Pérez-López Jesús, Feria Ana B, Gandullo Jacinto, de la Osa Clara, Jiménez-Guerrero Irene, Echevarría Cristina, Monreal José A, García-Mauriño Sofía
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes nº 6, 41012 Seville, Spain.
Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes nº 6, 41012 Seville, Spain.
Plants (Basel). 2023 Jun 23;12(13):2426. doi: 10.3390/plants12132426.
Phosphoenolpyruvate carboxylase (PEPC) plays central roles in photosynthesis, respiration, amino acid synthesis, and seed development. PEPC is regulated by different post-translational modifications. Between them, the phosphorylation by PEPC-kinase (PEPCk) is widely documented. In this work, we simultaneously silenced the three sorghum genes encoding PEPCk (Sb-) by RNAi interference, obtaining 12 independent transgenic lines ( lines), showing different degrees of Sb silencing. Among them, two T2 homozygous lines ( and ) were selected for further evaluation. Expression of Sb was reduced by 65% and 83% in and illuminated leaves, respectively. Expression of Sb was higher in roots and decreased by 50% in and in this tissue. Expression of Sb was low and highly variable. Despite the incomplete gene silencing, it decreased the degree of phosphorylation of PEPC in illuminated leaves, P-deficient plants, and NaCl-treated plants. Both leaves and seeds of lines had altered metabolic profiles and a general decrease in amino acid content. In addition, lines showed delayed flowering, and 20% of plants did not produce flowers at all. The total amount of seeds was lowered by 50% and 36% in and lines, respectively. The quality of seeds was lower in lines: lower amino acid content, including Lys, and higher phytate content. These data confirm the relevance of the phosphorylation of PEPC in sorghum development, stress responses, yield, and quality of seeds.
磷酸烯醇式丙酮酸羧化酶（PEPC）在光合作用、呼吸作用、氨基酸合成和种子发育中发挥着核心作用。PEPC受到不同的翻译后修饰调控。其中，PEPC激酶（PEPCk）介导的磷酸化作用已有广泛报道。在本研究中，我们通过RNA干扰同时沉默了高粱中编码PEPCk的三个基因（Sb-），获得了12个独立的转基因株系，这些株系表现出不同程度的Sb基因沉默。其中，选取了两个T2纯合株系（和）进行进一步评估。在和的光照叶片中，Sb的表达分别降低了65%和83%。Sb在根中的表达较高，而在这两个株系的该组织中降低了50%。Sb的表达较低且变化很大。尽管基因沉默不完全，但它降低了光照叶片、缺磷植株和经NaCl处理植株中PEPC的磷酸化程度。株系的叶片和种子均具有改变的代谢谱，氨基酸含量普遍下降。此外，株系表现出开花延迟，20%的植株根本不产生花。和株系的种子总量分别降低了50%和36%。株系的种子质量较低：氨基酸含量较低，包括赖氨酸，植酸盐含量较高。这些数据证实了PEPC磷酸化在高粱发育、胁迫响应、产量和种子质量方面的相关性。
