Understanding the mechanism of lipolysis in plants: an opportunity to increase oil yield in crops

来自种子的油是人类和牲畜的主要营养来源。它还具有许多重要的工业用途，其中包括提供日益重要的可再生能源(生物柴油)来源。种子发育过程中油脂积累的速度主要受生物合成的影响。然而，许多研究报告称，在种子发育过程中，也会有大量的油被周转。根据物种和生长条件的不同，阻止这种周转可能会使石油水平上升5%至25%。控制种子中的油分解需要了解分子机制，而直到最近，这方面的知识还完全缺乏。这一过程也发生在种子萌发之后，在为早期幼苗生长提供能量方面发挥着根本的重要作用。通过分离模式油料植物拟南芥中的突变体，我对油脂分解的机制有了新的见解，这些突变体在萌发后的生长中受到损害。我发现，其中一种名为糖依赖的突变体在三酰甘油水解酶中存在缺陷，这种酶催化了油脂分解的第一步。在这个突变体中，油的分解速度大大减慢，结果是发育中的种子积累了显着更多的油。这项建议的目标是(I)研究SDP1是如何被调控的，并确定是否可以在种子发育期间而不是在萌发之后抑制油的分解。这将允许在对苗木活力影响最小的情况下提高油料产量。(Ii)确定与SDP1一起发挥作用的更多结构和调节蛋白，以控制石油分解的速度。这些蛋白质的破坏将被用来完全阻止石油分解，从而最大限度地增加石油积累。(3)研究SDP1在作物油菜品种中的作用，并确定是否也可以通过削弱油料周转来增加油料产量。解决这些目标将极大地有助于我们对脂解的机制和调控的基础知识，脂解是许多植物生命周期中必不可少的主要代谢过程。这项工作还可能导致开发出产油量更高的农作物。

Oil from seeds forms a major source of nutrition for humans and livestock. It also has many important industrial uses, among them providing an increasingly relevant source of renewable energy (bio-diesel). The rate of oil accumulation in developing seeds is governed predominantly by biosynthesis. However, a number of studies have reported that a significant amount of oil is also turned over during seed development. Blocking this turnover could potentially elevate oil levels by between 5 and 25%, depending on the species and growth conditions. Controlling oil breakdown in seeds requires knowledge of the molecular mechanism, which until recently was completely lacking. This process also occurs after seed germination where it plays a fundamentally important role in providing energy for early seedling growth. I have gained a new insight into the mechanism of oil breakdown by isolating mutants in the model oilseed plant Arabidopsis that are impaired in post-germinative growth. I have discovered that one of these mutants, called sugar-dependent1, has a defect in the enzyme triacylglycerol hydrolase, which catalyses the first step in oil breakdown. The rate of oil breakdown is dramatically slowed in this mutant and as a consequence the developing seeds accumulate significantly more oil. The goals of this proposal are (i) To study how SDP1 is regulated and establish whether oil breakdown can be inhibited during seed development and not following germination. This would allow oil yield to be enhanced with the minimum impact on seedling vigour. (ii) To identify additional structural and regulatory proteins that function with SDP1 to govern the rate of oil breakdown. Disruption of these proteins will be used to block oil breakdown completely and thereby maximize oil accumulation. (iii) To investigate the role of SDP1 in the crop species oilseed rape and determine if oil yield can also be increased by impairing oil turnover. Addressing these objectives will contribute greatly to our fundamental knowledge of the mechanism and regulation of lipolysis, which is major metabolic process that is essential for the life cycle of many plants. The work could also lead to the development of crop plants with a higher oil yield.