Researchers have pinpointed a key gene responsible for the multiovary trait in wheat, a discovery that could help increase grain number and improve crop yields. Adam Schoen, Guilherme V. Yoshikawa, Parva Kumar Sharma and Vijay Tiwari published their research in the paper "WUSCHEL-D1 upregulation enhances grain number by inducing formation of multiovary-producing florets in wheat." The gene, called WUSCHEL-D1 (WUS-D1), is normally dormant in wheat’s D genome but becomes highly active in multiovary wheat lines, leading to the formation of multiple fertile ovaries per floret.
The multiovary trait, known as Mov-1, allows wheat florets to produce up to three grains instead of one, potentially boosting productivity. Scientists generated a detailed genome assembly of a multiovary wheat line and found a unique chromosomal rearrangement that activates WUS-D1. This activation enlarges floral meristems, the plant tissue where flowers develop, enabling the formation of extra pistils.
Genetic mapping narrowed the responsible region to a small segment containing only two genes, with WUS-D1 identified as the causal gene. Expression studies showed WUS-D1 is upregulated up to 34.5-fold in developing inflorescences of multiovary wheat compared to normal wheat. Further experiments using mutants confirmed that loss of WUS-D1 function suppresses the multiovary trait, proving its essential role.
Microscopic analysis revealed that multiovary wheat plants have larger inflorescence and floral meristems, with more cells and greater separation between floral organs. These changes support the development of additional ovaries and grains per floret.
The discovery aligns with similar findings in other crops where WUSCHEL-related genes regulate flower and organ number. Researchers believe the unique genome rearrangement in multiovary wheat alters chromatin structure, enabling WUS-D1’s increased activity.
This breakthrough provides a foundation for gene-editing strategies targeting meristem regulators like WUS-D1 to enhance grain number without compromising grain size. Such advances could help wheat breeders develop higher-yielding varieties, addressing global food security challenges as wheat yields have plateaued in recent decades.
