Brenya Eric, Dutta Esha, Herron Brittani, Walden Lauren H, Roberts Daniel M, Binder Brad M
Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
Genome Science and Technology Program, University of Tennessee, Knoxville, TN 37996, USA.
PNAS Nexus. 2023 Jul 18;2(7):pgad216. doi: 10.1093/pnasnexus/pgad216. eCollection 2023 Jul.
Enhancing crop yields is a major challenge because of an increasing human population, climate change, and reduction in arable land. Here, we demonstrate that long-lasting growth enhancement and increased stress tolerance occur by pretreatment of dark grown seedlings with ethylene before transitioning into light. Plants treated this way had longer primary roots, more and longer lateral roots, and larger aerial tissue and were more tolerant to high temperature, salt, and recovery from hypoxia stress. We attributed the increase in plant growth and stress tolerance to ethylene-induced photosynthetic-derived sugars because ethylene pretreatment caused a 23% increase in carbon assimilation and increased the levels of glucose (266%), sucrose/trehalose (446%), and starch (87%). Metabolomic and transcriptomic analyses several days posttreatment showed a significant increase in metabolic processes and gene transcripts implicated in cell division, photosynthesis, and carbohydrate metabolism. Because of this large effect on metabolism, we term this "ethylene-mediated metabolic priming." Reducing photosynthesis with inhibitors or mutants prevented the growth enhancement, but this was partially rescued by exogenous sucrose, implicating sugars in this growth phenomenon. Additionally, ethylene pretreatment increased the levels of and encoding invertases that hydrolyze sucrose, and mutants did not respond to ethylene pretreatment with increased growth indicating increased sucrose breakdown is critical for this trait. A model is proposed where ethylene-mediated metabolic priming causes long-term increases in photosynthesis and carbohydrate utilization to increase growth. These responses may be part of the natural development of seedlings as they navigate through the soil to emerge into light.
由于人口增长、气候变化和耕地减少，提高作物产量是一项重大挑战。在此，我们证明，在转入光照之前，用乙烯对黑暗中生长的幼苗进行预处理，可实现持久的生长增强和胁迫耐受性提高。以这种方式处理的植物主根更长，侧根更多、更长，地上组织更大，并且对高温、盐分以及从缺氧胁迫中恢复的耐受性更强。我们将植物生长和胁迫耐受性的提高归因于乙烯诱导的光合衍生糖，因为乙烯预处理使碳同化增加了23%，并提高了葡萄糖（266%）、蔗糖/海藻糖（446%）和淀粉（87%）的水平。处理后几天的代谢组学和转录组学分析表明，与细胞分裂、光合作用和碳水化合物代谢相关的代谢过程和基因转录本显著增加。由于对代谢有如此大的影响，我们将此称为“乙烯介导的代谢引发”。用抑制剂或突变体降低光合作用可阻止生长增强，但外源蔗糖可部分挽救这种情况，这表明糖参与了这种生长现象。此外，乙烯预处理提高了编码水解蔗糖的转化酶的 和 的水平， 突变体对乙烯预处理没有表现出生长增加的反应，这表明蔗糖分解增加对该性状至关重要。我们提出了一个模型，其中乙烯介导的代谢引发导致光合作用和碳水化合物利用的长期增加，从而促进生长。这些反应可能是幼苗在土壤中生长并出土见光这一自然发育过程的一部分。
