Vartanian N., Marcotte L., Giraudat J.
Institut des Sciences Vegetales, Centre National de la Recherche Scientifique UPR40, 91198 Gif sur Yvette Cedex, France.
Plant Physiol. 1994 Feb;104(2):761-767. doi: 10.1104/pp.104.2.761.
Drought rhizogenesis is an adaptive strategy that occurs during progressive drought stress and is characterized in the Brassicaceae and related families by the formation of short, tuberized, hairless roots. These roots are capable of withstanding a prolonged drought period and give rise to a new functional root system upon rehydration. The kinetics of drought rhizogenesis during progressive water shortage was analyzed in the Arabidopsis thaliana wild-type ecotypes Landsberg erecta and Columbia. In both genotypes, this response started from a similar threshold of soil humidity (about 2%). The intensity of drought rhizogenesis was compared in various A. thaliana hormonal mutants. The wild-type lines and most of the mutants achieved a similiar drought rhizogenetic index (DRI), defined as the maximum number of short roots produced per mg of root biomass, after progressive drought stress. However, this DRI was dramatically reduced in the abscisic acid (ABA)-deficient aba, ABA-insensitive abi1-1, and auxin-resistant axr1-3 mutants. These data indicate that endogenous ABA and auxin play a promotive role in drought rhizogenesis. The DRI was highly increased in the gibberellin (GA) biosynthetic mutant ga5, suggesting that some GAs might also participate in this process. The possible role and identity of the GA species involved is discussed in view of the unaltered DRI values of the ga2, ga3, and ga4 mutants. The present analysis also allowed further discrimination among the various ABA-insensitive (abi1 versus abi2 and abi3) and auxin-resistant (axr1 versus aux1) mutants tested. In particular, drought rhizogenesis is the first physiological response shown to be differentially affected by the abi1-1 and abi2-1 mutations.
干旱诱导生根是一种在渐进性干旱胁迫期间出现的适应性策略，在十字花科及相关科中，其特征是形成短的、块茎状的、无毛的根。这些根能够经受长时间的干旱期，并在复水后产生新的功能根系。在拟南芥野生型生态型Landsberg erecta和Columbia中分析了渐进性缺水期间干旱诱导生根的动力学。在这两种基因型中，这种反应都始于相似的土壤湿度阈值（约2%）。比较了各种拟南芥激素突变体中干旱诱导生根的强度。野生型品系和大多数突变体在渐进性干旱胁迫后达到了相似的干旱诱导生根指数（DRI），定义为每毫克根生物量产生的短根最大数量。然而，在脱落酸（ABA）缺陷型aba、ABA不敏感型abi1-1和生长素抗性型axr1-3突变体中，这种DRI显著降低。这些数据表明内源性ABA和生长素在干旱诱导生根中起促进作用。在赤霉素（GA）生物合成突变体ga5中，DRI高度增加，这表明一些GA也可能参与这一过程。鉴于ga2、ga3和ga4突变体的DRI值未改变讨论了所涉及的GA种类的可能作用和身份。本分析还进一步区分了所测试的各种ABA不敏感（abi1与abi2和abi3）和生长素抗性（axr1与aux1）突变体。特别是，干旱诱导生根是第一个被证明受abi1-1和abi2-1突变差异影响的生理反应。
