Computational and Transcriptomic Analysis Unraveled OsMATE34 as a Putative Anthocyanin Transporter in Black Rice (Oryza sativa L.) Caryopsis.

Enerand Mackon,Qiufeng Li,Babar Usman,Yafei Ma,Yitong Zhao,Guibeline Charlie Jeazet Dongho Epse Mackon,Piqing Liu

doi:10.3390/genes12040583

Abstract

Anthocyanin is a flavonoid compound with potential antioxidant properties beneficial to human health and sustains plant growth and development under different environmental stresses. In black rice, anthocyanin can be found in the stems, leaves, stigmas, and caryopsis. Although the anthocyanin biosynthesis in rice has been extensively studied, limited knowledge underlying the storage mechanism and transporters is available. This study undertook the complementation of computational and transcriptome analysis to decipher a potential multidrug and toxic compound extrusion (MATE) gene candidate for anthocyanin transportation in black rice caryopsis. The phylogenetic analysis showed that OsMATE34 has the same evolutionary history and high similarities with VvAM1, VvAM3, MtMATE2, SlMATE/MTP77, RsMATE8, AtFFT, and AtTT12 involved in anthocyanin transportation. RNA sequencing analysis in black caryopsis (Bc; Bc11, Bc18, Bc25) and white caryopsis (Wc; Wc11, Wc18, Wc25), respectively, at 11 days after flowering (DAF), 18 DAF, and 25 DAF revealed a total of 36,079 expressed genes, including 33,157 known genes and 2922 new genes. The differentially expressed genes (DEGs) showed 15,573 genes commonly expressed, with 1804 and 1412 genes uniquely expressed in Bc and Wc, respectively. Pairwise comparisons showed 821 uniquely expressed genes out of 15,272 DEGs for Wc11 vs. Bc11, 201 uniquely expressed genes out of 16,240 DEGs for Wc18 vs. Bc18, and 2263 uniquely expressed genes out of 16,240 DEGs for Wc25 vs. Bc25. Along with anthocyanin biosynthesis genes (OsPAL, OsCHS, OsCHI, OsF3H, OsDFR, OsANS, and OsUFGT/Os3GT), OsMATE34 expression was significantly upregulated in all Bc but not in Wc. OsMATE34 expression was similar to OsGSTU34, a transporter of anthocyanin in rice leaves. Taken together, our results highlighted OsMATE34 (Os08g0562800) as a candidate anthocyanin transporter in rice caryopsis. This study provides a new finding and a clue to enhance the accumulation of anthocyanin in rice caryopsis.

Highlights

Our results showed that Pt3G was not detected in both black and white caryopsis, while C3G and P3G were detected only in black caryopsis (Table 1)
This study aimed to identify and characterize the multidrug and toxic compound extrusion (MATE) transporter involved in anthocyanin transportation in rice, mainly in rice caryopsis
Based on the computational and transcriptome results, we suggested that OsMATE34 (Os08g0562800) along with OsGSTU34 (Os10g0395400) were involved in anthocyanin transportation in black rice caryopsis

Summary

Introduction

Rice (Oryza sativa L.) is the main staple food consumed by half of the world population and almost 60% of China’s population [1]. The world’s population is expected to reach 9.7 billion by 2050; food and energy demands should be a great challenge [2]. To ensure food and nutritional security, new strategies should be adopted to increase food production and nutritional values [3]. Increasing interest in health-promoting food has significantly generated a substantial market for potential nutritionally valuable rice [4]

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