Screening for favorable crop properties using photosynthetic light

An international effort called Achieving Increased Photosynthetic Efficiency (RIPE) aims to transform crops ’ability to convert sunlight and carbon dioxide into higher yields. To achieve this, scientists are analyzing thousands of plants to find out what adjustments to the structure of the plant or its cellular machines could increase production. Researchers at the University of Illinois have discovered a new approach to assessing the photosynthetic capacity of crops to determine these traits with the best performance and speed up the verification process, according to a new study in Journal of Experimental Botany.

“Photosynthesis is the entry point for carbon dioxide to become everything that allows plants to grow, but measuring canopy photosynthesis is really difficult,” said Carl Bernacchi, a plant physiologist at the U.S. Department of Agriculture’s Illinois-based Department of Agriculture. , Carl R. Woese Institute of Genomic Biology. “Most methods take a lot of time and measure only one leaf when in agriculture the function of all the leaves on all the plants is really important.”

Bernacchi’s team uses two spectral instruments simultaneously – a hyperspectral camera to scan crops and a spectrometer used to record very detailed information about sunlight – to quickly measure a signal called Solar Induced Fluorescence (SIF) that plants emit when they become ‘energy’ -excited during photosynthesis.

With this SIF signal, the team gains critical insight into photosynthesis that could ultimately lead to improved crop yields.

They found that a key portion of the SIF signal correlated better with photosynthetic capacity. This ‘SIF yield’ makes up only a fraction of the energy that plants emit as SIF to the energy that plants capture in total, but it contains important information.

“With this insight, we can use several instruments in a synergistic way for more accurate assessments and we can make these tools and pipelines more accessible to people interested in advancing photosynthesis translation,” said Peng Fu, a postdoctoral researcher who led this work in Illinois.

In this study, they selected certain ranges of light that are known to be associated with SIF (and are already well understood physiologically) to better understand what hyperspectral data are actually needed to make these estimates.

In the past, they relied on expensive hyperspectral cameras that captured thousands of beams of light. “However, this study suggests that much cheaper cameras could be used instead, now that we know which light belts are needed,” said Matthew Siebers, a postdoctoral researcher in Illinois.

These tools could accelerate progress for orders of magnitude, said Katherine Meacham-Hensold, also a postdoctoral researcher in Illinois. “This technology is changing games for researchers purifying photosynthesis as a means to help achieve the yields we will need to feed humanity of this century.”

Reference: Fu P, Meacham-Hensold K, Siebers MH, Bernacchi CJ. Inverse relationship between solar energy-induced fluorescence yield and photosynthetic capacity: used for field phenotyping. J. Exp. Bot. 2020. doi: 10.1093 / jxb / eraa537

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