Silicon nutrition increases grain yield, which, in turn, exerts a feed‐forward stimulation of photosynthetic rates via enhanced mesophyll conductance and alters primary metabolism in rice

Abstract

SummarySilicon (Si) is not considered to be an essential element for higher plants and is believed to have no effect on primary metabolism in unstressed plants. In rice (Oryza sativa), Si nutrition improves grain production; however, no attempt has been made to elucidate the physiological mechanisms underlying such responses.Here, we assessed crop yield and combined advanced gas exchange analysis with carbon isotope labelling and metabolic profiling to measure the effects of Si nutrition on rice photosynthesis, together with the associated metabolic changes, by comparing wild-type rice with the low-Si rice mutant lsi1 under unstressed conditions.Si improved the harvest index, paralleling an increase in nitrogen use efficiency. Higher crop yields associated with Si nutrition exerted a feed-forward effect on photosynthesis which was fundamentally associated with increased mesophyll conductance. By contrast, Si nutrition did not affect photosynthetic gas exchange during the vegetative growth phase or in de-grained plants. In addition, Si nutrition altered primary metabolism by stimulating amino acid remobilization.Our results indicate a stimulation of the source capacity, coupled with increased sink demand, in Si-treated plants; therefore, we identify Si nutrition as an important target in attempts to improve the agronomic yield of rice.

Metabolic alterations triggered by silicon nutrition: Is there a signaling role for silicon?

“…Keywords: silicon (Si), signaling, metabolite profile, amino acid remobilization between Si concentration and the levels of compounds intimately associated with respiration (isocitrate and 2-oxoglutarate), and a handful of amino acids (alanine, arginine, glutamine, ornithine, isoleucine, methionine and valine). 12 When taken together, we clearly demonstrated that, at least under the conditions explored in our study, Si nutrition plays an important role in modulating the rate of flux from 2-oxoglutarate into amino acid metabolism, supporting the emergent view that amino acid metabolism is a tightly and intricately controlled network. 13,14 Accordingly, an increased incorporation of amino acids in storage proteins could be anticipated.…”

“…11 We have recently demonstrated that Si nutrition impacts the source-sink relationship and stimulates amino acid remobilization in rice. 12 We demonstrated that Si-treated plants have reduced levels of several amino acids, a fact linked with an augmentation of the sink strength which was clearly mediated by Si nutrition with little, if any, impact on growth per se. 12 Although Si did not affect the actual rate of 14 C incorporation into amino acids (Table 1), our data support a role for Si nutrition in orchestrating amino acid remobilization.…”

“…12 We demonstrated that Si-treated plants have reduced levels of several amino acids, a fact linked with an augmentation of the sink strength which was clearly mediated by Si nutrition with little, if any, impact on growth per se. 12 Although Si did not affect the actual rate of 14 C incorporation into amino acids (Table 1), our data support a role for Si nutrition in orchestrating amino acid remobilization. We observed a strong correlation Although the beneficial role of silicon (Si) in stimulating the growth and development of many plants is generally accepted, our knowledge concerning the physiological and molecular mechanisms underlying this response remains far from comprehensive.…”

“…Our recent results 12 suggest that Si-mediated metabolic alterations are a complex phenomenon that is clearly worthy of more detailed analysis at both molecular and biochemical levels.…”

Growth and Production of rice (oryza sativa l.) under different fertilization plans with Silicon

“…Silicon is attributed with many beneficial effects for the cultivation of rice, as it increases the tolerance of plants to the abiotic stress caused by drought and biotic stress and reduces the incidence of diseases such as Pyricularia (Mauad, Costa, Cruscial, Grassi-Filho and Corrêa, 2013), because this nutrient reinforces the cell wall (Epstein, 1999) and, thereby, increases the mass and grain production (Detmann et al, 2012), also it helps to maintain high amounts of dry biomass (Tamai and Ma, 2008).…”