CcNAC6 Acts as a Positive Regulator of Secondary Cell Wall Synthesis in Sudan Grass (Sorghum sudanense S.)

TL;DR

This study identifies CcNAC6 as a key gene involved in secondary cell wall synthesis in Sudan grass, which affects forage digestibility for ruminants.

Contribution

The study reveals CcNAC6 as a novel positive regulator of secondary cell wall synthesis in Sudan grass through its interaction with CcCP1.

Findings

Overexpression of CcNAC6 in Arabidopsis significantly increased lignin content.

CcNAC6 localizes to the nucleus and interacts with CcCP1, a protein linked to secondary cell wall synthesis.

CcNAC6 is proposed as a main regulator of secondary cell wall synthesis in Sudan grass.

Abstract

The degree of forage lignification is a key factor affecting its digestibility by ruminants such as cattle and sheep. Sudan grass (Sorghum sudanense S.) is a high-quality sorghum forage, and its lignocellulose is mostly stored in the secondary cell wall. However, the secondary cell wall synthesis mechanism of Sudan grass has not yet been studied in depth. To further study the secondary cell wall synthesis mechanism of Sudan grass using established transcriptome data, this study found that CcNAC6, a homologous gene of Arabidopsis AtSND2, is related to the secondary cell wall synthesis of Sudan grass. Accordingly, we constructed a CcNAC6-overexpressing line of Arabidopsis to investigate the function of the CcNAC6 gene in secondary cell wall synthesis. The results showed that the overexpression of the CcNAC6 gene could significantly increase the lignin content of Arabidopsis. Based on subcellular localization analysis, CcNAC6 is found in the nucleus. In addition, yeast two-hybridization screening showed that CcCP1, associated with secondary cell wall synthesis, can interact with CcNAC6. Therefore, the above results indicate that CcNAC6 has a positive regulatory effect on the secondary cell wall synthesis of Sudan grass, and it is speculated that CcNAC6 may be the main regulator of the secondary cell wall synthesis of Sudan grass through its interaction with another regulatory protein, CcCP1. This study provides a theoretical basis and new genetic resources for the creation of new Sudan grass germplasm with a low lignin content.

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