Comparative transcriptome analysis of oat varieties with different flowering performances under a short-day...

Insensitivity to day length is an essential trait for oat cultivation and its geographical spread to a wide range of latitudes. Daylength-insensitive oat cultivars can flower normally from low to high latitudes and may be especially well suited for a double-cropping system. However, few studies have investigated the regulatory mechanisms involved in flowering in photoperiod-insensitive oats.

In this study, we compared the developmental stages of shoot apical meristems (SAMs) and transcriptome profiles between the photoperiod-insensitive oat cultivar VAO-8 and the photoperiod-sensitive oat cultivar Baiyan 2 at four time points under a short-day photoperiod. The development of Baiyan 2 was affected by short-day length, and SAMs persisted in the vegetative stage. VAO-8 responded less to photoperiod and matured normally under a short-day photoperiod. Comparative transcriptome data of the two cultivars revealed a total of 824, 1,189, 646 and 1,145 differentially expressed genes (DEGs) between VAO-8 and Baiyan 2 at four time points. Functional enrichment analysis revealed that metabolic processes related to chlorophyll biosynthesis, photosynthesis, carbohydrate metabolism and the secondary metabolism were significantly enhanced in VAO-8 compared with those in Baiyan 2. The upregulated genes involved in these processes may contribute to the flowering of VAO-8 under a short-day photoperiod. Furthermore, the differential expression of 93 transcription factor genes involved in multiple flowering pathways was observed, and these genes may play important roles in the regulation of VAO-8 flowering.

The results provide a comprehensive understanding of the photoperiod-insensitive molecular mechanism of oats at the transcriptional level under a short-day photoperiod, which lay a foundation for breeding photoperiod-insensitive oat cultivars.