Department of Biology, Wake Forest University, Room 226 Winston Hall, Box 7325, Winston-Salem, NC 27109, USA.
Plant J. 2010 Jan;61(1):3-15. doi: 10.1111/j.1365-313X.2009.04027.x. Epub 2009 Sep 29.
In this study we investigated the role of ethylene in the formation of lateral and adventitious roots in tomato (Solanum lycopersicum) using mutants isolated for altered ethylene signaling and fruit ripening. Mutations that block ethylene responses and delay ripening -Nr (Never ripe), gr (green ripe), nor (non ripening), and rin (ripening inhibitor) - have enhanced lateral root formation. In contrast, the epi (epinastic) mutant, which has elevated ethylene and constitutive ethylene signaling in some tissues, or treatment with the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC), reduces lateral root formation. Treatment with ACC inhibits the initiation and elongation of lateral roots, except in the Nr genotype. Root basipetal and acropetal indole-3-acetic acid (IAA) transport increase with ACC treatments or in the epi mutant, while in the Nr mutant there is less auxin transport than in the wild type and transport is insensitive to ACC. In contrast, the process of adventitious root formation shows the opposite response to ethylene, with ACC treatment and the epi mutation increasing adventitious root formation and the Nr mutation reducing the number of adventitious roots. In hypocotyls, ACC treatment negatively regulated IAA transport while the Nr mutant showed increased IAA transport in hypocotyls. Ethylene significantly reduces free IAA content in roots, but only subtly changes free IAA content in tomato hypocotyls. These results indicate a negative role for ethylene in lateral root formation and a positive role in adventitious root formation with modulation of auxin transport as a central point of ethylene-auxin crosstalk.
在这项研究中，我们使用乙烯信号转导和果实成熟突变体研究了乙烯在番茄（Solanum lycopersicum）侧根和不定根形成中的作用。阻断乙烯反应并延迟成熟的突变体 -Nr（不成熟）、gr（绿色成熟）、nor（不成熟）和 rin（成熟抑制剂）-增强了侧根的形成。相比之下，乙烯和组成型乙烯信号在一些组织中升高的 epi（反卷）突变体，或用乙烯前体 1-氨基环丙烷羧酸（ACC）处理，减少了侧根的形成。ACC 处理抑制侧根的起始和伸长，除了在 Nr 基因型中。根向基和向顶吲哚-3-乙酸（IAA）运输随 ACC 处理或 epi 突变体而增加，而在 Nr 突变体中，与野生型相比，生长素运输较少，且对 ACC 不敏感。相反，不定根的形成过程对乙烯表现出相反的反应，用 ACC 处理和 epi 突变体增加不定根的形成，而 Nr 突变体减少不定根的数量。在下胚轴中，ACC 处理负调控 IAA 运输，而 Nr 突变体在下胚轴中表现出增加的 IAA 运输。乙烯显著降低根中的游离 IAA 含量，但仅略微改变番茄下胚轴中的游离 IAA 含量。这些结果表明乙烯在侧根形成中起负作用，在不定根形成中起正作用，以生长素运输为乙烯-生长素相互作用的中心点。
