The role of agrochemistry in providing the world population with plant protein

Global protein deficit and crop production challenges

The problem of food protein shortage in the world is escalating every year, evolving from an economic issue into a social one. About half of the Earth's population suffers from protein deficiency. Since animal-based products are not accessible to everyone, increasing the productivity of crop production remains the key way to solve this problem.

• Global protein deficit — 10–25 million tons per year
• Average consumption per person — 60 g per day (with a norm of 70 g)
• Population with protein deficiency — about 1/2 of the planet’s 6 billion inhabitants

The physiological need for protein in humans depends on age, physical activity, and health status. On average, it is 60–100 g per day, or 12–15% of total caloric intake (with proteins of animal and plant origin accounting for 6–8% of energy each). Daily protein intake requirements for various population groups and different physical conditions are provided in the table.

For an adult, the average daily requirement is 1 g of protein per 1 kg of body weight. Children require more — from 1.05 to 4.00 g per 1 kg of body weight depending on age. For a 30-year-old man, the necessary level of consumption in terms of nitrogen is equal to 9.0–9.2 g per day per 1 kg of body weight.

The highest protein harvest and valuable lysine are provided by grain legumes. In crop rotation, the following crops are most effective for these purposes:

• soybean;
• chickpea;
• lentil;
• pea;
• lupine.

However, legumes are not traditional for all peoples, and soil-climatic conditions often hinder the expansion of their sowing areas. Therefore, an agronomist needs to work on increasing the protein content in all cultivated crops, including cereals and oilseeds.

Managing crop quality through mineral nutrition systems

Mineral nutrition of plants directly affects both the quantity of protein in the harvest and its quality parameters. Under the influence of fertilizers, the amino acid composition and the content of free amino acids change. The need for nutrients varies depending on the growing season, which must be taken into account when planning treatments.

Phosphorus is necessary for plants immediately after seedling emergence. With its low content in the soil, the application of granular superphosphate into rows is required, which accelerates root development. The second peak of demand for phosphorus occurs during the flowering phase and the formation of the commercial harvest, when the element is involved in protein synthesis.

Potassium is absorbed by plants throughout almost the entire growing season, but most intensively before flowering. This element activates key life processes in the plant organism. Timely potassium nutrition has a positive effect on the final protein content in the product.

Wet gluten is a protein mass that remains after washing dough with water. It consists of 2/3 water and 1/3 dry matter, represented mainly by insoluble proteins. Based on quality, gluten is divided into three groups: I (good), II (satisfactory), and III (unsatisfactory).

Depending on the protein content and gluten, common wheat is divided into three main quality groups.

In addition to nitrogen, phosphorus, and potassium, plants require other meso- and microelements to form the protein complex. The crop nutrition system must include silicon, calcium, magnesium, sulfur, iron, as well as micro- and ultra-microelements. Their balanced uptake determines the quality of the future protein.

Traditional breeding and protoplast fusion require too much time and do not always lead to improvements in economically valuable traits. They cannot keep up with the growth of the Earth's population, which will reach 11 billion people by 2050. Genetic engineering methods allow for a quick solution to the plant protein deficit problem. They are based on plant totipotency — the ability of plant cells and protoplasts to develop into a full-fledged organism after the introduction of target genes with specified properties.

Practical Application of Transgenic Technologies in Crop Production

Over the last two decades, genetic engineering has become a crucial tool for improving harvest quality. The transfer of genetic material is performed using two main methods: vector-mediated (using agrobacteria and viruses) or direct DNA transfer.

The entire transformation process proceeds in three sequential stages:

1. Isolation of the target gene from donor DNA.
2. Obtaining recombinant (hybrid) DNA molecules.
3. Introduction of these into the living cells of the modified plant to obtain new traits.

Today, these technologies are most actively applied to soybean, wheat, maize, tomatoes, sugar beet, cotton, and oilseed rape. Modification allows for targeted correction of the amino acid composition of grain. For example, proteins in the endosperm of cereals are poor in lysine, tryptophan, and methionine, while storage proteins of grain legumes are poor in methionine. Introducing additional lysine codons into the genes of storage proteins (prolamins) fully solves this problem.

In experiments, dozens of storage protein genes have already been characterized and cloned:

• barley hordeins;
• wheat gliadins and glutenins;
• maize zeins;
• rice oryzenins.

Transformation of wheat with a modified gene of one of the glutenin subunits activates the synthesis of this protein, which significantly improves the baking properties of the flour. Practical developments have already been implemented in many countries: the area under transgenic soybean, rice, potato, raspberry, and strawberry is growing. In the USA, approximately 3,000 food products are produced using genetically modified soybean — from baby cereals and sauces to soups and canned goods.