Dipartimento di AGRARIA, Università Mediterranea di Reggio Calabria, Feo di Vito, I-89124 Reggio Calabria, Italy.
Dipartimento di Biologia, Ecologia e Scienze della Terra (DiBEST), Università della Calabria, 87040 Arcavacata di Rende, CS, Italy.
Plant Physiol Biochem. 2017 Dec;121:14-20. doi: 10.1016/j.plaphy.2017.10.005. Epub 2017 Oct 19.
Farnesene is a sesquiterpene with semiochemical activity involved in interspecies communication. This molecule, known for its phytotoxic potential and its effects on root morphology and anatomy, caused anisotropic growth, bold roots and a "left-handedness" phenotype. These clues suggested an alteration of auxin distribution, and for this reason, the aim of the present study was to evaluate its effects on: i) PIN-FORMED proteins (PIN) distribution, involved in polar auxin transport; ii) PIN genes expression iii) apical meristem anatomy of primary root, in 7 days old Arabidopsis thaliana seedlings treated with farnesene 250 μM. The following GFP constructs: pSCR::SCR-GFP, pDR5::GFP,pPIN1::PIN1-GFP, pPIN2::PIN2-GFP, pPIN3::PIN3-GFP, pPIN4::PIN4-GFP and pPIN7::PIN7-GFP were used to evaluate auxin distribution. Farnesene caused a reduction in meristematic zone size, an advancement in transition zone, suggesting a premature exit of cells from the meristematic zone, a reduction in cell division and an impairment between epidermal and cortex cells. The auxin-responsive reporter pDR5::GFP highlighted that auxin distribution was impaired in farnesene-treated roots, where auxin distribution appeared maximum in the quiescent center and columella initial cells, without extending to mature columella cells. This finding was further confirmed by the analysis on PIN transport proteins distribution, assessed on individual constructs, which showed an extreme alteration mainly dependent on the PIN 3, 4 and 7, involved in pattern specification during root development and auxin redistribution. Finally, farnesene treatment caused a down-regulation of all the auxin transport genes studied. We propose that farnesene affected auxin transport and distribution causing the alteration of root meristem, and consequently the left-handedness phenotype.
法呢烯是一种具有半化学活性的倍半萜烯，参与种间通讯。这种分子以其植物毒性潜力及其对根形态和解剖结构的影响而闻名，导致了各向异性生长、粗壮的根和“左手”表型。这些线索表明生长素分布发生了改变，因此，本研究的目的是评估法呢烯对以下方面的影响：i）参与极性生长素运输的 PIN 形成蛋白（PIN）分布；ii）PIN 基因表达；iii）拟南芥初生根顶端分生组织的解剖结构，在 7 天大的幼苗中用 250 μM 法呢烯处理。使用以下 GFP 构建体：pSCR::SCR-GFP、pDR5::GFP、pPIN1::PIN1-GFP、pPIN2::PIN2-GFP、pPIN3::PIN3-GFP、pPIN4::PIN4-GFP 和 pPIN7::PIN7-GFP 来评估生长素分布。法呢烯导致分生组织区大小减小，过渡区提前，表明细胞过早地从分生组织区退出，细胞分裂减少，表皮细胞和皮层细胞之间受损。生长素应答报告基因 pDR5::GFP 突出表明，法呢烯处理的根中生长素分布受损，在静止中心和中柱初始细胞中生长素分布最大，而不延伸到成熟的中柱细胞。这一发现通过分析单个构建体上的 PIN 运输蛋白分布进一步得到证实，结果表明主要依赖于 PIN3、4 和 7 的极度改变，它们参与了根发育过程中的模式形成和生长素再分布。最后，法呢烯处理导致所有研究的生长素运输基因下调。我们提出，法呢烯影响生长素的运输和分布，导致根分生组织的改变，进而导致左手表型。
