Genome-Wide Transcriptome Analysis of Rice Transporters and Its Application to Elucidate the Uncharacterized Functions of OsABCC7 Gene Using the CRISPR/Cas9 System

The Rice Transporter Database (https://ricephylogenomics.ucdavis.edu/transporter/tree.php) integrates host functional genomic information for 1228 putative rice transporters. Here, when we analyzed diverse transcriptome data, we found that 270 transporter genes were preferentially expressed in tissue- and organ-specific patterns. Specifically, transcription of 205 genes was upregulated in response to abiotic stressors, such as salt, drought, cold, and heat; 231 genes were upregulated in response to hormones, such as ABA, gibberellic acid, cytokines, auxin, and jasmonic acid; and 60 genes were upregulated in response to pathogens, such as fungi, bacteria, viruses, and insects. Among them, the functions of 49 genes were characterized using the information acquired from the OGRO database. The association between the transporter families and featured expression patterns were also assessed. The ABC transporter family was found to be associated with root-preferential expression, the responses of M. oryzae and Xoo to infection, and treatment with the hormone JA. On the other hand, the TAT transporter family was found to be significantly enriched in the categories of heat stress and preferential shoot/leaf-expression. POT was highly enriched when coupled with M. oryzae/Xoo infection and tZ hormone treatment. The application to identify the function of predicted ABA responded OsABCC7 transporter genes in rice revealed that the expression of OsABCC7 was triggered by exogenous ABA and that the CRISPR–Cas9 mutant was sensitive to ABA. These predicted results can serve as a premise for more specific studies in the future and contribute to the foundation of transporter research in rice.