss of membrane integrity;
Little or no antioxidant defense response;
Dramatically reduced rates of photosynthesis,
Chronic Low to Some visible injury;
moderate,Antioxidant defense response;
lengthy Reduced rates of photosynthesis;
Chlorophyll loss;
Premature senescence,
Repeated Low to Little or no injury;
moderate,Acclimation (hardening);
periodic Improved antioxidant defense response;
Higher rates of photosynthesis,
Improved yield relative to chronic exposure,
第七节 植物对非生物胁迫的适应机理
? 各种胁迫对植物的影响相互关联；植物对各种
胁迫的适应性也相互联系
? 交叉适应（ Cross adaptation; Cross protection),
植物在适应了一种胁迫环境后，增强了对另一
种胁迫因子的抗性现象
? 交叉适应现象反应了植物对各种胁迫的适应性
有着共同的机理
1、膜脂
低温诱导膜脂由液晶态向凝胶态转变 (固化 )，导致膜透
性增大，物质外渗。
膜脂的 不饱和脂肪酸含量 (不饱和度 )越高，膜的 流动
性 越大, 抗冷性 越强。
2、自由基
自由基
清除系统, 酶类 (SOD,POX,GSG-PX)；
非酶类（ Vit E,谷胱甘肽、抗坏血酸等）。
正常条件：体内自由基产生和清除系统处于平衡,
自由基水平极低；
逆境条件：清除系统降低，自由基上升，膜受伤害。
3、胁迫蛋白
逆境抑制细胞内正常的蛋白合成，但诱导出一些新的蛋
白质，即胁迫蛋白。如,
高温诱导热激蛋白、低温诱导冷驯化蛋白、盐渍诱导
渗压素
胁迫蛋白的产生往往增强植物的抗胁迫能力；
不同胁迫条件诱导的胁迫蛋白常常相同或相似，如,
缺水、盐渍亦可诱导热激蛋白等
对胁迫蛋白基因的研究可望从根本上提高植物的抗逆性。
4,ABA的调节
? ABA是植物适应各种胁迫条件的重要调节物
质,
各种胁迫调节均诱导内源 ABA水平升高；
外源 ABA处理，可以提高植物对各种胁迫
的抗性。
? ABA诱导抗性的原因,
诱导 ABA响应基因表达出响应蛋白，类似与
胁迫蛋白；
诱导渗透调节物质产生,
诱导休眠、生长延缓及气孔 关闭等
5、渗透调节
植物通过合成 渗透调节物质 来抵抗各种逆
境。
主要渗透调节物质,脯氨酸、甜菜碱、甘
露醇等
渗透调节物质的作用,
I 降低细胞水势，防止水分散失，即保
持原生质与环境之间的水分平衡
II 增强结构蛋白的水合结构和稳定性，
保护膜结构完整
