Carotenoid biosynthesis and accumulation in fleshy fruits of Lycium L.

Ying WANG, Yongliang LIU,  Shaohua ZENG and Hao CHEN

Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650

Lycium L. is a genus of Solanaceae containing about 80 species distributed in the temperate and subtropical zones. Lycium species are mostly found in dry, semi-saline environments. Chinese Pharmacopoeia (2010) recorded Lycii Fructus (Gouqizi, dry red fruit [RF] of L. barbarum), and Lycii Cortex (Digupi, dry root bark of L. chinense and L. barbarum). Black fruits (BF) of L. ruthenicum have been used as folk medicine, especially in Tibetan and Mongolian medicine. Therefore, wolfberry (or Goji, Gouqi) nowadays in China refers to the products prepared from L. chinense, L. barbarum, and L. ruthenicum, which is one of the most famous anti-aging herbs. Transcriptome sequencing and chloroplast development have been investigated for identification of key genes involved in the biosynthesis and accumulation of carotenoids, especially zeaxanthin dipalmitate. The failure of the chromoplast development in BF causes low carotenoid biosynthesis levels and continuous carotenoid degradation, which ultimately leads to undetectable carotenoid levels in ripe BF. In contrast, the successful chromoplast biogenesis in RF furnishes the sink necessary for carotenoid storage. The abundant zeaxanthin accumulation in RF is primarily determined via the high levels of carotenoid biosynthesis, transportation, and storage, as well as the lack of carotenoid degradation, which are regulated at the transcriptional level. Function of several key genes will be characterized and reported.