Effect of lipo-chitooligosaccharide on early growth of C4 grass seedlings.

Kiwamu Tanaka,Dong Xu,An Q Pham,Shiqi Cui,Zhanyuan J Zhang,Hyeyoung Lee,Saad M Khan,Trupti Joshi,Gary Stacey,Josef M Batek,Jing Qiu,Sung-Hwan Cho

doi:10.1093/jxb/erv260

Abstract

Although lipo-chitooligosaccharides (LCOs) are important signal molecules for plant-symbiont interactions, a number of reports suggest that LCOs can directly impact plant growth and development, separate from any role in plant symbioses. In order to investigate this more closely, maize and Setaria seedlings were treated with LCO and their growth was evaluated. The data indicate that LCO treatment significantly enhanced root growth. RNA-seq transcriptomic analysis of LCO-treated maize roots identified a number of genes whose expression was significantly affected by the treatment. Among these genes, some LCO-up-regulated genes are likely involved in root growth promotion. Interestingly, some stress-related genes were down-regulated after LCO treatment, which might indicate reallocation of resources from defense responses to plant growth. The promoter activity of several LCO-up-regulated genes using a β-glucuronidase reporter system was further analysed. The results showed that the promoters were activated by LCO treatment. The data indicate that LCO can directly impact maize root growth and gene expression.

Highlights

Plants interact with various beneficial, symbiotic microorganisms such as rhizobial bacteria and mycorrhizal fungi, which provide plants with nutrients
It was previously reported that LCO treatment of legumes, such as Medicago truncatula, can affect root growth and branching (Maillet et al, 2011; Olah et al, 2005; Sun et al, 2015)
LCO-induced root growth promotion was observed in the C3, non-legume plant, rice, which was significantly attenuated in a dmi3 mutant (Sun et al, 2015)

Summary

Introduction

Plants interact with various beneficial, symbiotic microorganisms such as rhizobial bacteria and mycorrhizal fungi, which provide plants with nutrients. LCOs secreted by symbiotic bacteria, rhizobia, are essential for the establishment of the nitrogen-fixing symbiosis between rhizobia and roots of legume plants (Oldroyd and Downie, 2008). Since this symbiosis results in the formation of root nodules, these LCOs are commonly referred to as Nod factors. LCOs were identified as the Myc factors produced by arbuscular mycorrhizal fungi, which colonize the roots of most plants to improve plant nutrition and water uptake (Maillet et al, 2011).

Methods

Results

Conclusion