Overexpression of Terpenoid Biosynthesis Genes From Garden Sage (Salvia officinalis) Modulates Rhizobia Interaction and Nodulation in Soybean.

Long Miao,Vagner A Benedito,Salma Saleh Alrdahe,Jian Zhao,Doaa B Darwish,Qiuqiang Hou,Ahmed Ali,Mohammed Ali,Xiaobo Wang,Million Tadege

doi:10.3389/fpls.2021.783269

Abstract

In legumes, many endogenous and environmental factors affect root nodule formation through several key genes, and the regulation details of the nodulation signaling pathway are yet to be fully understood. This study investigated the potential roles of terpenoids and terpene biosynthesis genes on root nodule formation in Glycine max. We characterized six terpenoid synthesis genes from Salvia officinalis by overexpressing SoTPS6, SoNEOD, SoLINS, SoSABS, SoGPS, and SoCINS in soybean hairy roots and evaluating root growth and nodulation, and the expression of strigolactone (SL) biosynthesis and early nodulation genes. Interestingly, overexpression of some of the terpenoid and terpene genes increased nodule numbers, nodule and root fresh weight, and root length, while others inhibited these phenotypes. These results suggest the potential effects of terpenoids and terpene synthesis genes on soybean root growth and nodulation. This study provides novel insights into epistatic interactions between terpenoids, root development, and nodulation in soybean root biology and open new avenues for soybean research.

Highlights

Soybean nodulation occurs through symbiotic interactions between root cortical cells and the soil bacteria, Bradyrhizobium japonicum, leading to the formation of novel structures called root nodules
The expression patterns of putative terpenoid biosynthesis genes of soybean were uncovered by transcript analysis across nine tissues using the Phytozome database
We identified genetic components of terpenoid biosynthesis in the soybean genome by searching sequences similar to those well characterized in the garden sage (S. officinalis, Lamiaceae) (Supplementary Figure 1), examined their expression patterns across various tissues and organs by using the Phytozome database (Supplementary Figure 2) and inferred the putative sub-cellular localization of sage genes based on Arabidopsis protein localizations using the Cell eFP Browser (Supplementary Figure 3)

Summary

Introduction

Soybean nodulation occurs through symbiotic interactions between root cortical cells and the soil bacteria, Bradyrhizobium japonicum, leading to the formation of novel structures called root nodules. Terpenoids on Soybean Root Growth and Nodulation ammonia, which is available for the plant (Ferguson et al, 2005). Root nodule formation is strictly controlled locally and systemically by several plant hormones and metabolic genes during nodule initiation, nodule development, and active nitrogen fixation. Several genes related to specialized metabolisms in legumes (e.g., terpenoid and phenylpropanoid biosynthesis) were identified by microarray analysis in Lotus japonicus nodules with higher expression levels in the nodule parenchyma and the nodule vascular bundle compared with the infection zone (Takanashi et al, 2012). The knockdown of the gene 3-Hydroxy3-Methylglutaryl Coenzyme-A Reductase (MtHMGR1) in Medicago truncatula led to a dramatic decrease in nodulation, confirming that a key enzyme regulating the Mevalonate (MVA) pathway, MtHMGR1, interacts with DMI2 and is required for nodule development (Kevei et al, 2007; Venkateshwaran et al, 2015). The gene silencing of GmMAX1a and GmMAX4a by RNA interference (RNAi) resulted in a drastic reduction in nodule numbers (Haq et al, 2017; Rehman et al, 2018; Ahmad et al, 2020)

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Conclusion