Mango trees frequently display polyembryony, a trait where seeds generate multiple embryos, one of which is sexually derived while the others are clonal copies of the parent tree. This characteristic is critical for ensuring consistency in agriculture, particularly for rootstock production. Until now, the genetic basis for this phenomenon remained unclear, presenting challenges for breeders who rely on vegetative propagation to maintain uniformity in heterozygous plants. These challenges highlighted the necessity of exploring the genetics behind mango polyembryony to enhance breeding strategies.
The study (DOI: 10.1093/hr/uhad227), led by the Volcani Research Center and an international team, was published on November 8, 2023, in Horticulture Research. Using advanced genetic tools, the researchers pinpointed the reproductive wuschel-related protein (MiRWP) gene as the driver of polyembryony in mango. Their research demonstrates how a promoter insertion in this gene triggers the formation of multiple embryos. Conducted across Israel, the UK, and Australia, the study offers fresh insights into the potential for leveraging this genetic mechanism for asexual plant reproduction.
The research delves into the natural occurrence of polyembryony in both mango and citrus. By analyzing a wide range of mango varieties, the team identified the MiRWP gene as the critical factor behind this trait. The promoter insertion in the MiRWP gene was found to significantly alter gene expression, leading to the development of multiple embryos—either sexually derived or vegetative clones of the mother tree. The gene is also an ortholog to CitRWP, which induces polyembryony in citrus, indicating a case of convergent evolution in these species. The team utilized high-throughput genotyping and next-generation sequencing to fine-map the polyembryony locus on chromosome 7 of the mango genome, revealing genetic differences between polyembryonic and monoembryonic varieties. These results help explain how apomixis—reproduction without fertilization—occurs in mango and citrus.
Dr. Yuval Cohen, the lead researcher, highlighted the potential impact of these findings: “This discovery paves the way for breakthroughs in agricultural biotechnology. Understanding the genetic mechanisms behind polyembryony opens up possibilities for applying this trait to other crops. By enabling clonal reproduction through seeds, we can significantly enhance breeding programs. Moreover, this research underscores the intriguing case of convergent evolution in species like mango and citrus, where similar traits evolved independently.”
The identification of the MiRWP gene presents exciting prospects for agriculture. Manipulating this gene could enable breeders to propagate mango and other fruit trees clonally via seeds, reducing the need for grafting. This could lead to more efficient production of uniform plants, especially for crops where vegetative propagation proves challenging. Furthermore, the insights gained from studying mango polyembryony could extend to other crops, offering new tools to improve agricultural productivity and sustainability.
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References
DOI
10.1093/hr/uhad227
Original Source URL
https://doi.org/10.1093/hr/uhad227
Funding information
The research was supported by Research Grant No. IS-5106-18R from BARD, The United States–Israel Binational Agricultural Research and Development Fund (granted to A.S., D.N.K., Y.C., and R.O.), and by grants No. 203-0859 (granted to A.S. and R.O.) and No. 203-0110 (granted to Y.C.) from the Chief Scientist of the Israeli Ministry of Agriculture. D.N.K. was supported by a grant from the USDA National Institute of Food and Agriculture (USDA-NIFA 2018-51181-28375).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number two 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.