铬(Cr)的过度积累会严重损害生理和生化过程,从而抑制植物的生长。植物中的六价铬[Cr(VI)]引起的变化已在生理或分子水平上得到广泛阐明,而对三价铬[Cr(III)]知之甚少。这里,我们发现Cr(III)和Cr(VI)均显着抑制水稻植株的根系生长。然而,Cr(VI)下的水稻植株对根系生长的抑制作用明显小于Cr(III)下的水稻植株,这可能归因于Cr(III)和Cr(VI)对水稻的不同效应。出乎意料的是,与Cr(VI)类似,Cr(III)可以被水稻根部主动吸收;而它们表现出不同的动力学吸收模式。此外,Cr(VI)下的根至茎Cr易位远低于Cr(III)。这些结果表明,摄取,易位,Cr(III)的毒性与Cr(VI)的毒性有很大差异。水稻根的转录组分析揭示了一系列参与解毒的基因家族,包括ATP结合盒(ABC)转运蛋白,多药和有毒复合挤压蛋白(MATE),和Tau类谷胱甘肽S-转移酶(GSTU),与水稻根中Cr的积累和解毒密切相关。此外,与Cr(III)相比,Cr(VI)上调了这些基因家族的更多成员,表明它们在Cr吸收中的重要作用,易位,和排毒,特别是在Cr(VI)应力下。gstu9和gstu10/50突变体与野生型的进一步比较证实,GSTU在Cr(III)或Cr(VI)胁迫期间在细胞内Cr转运和氧化还原稳态中起着复杂的作用。一起来看,我们的发现为Cr(III)和Cr(VI)在水稻根中的差异行为提供了新的见解,以及新的候选基因,如OsABCs和OsGSTU,为了进一步阐明摄取的机制,易位,和Cr(III)和Cr(VI)的解毒。
Excessive accumulation of chromium (Cr) causes severe damage to both physiological and biochemical processes and consequently growth repression in plants. Hexavalent chromium [Cr(VI)]-elicited alterations in plants have been widely elucidated at either physiological or molecular level, whereas little is known about trivalent chromium [Cr(III)]. Here, we found that both Cr(III) and Cr(VI) significantly inhibited root growth in rice plants. However, rice plants under Cr(VI) showed significantly less inhibition in root growth than those under Cr(III) at low levels, which might be attributed to the different hormetic effects of Cr(III) and Cr(VI) on rice plants. It was unexpected that Cr(III) could be actively taken up by rice roots similarly to Cr(VI); whereas they exhibited different kinetic uptake patterns. Furthermore, root-to-shoot Cr translocation under Cr(VI) was much lower than that under Cr(III). These results indicate that the uptake, translocation, and toxicity of Cr(III) differed greatly from those of Cr(VI). Transcriptome profiling of rice roots revealed that a series of gene families involved in detoxification, including ATP-binding cassette (ABC) transporters, multidrug and toxic compound extrusion proteins (MATEs), and Tau class glutathione S-transferases (GSTUs), were significantly associated with Cr accumulation and detoxification in rice roots. In addition, much more members of these gene families were upregulated by Cr(VI) compared to Cr(III), suggesting their vital roles in Cr uptake, translocation, and detoxification, especially under Cr(VI) stress. Further comparison of gstu9 and gstu10/50 mutants with their wild type confirmed that GSTUs play complex roles in the intracellular Cr transport and redox homeostasis during Cr(III) or Cr(VI) stress. Taken together, our findings provides new insights into the differential behaviors of Cr(III) and Cr(VI) in rice roots, as well as new candidate genes such as OsABCs and OsGSTUs, to further elucidate the mechanisms of the uptake, translocation, and detoxification of Cr(III) and Cr(VI).