The habituated rice calli grown on an auxin-free medium were isolated from rice embryo-derived calli previously cultivated on medium supplemented with 2,4-D. The habituated rice calli grow faster than the non-habituated ones, particularly during the first week. We performed microarray analysis to unravel the changes in the transcriptomic level of rice calli grown on hormone-free medium. Several genes related to hormone metabolism and signaling were differentially expressed between the two calli types. Especially, the expressions of two amido-transferase enzymes genes Gretchen Hagen 3s (GH3.1 and GH3.8) were down-regulated and one indole-3-acetic acid (IAA)-amino acid (IAA-AA) hydrolase gene ILR1-like 3 was up-regulated in habituated calli compared to non-habituated. We further assessed the contents of different hormones in these two calli kinds. The IAA content was indeed significantly increased by about 7 times in habituated calli compared to non-habituated, initially grown in plant hormone-free medium. In parallel to the increase in the endogenous auxin, IAA-AA conjugates, abscisic acid (ABA), ethylene and GA12, GA19, GA29 were decreased in the habituated calli. Our results indicate that the regeneration of endogenous auxin is essential and required for the habituation of callus cells. The changes in the endogenous hormones might be coordinated and monitored during the habituation process by various biological pathways. Eventually, this study debates the interrelated changes and adjustment in endogenous plant hormones occurred (happened) in the habituated calli. This report exhibits also a completely different hormonal composition status for each rice calli, which might potentially be responsible for the calli growth regulation and its acclimation process.

中文翻译：

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水稻愈伤组织适应 2,4-D 游离培养基后活性内源 IAA 的再生

在不含生长素的培养基上生长的习惯性水稻愈伤组织是从先前在补充有 2,4-D 的培养基上培养的水稻胚来源愈伤组织中分离出来的。习惯的水稻愈伤组织比非习惯的愈伤组织生长得更快，尤其是在第一周。我们进行了微阵列分析，以揭示在无激素培养基上生长的水稻愈伤组织转录组水平的变化。与激素代谢和信号传导相关的几个基因在两种愈伤组织类型之间差异表达。特别是，两种酰胺基转移酶基因 Gretchen Hagen 3s（GH3.1 和 GH3.8）的表达下调，一种吲哚-3-乙酸（IAA）-氨基酸（IAA-AA）水解酶基因 ILR1-与非习惯性愈伤组织相比，like 3 在习惯性愈伤组织中上调。我们进一步评估了这两种愈伤组织中不同激素的含量。与最初在无植物激素培养基中生长的非习惯性愈伤组织相比，习惯性愈伤组织的 IAA 含量确实显着增加了约 7 倍。与内源性生长素增加的同时，IAA-AA 结合物、脱落酸 (ABA)、乙烯和 GA12、GA19、GA29 在习惯愈伤组织中减少。我们的结果表明，内源性生长素的再生对于愈伤组织细胞的适应是必不可少的和必需的。内源性激素的变化可能在适应过程中通过各种生物途径进行协调和监测。最终，这项研究讨论了习惯性愈伤组织中发生（发生）的内源植物激素的相关变化和调整。该报告还展示了每种水稻愈伤组织完全不同的激素成分状态，