Effect of low-temperature storage on the content of folate, vitamin B6 , ascorbic acid, chlorogenic acid, tyrosine, and phenylalanine in potatoes.

BACKGROUND: Changes in the metabolite composition of potato tubers during low-temperature storage can affect their nutritional value, susceptibility to bruising, and processing qualities. Here, we measured changes in the amounts of folate, vitamin B6 , and vitamin C, and the blackspot pigment precursors chlorogenic acid and tyrosine, as well as phenylalanine, in five potato varieties stored at 7.8 °C for 8 months in 2015 and 2016. RESULTS: Folate content increased in all varieties in both years during low-temperature storage, with statistically significant changes occurring in six out of eight conditions. Increase rates ranged from 11% to 141%. Vitamin B6 content increased in all varieties during the storage period, but changes were statistically significant in only two out of eight conditions. Increase rates ranged from 5% to 24%. Ascorbic acid content decreased in all varieties in both years during the storage period. Decrease rates ranged from 16% to 78%, and were statistically significant in seven out of eight conditions. For chlorogenic acid, no consistent trend was observed. Changes varied between -14% and +14%, but none was statistically significant. Tyrosine content increased in all varieties in both years, except in Sage Russet in 2015. Increase rates ranged from 19% to 238% and were statistically significant in three out of seven conditions. Changes in phenylalanine content were very similar to those observed for tyrosine, with increases up to 272% in Teton Russet. CONCLUSIONS: These results show that storage at low temperature substantially affects tuber nutritional quality and biochemical bruising potential. © 2019 Society of Chemical Industry.

Arabidopsis thaliana PDX1.2 is critical for embryo development and heat shock tolerance.

MAIN CONCLUSION: PDX1.2 is expressed in the basal part of the globular-stage embryo, and plays critical roles in development, hypocotyl elongation, and stress response. The Arabidopsis thaliana PDX1.2 protein belongs to a small family of three members. While PDX1.1 and PDX1.3 have been extensively described and are well established to function in vitamin B6 biosynthesis, the biological role of PDX1.2 still remains elusive. Here, we show that PDX1.2 is expressed early in embryo development, and that heat shock treatment causes a strong up-regulation of the gene. Using a combined genetic approach of T-DNA insertion lines and expression of artificial micro RNAs, we can show that PDX1.2 is critically required for embryo development, and for normal hypocotyl elongation. Plants with reduced PDX1.2 expression also display reduced primary root growth after heat shock treatments. The work overall provides a set of important new findings that give greater insights into the developmental role of PDX1.2 in plants.