Gravity-shaped plant architecture to enhance dense planting, lodging resistance and substance uptake and their applications in maize and other crop breeding.

BACKGROUND: Gravity is a ubiquitous environmental force that shapes plant architecture. Shoots occupy aerial space to absorb light and carbon dioxide, while roots spread in soil to capture water and nutrients. To ensure plants obtain survival resources, gravity not only promotes vertical growth and thus resists lodging, but also enables plants to stretch horizontally with a certain lateral organ angle and thus affects their high-density planting tolerance. Meanwhile, a large root angle often enhances plant lodging resistance. Further, roots with flexible angles and depth can cope with complex soil conditions and ensure substance uptake. To date, a growing number of gravitropic genes have been identified in crops. However, most studies have focused on individual genes within specific regulation pathways, leading to a fragmented understanding of gravitropic regulation mechanisms. Therefore, a systematic summary of recent progress in this field is needed.

AIM OF REVIEW: This review provides systematic insights into gravity-shaped plant architecture, which is critical to molecular breeding of maize and other crops to enhance dense planting, lodging resistance, and substance uptake.

KEY SCIENTIFIC CONCEPTS OF REVIEW: In this review, we systematically organized the molecular mechanisms of gravity signaling in plants and highlighted advances over the past few decades. Next, we analyzed gravitropic genes in crops that control agronomic traits to enhance crop dense planting, lodging resistance, and substance uptake, such as rice tiller angle, maize leaf angle, root growth angle and depth, and uptake of water, nutrients, and ions, and then predicted potential 69 gravitropic genes simultaneously related to these breeding traits in maize through homology alignment and expressing tissue analysis. Furthermore, the significance of gravitropic genes in maize and other crop breeding is explored. Finally, we discussed the importance of molecular gravitropism and outlined future research strategies on its breeding applications.