Tocopherol Biosynthesis Dynamics in Almond Kernel Development

Almond is one of the most important tree nut crops, due to its high nutritive value, namely in lipids and tocopherol richness. Its production in Portugal has been increasing during the last years. Tocopherol (Vitamin E) is an important antioxidant that prevents the peroxidation of unsaturated fatty acids, increasing storage life of almonds. It is highly effective in preventing cardiovascular diseases by inhibiting platelet aggregation. Genes involved in its biosynthesis have been characterized in other species, but few studies have been made in almonds.

The aim of this work was the study of change in tocopherol content during almond kernel maturation and molecular mechanisms underlying its biosynthetic pathway.

Different stages of kernel development of variety Soleta were morphologically characterized from March to August in Alentejo region, Portugal. The tocopherol profile was analyzed and quantified by HPLC, using fluorescence detection and a normal-phase silica column. For analysis of transcript abundance by RT-qPCR, total RNA extractions of almond kernels were optimized, followed by synthesized cDNA. Sequence transcripts of vte2, vte3 and vte4, involved in tocopherol synthesis, were confirmed by Sanger sequencing.

It was possible to observe a progressive increase in α-tocopherol content in kernels development over the months, with higher increments in the mature stages. In the future, the differential expression level of candidate genes involved in tocopherol synthesis will be characterized using RT-qPCR. This study intends to reveal new insight into the tocopherol biosynthetic pathway which may impact kernel composition.