Quilliam Richard S, Swarbrick Philip J, Scholes Julie D, Rolfe Stephen A
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
J Exp Bot. 2006;57(1):55-69. doi: 10.1093/jxb/erj039. Epub 2005 Dec 9.
Chlorophyll fluorescence imaging provides a non-invasive and non-destructive means with which to measure photosynthesis. This technique has been used, in combination with 14CO2 feeding, to study the spatial and temporal changes in source-sink relationships which occur in mechanically wounded leaves of Arabidopsis thaliana. Twenty-four hours after wounding, cells proximal to the wound margin showed a rapid induction of PhiII upon illumination (a measure of the efficiency of photosystem II photochemistry) whilst cells more distal to the wound margin exhibited a much slower induction of PhiII and a large, transient increase in NPQ (a measure of the rate constant for non-photochemical energy dissipation within the light-harvesting antenna). These results are indicative of an increase in sink strength in the vicinity of the wound and this was confirmed by the retention of 14C photosynthate in this region. It has been hypothesized that wound-induced cell wall (apoplastic) invertase (cwINV) activity plays a central role in generating localized increases in sink strength in stressed plant tissue and that hexose sugars generated by the sucrolytic activity of cwINV may act as a signal regulating gene expression. Enzyme activity measurements, quantitative RT-PCR, and T-DNA insertional mutagenesis have been used to determine that expression of AtcwINV1 is responsible for all induced cwINV activity in mechanically wounded leaves. Whilst inactivation of this gene abolished wound-induced cwINV activity, it did not affect localized alterations in source-sink relationships of wounded leaves or wound-regulated gene expression. The signals that may regulate source-sink relationships and signalling in wounded leaves are discussed.
叶绿素荧光成像提供了一种用于测量光合作用的非侵入性和非破坏性方法。该技术已与¹⁴CO₂饲喂相结合，用于研究拟南芥机械损伤叶片中源 - 库关系的时空变化。损伤后24小时，伤口边缘近端的细胞在光照时显示出快速的光系统II光化学效率指标（PhiII）诱导，而伤口边缘远端的细胞PhiII诱导则慢得多，并且非光化学淬灭（NPQ，光捕获天线内非光化学能量耗散速率常数的指标）出现大幅短暂增加。这些结果表明伤口附近的库强度增加，¹⁴C光合产物在该区域的保留证实了这一点。据推测，伤口诱导的细胞壁（质外体）转化酶（cwINV）活性在应激植物组织中局部库强度增加中起核心作用，并且cwINV的蔗糖分解活性产生的己糖可能作为调节基因表达的信号。酶活性测量、定量RT-PCR和T-DNA插入诱变已用于确定AtcwINV1的表达负责机械损伤叶片中所有诱导的cwINV活性。虽然该基因的失活消除了伤口诱导的cwINV活性，但它并未影响受伤叶片源 - 库关系的局部改变或伤口调节的基因表达。本文讨论了可能调节受伤叶片源 - 库关系和信号传导的信号。
