Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B3, Ciudad Universitaria, C. P. 58030, Morelia, Michoacán, Mexico.
Molecular and Developmental Complexity Group, Unidad de Genómica Avanzada, Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Campus Irapuato, Guanajuato, Mexico.
Plant Sci. 2019 Mar;280:175-186. doi: 10.1016/j.plantsci.2018.11.019. Epub 2018 Nov 30.
The plant hormone ethylene induces auxin biosynthesis and transport and modulates root growth and branching. However, its function on root stem cells and the identity of interacting factors for the control of meristem activity remains unclear. Genetic analysis for primary root growth in wild-type (WT) Arabidopsis thaliana seedlings and ethylene-related mutants showed that the loss-of-function of CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) inhibits cell division and elongation. This phenotype is associated with an increase in the expression of the auxin transporter PIN2 and a drastic decrease in the expression of key factors for stem cell niche maintenance such as PLETHORA1, SHORT ROOT and SCARECROW. While the root stem cell niche is affected in ctr1 mutants, its maintenance is severely compromised in the ctr1-1eir1-1(pin2) double mutant, in which an evident loss of proliferative capacity of the meristematic cells leads to a fully differentiated root meristem shortly after germination. Root traits affected in ctr1-1 mutants could be restored in ctr1-1ein2-1 double mutants. These results reveal that ethylene perception via CTR1 and EIN2 in the root modulates the proliferative capacity of root stem cells via affecting the expression of genes involved in the two major pathways, AUX-PIN-PLT and SCR-SHR, which are key factors for proper root stem cell niche maintenance.
植物激素乙烯诱导生长素的生物合成和运输，并调节根的生长和分枝。然而，其对根干细胞的功能以及参与调节分生组织活性的相互作用因子的身份仍不清楚。对野生型（WT）拟南芥幼苗和乙烯相关突变体的主根生长的遗传分析表明，组成型三重反应 1（CTR1）的功能丧失抑制细胞分裂和伸长。这种表型与生长素转运蛋白 PIN2 的表达增加以及干细胞龛维持的关键因子如 PLETHORA1、SHORT ROOT 和 SCARECROW 的表达急剧下降有关。虽然 ctr1 突变体中的根干细胞龛受到影响，但在 ctr1-1eir1-1（pin2）双突变体中，其维持受到严重损害，其中分生细胞的增殖能力明显丧失，导致在萌发后不久完全分化的根分生组织。ctr1-1 突变体中受影响的根性状可以在 ctr1-1ein2-1 双突变体中恢复。这些结果表明，根中通过 CTR1 和 EIN2 感知乙烯通过影响参与两个主要途径（AUX-PIN-PLT 和 SCR-SHR）的基因的表达来调节根干细胞的增殖能力，这是正确维持根干细胞龛的关键因素。
