Insight Into the Multiple Branches Traits of a Mutant in Larix olgensis by Morphological, Cytological, and Transcriptional Analyses.

Kewei Cai,Yonghong Cui,Guangyan Li,Xueyan Zhou,Xiyang Zhao,Ye Kang,Xiaona Pei,Xiaoming Yang,Xiang Li

doi:10.3389/fpls.2021.787661

Kewei Cai, Yonghong Cui + Show 7 more

Open Access

https://doi.org/10.3389/fpls.2021.787661

Copy DOI

Abstract

Larix olgensis is a tall deciduous tree species that has many applications in the wood fiber industry. Bud mutations are somatic mutations in plants and are considered an ideal material to identify and describe the molecular mechanism of plant mutation. However, the molecular regulatory mechanisms of bud mutations in L. olgensis remain unknown. In this study, dwarfed (or stunted), short-leaved, and multi-branched mutants of L. olgensis were found and utilized to identify crucial genes and regulatory networks controlling the multiple branch structure of L. olgensis. The physiological data showed that the branch number, bud number, fresh and dry weight, tracheid length, tracheid length-width ratio, inner tracheid diameter, and epidermal cell area of mutant plants were higher than that of wild-type plants. Hormone concentration measurements found that auxin, gibberellin, and abscisic acid in the mutant leaves were higher than that in wild-type plants. Moreover, the transcriptome sequencing of all samples using the Illumina Hiseq sequencing platform. Transcriptome analysis identified, respectively, 632, 157, and 199 differentially expressed genes (DEGs) in buds, leaves, and stems between mutant plants and wild type. DEGs were found to be involved in cell division and differentiation, shoot apical meristem activity, plant hormone biosynthesis, and sugar metabolism. Furthermore, bZIP, WRKY, and AP2/ERF family transcription factors play a role in bud formation. This study provides new insights into the molecular mechanisms of L. olgensis bud and branch formation and establishes a fundamental understanding of the breeding of new varieties in L. olgensis.

Highlights

Somatic mutations are mutations that occur in an organism’s cell other than in a gamete, germ cell, or gametocyte (Jung et al, 2015)
“transcription factors,” “signal transduction,” and “biosynthesis of other secondary metabolites” were enriched (Figure 4E and Supplementary Table 11). These results suggested that there are many changes in genes involved in plant hormone signal transduction, metabolic pathways, and signaling and cellular processes, which may play an important role in bud mutation
We found that the L. olgensis mutant plants had the following traits: dwarf, short leaves, and multiple branches, which is significantly different from the wild-type plant

Summary

Introduction

Somatic mutations are mutations that occur in an organism’s cell other than in a gamete, germ cell, or gametocyte (Jung et al, 2015). Apart from the artificial mutations induced in model plants, naturally occurring mutations are widely found in most species. Somatic mutations, which are not usually transmitted to the offspring, are different from germline mutations, which can be passed on to the descendants of an organism (Liu et al, 2021). This distinction may be blurred in plants, which lack a dedicated germline, and can propagate asexually through grafting, cutting, and other mechanisms (Foster and Aranzana, 2018)

Methods

Results

Conclusion