Comparative Transcriptome Analysis Provides New Insights into the Molecular Regulatory Mechanism of Adventitious Root Formation in Ramie (Boehmeria nivea L.).

Kunmei Chen,Gang Gao,Bing Guo,Chunming Yu,Xiaofei Wang,Jikang Chen,Ping Chen,Aiguo Zhu

doi:10.3390/plants10010160

Kunmei Chen, Gang Gao + Show 6 more

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https://doi.org/10.3390/plants10010160

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Abstract

The occurrence of adventitious roots is necessary for the survival of cuttings. In this study, comparative transcriptome analysis between two ramie (Boehmeria nivea L.) varieties with different adventitious root (AR) patterns was performed by mRNA-Seq before rooting (control, CK) and 10 days water-induced adventitious rooting (treatment, T) to reveal the regulatory mechanism of rooting. Characterization of the two ramie cultivars, Zhongzhu No 2 (Z2) and Huazhu No 4 (H4), indicated that Z2 had a high adventitious rooting rate but H4 had a low rooting rate. Twelve cDNA libraries of the two varieties were constructed, and a total of 26,723 genes were expressed. In the non-water culture condition, the number of the distinctive genes in H4 was 2.7 times of that in Z2, while in the water culture condition, the number of the distinctive genes in Z2 was nearly 2 times of that in H4. A total of 4411 and 5195 differentially expressed genes (DEGs) were identified in the comparison of H4CK vs. H4T and Z2CK vs. Z2T, respectively. After the water culture, more DEGs were upregulated in Z2, but more DEGs were downregulated in H4. Gene ontology (GO) functional analysis of the DEGs indicated that the polysaccharide metabolic process, carbohydrate metabolic process, cellular carbohydrate metabolic process, cell wall macromolecule metabolic process, and photosystem GO terms were distinctively significantly enriched in H4. Simultaneously, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that photosynthesis, photosynthesis antenna proteins, and starch and sucrose metabolism pathways were distinctively significantly enriched in H4. Moreover, KEGG analysis showed that jasmonic acid (JA) could interact with ethylene to regulate the occurrence and number of AR in Z2. This study reveals the transcriptomic divergence of two ramie varieties with high and low adventitious rooting rates, and provides insights into the molecular regulatory mechanism of AR formation in ramie.

Highlights

The rooting ability of clones is the key factor to determine the success of the propagation of cuttings, and it is the main criterion for distinguishing the adaptability and resistance of clones
This study reports the transcriptomic analysis of two ramie varieties Zhongzhu No2 (Z2) and Huazhu No4 (H4) with a distinct rooting rate to uncover the molecular mechanisms regulating adventitious rooting in ramie cuttings
Five days after the water culture, white root primordia of Zhongzhu No 2 (Z2) and Huazhu No 4 (H4) emerged from the stem epidermis section in the water, and more root primordia were observed on Z2 than that on H4

Summary

Introduction

The rooting ability of clones is the key factor to determine the success of the propagation of cuttings, and it is the main criterion for distinguishing the adaptability and resistance of clones. Adventitious root (AR) is the root of cuttage plants which is an important organ for water and inorganic salt absorption and assimilate storage, and plays an important role in stress resistance [1,2]. The occurrence of AR enlarges the root system of plants and enables plants and cells to regenerate. When plants suffer from hypoxia or other stress, AR can significantly improve the survival ability of plants [3]. In-depth understanding of the mechanism of AR is helpful to improve the survival rate of cuttings and the survival ability of plants under stress

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