Chinese scientists uncover solution to crops' midday 'lunch break'

Chinese scientists have identified a mechanism that helps crops withstand intense midday sunlight, a breakthrough that could boost yields and improve resilience to environmental stress.

The findings, published on June 18 in the peer-reviewed journal Cell by researchers from the Institute of Genetics and Developmental Biology under the Chinese Academy of Sciences and their collaborators, address a phenomenon known as crops' midday "lunch break."

The term refers to a period, typically between noon and 2 p.m., when high temperatures and strong sunlight suppress photosynthesis and reduce the accumulation of organic matter.

Strong midday sunlight is a double-edged sword for crops. While abundant light fuels plant growth, it can also trigger a photosynthetic slowdown that researchers estimate may reduce yields by around 30%.

Traditionally, scientists believed that intense light generated singlet oxygen inside chloroplasts, damaging the organelles before triggering defensive responses. In other words, plants were thought to activate protection mechanisms only after damage had already occurred.

The new study found that a protein called MBS1 can directly sense singlet oxygen under intense light and rapidly form condensates around chloroplasts. Acting like sunscreen, these condensates help protect chloroplasts and photosynthesis from damage, providing a fast and targeted defense against excessive light.

The research team conducted four years of field trials in Hainan, Beijing and Heilongjiang. The results showed that increasing MBS1 expression significantly enhanced rice plants' tolerance to intense sunlight, leading to stable or higher yields without affecting normal growth and development.

According to Kuang Tingyun, an academician of the Chinese Academy of Sciences, the discovery could be combined with molecular breeding and precision regulation techniques and applied to a wide range of crops.

"The principle can be applied not only to rice but also to wheat and many other plants. Its agricultural potential is enormous and could have a major impact," Kuang said.

He added that overcoming crops' midday "lunch break" could significantly increase carbon dioxide fixation by plants, contributing to China's carbon reduction goals.