The Role of Gibberellins in Revolutionizing Agriculture – Understanding the Science Behind High-Yield Crops

　　Since the 20th century, the rapid development of science and technology has greatly improved the level of medical and health care, greatly reduced the population mortality rate, and caused rapid growth in the population. At the beginning of the 20th century, the world’s total population was only 1.6 billion; at the end of the 20th century, the world’s total population soared to 6 billion; by the end of 2022, the world’s total population has reached 8 billion. The explosive growth of population, frequent occurrence of extreme weather, and geopolitical conflicts have become the main reasons for the intensification of the global food crisis. How to improve crops, cultivate new varieties, and increase grain yields have been the focus and direction of efforts of many crop researchers.
The “Green Revolution” and the Nobel Peace Prize

　　Norman Ernest Blaug, a famous American agricultural scientist, plant breeder, and plant pathologist, has long been engaged in research on wheat variety improvement. Borlaug’s successful improvement of wheat varieties increased Mexico’s wheat production in 1963 by six times that of 1944, making Mexico a wheat exporting country (95% of the wheat it exported was Borlaug). cultivated by the style). From 1964 to 1979, Borlaug served as director of the International Corn and Wheat Improvement Center. In 1965, Borlaug began to promote the dwarf wheat he cultivated in Pakistan and India, which increased wheat production in these two countries at an annual rate of 70%, effectively controlling the spread of famine in the two countries.
　　In 1968, the United States Agency for International Development (USAID) called the phenomenon of food growth in the Indian subcontinent the “Green Revolution” in its annual report. This concept refers to the process of breeding high-yielding varieties and improving agricultural technology initiated by Borlaug. A series of agricultural innovations, and Borlaug himself is known as the “Father of the Green Revolution.” In 1970, Borlaug won the Nobel Peace Prize. In 1986, Borlaug founded the World Food Prize Foundation; on June 7, 1996, Borlaug became a foreign academician of the Chinese Academy of Engineering.
　　The “Green Revolution” reversed the situation of famine in many parts of the world in the mid-20th century, helping at least 1 billion people escape the threat of hunger. At least 19 developing countries have successfully achieved self-sufficiency in food amid high population growth, saving hundreds of millions of lives. Thousands of lives.
　　Borlaug developed many stocky varieties of wheat that were only three-quarters the height of ordinary wheat. What’s the benefit? First, dwarf varieties are less prone to lodging. People often say that “big trees attract the wind”. If a plant grows thin and tall, it will be easily broken or fallen from the roots or stems in wind and rain, while dwarf varieties are not easy to fall under the influence of external forces. Secondly, dwarf varieties are beneficial to increase yields. Just as a person’s energy is limited, so is the energy of plants. If most of the energy is used to grow, there will be no more energy to produce fruit, and the yield will naturally decrease. In addition to wheat dwarf varieties, breeders have also selected high-yielding rice dwarf varieties. These varieties not only have the characteristics of lodging resistance and high yield, but also have the advantages of easy management and easy straw handling, making them excellent varieties in agricultural production.

“Gigantism” and “bakanae disease”

　　For the human body, if the adenohypophysis secretes too much growth hormone, it will cause hypertrophy of soft tissues, bones and internal organs and endocrine and metabolic disorders. When the disease occurs before puberty and the epiphysis is not closed, it is called “giantism”; when the disease occurs after puberty and the epiphysis is closed, it is called “acromegaly”. Children suffering from “giantism” will show excessive growth and development in the early stages. The height can exceed 2 meters at around the age of 10. They often have strong muscles, amazing arm strength, and early development of sexual organs; when the disease progresses to the decline stage (lasting four to five years) At this time, they will experience symptoms such as lack of energy, weakness in limbs, muscle relaxation, hair loss, and metabolic slowdown. Many patients with “giantism” do not live long and often die in their twenties or thirties.
　　Rice also has a disease similar to human “giantism”, which is called “bakanae disease”. Rice infected with “bakanae disease” will grow wildly and the stalks will grow very high, but the rice harvest will be reduced by more than 70%, and the rice quality is not good. Unlike human gigantism, rice “Bakanae disease” is also contagious and can be spread among rice plants. Therefore, “bakanae disease” is a very serious crop disease. Once it breaks out, large areas of fertile farmland will almost lose their harvest.
Discovery and research of gibberellins

　　At first, people did not know what caused rice to suffer from “bakanae disease”. It was not until 1898 that Japanese scientists confirmed that “bakanae disease” was caused by a fungal infection; it took several decades for scientific researchers to discover This fungus is Gibberella sp. After they inoculated normal-growing rice with Gibberella, they found that the rice would grow stems and leaves wildly, showing symptoms similar to “bakanae disease”; even if the active Gibberella was removed and the rice was treated with only culture fluid that had been cultured, the rice would still develop Similar symptoms occur. This shows that active Gibberella secretes certain substances in the culture solution, and these substances have the function of promoting plant elongation. Later, people called a class of compounds produced by Gibberella that can promote the growth of seedlings called gibberellin (GA).
　　High-yielding varieties all have one characteristic in common – short stature. Why are they so much shorter than normal plants? This is actually related to gibberellins. Gibberellin in plants is like a commander, which conveys instructions to plants for high growth through signal transduction. In dwarf varieties, either the gibberellin is not signaling normally, or the “communicator” is not signaling properly. In this way, plants that have not received instructions will not consume too much nutrients to grow taller, but can save most of the nutrients to bear fruit, thus becoming a high-yielding variety. This is also the reason why Blaug improved dwarf varieties such as wheat and corn.

Rice lodging in large areas

　　Gibberellins are a class of plant hormones belonging to the diterpenoids. In the life cycle of higher plants, erythroxin plays an important regulatory role. It is involved in seed germination, hypocotyl and stem elongation, leaf extension, epidermal trichome development, flowering time, floral organ development, and fruit ripening. Process control. More than 100 erythritoxins with clear structures have been identified from different species, and they are named GA1-GA136 according to the chronological order of discovery. However, studies have found that only a few types of gibberellins can regulate plant growth, such as GA1, GA3, GA4, GA7, etc.
　　The “Green Revolution” of the 20th century played an important role in agricultural production, especially in high-yield breeding. The dwarf crops used were caused by mutations in gibberellin synthesis or response. The dwarf stem characteristics caused by gibberellin abnormalities allow crops to reduce nutrient allocation to stem elongation and increase nutrient allocation to seed growth, thereby increasing yield. At the same time, the dwarf stalk characteristics also make the crops easier to cultivate and manage, reducing losses caused by crop lodging.
　　Crops cannot normally obey the orders of gibberellin, which creates high-yielding varieties; high-yielding varieties also ensure sufficient food so that people can have enough to eat. The little gibberellin has such a great contribution, its existence should not be underestimated!