Wu Junqing, Cheng Jie, Xu Chunmiao, Qi Shilian, Sun Wenru, Wu Shuang
College of Horticulture, FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 35002 Fujian, China.
Hortic Res. 2020 Oct 1;7(1):166. doi: 10.1038/s41438-020-00386-x. eCollection 2020.
Flooding tolerance is an important trait for tomato breeding. In this study, we obtained a recessive mutant exhibiting highly enhanced submergence resistance. Phenotypical analyses showed that this () mutant displays slightly chlorotic leaves and spontaneous initiation of adventitious roots (ARs) on stems. The mutation was mapped to the phytochromobilin synthase gene (), in which a single amino acid substitution from asparagine to tyrosine occurred. In addition to the classic function of in phytochrome and chlorophyll biogenesis in leaves, we uncovered its novel role in mediating AR formation on stems. We further observed temporal coincidence of the two phenotypes in the mutant: chlorosis and spontaneous AR formation and revealed that AU functions by maintaining heme homeostasis. Interestingly, our grafting results suggest that heme might play roles in AR initiation via long-distance transport from leaves to stems. Our results present genetic evidence for the involvement of the -heme oxygenase-1-heme pathway in AR initiation in tomato. As fruit production and yield in the mutant are minimally impacted, the mutation identified in this study may provide a target for biotechnological renovation of tomato germplasm in future breeding.
耐涝性是番茄育种的一个重要性状。在本研究中，我们获得了一个隐性突变体，其耐淹性显著增强。表型分析表明，这个（）突变体叶片略显黄化，茎上能自发产生不定根（ARs）。该突变被定位到藻胆素合酶基因（），其中发生了单个氨基酸从天冬酰胺到酪氨酸的替换。除了在叶片中参与光敏色素和叶绿素生物合成的经典功能外，我们还发现了它在介导茎上不定根形成中的新作用。我们进一步观察到该突变体中两种表型的时间一致性：黄化和自发不定根形成，并揭示了AU通过维持血红素稳态发挥作用。有趣的是，我们的嫁接结果表明，血红素可能通过从叶片到茎的长距离运输在不定根起始中发挥作用。我们的结果为番茄中-血红素加氧酶-1-血红素途径参与不定根起始提供了遗传学证据。由于该突变体的果实产量和产量受到的影响最小，本研究中鉴定出的突变可能为未来育种中番茄种质的生物技术改良提供一个靶点。
