S01 - Session O7 - Deciphering the genetic basis of tocopherol biosynthesis in almond kernel

Authors: Gonçalo Almeida , Ana Luísa Ferreira Faustino *, R. Costa Pires, David Soldado, Liliana Cachucho, M. Margarida Oliveira, Eliana Jerónimo, Liliana Marum

Tocopherol, an important antioxidant with radical scavenging abilities, is present in high concentrations in almond kernels. It helps to maintain the stability of almond quality by increasing its storage life. Four isomers are found in almond, however, α-tocopherol is present in high concentrations, while it also is the most biologically active form of vitamin E used by the human body. While some studies have focused on the tocopherol contents and composition, no information is available concerning the gene network involved in its biosynthesis. In Portugal, an exponential increase in the planted area of almond trees has been observed over the last 5 years, mainly due to increased water availability and the introduction of new cultivation systems. The aim of this work was to study the tocopherol content of traditional and commercial varieties produced in Alentejo, Portugal, at different kernel developmental stages. Moreover, molecular mechanisms underlying its biosynthetic pathway were initiated. The tocopherol profiles were analyzed and quantified by HPLC. Total RNA extractions were optimized and the concentrations and quality of the RNA samples were analysed by fluorometric and electrophoresis techniques. Sequence transcripts of vte1 , vte2 and vte4 involved in tocopherol synthesis, were confirmed by Sanger sequencing. The differential expression level of candidate genes was characterized using RT-qPCR. An increase in α-tocopherol content was observed along kernel development, with a higher increment between T2 (86 days post-anthesis (DPA)) and T3 (116 DPA) stages. Preliminary results allowed the determination of the gene expression profiles of vte1 , vte2 and vte4 along with maturation development, and in different almond varieties at the mature stage. New reference genes are being optimized in order to confirm the expression profile of the candidate genes. The identification and characterization of key genes in the tocopherol biosynthesis will contribute to future breeding programs aimed at increasing tocopherol content via biotechnological strategies.