ISWC OpenIR  > 水保所知识产出(1956---)
植物整体水分平衡的生理生态调控机制研究
王卫锋
Subtype博士
Thesis Advisor张岁岐
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword整株水分平衡 导水特性 水通道蛋白 Spac 抗旱性 染色体倍性 水分胁迫
Abstract

水资源不足是干旱半干旱地区生态环境和农业生产的主要限制因素。植物水
分平衡的生理生态基础研究是发展节水农业和生态建设的重要依据。植物可以通
过调节根茎枝叶等部位的导水特性以维持整体水分平衡,而水通道蛋白的深入研
究将有助于揭示植物水分关系的生理生态机制。本论文选用玉米(Zea mays L.)、
小麦(Triticum spp.)和甜高粱(Sorghum bicolor (L.) Moench)为实验材料,通过
人工控制环境条件下以聚乙二醇诱导形成短期或长期水分胁迫处理,研究了水通
道蛋白转录调节、从细胞到整株各尺度导水特性响应以及叶片水氮利用能力变化。
取得主要结果如下:
(1). 恒定环境条件下玉米 478 的叶蒸腾速率、根导水率、叶导水率和整株导水
率均表现明显日变化,且各参数间均存在显著正相关关系。这对于维持植株整体
水分平衡是必要的。水分胁迫处理 2 小时后,玉米 478 根导水率显著降低而叶导
水率却显著升高;叶片中 ZmPIPs 基因的转录量也显著增加,尤其是 ZmPIP1;2;
而根中仅 ZmPIP2;5 的转录水平显著下调,表明 ZmPIPs 可能参与了根叶导水特性
的短期调节过程。
(2). 干旱敏感玉米 478 的叶蒸腾速率呈明显的日变化规律,而抗旱性较强的天
四较低且维持恒定;478 在叶片水力结构、根叶形态和根导水率等方面均表现出适
应高蒸腾耗水的特征;478 和天四通过不同的叶内部水势差调节策略维持叶片水分
平衡。短期水分胁迫下,478 的根导水率下降而叶导水率增加,且叶蒸腾降低幅度
却较小导致其体内水分亏缺;而天四的叶蒸腾速率大幅下降且根导水率在胁迫 8
小时后部分恢复。低叶蒸腾、水分胁迫后蒸腾迅速降低以及根导水率能部分恢复
等特性可能是天四保持水分平衡的重要原因。
(3). 正常供水天四和 478 的根叶中各 ZmPIPs 基因的转录水平存在明显差异,
其中 ZmPIP1;5 在 478 中转录量较大而在天四中检测不到。PEG 诱导水分胁迫处理
2 小时内,天四根中各 ZmPIPs 转录水平总体上调而叶片中总体下调,可能有助于
其增加根系吸水同时减少叶片失水;478 根中和叶片中各 ZmPIPs 的 mRNA 相对含量表现短暂的升高过程,这可能与其叶片蒸腾失水降低幅度较小有关。
(4). 随着染色体倍性增加,小麦叶蒸腾失水和根系吸水能力均不断增大,而皮
层细胞体积却逐渐减小。在正常供水或水分胁迫条件下,叶蒸腾速率、单根导水
率、根细胞导水率以及 TaPIPs 转录水平之间均存在显著正相关关系。皮层细胞体
积可能参与调节根径向水流各途径的相对贡献。在小麦进化过程中,根中 TaPIP
基因转录水平、细胞-细胞途径和质外体途径均显著增加,进而增强根系吸水能力
以满足冠层耗水增加从而维持整株水分平衡。
(5). 既然植物的基因表达、不同尺度导水特性和叶蒸腾之间存在一致性关系,
那么叶片水分利用特性可能对整株耗水起控制作用。高抗旱性甜高粱对长期水分
胁迫的适应过程中,叶片瞬时水分利用效率(WUE)显著增加,叶面积和单株耗
水均显著降低,而干物质积累却变化不显著;叶氮积累显著降低;而光合氮利用
效率(PNUE)和氮利用效率(NUE)显著增加。在干旱适应过程中,甜高粱叶片
PNUE 提高可能是 WUE 提高并减少植株耗水的原因之一。
本论文通过分析控制环境条件下所取得的实验数据,较深入探讨了植物水分
平衡生理生态机制中的一些科学问题。研究结果有助于深化植物整体抗旱性的生
物学基础的认识,为深入研究水-氮-碳三者间协调关系的生理机制提供基础,并为
通过基因改良提高植物水分利用效率提供实验依据。
关键 词 :整株水分平衡;导水特性;水通道蛋白;SPAC;抗旱性;染色体倍性;
水分胁迫

Other Abstract

Water shortage often limits the ecological environment and agricultural production
in the arid and semi-arid area. Understanding the ecophysiological basis of high
efficiency of plant water use is very important for developing water-saving agriculture
and constructing ecological civilization. Plant can maintain water balance with variable
hydraulic properties and aquaporins could be involved, which may help to understand
the ecophysiological mechanisms of plant water relations. This dissertation used the
hydroponically grown maize (Zea mays L.), wheat (Triticum spp.) and sweet sorghum
(Sorghum bicolor (L.) Moench) seedlings as experimental materials, and used cell- and
root- pressure probes, high pressure flow meter and quantitive real-time PCR to
measure the responses of cell, single root, root and shoot and whole-plant hydraulics
and aquaporin genes transcription to short-term and long-term water stress induced by
PEG6000 and root excision. The main results are as follows:
(1). The leaf hydraulic conductivity (K leaf ) of Line 478 varied diurnally and
correlated with whole plant hydraulic conductivity. Similar diurnal rhythms of K leaf and
the root hydraulic conductivity (K root ) could be important to maintaining whole plant
water balance. K root significantly correlated with leaf transpiration rate (E). After 2 h of
osmotic stress, the K root of stressed plants significantly declined but K leaf increased; the
transcription of four ZmPIPs was significantly up regulated in leaves, especially for
ZmPIP1;2, and ZmPIP2;5 was down regulated in roots. The up-regulated K leaf and
down-regulated K root may break the water balance; and ZmPIPs genes may get involved
in the hydraulics changes during short-term water stress.
(2). The E and leaf water potential of 478 varied diurnally, but those of Tian4,
which is more drought resistant, were more constant. Line 478 had advantages on leaf
hydraulic architecture, leaf and root morphology, K leaf and K root , which may contribute  to the higher E. The K leaf and K root of both Tian4 and 478 varied diurnally. The K root of
both Tian4 and 478 was reduced under osmotic stress, but the K root of Tian4
subsequently recovered. A lower and rapidly reduced leaf water loss and the recovery of
root hydraulics during short-term osmotic stress may account for the ability of
drought-resistant maize to maintain plant water balance.
(3). The transcription levels of ZmPIPs in mature leaves and roots of well watered
Tian and 478 were significantly different. ZmPIP1;5 was highly expressed in 478 but its
mRNA was not detected in Tian4. Within 2 h of water stress induced by PEG, the
transcription levels of ZmPIPs were up-regulated in roots but were down-regulated in
leaves of Tian4, which may be help to increase water uptake and decrease water loss; in
leaves and roots of 478 plants, the transcription levels of ZmPIPs both showed an
temporary increase, which may contribute to the higher leaf water transpiration.
(4). The E, single root (Lp root ) and cell (Lp cell ) hydraulic conductivity of wheat
increased with increasing ploidy, but the V cell was reduced. Osmotic stress significantly
reduced the E, Lp cell , Lp root , and the relative mRNA content of TaPIP1;2 and TaPIP2;5
in wheat. Under well-watered or osmotic stress conditions, Lp root positively correlated
with the E and Lp cell ; the relative mRNA content of TaPIP1;2 and TaPIP2;5
significantly correlated with Lp cell and Lp root , respectively. Lp cell was reduced, but the
Lp cell /Lp root increased with increasing V cell , suggesting that V cell may affect root radical
water transport. Thus, the increased Lp cell
(5). The P n of stressed plants totally recovered three days later while g s were
consistently lower than the controls, getting an improved instantaneous water-use
efficiency (WUE). During prolonged water stress, the total water loss per plant of
stressed plants reduced significantly, while the dry mass of the whole plant did not
change, and leaf dry mass per unit area increased. The total leaf nitrogen, leaf nitrogen
per unit area and leaf nitrogen concentration of stressed plants reduced significantly. But
the photosynthetic nitrogen-use efficiency (PNUE) and dry mass based nitrogen-use
efficiency (NUE) increased significantly. WUE positively correlated with PNUE. Both
improved water- and nitrogen-use efficiencies of sweet sorghum under water stress may
partly explain its physiological acclimation to drought.
and transcription levels of TaPIP1;2 and
TaPIP2;5 in wheat roots provides insight into the mechanisms underlying enhanced root
water uptake during wheat evolution.
Based on the experimental data obtained from maize, wheat and sweet sorghum  grown under controlled conditions, some important issues on the mechanism of
whole-plant water balance were concerned in this dissertation. The results can
contribute to understand the biological bases of plant integrative drought-resistance, to
clarify the physiological mechanisms of water-nitrogen-carbon relations, and to improve
the water use efficiency of plant by gene modification.
KEY WORDS: whole-plant water balance; aquaporin; hydraulic conductivity; SPAC;
drought-resistance; chromosome ploidy; water stress

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8983
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
王卫锋. 植物整体水分平衡的生理生态调控机制研究[D]. 北京. 中国科学院研究生院,2013.
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