Plant growth promotion by the interaction of a novel synthetic small molecule with GA‐DELLA function

Abstract

Synthesized small molecules are useful as tools to investigate hormonal signaling involved in plant growth and development. They are also important as agrochemicals to promote beneficial properties of crops in the field. We describe here the synthesis and mode of action of a novel growth‐promoting chemical, A1. A1 stimulates enhanced growth in both shoot and root tissues of plants, acting by increasing both dry and fresh weight. This suggests that A1 not only promotes uptake of water but also increases production of cellular material. A1 treatment of Arabidopsis leads to the degradation of DELLA growth‐inhibitory proteins suggesting that A1‐mediated growth promotion is dependent upon this mechanism. We performed genetic analysis to confirm this and further dissect the mechanism of A1 action upon growth in Arabidopsis . A quintuple della mutant was insensitive to A1, confirming that the mode of action was indeed via a DELLA‐dependent mechanism. The ga1‐5 gibberellin synthesis mutant was similarly insensitive, suggesting that to promote growth in Arabidopsis A1 requires the presence of endogenous gibberellins. This was further suggested by the observation that double mutants of GID1 gibberellin receptor genes were insensitive to A1. Taken together, our data suggest that A1 acts to enhance sensitivity to endogenous gibberellins thus leading to observed enhanced growth via DELLA degradation. A1 and related compounds will be useful to identify novel signaling components involved in plant growth and development, and as agrochemicals suitable for a wide range of crop species.

A comparative analysis of small RNA sequencing data in tubers of purple potato and its red mutant reveals small RNA regulation in anthocyanin biosynthesis

“…The target gene of miR171b-3p, PGSC0003DMG400012683 , encoded DELLA protein. DELLA proteins are important repressors of GA signaling ( Chai et al, 2022 ; Sukiran et al, 2022 ). Plant hormones are involved in anthocyanin biosynthesis, such as auxin ( Ji et al, 2015 ; Liu, Shi & Xie, 2014 ), abscisic acid (ABA) ( Balint & Reynolds, 2013 ; Leão et al, 2014 ) and gibberellic acid (GA) ( Loreti et al, 2008 ).…”

Plants and Small Molecules: An Up-and-Coming Synergy

“…A similar experiment with the GA biosynthetic mutant ga1-5, which has low levels of GA and consequently is a dwarf and displays a shorter hypocotyl than the wild type [41,42], clearly revealed that A1 treatment was not able to rescue the hypocotyl elongation phenotype, thus pointing out that A1 requires both GA and DELLA for its growth-promoting effect. Surprisingly, the addition of the A1 compound could not rescue the hypocotyl phenotype of the GA receptors' gid double mutants, suggesting that this small compound acts upstream of the GA receptors [38]. Therefore, although this work presents an interesting compound able to increase plant growth, there is still a need to investigate the MoA (mode of action) of the A1 small molecule to make it a remarkable agrochemical candidate.…”

“…Unveiling the mechanism of action of EH-1 will lead to insights into the action of ethylene and the ethylene-mediated triple response, while it could become a promising compound to improve the fruit yield of crop species. [32], A1 [38], LS [56], EH-1 [65], Phe-Ade [48], PPBo, NPA, TIBA and Kyn [54].…”

“…The research interest on GAs has been continuously increasing since the so-called "green revolution" due to their growth-promoting action, which is particularly relevant in agriculture to enhance crop yields. By means of a chemical approach, a naphthalene sulfonamide compound named A1 (Figure 3) has recently been identified for its growth-promoting activity [38]. This small molecule is a non-chlorinated analogue of the naphthalene sulfonamide compounds W5 (N-(6-aminohexyl)-1-naphthalenesulfonamide) and W7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide), previously identified as calmodulin inhibitors [39] and used in plants as growth-promoting chemicals.…”

“…Although W7 differs only in the chlorine C-5 substituent in respect to W5, thus displaying a high degree of structural similarity, these compounds showed different efficacy in terms of Ca 2+ response, with W5 being significantly less effective than W7 [39]. Therefore, more recently, different analogues of W5 and W7 were synthesized and tested in plants [38]. In contrast to all the new calmodulin inhibitors, the A1 small molecule was able to promote root growth instead of inhibiting it.…”