Challenges facing sustainable protein production: Opportunities for cereals

Abstract

Rising demands for protein worldwide are likely to drive increases in livestock production, as meat provides ∼40% of dietary protein. This will come at a significant environmental cost, and a shift toward plant-based protein sources would therefore provide major benefits. While legumes provide substantial amounts of plant-based protein, cereals are the major constituents of global foods, with wheat alone accounting for 15-20% of the required dietary protein intake. Improvement of protein content in wheat is limited by phenotyping challenges, lack of genetic potential of modern germplasms, negative yield trade-offs, and environmental costs of nitrogen fertilizers. Presenting wheat as a case study, we discuss how increasing protein content in cereals through a revised breeding strategy combined with robust phenotyping could ensure a sustainable protein supply while minimizing the environmental impact of nitrogen fertilizer.

Keywords: grain protein content; innovative breeding; protein nutrition; sustainability.

Figure 1

Rising trends in global meat consumption. (A) Average meat consumption per capita in 2020. Labels are added for countries with over 100 kg per capita consumption. (B) Changes in meat consumption trends from 1961 to 2020 across different continents and globally. Average global consumption has increased by nearly 20 kg. Figure created with data from Our World in Data (Ritchie et al., 2017).

Figure 2

Climate and pathogenicity risks associated with increased animal farming. (A) Greenhouse gas emissions from meat and dairy are highest, whereas emissions from plant-based foods are more than 10 times lower. (B) Meat products, especially beef and mutton, use at least 100 times more land area per 100 g of protein than cereals. These data further emphasize how livestock production contributes to global warming and land losses. The graphs were produced using data from Poore and Nemecek (Poore and Nemecek, 2018) and Our World in Data (Ritchie and Roser, 2020). (C) Anthropogenic activities such as intensive animal farming, wildlife trade, population growth, and urbanization lead to imbalances in natural habitats because of biodiversity loss, deforestation, and climate change. These factors are interconnected and often overlap. As a result, humans are exposed to wildlife, which can cause the spillover of zoonotic pathogens into human populations and can lead to infectious diseases.

Figure 3

Potential of insects and algae to provide protein in comparison with meat and plants. The diagram shows advantages and disadvantages of each of these sources in the context of potential protein supply. + refers to advantage, – refers to disadvantage, and ± refers to intermediate effect. ∗Figure created with BioRender.com.

Figure 4

Comparison of current breeding pipeline and a proposed new breeding pipeline. The current breeding pipeline follows the conventional breeding method in which thousands of rows are phenotypically screened to select for yield components like grain yield, height, heading, etc. In the later stages, a few selected lines are screened for grain and flour quality characteristics such as GPC; however much of the genetic diversity has been lost by this stage. The new (proposed) breeding pipeline can benefit from high-speed testing technology like hyperspectral imaging to rapidly and non-destructively test GPC in large populations in real time. In addition, advanced genetic tools can rapidly screen large populations for new variations on the basis of associations between phenotypes and genotypes. In this way, quality characteristics like GPC can be targeted much earlier in the breeding process when the germplasm has maximum genetic potential. ∗Figure created with BioRender.com.