Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems (BIOSYST), KU Leuven, Willem de Croylaan 42, bus 2428, 3001 Leuven, Belgium.
BMC Plant Biol. 2014 Jan 8;14:11. doi: 10.1186/1471-2229-14-11.
Solanum lycopersicum or tomato is extensively studied with respect to the ethylene metabolism during climacteric ripening, focusing almost exclusively on fruit pericarp. In this work the ethylene biosynthesis pathway was examined in all major tomato fruit tissues: pericarp, septa, columella, placenta, locular gel and seeds. The tissue specific ethylene production rate was measured throughout fruit development, climacteric ripening and postharvest storage. All ethylene intermediate metabolites (1-aminocyclopropane-1-carboxylic acid (ACC), malonyl-ACC (MACC) and S-adenosyl-L-methionine (SAM)) and enzyme activities (ACC-oxidase (ACO) and ACC-synthase (ACS)) were assessed.
All tissues showed a similar climacteric pattern in ethylene productions, but with a different amplitude. Profound differences were found between tissue types at the metabolic and enzymatic level. The pericarp tissue produced the highest amount of ethylene, but showed only a low ACC content and limited ACS activity, while the locular gel accumulated a lot of ACC, MACC and SAM and showed only limited ACO and ACS activity. Central tissues (septa, columella and placenta) showed a strong accumulation of ACC and MACC. These differences indicate that the ethylene biosynthesis pathway is organized and regulated in a tissue specific way. The possible role of inter- and intra-tissue transport is discussed to explain these discrepancies. Furthermore, the antagonistic relation between ACO and E8, an ethylene biosynthesis inhibiting protein, was shown to be tissue specific and developmentally regulated. In addition, ethylene inhibition by E8 is not achieved by a direct interaction between ACO and E8, as previously suggested in literature.
The Ethylene biosynthesis pathway and E8 show a tissue specific and developmental differentiation throughout tomato fruit development and ripening.
番茄（Solanum lycopersicum）或西红柿在成熟过程中的乙烯代谢方面进行了广泛研究，主要集中在果实的果皮上。在这项工作中，研究了番茄所有主要果实组织（果皮、隔膜、果心、胎座、腔室凝胶和种子）中的乙烯生物合成途径。在整个果实发育、成熟和采后贮藏过程中，测量了组织特异性乙烯产生率。评估了所有乙烯中间代谢物（1-氨基环丙烷-1-羧酸（ACC）、丙二酰-ACC（MACC）和 S-腺苷-L-甲硫氨酸（SAM））和酶活性（ACC-氧化酶（ACO）和 ACC-合成酶（ACS））。
所有组织的乙烯产生都表现出相似的成熟模式，但幅度不同。在代谢和酶水平上，组织类型之间存在明显差异。果皮组织产生的乙烯量最高，但 ACC 含量低，ACS 活性有限，而腔室凝胶积累了大量的 ACC、MACC 和 SAM，仅表现出有限的 ACO 和 ACS 活性。中央组织（隔膜、果心和胎座）显示出 ACC 和 MACC 的强烈积累。这些差异表明，乙烯生物合成途径以组织特异性的方式组织和调节。讨论了跨组织和组织内运输的可能作用，以解释这些差异。此外，ACO 和 E8（一种抑制乙烯生物合成的蛋白质）之间的拮抗关系表现出组织特异性和发育调控。此外，如文献中先前提出的那样，E8 对乙烯的抑制不是通过 ACO 和 E8 之间的直接相互作用实现的。
在番茄果实发育和成熟过程中，乙烯生物合成途径和 E8 表现出组织特异性和发育分化。
