Investigating solar protection during plant growth

项目亮点：-通过与华威大学的生命科学家和化学家合作，获得以了解“生命的生物物理学”为中心的不同技能-揭开花园水芹芽(十字花科成员)中发生的能量转移机制，特别是在宇宙工业中用作抗氧化剂和防晒剂的光吸收分子(如芥子酰苹果酸)内-更好地了解何时收获花园水芹芽的光吸收剂，最终在使用更少的自然资源(如水)和生长添加剂方面使环境受益[1，2]。特别令人感兴趣的是太阳紫外线辐射光谱的高能成分，UV-B(280-315 nm)和较短波长的UV-A光谱(&lt；340 nm)，此后称为UV-辐射(UVR)。在植物中，UVR在许多过程中发挥信号转导作用，包括免疫反应、植物形态和苯丙烷途径[2，3]。众所周知，紫外线照射生物体的有害影响，例如，光合作用降低、生长抑制和对病原体的敏感性[4，5]。因此，植物通过苯丙烷途径合成和在表皮组织中沉积吸收紫外线的化合物，以抵御过多的紫外线[2，3]具体而言，对十字花科植物拟南芥基因突变的研究发现，苯丙烷途径可能被破坏，从而降低植物表皮中存在的芥子酸酯的浓度，使植物对紫外线辐射高度敏感[6-11]。这些实验表明芥子酸酯可能是十字花科植物使用的UVR筛选分子。芥子酸酯是芥子酸的衍生物，与芥子酰苹果酸(图1)密切相关，芥子酰苹果酸一直是拟南芥植物叶片上表皮中的主要酯成分[7，8，11]。我们最近提出，芥子酸酯的防晒作用是由分子异构化驱动的[12-14]；这些酯吸收紫外线，并通过分子扭曲，将潜在的破坏性吸收的紫外线转化为振动运动(或热)。在将这些热能转移到周围环境后，酯类就准备好重新吸收进一步的紫外线，从而为植物提供必要的日光保护。然而，有趣的问题出现了，包括：(1)在植物的生长周期中，这些酯类物种的组成是什么；(2)它们的组成如何随植物的地理位置而变化？在这份博士提案中，我们的目标是解决这些问题。我们将特别关注十字花科的另一个成员，花园水芹芽。我们将确定这些酯(以‘提取物’的形式)在花园水芹芽生长周期中的组成，并确定地理位置(例如英国北部和南部)如何影响这种组成。重要的是，我们将使用基于激光光谱的最先进的分析技术来确定它们的防晒机制，以尽可能接近它们的自然环境。我们的洞察力可能会影响人们在植物生长周期的哪个阶段收获这些提取物，这些提取物在化妆品行业被广泛使用，例如，作为抗氧化剂和SPF增强剂。

Project Highlights: - Acquire diverse skills set centred on understanding of the 'Biophysics of Life' by working with Life Scientists and Chemists at Warwick University - Unravel the energy transfer mechanisms occurring in Garden Cress Sprout (a member of the Brassicaceae family), specifically within light absorbing molecules (eg sinapoyl malate) used as antioxidants and solar protection in the cosmeceutical industry- Develop a better appreciation of when to harvest Garden Cress Sprout for its light absorbers, ultimately benefitting the environment in terms of using less natural resources (eg water) and growth additivesOverviewUltraviolet radiation that reaches the Earth's surface has extensive impact on the biosphere [1,2]. Of particular interest is the high energy component of solar UV radiation spectrum, the UV-B (280-315 nm) and shorter wavelengths of the UV-A spectrum (<340 nm) termed, henceforth, UV-radiation (UVR). In plants, UVR acts as a signal transducer for numerous processes including immune response, plant morphology and the phenylpropanoid pathway [2,3]. Deleterious effects of UVR exposure to organisms are widely known, for example, reduction of photosynthesis, growth inhibition and susceptibility to pathogens [4,5]. As such, plants synthesize and deposit UVR-absorbing compounds in epidermal tissue via the phenylpropanoid pathway to protect against too much UVR [2,3] Specifically, studies of gene mutations in the plant Arabidopsis thaliana, a member of the Brassicaceae family, have found that the phenylpropanoid pathway could be disrupted such that the concentration of sinapate esters present in the epidermal layers of the plant are reduced, rendering the plant hypersensitive to UVR exposure [6-11]. Such experiments point towards sinapate esters as being the likely class of UVR screening molecules used by Brassicaceae plants. Sinapate esters are a derivative of sinapic acid, and closely related to sinapoyl malate (Figure 1) which has been the dominant ester- constituent deposited in the upper epidermis of Arabidopsis plant leaves [7,8,11]. We have recently proposed that solar protection of sinapate esters is driven by a molecular isomerisation [12-14]; the esters absorb UVR and, through a molecular twist, they convert potentially damaging absorbed UVR into vibrational motion (or heat). Having transferred this heat energy to the surrounding environment, the esters are then ready to reabsorb further UVR and hence provide the plant with the necessary solar protection. However, intriguing questions arise including: (1) what is the composition of these ester-species during the growth cycle of the plant; and (2) how do their composition vary with geographic location of the plant? In this PhD proposal, our aim is to address these questions. We will specifically focus on another member of the Brassicaceae family, that of the Garden Cress Sprout. We will determine the composition of these esters (in the form of 'extracts') during the Garden Cress Sprout growth cycle and establish how geographic location (eg northern vs southern parts of UK) impacts this composition. Importantly, we will use state of the art analytical techniques based on laser spectroscopy to determine their solar protection mechanisms in as close to their natural environment as possible. Our insight could impact which stage of the growth cycle one harvests the plant for these extracts, which are finding widespread use, for example, in the cosmeceutical industries as antioxidants and SPF boosters.