Gene-Specific Effects of Three Cry Transgenes on Rhizosphere Microbiota in Catalpa bungei
Xiaofeng Mao1,#, Fenni Lv1,2,#, Shaofeng Li3, Lulu Gao1,2, Wenjun Ma4, Donglai Liu1, Binpeng Wu1, Yanan Wu1, Peng Wang1,2,*, Naiwei Li1,*
1
Jiangsu Key Laboratory for Conservation and Utilization of Plant Resources, Institute of Botany, Jiangsu Province & Chinese Academy of Sciences, Nanjing, China
2
Jiangsu Engineering Research Center for Landscape Plant Resources and Germplasm Innovation, Nanjing, China
3
State Key Laboratory of Tree Genetics and Breeding, Experimental Center of Forestry in North China, National Permanent Scientific Research Base for Warm Temperate Zone Forestry of Jiulong Mountain in Beijing, Chinese Academy of Forestry, Beijing, China
4
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
* Corresponding Author: Peng Wang. Email: 
; Naiwei Li. Email: 
# These authors contributed equally to this work
Phyton-International Journal of Experimental Botany https://doi.org/10.32604/phyton.2026.072636
Received 31 August 2025; Accepted 05 January 2026; Published online 14 January 2026
Abstract
Catalpa bungei, a fast-growing timber tree, is threatened by the lepidopteran pest
Omphisa plagialis. Previous studies in our laboratory successfully generated transgenic
C. bungei lines overexpressing
Cry genes (
Cry1Ab,
Cry2A, and
Cry9-2) that exhibited resistance to
O. plagialis, but their potential impact on soil bacterial communities remains unclear. In this study, we analyzed nine transgenic
C. bungei lines (three independent lines for each
Cry gene) to characterize their rhizosphere bacterial communities using high-throughput sequencing of the 16S ribosomal DNA (rDNA) V4–V5 regions. A total of 628 amplicon sequence variants (ASVs) were shared among all transgenic and wild-type (WT) lines, forming a stable core microbiome dominated by Proteobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota. Alpha diversity showed no significant differences, while beta diversity revealed minor but distinct compositional shifts.
Cry1Ab lines exhibited higher abundances of fast-growing taxa, particularly Proteobacteria and Bacteroidota;
Cry2A lines displayed intermediate profiles, whereas
Cry9-2 lines were nearly indistinguishable from WT communities. Linear discriminant analysis of the effect size revealed significant enrichment of taxa such as Burkholderiaceae and
Ralstonia in the
Cry1Ab rhizosphere, in contrast to the higher abundance of Chloroflexi in the WT. Functional predictions indicated consistent metabolic pathways across all treatments, suggesting strong ecological redundancy. This study demonstrates minimal impact on rhizosphere microbial communities in transgenic
C. bungei plants. The
Cry9-2 construct exhibited superior environmental stability, whereas the
Cry1Ab construct caused only slight but ecologically acceptable shifts. These findings support the ecological safety of
Bt-transgenic
C. bungei and identify
Cry9-2 as a particularly favorable candidate for forestry applications. This comparative evaluation of three
Cry genes in a tree species provides a framework for future gene-specific biosafety assessments in woody plants.
Keywords
Catalpa bungei;
Cry genes; rhizosphere microbiome; 16S rDNA sequencing; environmental biosafety
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