番茄或西红柿在成熟之前是绿色的,含有少量的叶绿素,所以也可以进行光合作用。西红柿的果实进行光合作用同化的碳和营养物质对它的能量代谢或发育贡献不大,也就是说,植株并不指望它的果实能给自身的物质和能量做出多大的贡献。一般情况下,花或果实做为繁殖器官,需要其它组织或器官的养分供给。但,果实进行光合作用的意义何在呢? 德国科学家发现与不能进行光合作用的果实相比,绿色的番茄在收获时坐果率更高、种子的数量更多、维生素 E 的含量也越高。 “Tomato fruit photosynthesis is seemingly unimportant in primary metabolism and ripening but plays a considerable role in seed development” ,翻译的大意“番茄果实光合作用表面上在初级代谢和成熟中作用不大,但在种子发育中扮演着重要作用”一文近日发表在 Plant Physiology. 违背自然规律,就有降低繁衍的可能。这项研究阐述了果实在发育早期含有叶绿素进行光合作用的进化意义。 成色不佳的果实种子自然也就少了,就这么一个朴素的道理成就了一篇 Plant Physiology ,把目光放在榆树 ( 先花后叶 ) 绿色的翅果或者大豆绿色的荚果或许也有类似重大的发现。
同样是荷兰人的观点评述,同样发表在 Trends in Plant Science ,作者从多个层面论述了植物光合作用的自然基因变异 ( Natural genetic variation in plant photosynthesis.pdf )。 A new angle to photosynthesis research 光合作用的基因变异的遗传因子知之甚少 Levels of photosynthetic variation 叶片,植株和冠层都存在光合差异 What is the cause of photosynthetic variation? 这个应该主要由进化决定,当然环境对光合类型的改变有时也很大 Investigations into natural genetic variation in photosynthesis * Ecophysiological studies * Agronomic studies 光合基因变异的研究主要集中在生理生态和农艺性状方面 Robust and reproducible phenotyping 重复和积累数据 How to investigate natural genetic variation in photosynthesis 一些生化和分子生物学手段 -------------------------------------------------------------------------------------------- 文中光合速率和产量的关系讨论很有意思,一直以来光合作用与作物产量或生物量是大家争论的热点,如光合作用大的,其产量不一定就高。在叶面积和光入射的角度一样的情况,总体而言, 光合速率越大的植物往往生物量积累也越多 。 -------------------------------------------------------------------------------------------- 有用的专业词汇表 : Gene a DNA sequence containing a protein coding region and all the regulatory elements in the direct vicinity needed for transcription of this protein coding region. Genetic factor a DNA sequence that contributes to the phenotype of an individual, because it comprises a gene or sequences contributing to the expression of a gene. Genome-wide association study a quantitative genetic approach used to find genetic associations between genotype and phenotype in a population of individuals of unknown relatedness, to identify genetic loci contributing to such a phenotype. Genotype the specific genetic constitution of an individual, determined by its nuclear and cytoplasmic DNA sequence. Leaf area index measure of the total leaf area per unit ground area. Natural genetic variation the genetic variation that occurs both within (intraspecific) and between (interspecific) species. In this review we focus on spontaneously generated (natural) genetic variation found in crop as well as wild populations, as opposed to variation generated in the laboratory via mutagenesis or transgenesis. Photosynthesis (oxygenic) the process by which plants, eukaryotic algae and cyanobacteria use light in the approximate wavelength range of 400–700 nm to split water, forming O 2 and reducing CO 2 to an organic form, thus converting some of the absorbed light into chemical energy. Photosynthetic rate the rate of CO 2 fixation per unit area of leaf, usually expressed in μmol m –2 s –1 ; because photosynthesis occurs simultaneously with respiration, the rate of photosynthesis can be qualified as either a gross or a net rate. Phenotype the physical appearance of an individual as a consequence of its genotype and its environment. P max also known as A max , this is the maximum photosynthetic rate of a leaf under light saturated conditions; it can also be thought of as the photosynthetic capacity of the plant. Photosynthetic nitrogen use efficiency the efficiency with which a plant can use the available nitrogen in its leaves or other photosynthetic tissues for photosynthetic processes. Quantitative trait loci genetic loci, each corresponding to a region of the genome containing genetic factors for which variation can be found between the studied genotypes, that have a statistically significant association with a particular phenotype, and the trait values of which are expressed in a continuous rather than discrete manner. Single nucleotide polymorphisms single base pair variants commonly used as genetic markers in quantitative genetic investigations.
Way等对能够释放异戊二烯的白杨杂交种和突变株的光合和叶绿素荧光特性在两种二氧化碳浓度环境下的差异进行了研究。他们发现高光对升高的二氧化碳浓度两种白杨的生长影响不大,但在42C高温胁迫下,生长在190ppm二氧化碳浓度里的突变株的净光合速率是野生型的一半,而在590ppm浓度里只有22%,最终作者认为升高的二氧化碳或许会减小异戊二烯释放对植物生长带来的好处。看来,升高的二氧化碳对植物生长是有利的。他们的论文“Enhanced isoprene-related tolerance of heat- and light-stressed photosynthesis at low, but not high, CO 2 concentrations”发表在Oecologia上。 异戊二烯(isoprene)一般在较高的温度才产生,产量与光强和温度正相关,与植物的光合作用密切相关,能够体现出植物的光合作用特征。 Enhanced isoprene-related tolerance of heat- and light-stressed.pdf 陆地生态系统植物挥发性有机化合物的排放及其生态学功能研究进展.pdf
对于植物而言,凡是绿色的部位基本上都能进行光合作用,种子也不例外。如豌豆(pea)和大麦(barley)的种子在发育早期就可以利用弱光进行光合作用,为植物体的生长提供还原力(ATP+NADPH)、为呼吸作用提供氧气。但并不是所有的“绿色”种子都能进行光合作用,如莲花(lotus)的种子就不能,Gradients of seed photosynthesis and its role for oxygen balancing.的作者认为有的种子之所以能进行光合作用,与他们所处的盐碱和干旱环境有关,但具体的机理还不明确。 Gradients of seed photosynthesis and its role for oxygen balancing.pdf
A Combination of Two Visible-Light Responsive Photocatalysts for Achieving the Z-Scheme in the Solid State. ACS Nano, 2011. 近日,韩国人使用复合光催化剂CdS/Au/TiO1.96C0.04模拟光合作用中的“Z”型反应制氢,发现其产量是没有掺杂C的4倍还多,效果理想,为人造光合作用的继续研究提供了一定的理论价值。上面的图片是他们文章里的,与下面两篇文章里的是十分相似的,可见科学研究向来是有一定的连续性和传承的,即使他们没有引用下面的两篇较早的文献。 模拟光合作用Z型反应光催化分解水的初步研究. 上海交通大学硕士论文, 2007. 半导体光解水研究进展. 材料导报, 2005. A Combination of Two Visible-Light Responsive Photocatalysts for Achieving the Z.pdf 模拟光合作用Z型反应光催化分解水的初步研究.pdf