Interplay between cytochrome c and gibberellins during Arabidopsis vegetative development

Abstract

We studied the effect of reducing the levels of the mitochondrial electron carrier cytochrome c (CYTc) in Arabidopsis thaliana. Plants with CYTc deficiency have delayed growth and development, and reach flowering several days later than the wild-type but with the same number of leaves. CYTc-deficient plants accumulate starch and glucose during the day, and contain lower levels of active gibberellins (GA) and higher levels of DELLA proteins, involved in GA signaling. GA treatment abolishes the developmental delay and reduces glucose accumulation in CYTc-deficient plants, which also show a lower raise in ATP levels in response to glucose. Treatment of wild-type plants with inhibitors of mitochondrial energy production limits plant growth and increases the levels of DELLA proteins, thus mimicking the effects of CYTc deficiency. In addition, an increase in the amount of CYTc decreases DELLA protein levels and expedites growth, and this depends on active GA synthesis. We conclude that CYTc levels impinge on the activity of the GA pathway, most likely through changes in mitochondrial energy production. In this way, hormone-dependent growth would be coupled to the activity of components of the mitochondrial respiratory chain.

Increased Gibberellins and Light Levels Promotes Cell Wall Thickness and Enhance Lignin Deposition in Xylem Fibers

“…In the lignin biosynthetic pathway, a profuse metabolic flexibility and refined gene regulation is observed, as well as a complex interaction between these processes and the environment ( Zhong and Ye, 2009 ; Zhao and Dixon, 2011 ). Linking data from other reports ( Kurepin et al, 2007 ; Dayan et al, 2010 ; Kurepin and Pharis, 2014 ; Fukuda et al, 2016 ) with the present study, it is possible to speculate that, DELLA levels should be low at increased levels of GAs, as in plants grown in low-irradiance environments, since they are subject to degradation promoted by GAs ( Ueguchi-Tanaka et al, 2007 ; Yamaguchi, 2008 ; Dixit, 2013 ; Racca et al, 2018 ), allowing PIF3 and PIF4 to be free to bind to their target genes. Shaded environments, although they lead to increased levels of endogenous GAs ( Kurepin et al, 2006 ), appear to show poor interaction with PIFs, providing greater accumulation of DELLA proteins and inhibition of important enzymes, like PAL ( Roberts et al, 2008 ; Locascio et al, 2013 ).…”

Unraveling the Initial Plant Hormone Signaling, Metabolic Mechanisms and Plant Defense Triggering the Endomycorrhizal Symbiosis Behavior

“…GA biosynthesis and signaling is coupled with active COX pathway and both are key components to promote plant growth. Arabidopsis CYTc deficient mutant plant contains less bioactive GA, less ATP but elevated DELLA protein levels and similar observation was noticed when mitochondrial (COX pathway) inhibitors is applied in wild type (Racca et al, 2018). GA can upregulate cytochrome C gene expression involved in the COX pathway (Yang and Komatsu, 2004) and GA biosynthesis inhibitor mimicks the effect of CYTc deficiency (Racca et al, 2018).…”

Arabidopsis thaliana SURFEIT1‐like genes link mitochondrial function to early plant development and hormonal growth responses

“…There are several examples that changes in mitochondrial function influence hormonal pathways related to growth (Berkowitz et al, 2016;Wang and Auwerx, 2017;Racca et al, 2018). Treatment of plants with inhibitors of the mitochondrial respiratory chain increases AOX expression and ROS production and decreases auxin signaling (Ivanova et al, 2014;Kerchev et al, 2014).…”