Jasmonic Acid Enhances Al-Induced Root Growth Inhibition

Abstract

Phytohormones such as ethylene and auxin are involved in the regulation of the aluminum (Al)-induced root growth inhibition. Although jasmonate (JA) has been reported to play a crucial role in the regulation of root growth and development in response to environmental stresses through interplay with ethylene and auxin, its role in the regulation of root growth response to Al stress is not yet known. In an attempt to elucidate the role of JA, we found that exogenous application of JA enhanced the Al-induced root growth inhibition. Furthermore, phenotype analysis with mutants defective in either JA biosynthesis or signaling suggests that JA is involved in the regulation of Al-induced root growth inhibition. The expression of the JA receptor CORONATINE INSENSITIVE1 (COI1) and the key JA signaling regulator MYC2 was up-regulated in response to Al stress in the root tips. This process together with COI1-mediated Al-induced root growth inhibition under Al stress was controlled by ethylene but not auxin. Transcriptomic analysis revealed that many responsive genes under Al stress were regulated by JA signaling. The differential responsive of microtubule organization-related genes between the wild-type and coi1-2 mutant is consistent with the changed depolymerization of cortical microtubules in coi1 under Al stress. In addition, ALMT-mediated malate exudation and thus Al exclusion from roots in response to Al stress was also regulated by COI1-mediated JA signaling. Together, this study suggests that root growth inhibition is regulated by COI1-mediated JA signaling independent from auxin signaling and provides novel insights into the phytohormone-mediated root growth inhibition in response to Al stress.

Arabidopsis RING E3 ubiquitin ligase JUL1 participates in ABA‐mediated microtubule depolymerization, stomatal closure, and tolerance response to drought stress

“…This finding was somewhat unexpected because the functional relationship between jasmonate defense signaling and microtubule dynamics is largely unknown (Kazan and Manners, 2008). However, it was observed that aluminum stress-induced cortical microtubule depolymerization in the root apex was delayed in coi1, a mutant of jasmonate receptor CORONATINE INSENSITIVE1 (COI1), compared to that in wild-type roots, suggesting that aluminum-induced depolymerization of cortical microtubules in the root apex is mediated by jasmonate signaling (Yang et al, 2017). Our subsequent phenotypic analyses revealed that the jul1 guard cells failed to respond to ABA, H 2 O 2 , and CaCl 2 , all of which are critical regulators of stomatal closure (Figure 4).…”

Putrescine alleviates aluminum toxicity in rice (Oryza sativa) by reducing cell wall Al contents in an ethylene‐dependent manner

“…Al toxicity limits crop productivity in acidic soils worldwide. A variety of signaling components are involved in plant responses to Al toxicity, such as nitric oxide (Zhang et al ), hydrogen sulfide (Zhu et al ) and jasmonic acid (Yang et al ). In this study, the content of the signaling molecule PUT in rice roots significantly increased under Al toxicity conditions (Fig.…”

Expression patterns and promoter analyses of aluminum-responsive NAC genes suggest a possible growth regulation of rice mediated by aluminum, hormones and NAC transcription factors

“…To date, no cis -acting elements have been reported in the promoter regions of Al-regulated NAC genes. Al generates complex metabolic responses [36,37], where phytohormones like auxin [38], ethylene [38,39], and jasmonic acid [40] intervene. Together, these signaling molecules may mediate stimulation or inhibition of root growth and development, depending on whether Al is found in beneficial or toxic concentrations, respectively.…”