Agriculture

This common weed can offer drought-resistant crops

Scientists integrated two metabolic pathways to produce a novel type of photosynthesis that enables the weed to withstand drought while remaining highly productive.

 
By Arya Rohini
Published: Monday 08 August 2022
Purslane possesses the evolutionary adaptations that allow it to be both highly productive and drought tolerant. Photo: iStock
Purslane possesses the evolutionary adaptations that allow it to be both highly productive and drought tolerant. Photo: iStock Purslane possesses the evolutionary adaptations that allow it to be both highly productive and drought tolerant. Photo: iStock

A common weed — Portulaca oleracea, commonly known as purslane, offers important clues about creating drought-tolerant crops in a world beset by climate change, noted a new study.

Purslane has the evolutionary adaptations that help it to be both highly productive and drought tolerant, an unlikely combination for a plant, said the findings of the study published August 5, 2022, in the journal Science Advances.

Yale University scientists integrated two metabolic pathways to produce a novel type of photosynthesis that enables the weed to withstand drought while remaining highly ‘productive’.

“This is a very rare combination of traits and has created a kind of ‘super plant’ — one that could be potentially useful in endeavours such as crop engineering,” said Erika Edwards, Yale professor of ecology and evolutionary biology and senior author of the study.

Plants have independently evolved various mechanisms to improve photosynthesis, the process by which green plants use sunlight to synthesise nutrients from carbon dioxide and water. 

For instance, corn and sugarcane evolved C4 photosynthesis, which allows the plant to remain productive under high temperatures. 

Succulents such as cacti and agaves possess another type called CAM photosynthesis, which helps them survive in deserts and other areas with little water.

Both C4 and CAM serve different functions but recruit the same biochemical pathway to act as ‘add-ons’ to regular photosynthesis, noted in the study.

The study, led by co-corresponding authors and postdoctoral scholars Jose Moreno-Villena and Haoran Zhou, conducted a spatial analysis of gene expression within the leaves of purslane and found that C4 and CAM activity is totally integrated. 

They operate in the same cells, with products of CAM reactions being processed by the C4 pathway. This system provides unusual levels of protection for a C4 plant in times of drought.

Understanding this novel metabolic pathway could help scientists devise new ways to engineer crops such as corn to help withstand prolonged drought, the authors noted.

“In terms of engineering a CAM cycle into a C4 crop, such as maize, there is still a lot of work to do before that could become a reality,” added Edwards.

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