KSEF R&D Excellence: Efficient Leaf Aldehyde Production

Leaf aldehyde, 2(E)-hexenaI, is an important flavor and aroma ingredient in foods and beverages. It can also be used to treat plants and plant products such as fruit for enhanced disease resistance, shelf life, and quality and reduce food-borne disease organisms on food handling equipment. Leaf aldehyde is currently valued as much as $100 per kg and the market for such compounds has increased> 70% in the past 10 years. There is a large interest in natural sources ofthis compound. Commercial production is currently accomplished with watermelon leaves apparently due to its very high hydroperoxide lyase (HL) activity. Activities of genes encoding HLs from watermelon and tobacco will be expressed in E. coli in comparison to Arabidopsis and that with the highest activity will be transferred into tobacco. We will also examine new methods for increasing expression of the HL gene that will be applicable to other molecular farming uses of crop plants including tobacco as well as fundamental bioscience research. The overall goal of this research is to improve natural leaf aldehyde production systems to more commercially viable, economical levels. This will involve the genetic enhancement of Nicotiana leaves for much increased expression of hydroperoxide lyase (HL) via transformation and transfection including trans-activation and use of soybean seed lipoxygenase genetic materials. The overall goal of this research is to achieve the increased formation of leaf aldehyde, 2(E)- hexenal, from plants by enhanced expression of the key enzyme involved in its formation, HL. Specifically we propose to: 1.) Over-express HL with very high leaf aldehyde formation activity in leaves. 2.) Examine methods for increasing expression ofHL from (1) for maximal activity in leaves. 3.) Optimize final bioreactor systems including amount and type of lipoxygenase and initial feedstock source.