Defining Color Change in Pitaya: A Close Look at Betacyanin Synthesis Genes in Stenocereus queretaroensis

Abstract

Betalains are tyrosine-derived plant pigments present in several species of the Caryophyllales order. Betalains are classified in red betacyanins and yellow betaxanthins and are implicated in plant stress tolerance and visual attraction for pollinators. The compounds are used as natural colorants in many industries. Today, there is little information on betalain biosynthesis with several key enzymes that remain unknown on plants of the Caryophyllales order. Omic tools have proven to be very useful in gaining insights into various molecular mechanisms. In this study, we used suspension cells from fruits of the cactus Stenocereus queretaroensis. Two growing conditions were used to perform RNA-seq and differential expression analysis to help identify betalain biosynthesis-related genes. We found 98 differential expressed genes related to aromatic amino acids and betalain biosynthesis pathways. Interestingly, we found that only one gene of the betalain synthesis pathway was differentially expressed. The rest of the genes belong to the aromatic amino acid pathway, including hydroxy phenylpyruvate-related genes, suggesting the possibility of an alternative biosynthetic pathway similar to that observed in legumes.

Evaluation of Natural Pigments Production in Response to Various Stress Signals in Cell Lines of Stenocereus queretaroensis

“…Osmotic stress was simulated using polyethylene glycol 6000 [ 3 , 4 , 5 , 6 ] (PEG 6000 MERCK) in sqY1 and sqR1 cell lines. In 250 mL Erlenmeyer flasks, 40 mL of cactus culture medium containing 3%, 4% and 5% PEG 6000 were added and sterilized in an autoclave (Novatech) at a pressure of 1 kg/cm 2 and a temperature of 121 °C for 15 min; subsequently, using pipettes, 10 mL of cells from 14-day-old sqY1 and sqR1 lines were added due to their abundant cell development.…”

“…For that reason, it is essential to develop methods to obtain these metabolites. Some secondary metabolites are synthesized as a response to stress; therefore, cell cultures exposed to different conditions such as drought, salinity, UV radiation, etc., are capable of altering the metabolism and thus increases the number of secondary metabolites [ 4 , 5 , 6 , 7 , 8 ]. The cactaceae family has CAM metabolisms and grows in diverse regions of the world; in addition, they are emblematic plants of the desert areas in México since the pre-Columbian time [ 9 , 10 , 11 ].…”

“…Betalains are subdivided into betacyanins (red) and betaxanthins (yellow). Compared to other pigments, such as anthocyanins and carotenoids, betalains have superior qualities, promising for their application in the industry; these include high water solubility, high stability, and color variability based on pH conditions [ 3 , 4 , 5 , 6 , 7 ], as well as the attractive characteristic of being odorless and tasteless [ 23 ]. Betalains are not only defined by these characteristics, but also by their bioactive qualities as anticarcinogens and antioxidants [ 24 ].…”