AgMYB2 transcription factor is involved in the regulation of anthocyanin biosynthesis in purple celery (Apium graveolens L.)

Abstract

This study showed that an R2R3-MYB transcription factor, AgMYB2, functions in anthocyanin biosynthesis and accumulation in purple celery. Anthocyanins are involved in tissue coloration and stress response in plants. Foods containing high anthocyanin content are also beneficial to human health. Purple celery accumulated amounts of anthocyanins in the petioles. The biosynthesis of anthocyanin in plants is mainly regulated by the R2R3-MYB transcription factor (TF). However, the R2R3-MYB TF that controls anthocyanin accumulation in purple celery remains unclear. In this study, an R2R3-MYB TF gene, AgMYB2, was cloned from purple celery and characterized as anthocyanin biosynthetic regulator. Sequence analysis indicated that AgMYB2 contained highly conserved R2R3 domain and two anthocyanin characteristic motifs, ANDV motif and KPRPR[S/T]F motif. The relative expression level of AgMYB2 in purple celery was significantly higher than that in non-purple celery at three developmental stages. Heterologous expression of AgMYB2 in Arabidopsis generated more anthocyanins and resulted in dark-purple leaves and flowers. The expression levels of anthocyanin biosynthetic genes and the antioxidant activity of transgenic Arabidopsis carrying AgMYB2 were up-regulated. The determination of anthocyanin glycosylation activity of Arabidopsis crude enzyme verified the anthocyanin biosynthesis regulatory function of AgMYB2 at the protein level. The interaction between AgMYB2 and bHLH proteins was shown by yeast two-hybrid assay. The results will help to elucidate the molecular mechanism of anthocyanin biosynthesis in purple celery and provide an approach for cultivating plants with high anthocyanin content.

A genome-wide association study uncovers a critical role of the RsPAP2 gene in red-skinned Raphanus sativus L.

“…Moreover, the transcript levels of several key structural genes exhibited significant increases in both RsPAP2-overexpressing Arabidopsis plants and radish cotyledons. This phenomenon has also been noted for genes in other plants, such as OvPAP2 in oilseed rape 42 , NtMYB2 in Chinese narcissus 43 , and AgMYB2 in purple celery 44 . These findings indicated that RsPAP2 might promote ATC biosynthesis by positively regulating several critical ATC-related genes in radish.…”

Two MYB transcription factors (CsMYB2 and CsMYB26) are involved in flavonoid biosynthesis in tea plant [Camellia sinensis (L.) O. Kuntze]

“…An R2R3-MYB TF, OjMYB1, was reported to be involved in anthocyanin biosynthesis in Oenanthe javanica [ 5 ]. AgMYB2 is involved in the regulation of anthocyanin biosynthesis in purple celery [ 21 ]. MdMYBA induces anthocyanin accumulation in the reproductive tissues of transgenic tobacco [ 22 ].…”

The genome sequence of celery (Apium graveolens L.), an important leaf vegetable crop rich in apigenin in the Apiaceae family

“…The total number of NBS-LRR genes was 146 in carrot 20 , 176 in Arabidopsis 57 , 107 in maize 58 , and 472 in rice 59 . Among these genes in the celery genome, one class, NBS, presented a markedly greater number in celery (126 genes) than in other plants including carrot (19), Arabidopsis (1), maize (7) and rice (25). The NBS-LRR genes present in monocotyledons and dicotyledons showed different characteristics.…”

“…In particular, the content of apigenin in celery is higher than that in other plants 6 . Many studies on the isolation, identification, and application of flavonoids in celery have been carried out 4,7,8 . Apigenin and luteolin exhibit a wide range of pharmacological effects, including anti-bacterial, anti-oxidation, and cardiovascular protective effects 9,10 .…”