About This Project

The carbon cycle is disrupted by human activities, leading to global warming. The Harnessing Plants Initiative is focused on engineering Salk Ideal crops designed to capture and store atmospheric carbon in the soil for long periods through larger, deeper root systems. Early conceptual data suggests that targeting ethylene hormonal responses in a cell-specific manner could be key to achieving this goal. The grant focuses on developing the necessary technical tools for this approach.

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Motivating Factor

Human activity has significantly disrupted the carbon cycle, accelerating global warming. The State of Carbon Dioxide Removal report [1] estimates that 7–9 Gt CO2 removal will be required each year to achieve the climate targets of the 2015 Paris Agreement (limit global warming to 2°C by 2050). The 2023 UN Emissions Gap Report highlights insufficient emission reductions [2]. As a result, global temperatures could rise by 2.5-2.9°C. Current carbon drawdown solutions, such as afforestation, Bioenergy with Carbon Capture and Storage [3], and direct air capture [4], face challenges related to land use, cost, ecological risks, and scalability, making them insufficient for large-scale implementation. More efficient, cost-effective, and sustainable solutions, like engineered crops enhanced with deeper roots to capture and store carbon in soil, are needed to meet urgent climate targets. They represent a sustainable, self-generating technology capable of global implementation. [5, 6, 7]

Specific Bottleneck

Targeting hormonal responses is a powerful way to modify root system architecture. Hormones regulate root growth by controlling cell division, elongation, and differentiation. By adjusting hormone pathways, we can promote deeper, bigger root systems or modify lateral root angles to enhance soil penetration and resource acquisition. Ethylene, a key plant hormone, has been shown to play a role in both root elongation and lateral root angle [8, 9, 10], allowing precise control over root architecture. However, ethylene’s pleiotropic effects—such as its involvement in fruit ripening, biotic and abiotic stress responses, and senescence [11]—pose risks, as altering one trait may inadvertently affect others. For example, reducing ethylene responses can enhance root growth but may also accelerate leaf senescence or decrease stress tolerance, requiring careful regulation of ethylene levels [12].

Actionable Goals

To address this challenge, we propose to focus on tissue-specific modulation of ethylene responses, in root cells, in different important crops. The goal is to achieve cell-specific expression of ethylene response-regulating factors, such as ethylene receptors or downstream signaling components, that target root growth without impacting other plant tissues and physiological responses. This can be achieved through engineered promoter sequences that suppress ethylene signaling exclusively in the root system. Such an approach would allow for precise control over root elongation, lateral roots angle, and soil penetration, optimizing carbon sequestration without triggering unwanted side effects like accelerated leaf senescence or altered stress responses. Ultimately, tissue-specific modulation of ethylene will provide a scalable method to enhance root architecture of main crops for improved carbon storage while maintaining overall plant health and performance.