Effects of continuous subculture on the growth and endogenous hormones of Brachythecium plumosum

The cultivation and restoration of rock moss crusts is a potential new measure for ecological restoration in the Qinling mining area. However, the insufficient supply of moss seed sources has become a significant bottleneck in practical application. Exploring the generational changes in the growth, endogenous hormone indicators, and colonization ability of Brachythecium plumosum through successive subcultures using limited natural mosses can provide theoretical support for the large-scale subculture and expansion of seed sources, which is of great significance for the industrialization of moss crust ecological restoration.

The dominant species Brachythecium plumosum from rock-dwelling biocrusts was subjected to three successive subculture cycles (30 days per generation) under controlled laboratory conditions. Intergenerational differences in coverage, new branch length, branch number, and six endogenous hormones (including IAA and ABA) were analyzed, with their correlations examined.

1) Successive subcultures induced significant variations in endogenous hormone profiles across generations, potentially explaining observed growth index disparities; 2) Endogenous hormones exhibited varying correlations with growth indices: IAA showed positive correlations with growth parameters, whereas ABA displayed negative correlations, with these relationships depending on developmental stages; 3) After three consecutive subcultures, the indoor-cultivated Brachythecium plumosum still maintained a high propagation efficiency. After 32 days of outdoor colonization, there were no significant differences in growth indicators among different subculture generations.

The endogenous hormone contents of indoor-cultivated Brachythecium plumosum showed obvious generational differences, and the correlations with growth indicators varied with the growth and development stages of Brachythecium plumosum. These factors might jointly cause the generational differences in growth indicators. The growth indicators of Brachythecium plumosum could still maintain a high level at the end of cultivation after successive subcultures, and there were no generational differences in outdoor colonization ability, indicating that subculture expansion can be used to continuously obtain Brachythecium plumosum seed sources.