Mitochondria are widely known as the “powerhouses” of the cell, generating the energy needed for life. But in plants, their role goes far beyond metabolism. Communication between the nucleus and mitochondria is essential for coordinating growth, development, and stress responses. One notable model for studying this interaction is cytoplasmic male sterility (CMS), which is regulated by a class of nuclear genes called restorer-of-fertility-like (RFL) genes. While RFLs have been primarily linked to reproductive development, mounting evidence suggests they may be involved in broader biological processes. Due to these gaps in knowledge, there is growing interest in uncovering whether RFL genes also influence woody tissue development, such as wood formation in trees.
Scientists from Southwest University in China have uncovered a surprising function for a gene long associated with fertility restoration. Their study (DOI: 10.1093/hr/uhae188), published on July 15, 2024, in Horticulture Research, shows that PtoRFL30, a nuclear gene encoding a mitochondrial-targeted protein, acts as a key regulator of wood formation in poplar. By altering mitochondrial activity and reshaping auxin hormone levels, PtoRFL30 influences the vascular cambium—the stem’s growth engine. This groundbreaking research highlights how energy signals from within the cell’s powerhouse help orchestrate the construction of wood.
The researchers first identified 32 RFL genes in poplar, focusing on PtoRFL30 due to its strong expression in the vascular cambium. Genetic manipulation experiments revealed that overexpression of PtoRFL30 reduced plant height, stem diameter, and xylem development, while RNA interference had the opposite effect, boosting wood formation.
Microscopy and GUS staining confirmed PtoRFL30’s localization in stem cambial zones. Subcellular imaging showed that the protein resides in mitochondria. Functional analysis revealed that PtoRFL30 impacts ATP production and reactive oxygen species (ROS) levels, key indicators of mitochondrial health.
Importantly, the study linked mitochondrial changes to hormone regulation. PtoRFL30 modulated the expression of auxin biosynthesis and transport genes, leading to corresponding shifts in auxin accumulation. When auxin levels were artificially restored or suppressed using NAA and NPA, the wood growth phenotypes in transgenic plants were reversed—confirming auxin’s central role. Furthermore, treating plants with mitochondrial inhibitors mimicked the effects of PtoRFL30 overexpression, solidifying the protein’s role in mitochondrial homeostasis. This dual regulation of energy and hormone pathways presents a new model of how tree wood forms at the molecular level.
“Our work reveals an entirely new function for a gene family previously tied only to fertility,” said Prof. Keming Luo, co-corresponding author of the study. “PtoRFL30 is like a conductor managing an orchestra of energy signals and hormone flows to control how wood develops in trees. Understanding this regulatory mechanism not only reshapes our view of plant development but also opens up possibilities for improving wood production by targeting internal signaling pathways. This is a big step in decoding how trees grow from the inside out.”
The discovery of PtoRFL30 as a master regulator of wood formation has broad implications for forestry, bioenergy, and plant biology. With further study, this gene could become a valuable target for genetic engineering aimed at enhancing biomass yield or adapting trees to climate stress. The findings also deepen our understanding of how mitochondria coordinate with hormones to control plant structure, offering clues for improving growth in other woody species. Ultimately, this research paves the way for new strategies in sustainable tree breeding by tapping into the cell’s internal power grid.
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References
DOI
10.1093/hr/uhae188
Original Source URL
https://doi.org/10.1093/hr/uhae188
Funding information
This work was supported by grants from the National Science Foundation of China (31870175, 32201579, 32271906, and 32271826) and the Fundamental Research Funds for the Central Universities (SWU-KQ22066).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.