Li Qiang, Chakrabarti Manohar, Taitano Nathan K, Okazaki Yozo, Saito Kazuki, Al-Abdallat Ayed M, van der Knaap Esther
State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding, China.
Center for Applied Genetic Technologies, University of Georgia, Athens, GA, USA.
J Exp Bot. 2021 Feb 24;72(4):1225-1244. doi: 10.1093/jxb/eraa518.
The sizes of plant organs such as fruit and seed are crucial yield components. Tomato KLUH underlies the locus fw3.2, an important regulator of fruit and seed weight. However, the mechanism by which the expression levels of KLUH affect organ size is poorly understood. We found that higher expression of SlKLUH increased cell proliferation in the pericarp within 5 d post-anthesis in tomato near-isogenic lines. Differential gene expression analyses showed that lower expression of SlKLUH was associated with increased expression of genes involved in lipid metabolism. Lipidomic analysis revealed that repression of SlKLUH mainly increased the contents of certain non-phosphorus glycerolipids and phospholipids and decreased the contents of four unknown lipids. Co-expression network analyses revealed that lipid metabolism was possibly associated with but not directly controlled by SlKLUH, and that this gene instead controls photosynthesis-related processes. In addition, many transcription factors putatively involved in the KLUH pathway were identified. Collectively, we show that SlKLUH regulates fruit and seed weight which is associated with altered lipid metabolism. The results expand our understanding of fruit and seed weight regulation and offer a valuable resource for functional studies of candidate genes putatively involved in regulation of organ size in tomato and other crops.
果实和种子等植物器官的大小是关键的产量构成要素。番茄KLUH基因位于fw3.2位点，是果实和种子重量的重要调控因子。然而，KLUH基因表达水平影响器官大小的机制尚不清楚。我们发现，在番茄近等基因系中，SlKLUH基因的高表达在开花后5天内增加了果皮中的细胞增殖。差异基因表达分析表明，SlKLUH基因的低表达与脂质代谢相关基因的表达增加有关。脂质组学分析显示，SlKLUH基因的抑制主要增加了某些非磷甘油脂和磷脂的含量，并降低了四种未知脂质的含量。共表达网络分析表明，脂质代谢可能与SlKLUH基因相关，但不受其直接控制，该基因反而控制光合作用相关过程。此外，还鉴定出许多可能参与KLUH途径的转录因子。总体而言，我们表明SlKLUH基因调节果实和种子重量，这与脂质代谢改变有关。这些结果扩展了我们对果实和种子重量调控的理解，并为番茄和其他作物中可能参与器官大小调控的候选基因的功能研究提供了宝贵资源。
