Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea.
Department of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Korea.
BMC Plant Biol. 2023 May 26;23(1):281. doi: 10.1186/s12870-023-04299-4.
Leaf explants are major materials in plant tissue cultures. Incubation of detached leaves on phytohormone-containing media, which is an important process for producing calli and regenerating plants, change their cell fate. Although hormone signaling pathways related to cell fate transition have been widely studied, other molecular and physiological events occurring in leaf explants during this process remain largely unexplored.
Here, we identified that ethylene signals modulate expression of pathogen resistance genes and anthocyanin accumulation in leaf explants, affecting their survival during culture. Anthocyanins accumulated in leaf explants, but were not observed near the wound site. Ethylene signaling mutant analysis revealed that ethylene signals are active and block anthocyanin accumulation in the wound site. Moreover, expression of defense-related genes increased, particularly near the wound site, implying that ethylene induces defense responses possibly by blocking pathogenesis via wounding. We also found that anthocyanin accumulation in non-wounded regions is required for drought resistance in leaf explants.
Our study revealed the key roles of ethylene in the regulation of defense gene expression and anthocyanin biosynthesis in leaf explants. Our results suggest a survival strategy of detached leaves, which can be applied to improve the longevity of explants during tissue culture.
叶片外植体是植物组织培养的主要材料。在含有植物激素的培养基上培养离体叶片是产生愈伤组织和再生植物的重要过程，这会改变它们的细胞命运。尽管与细胞命运转变相关的激素信号通路已被广泛研究，但在这个过程中叶片外植体中发生的其他分子和生理事件在很大程度上仍未被探索。
在这里，我们发现乙烯信号调节叶片外植体中抗病基因和花色素苷积累的表达，影响它们在培养过程中的存活。花色素苷在叶片外植体中积累，但在伤口部位观察不到。乙烯信号突变体分析表明，乙烯信号是活跃的，并阻止伤口部位花色素苷的积累。此外，防御相关基因的表达增加，特别是在伤口部位附近，这表明乙烯可能通过阻断伤口引发的病害来诱导防御反应。我们还发现，非创伤部位花色素苷的积累是叶片外植体抗旱性所必需的。
我们的研究揭示了乙烯在调节叶片外植体中防御基因表达和花色素苷生物合成中的关键作用。我们的结果表明，离体叶片有一套生存策略，这可以应用于提高组织培养中外植体的寿命。
