BIOLOGICAL SYNTHESIS OF ASTAXANTHIN IN APPLE CALLUS BY GENETIC TRANSFORMATION OF BKT AND CRTR-B FROM HAEMATOCOCCUS PLUVIALIS
Apples may suffer sunburn during the growing season due to photooxidation damage. Astaxanthin is a red ketonic carotenoid which is reported to have stronger antioxidant activity against photooxidation compared to its precursors, zeaxanthin and β-carotene. Apples contain no astaxanthin, only these precursors. Levels of β-carotene in Gala apple were previously determined as 183.24 and 113.14 µg/100 g in peel and in flesh respectively. The key enzymes controlling astaxanthin biosynthesis, β-carotene ketolase (BKT) and β-carotene hydroxylase (CRTR-B) are encoded by bkt and crtR-B respectively. In the present study we used Agrobacterium tumefaciens to mediate transformation of bkt and crtR-B from Haematococcus pluvialis, into Gala using the plant expression vector pCAMBIA1301-bkt-CrtR-B, with the goal of enhancing antioxidant ability against sunburn. PCR amplification and RT-PCR analysis confirmed that both bkt and crtR-B genes had been integrated into the genome of Brookfield Gala and were expressed simultaneously with pink color in the callus. The highest content of astaxanthin in the callus of transgenic plants was 0.43±0.1 μg/g FW. The transgenic apples were expected to be not only resistant against sunburn, but also of significance for improvement of nutritional quality and commercial value of apples.
Jia, D., Fan, L., Shen, J., Liu, C., Yuan, Y., Qin, S. and Cui, C. (2014). BIOLOGICAL SYNTHESIS OF ASTAXANTHIN IN APPLE CALLUS BY GENETIC TRANSFORMATION OF BKT AND CRTR-B FROM HAEMATOCOCCUS PLUVIALIS. Acta Hortic. 1048, 143-149
apple, astaxanthin, β-carotene ketolase, β-carotene hydroxylase, Agrobacterium-mediated transformation