Zhang Wei, Wu Jing, He Junhu, Liu Chaoyang, Yi Wen, Xie Jingyao, Wu Ya, Xie Tao, Ma Jun, Zhong Ziqin, Yang Mingzhe, Chen Chengjie, Luan Aiping, He Yehua
Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crop in South China, Ministry of Agriculture and Rural Areas, College of Horticulture, South China Agricultural University, No. 483, Wushan Road, Wushan Street, Tianhe District, Guangzhou, Guangdong, 510642, China.
Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences/National Key Laboratory for Tropical Crop Breeding, Yazhouwan Technology City, Sanya, Hainan, 572024, China/Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China, Ministry of Agriculture and Rual Affairs/Key Laboratory of Tropical Crops Germplasm Resources Genetic Improvement and Innovation of Hainan Province, No.4, Xueyuan Road, Longhua District, Haikou, Hainan, 571101, China.
Hortic Res. 2024 Apr 25;11(6):uhae116. doi: 10.1093/hr/uhae116. eCollection 2024 Jun.
Red fruit peel is an attractive target for pineapple breeding. Various pineapple accessions with distinct red coloration patterns exist; however, the precise molecular mechanism accounting for these differences remains unknown, which hinders the pineapple breeding process from combining high fruit quality with red peel. In this study, we characterized a transcription factor, AcMYB266, which is preferentially expressed in pineapple peel and positively regulates anthocyanin accumulation. Transgenic pineapple, , and tobacco plants overexpressing exhibited significant anthocyanin accumulation. Conversely, transient silencing of this gene led to decreased anthocyanin accumulation in pineapple red bracts. In-depth analysis indicated that variations of sequences in the promoter instead of the protein-coding region seem to contribute to different red coloration patterns in peels of three representative pineapple varieties. In addition, we found that was located in a cluster of four MYB genes exclusive to and conserved in species. Of this cluster, each was proved to regulate anthocyanin synthesis in different pineapple tissues, illustrating an interesting case of gene subfunctionalization after tandem duplication. In summary, we have characterized as a key regulator of pineapple red fruit peel and identified an MYB cluster whose members were subfunctionalized to specifically regulate the red coloration of different pineapple tissues. The present study will assist in establishing a theoretical mechanism for pineapple breeding for red fruit peel and provide an interesting case for the investigation of gene subfunctionalization in plants.
红色果皮是菠萝育种的一个有吸引力的目标。存在各种具有不同红色着色模式的菠萝种质；然而，解释这些差异的精确分子机制仍然未知，这阻碍了菠萝育种过程中将高果实品质与红色果皮相结合。在本研究中，我们鉴定了一个转录因子AcMYB266，其在菠萝果皮中优先表达并正向调节花青素积累。过表达AcMYB266的转基因菠萝和烟草植株表现出显著的花青素积累。相反，该基因的瞬时沉默导致菠萝红色苞片花青素积累减少。深入分析表明，启动子而非蛋白质编码区的AcMYB266序列变异似乎导致了三个代表性菠萝品种果皮不同的红色着色模式。此外，我们发现AcMYB266位于一个由四个MYB基因组成的基因簇中，该基因簇在菠萝物种中是独有的且保守的。在这个基因簇中，每个基因都被证明在不同的菠萝组织中调节花青素合成，说明了串联重复后基因亚功能化的一个有趣例子。总之，我们已将AcMYB266鉴定为菠萝红色果皮的关键调节因子，并鉴定了一个MYB基因簇，其成员已亚功能化以特异性调节不同菠萝组织的红色着色。本研究将有助于建立菠萝红色果皮育种的理论机制，并为植物基因亚功能化研究提供一个有趣的案例。
