DoSPR1-2 links cortical microtubule remodeling with drought responses in tropical tree

Transiently elevated expression of the gene DoSPR1-2 reduced drought tolerance in seedlings of the tropical tree Dalbergia odorifera, according to a study combining transcript analysis, stress phenotyping and cellular imaging. Plants with elevated expression wilted more strongly under water deficit and showed higher DAB and NBT staining, malondialdehyde content, peroxidase activity and electrolyte leakage. The experiments also placed the encoded protein at cortical microtubules, supporting DoSPR1-2 as a candidate component linking cytoskeletal organization with drought-related cellular responses.

The researchers used transcriptome profiling to identify DoSPR1-2 as a drought-responsive gene in the SPR1 family, which encodes a plant-specific microtubule-associated protein. Its transcript abundance decreased in leaves but increased at several measured time points in roots, revealing an organ-dependent expression response to water shortage. The researchers then examined the consequences of transiently elevating its expression in D. odorifera seedlings. Because drought severely restricts the establishment and growth of tropical woody plants, the work focused on a possible cellular mechanism through which such plants reorganize their cytoskeleton during drought stress.

Elevated-expression seedlings displayed more pronounced wilting than comparison plants under drought conditions. They also produced stronger DAB and NBT staining and had higher malondialdehyde content, peroxidase activity and electrolyte leakage than the comparison group. These measurements, taken together, indicated greater oxidative stress and cellular injury in the elevated-expression plants. The study did not establish that DoSPR1-2 directly regulates each of these biochemical or physiological outcomes; instead, the changes were associated with the experimental increase in its expression.

Cellular localization experiments supplied additional evidence for a connection between DoSPR1-2 and microtubule remodeling. When DoSPR1-2 was fused to green fluorescent protein and expressed in pavement cells of Nicotiana benthamiana, the fusion protein preferentially localized to an oryzalin-sensitive cortical microtubule network. It colocalized with MBD-mCherry, a microtubule marker, but not with an actin marker. In representative images, cells coexpressing DoSPR1-2 retained more continuous cortical microtubule arrays during water-deficit treatments than comparison cells, offering a visual link between the protein and drought-associated organization of cortical microtubules.

The findings identify DoSPR1-2 as a potential molecular bridge between cortical microtubule remodeling and drought-responsive processes in D. odorifera. Its changing transcript abundance, the stress-related phenotypes associated with elevated expression, and its localization in the heterologous Nicotiana system collectively support further investigation of its role in cytoskeletal reorganization. The scope of the evidence remains limited: the drought phenotype followed transient elevation of gene expression, localization was assessed in a different plant species, and the continuity of microtubule arrays was described from representative images. The study therefore does not demonstrate that changes in DoSPR1-2 abundance are necessary or sufficient for improved drought tolerance in D. odorifera, but it provides a candidate pathway for connecting drought-responsive cellular processes with microtubule dynamics.

Subject of Research: Drought-associated DoSPR1-2 expression and cortical microtubule organization in Dalbergia odorifera seedlings

Article Title: DoSPR1-2 links cortical microtubule remodeling with drought-stress responses in Dalbergia odorifera

Article References: Zhang, Z., Sui, Q., Zhang, Y., Gu, G., Zuo, Q., Zhao, Y., & Lian, N. (2026). DoSPR1-2 links cortical microtubule remodeling with drought-stress responses in Dalbergia odorifera. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10154-z

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10154-z

Keywords: DoSPR1-2, Dalbergia odorifera, drought stress, cortical microtubules, SPIRAL1 proteins, plant cytoskeleton, gene expression, tropical trees, oxidative stress, water deficit, links, cortical