背景回顾：ETHYLENE-INSENSITIVE 3/ETHYLENE-INSENSITIVE 3-LIKEs (EIN3/EILs) are important ethylene response factors during fruit ripening. 

提出问题：Here, we discovered that EIL2 controls carotenoid metabolism and ascorbic acid (AsA) biosynthesis in tomato (Solanum lycopersicum). 

结果1-eil2突变体表型：In contrast to the red fruits presented in the wild type (WT) 45 days after pollination, the fruits of CRISPR/Cas9 eil2 mutants and SlEIL2 RNAi lines (ERIs) showed yellow or orange fruits. 

结果2-转录+代谢：Correlation analysis of transcriptome and metabolome data for the ERI and WT ripe fruits revealed that SlEIL2 is involved in β-carotene and AsA accumulation. 

结果3-EIL2-ERFs-LCYB2-carotene：ETHYLENE RESPONSE FACTORs (ERFs) are the typical components downstream from EIN3 in the ethylene response pathway. Through a comprehensive screening of ERF family members, we determined that SlEIL2 directly regulates the expression of four SlERFs. Two of these, SlERF.H30 and SlERF.G6, encode proteins that participate in the regulation of LYCOPENE-β-CYCLASE 2 (SlLCYB2), encoding an enzyme that mediates the conversion of lycopene to carotene in fruits. 

结果4-EIL2-GPP3/MIOX1-AsA：In addition, SlEIL2 transcriptionally repressed L-GALACTOSE 1-PHOSPHATE PHOSPHATASE 3 (SlGPP3) and MYO-INOSITOL OXYGENASE 1 (SlMIOX1) expression, which resulted in 1.62 fold increase of AsA via both the L-galactose and myoinositol pathways. 

结论：Overall, we demonstrated that SlEIL2 functions in controlling β-carotene and AsA levels, providing a potential strategy for genetic engineering to improve the nutritional value and quality of tomato fruit.

EIN3/EILs是一类再果实成熟过程中发挥重要作用的乙烯响应因子。本文中，作者发现番茄EIL2控制类胡萝卜素的代谢和抗坏血酸AsA的生物合成。野生型的番茄在授粉45天后果实会变红色，但是通过CRISPR/Cas9获得的eil2突变体以及RNAi干扰获得的SlEIL2干扰株系ERIs则会表现出黄色或者橙色果实。通过对ERI和WT成熟果实的转录和代谢的相关性分析显示，SlEIL2参与了β-胡萝卜素和AsA的积累。在乙烯信号响应途径中，乙烯响应因子ERFs是EIN3的下游组分。通过对ERF家族成员的鉴定和分析，作者发现SlEIL2能够直接调控4个SlERFs的表达。其中两个SlERF.H30和SlERF.G6编码的蛋白参与番茄红素-β-环化酶编码基因SlLCYB2的调控，而SlLCYB2主要作用于果实中番茄红素向胡萝卜素的转变。另外，SlEIL2能够转录抑制L-半乳糖磷酸磷酸酶编码基因SlGPP3和肌醇加氧酶编码基因SlMIOX1的表达，从而通过L-半乳糖和肌醇途径将果实中的AsA降低了约1.62倍。综上，本文的研究揭示了SlEIL2作用于果实中β-胡萝卜素和AsA水平的控制，为未来番茄果实的营养和品质改良提供了基因工程的靶标基因。

doi: https://doi.org/10.1093/plphys/kiad151