Enhanced thylakoid photoprotection can increase yield and canopy radiation use efficiency in rice

Abstract

High sunlight can raise plant growth rates but can potentially cause cellular damage. The likelihood of deleterious effects is lowered by a sophisticated set of photoprotective mechanisms, one of the most important being the controlled dissipation of energy from chlorophyll within photosystem II (PSII) measured as non-photochemical quenching (NPQ). Although ubiquitous, the role of NPQ in plant productivity remains uncertain because it momentarily reduces the quantum efficiency of photosynthesis. Here we used plants overexpressing the gene encoding a central regulator of NPQ, the protein PsbS, within a major crop species (rice) to assess the effect of photoprotection at the whole canopy scale. We accounted for canopy light interception, to our knowledge for the first time in this context. We show that in comparison to wild-type plants, psbS overexpressors increased canopy radiation use efficiency and grain yield in fluctuating light, demonstrating that photoprotective mechanisms should be altered to improve rice crop productivity.

Dynamic non‐photochemical quenching in plants: from molecular mechanism to productivity

“…In this article we will focus on the role of NPQ in fast growing annual plants such as cereal crops. NPQ may enhance productivity by limiting damage (photoinhibition) (Hubbart et al , ) but also reduce plant yields by its overly‐protective persistence, lowering quantum yield in low light unnecessarily (Kromdijk et al , ). Such trade‐offs have been discussed previously across wide ecological scales and diverse organisms (Horton, ; Demmig‐Adams and Adams, ; Goss and Lepetit, ; Murchie and Harbinson, ) and create a complex picture that we attempt to address here.…”

“…Such kinetic properties of NPQ appear to have both a genetic and an environmental influence. Acclimation during growth under fluctuating light, as opposed to static light conditions induces a more rapid engagement of NPQ and in some cases a higher capacity (Demmig‐Adams et al , ; Hubbart et al , ) but not others (Vialet‐Chabrand et al , ). It is clear from genetic alterations in amounts and activities of key players, such as PsbS content and xanthophyll cycle enzymes, that genetic variation exists, as can be seen by comparing contrasting species (Demmig‐Adams et al , ).…”

“…Cultivation under static light indicated that growth was normal or suboptimal in overexpressors and the high NPQ hampered light induction of photosynthesis in conditions where RuBisCO and stomatal activity were less limiting. However, when stands of these plants were grown to full canopy stage in an agronomy style glasshouse, mimicking variable field conditions, there was a higher biomass and higher radiation use efficiency (biomass per unit radiation intercepted) in the over expressors (Hubbart et al , ; Hubbart et al , ). Growth under artificially variable light generated a similar response.…”

“…In part-agreement extensive photoinhibition was shown to occur in rice leaves with high NPQ levels even in optimal tropical conditions (Murchie et al, 1999). Furthermore, higher biomass and yields and lower photoinhibition were noted in rice over expressing PsbS in greenhouse conditions (Hubbart et al, 2018). The second route by which NPQ might impact productivity is the persistence of NPQ caused by zeaxanthin retention.…”

Uncovering candidate genes involved in photosynthetic capacity using unexplored genetic variation in Spring Wheat

“…To avoid oxidative stress and photoinhibition, photoprotective mechanisms can be activated in response to high irradiance 58 . There is evidence that photoinhibition has a large impact on biomass production in crops exposed to high light levels 59 and photoprotective mechanisms can increase yield and canopy RUE in rice 60 . Previous studies identified photoprotective genes associated with RUE 22 indicating that protection of photosynthetic machinery has an impact in wheat.…”