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InBrief · 21 Jan 2020

Rooting from Leaf Explants – What Happens Within the First Two Hours Matters

Many plants can regenerate a new, complete plant from a cut twig or a detached leaf. But its underlying mechanism related to wound signaling remained elusive until a recent report appeared in Nature Plants (doi: 10.1038/s41477-019-0408-x). By studying the rooting from leaf explants, leaf taken from the plant and grown in an artificial medium, scientists from the CAS Center for Excellence in Molecular Plant Sciences/Shanghai Institute of Plant Physiology and Ecology (SIPPE) illustrated that a serial of molecular events happening within the first 2 h are critical for the plant regeneration and rooting.

When a leaf is cut from Arabidopsis thaliana (a small flowering mustard plant), a fresh wound will be formed. At the same time, a plant hormone jasmonate (JA) surges during the first 10 minutes within the detached leaf, and peaks at around the 30th min, drops afterwards and disappears at around 4 h. This pulse of JA production sort of mimics an up-and-down wave. During the surging part of the JA wave, the increasing JA level promotes the production of auxin, another plant hormone that helps with plant growth and rooting. However, too much JA could reverse the effect to the opposite and inhibit plant growth and rooting. After 2 h, the JA wave slacks and the decreasing of JA allows a continuous accumulation of auxin afterwards, which finally acts to promote rooting from the detached leaf. This newly-identified signaling pathway shall help scientists find new angles to improve many widely-used plant regeneration techniques, such as grafting, cuttage and tissue cultures.
(By YAN Fusheng)