Enhancement of disease resistance and health-promoting properties of fresh fruits and vegetables by postharvest conditioning with controlled abiotic stresses

迄今为止，我们的目标一直是为新鲜水果和蔬菜开发有效的收获后保存方法。我们一直积极追求的一种方法是通过激素剂量的UV-C来增强植物组织对疾病的天然防御并延缓衰老过程。感兴趣的防御机制之一是在响应激素剂量的UV-C的抗微生物植物抗毒素的激发。在拟议的计划中，我们采用综合方法，不仅可以引发植物保护化合物和其他防御反应，还可以在新鲜农产品中积累有益健康的化合物（营养品）。由于植物次生代谢物的主要作用是保护植物免受生物和非生物胁迫，因此可以想象，可以使用这一原理提高其水平。这些代谢物的积累常常导致植物暴露于非生物胁迫或信号分子。因此，本研究的目的是通过提高植物防御和营养次生代谢产物的水平，以控制的方式与激素剂量的非生物胁迫和植物信号调节剂的收获后调理的新鲜水果和蔬菜的抗病性和促进健康的特性。首先将对胡萝卜进行研究，胡萝卜是一种可长期储存的作物，但易受各种病原体的影响;它含有植物抗毒素和抗癌化合物，其中一些具有这两种活性。具体而言，研究内容包括：（1）表征各种非生物胁迫的氧化胁迫强度，以及氧化还原信号和激素信号的特征，这些特征是非生物胁迫诱导次生代谢产物的基础，并确定选定作物的胁迫激素阈值;（2）筛选激素剂量的胁迫和植物信号调节剂，以提高活性次级代谢物的潜力;（3）评价互补应激和/或应激与信号调节剂之间在增强所需次级代谢物方面的交叉相互作用;以及（4）评价在储存期间响应于选择的胁迫而引发的活性化合物的抗病性和滴度的动态，并探索维持增强的属性。这种保存新鲜作物的新方法不仅有助于新鲜农产品行业延长其作物的可储存性并减少收获后的损失，而无需诉诸化学程序，而且还有助于他们确保更健康的人口。

Our goal to date has been to develop effective post-harvest preservation methods for fresh fruits and vegetables. One approach that we have been actively pursuing is the intensification of the natural defenses of the plant tissue against diseases and delaying senescence process by hormetic doses of UV-C. One of the defense mechanisms of interest was on the elicitation of antimicrobial phytoalexins in response to hormetic doses of UV-C. In the proposed program, we entertain an integrated approach to elicit not only plant-protecting compounds and other defense reactions but also to accumulate health-beneficial compounds (nutraceuticals) in fresh produce. Since the major roles of plant secondary metabolites are to protect plants from biotic and abiotic stresses, it is conceivable that their levels can be enhanced using this principle. Accumulation of such metabolites often results in plants exposed to abiotic stresses or signal molecules. Thus the objective of this research is to enhance the disease resistance and health-promoting properties of fresh fruits and vegetables through elevating the levels of plant defense and nutraceutical secondary metabolites by post-harvest conditioning with hormetic doses of abiotic stresses and plant signal modulators in a controlled manner. Studies will be carried out initially with carrot which is a long-term storable crop but susceptible to various pathogens; and contains phytoalexins and anticancer compounds, some of which exhibit both activities. Specifically, the research involves: (1) characterization of various abiotic stresses for their oxidative stress intensity as well as profiles of redox signals and hormonal signals, that underlie abiotic stress-induced secondary metabolites, and the determination of the hormetic thresholds of the stresses in selected crops; (2) screening of hormetic doses of stresses and plant signal modulators for their potential to enhance active secondary metabolites; (3) evaluation of cross-interactions between complementary stresses and/or stresses and signal modulators in the enhancement of desirable secondary metabolites; and (4) evaluation of the dynamics of the disease resistance and titers of the active compounds elicited in response to selected stresses during storage and explore ways to maintain their enhanced attributes. Such a novel approach to the preservation of fresh crops will not only help the fresh produce industry to extend the storability of their crops and reduce post-harvest losses without resorting to chemical programs, but also help them to ensure a healthier population.