Madmon Ortal, Mazuz Moran, Kumari Puja, Dam Anandamoy, Ion Aurel, Mayzlish-Gati Einav, Belausov Eduard, Wininger Smadar, Abu-Abied Mohamad, McErlean Christopher S P, Bromhead Liam J, Perl-Treves Rafael, Prandi Cristina, Kapulnik Yoram, Koltai Hinanit
Institute of Plant Sciences, Agricultural Research Organization (ARO), The Volcani Center, 50250, Bet Dagan, Israel.
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900, Ramat-Gan, Israel.
Planta. 2016 Jun;243(6):1419-27. doi: 10.1007/s00425-016-2477-7. Epub 2016 Feb 26.
MAX2/strigolactone signaling in the endodermis and/or quiescent center of the root is partially sufficient to exert changes in F-actin density and cellular trafficking in the root epidermis, and alter gene expression during plant response to low Pi conditions. Strigolactones (SLs) are a new group of plant hormones that regulate different developmental processes in the plant via MAX2, an F-box protein that interacts with their receptor. SLs and MAX2 are necessary for the marked increase in root-hair (RH) density in seedlings under conditions of phosphate (Pi) deprivation. This marked elevation was associated with an active reduction in actin-filament density and endosomal movement in root epidermal cells. Also, expression of MAX2 under the SCARECROW (SCR) promoter was sufficient to confer SL sensitivity in roots, suggesting that SL signaling pathways act through a root-specific, yet non-cell-autonomous regulatory mode of action. Here we show evidence for a non-cell autonomous signaling of SL/MAX2, originating from the root endodermis, and necessary for seedling response to conditions of Pi deprivation. SCR-derived expression of MAX2 in max2-1 mutant background promoted the root low Pi response, whereas supplementation of the synthetic SL GR24 to these SCR:MAX2 expressing lines further enhanced this response. Moreover, the SCR:MAX2 expression led to changes in actin density and endosome movement in epidermal cells and in TIR1 and PHO2 gene expression. These results demonstrate that MAX2 signaling in the endodermis and/or quiescent center is partially sufficient to exert changes in F-actin density and cellular trafficking in the epidermis, and alter gene expression under low Pi conditions.
MAX2/独脚金内酯信号在根的内皮层和/或静止中心部分足以引起根表皮中F-肌动蛋白密度和细胞运输的变化，并在植物对低磷条件的响应过程中改变基因表达。独脚金内酯（SLs）是一类新的植物激素，它们通过与受体相互作用的F-box蛋白MAX2来调节植物的不同发育过程。在磷酸盐（Pi）缺乏的条件下，SLs和MAX2对于幼苗根毛（RH）密度的显著增加是必需的。这种显著升高与根表皮细胞中肌动蛋白丝密度的积极降低和内体运动有关。此外，在稻草人（SCR）启动子控制下MAX2的表达足以使根具有SL敏感性，这表明SL信号通路通过一种根特异性但非细胞自主的调节作用模式起作用。在这里，我们展示了SL/MAX2的非细胞自主信号的证据，该信号源自根内皮层，并且是幼苗对Pi缺乏条件响应所必需的。在max2-1突变体背景下，SCR驱动的MAX2表达促进了根对低磷的响应，而向这些表达SCR:MAX2的株系补充合成SL GR24进一步增强了这种响应。此外，SCR:MAX2的表达导致表皮细胞中肌动蛋白密度和内体运动以及TIR1和PHO2基因表达的变化。这些结果表明，内皮层和/或静止中心中的MAX2信号部分足以引起表皮中F-肌动蛋白密度和细胞运输的变化，并在低磷条件下改变基因表达。
