College of Horticultural Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Plant Cell Rep. 2012 Aug;31(8):1425-35. doi: 10.1007/s00299-012-1258-4. Epub 2012 Apr 11.
In strawberry (Fragaria × ananassa Duch.), auxin has been recognized as the main signal molecule coordinating the growth and initiation of ripening of fruits. The molecular mechanism regulating auxin biosynthesis in strawberry remains unknown. This project reports two YUCCA flavin monooxygenase genes FaYUC1-2 isolated from cultivated strawberry. FaYUC1 and FaYUC2 are most homologous to AtYUC6 and AtYUC4, respectively. Significant expression of FaYUC1-2 is found in vegetative meristems and reproductive organs, with overlapping but distinct patterns. During fruit development, both transcripts of FaYUC1 and FaYUC2 in achenes reach a peak around large green fruit (G2) stage, but the sudden rise in FaYUC2 transcript level is much steeper and begins earlier than that in FaYUC1. FaYUC2 is also obviously expressed in the receptacles from green fruits, hinting another auxin source for receptacle development, other than achenes. FaYUC1 over-expression Arabidopsis exhibits typical auxin hyper-accumulation phenotype in many aspects, such as the narrow and downward curled leaves, strong apical dominance, short and hairy root. It is also severely sterile, due to the disruption of floral meristems initiation and floral organs development. Transgenic analysis indicates that strawberry YUC gene may hold conserved role in auxin biosynthesis like their homologs in other plants. Integrated with the spatiotemporal expression features, these results led us to propose that FaYUC1-2 may involve in many developmental processes including flower and fruit development in strawberry.
This paper is the first report of isolation and characterization of strawberry auxin biosynthesis genes. And their conserved functions in auxin biosynthesis were confirmed after ectopic expression.
在草莓（Fragaria × ananassa Duch.）中，生长素已被认为是协调果实生长和成熟启动的主要信号分子。调节草莓生长素生物合成的分子机制尚不清楚。本项目报道了从栽培草莓中分离得到的两个 YUCCA 黄素单加氧酶基因 FaYUC1-2。FaYUC1 和 FaYUC2 分别与 AtYUC6 和 AtYUC4 最同源。FaYUC1-2 的显著表达存在于营养分生组织和生殖器官中，具有重叠但不同的模式。在果实发育过程中，FaYUC1 和 FaYUC2 的两个转录本在瘦果中均在大绿果（G2）期左右达到峰值，但 FaYUC2 转录本水平的突然升高要陡峭得多，且开始得更早。FaYUC2 在绿色果实的果托中也明显表达，暗示果托发育的另一个生长素来源，而不仅仅是瘦果。FaYUC1 过表达拟南芥在许多方面表现出典型的生长素积累表型，如叶片狭窄向下卷曲、顶端优势强、根短而多毛。由于花分生组织起始和花器官发育的破坏，它也严重不育。转基因分析表明，草莓 YUC 基因在生长素生物合成中的作用可能与其他植物中的同源基因保守。综合时空表达特征，这些结果表明 FaYUC1-2 可能参与包括草莓花和果实发育在内的许多发育过程。
本文首次报道了草莓生长素生物合成基因的分离和鉴定。并通过异位表达证实了它们在生长素生物合成中的保守功能。
