Larsen P B, Tai C Y, Kochian L V, Howell S H
Boyce Thompson Institute, Cornell University, Ithaca, New York 14853, USA.
Plant Physiol. 1996 Mar;110(3):743-51. doi: 10.1104/pp.110.3.743.
Al-sensitive (als) mutants of Arabidopsis were isolated and characterized with the aim of defining mechanisms of Al toxicity and resistance. Most als mutants selected on the basis of root growth sensitivity to Al were recessive, and together the mutants constituted eight complementation groups. Also, in most als mutants, Al sensitivity appeared to be specific for Al relative to La (another trivalent cation), except als2, which was more sensitive to La than wild type. The tendency of roots on mutant seedlings to accumulate Al was examined by staining with morin and hematoxylin, dyes used to indicate the presence of Al. A significant increase in morin staining was observed in als5, consistent with its increased sensitivity to Al. Unexpectedly, als7 and als4 showed less morin staining, suggesting that the roots on these mutants accumulate less Al than wild type seedlings after exposure to Al-containing solutions. Roots of wild-type seedlings produce callose in response to AlCl3 concentrations that inhibit root growth. Only als5 accumulated more callose than wild type in response to low levels (25 mu M) of AICI3 However, als4 and als7 did not accumulate callose at this AlCl3 concentration even though root growth was significantly inhibited. The lack of callose accumulation in als4 and als7 suggests that there is not an obligatory relationship between callose deposition and Al-induced inhibition of root growth.
为了确定铝毒性和抗性机制，分离并鉴定了拟南芥的铝敏感（als）突变体。基于对铝的根生长敏感性选择的大多数als突变体是隐性的，这些突变体共同构成了八个互补群。此外，在大多数als突变体中，相对于镧（另一种三价阳离子），铝敏感性似乎对铝具有特异性，但als2除外，它对镧比野生型更敏感。通过用桑色素和苏木精染色来检测突变体幼苗根积累铝的趋势，这两种染料用于指示铝的存在。在als5中观察到桑色素染色显著增加，这与其对铝敏感性增加一致。出乎意料的是，als7和als4显示出较少的桑色素染色，这表明在暴露于含铝溶液后，这些突变体的根积累的铝比野生型幼苗少。野生型幼苗的根会响应抑制根生长的氯化铝浓度产生胼胝质。仅als5在低水平（25μM）的氯化铝作用下比野生型积累更多的胼胝质。然而，在这个氯化铝浓度下，即使根生长受到显著抑制，als4和als7也不积累胼胝质。als4和als7中胼胝质积累的缺乏表明胼胝质沉积与铝诱导的根生长抑制之间不存在必然联系。
