Anatomical Characteristics and Variation Mechanisms on the Thick-Walled and Dwarfed Culm of Shidu Bamboo (Phyllostachys nidularia f. farcta)

Abstract

Stable culm variants are valuable and important material for the study of culm development in bamboo plants. However, to date, there are few reports on the mechanism of variation of these bamboo variants. Phyllostachys nidularia f. farcta (Shidu bamboo) is a bamboo variant with stable phenotypes such as a dwarf culm with a thickened wall. In this study, we systematically investigated the cytological characteristics and underlying mechanism of morphological variation in culms of this variant using anatomical, mathematical statistical, physiological, and genomic methods. The anatomical observation and statistical results showed that the lateral increase of ground tissue in the inner layer of culm wall and the enlargement of vascular bundles are the anatomical essence of the wall thickening of Shidu bamboo; the limited elongation of fiber cells and the decrease in the number of parenchyma cells longitudinally are probably the main causes of the shortening of its internodes. A number of genes involved in the gibberellin synthesis pathway and in the synthesis of cell wall components are differentially expressed between the variant and its prototype, Ph. nidularia, and may play an important role in determining the phenotype of internode shortening in Shidu bamboo. The decrease in gibberellin content and the content of the major chemical components of the cell wall of Shidu bamboo confirmed the results of the above transcriptome. In addition, the variation in culm morphology in Shidu bamboo had little effect on the volume of the culm wall of individual internodes, suggesting that the decrease in the total number of internodes and the decrease in dry matter content (lignin, cellulose, etc.) may be the main factor for the sharp decline in culm biomass of Shidu bamboo.

Culm Morphological Analysis in Moso Bamboo Reveals the Negative Regulation of Internode Diameter and Thickness by Monthly Precipitation

“…Moso bamboo is widely distributed and extensively utilized in the bamboo industry [ 52 ], but its adaptability varies across different regions of China [ 47 , 53 ]. Therefore, investigating culm morphological variations among different Moso bamboo populations provides valuable genetic insights and identifies adaptations to diverse environmental conditions [ 46 ]. Despite being capable of sexual reproduction, Moso bamboo predominantly spreads through asexual reproduction [ 51 ].…”

“…This phenomenon is attributed to a reduction in both cell number and cell length within the internode [ 45 ]. In addition, the reduced culm diameter, shortened internode length, and diminished total number of internodes significantly decreased fresh weight, contributing to the reduced biomass and morphological development of the bamboo culm [ 46 ]. The mechanical properties of Moso bamboo culms are also significantly influenced by various environmental factors, including Moso bamboo populations, growth characteristics, and the growth environment [ 47 ].…”

Identification and Characterization of PRE Genes in Moso Bamboo (Phyllostachys edulis)

“…OsbHLH073 encodes an atypical bHLH protein and regulates plant height, internode elongation, and panicle extension by regulating GA biosynthesis genes [ 40 ]. The content of GAs in dwarf bamboo varieties is also lower than that in normal bamboos, implying that GA plays a major role in the height of Shidu bamboo [ 41 ]. Exogenous application of GA resulted in a significant increase in internode length in bamboo seedlings [ 42 ].…”