The Immortal Achievements of Gibberellin


Since the 20th century, the rapid development of science and technology has greatly improved the level of medical and health care, greatly reduced the mortality rate of the population, and shown rapid growth in the number of people. 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; At the end of 2022, the world's total population had reached 8 billion. Explosive population growth, frequent extreme weather, and geopolitical conflicts have become the main reasons for the exacerbation of the global food crisis. How to improve crops, cultivate new varieties, and increase grain output is the focus and direction of many crop researchers.

Norman Ernest Braug, a famous American agricultural scientist, plant breeder, and plant pathologist, has long been engaged in research on wheat variety improvement. Brauger's successful improvement of wheat varieties led to a six-fold increase in Mexico's wheat production in 1963 compared to 1944, making Mexico a wheat exporter (95% of the wheat varieties exported were bred by Brauger). From 1964 to 1979, Brauger was head of the International Maize and Wheat Improvement Center. In 1965, Brauger began to promote his dwarf wheat in Pakistan and India, where wheat production increased by 70% per year, effectively controlling the spread of famine in both countries.

In 1968, the U.S. Agency for International Development (USAID) referred to the Indian subcontinent's food growth phenomenon as the "Green Revolution" in its annual report, referring to a series of agricultural innovations initiated by Brauger to breed high-yielding varieties and improve agricultural technology, and Brauger himself is known as the "father of the Green Revolution". In 1970, Brauger was awarded the Nobel Peace Prize. In 1986, Brauger founded the World Food Prize Foundation; On June 7, 1996, Brauger became a foreign academician of the Chinese Academy of Engineering.

The "Green Revolution" reversed the famine in many parts of the world in the mid-20th century, helped at least 1 billion people escape the threat of hunger, and at least 19 developing countries successfully achieved food self-sufficiency in the face of high population growth, saving millions of lives.

Brauger developed a number of sturdy varieties of wheat that were only three-quarters as tall as ordinary wheat. What's in it for you? First of all, dwarf varieties are not prone to lodging. If the plant grows thin and tall, it is easy to break off or fall from the roots or stems in the wind and rain, while the dwarf varieties are not easy to lodging under the action of external forces. Secondly, dwarf varieties are beneficial for increasing yields. Just as a person's energy is limited, so is the energy of a plant, and if most of the energy is used to grow a child, there will be no more energy to bear 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, and are excellent varieties in agricultural production.

For the human body, if the pituitary gland secretes too much growth hormone, it will cause hyperplasia and hypertrophy of soft tissues, bones and internal organs, as well as endocrine and metabolic disorders. When the onset occurs before puberty and the epiphysis does not close, it is called "gigantism"; When the onset occurs after puberty and the epiphysis is closed, it is called "acromegaly". Children suffering from "gigantism" will show excessive growth and development in the early stage, and can be more than 2 meters tall at about 10 years old, often muscular, with amazing arm strength and early development of sexual organs; When the course of the disease progresses to a period of decline (which lasts for four or five years), they will experience symptoms such as lack of energy, weakness in the limbs, muscle relaxation, hair loss, and slowing metabolism. Many patients with gigantism do not live long, and most of them die at the age of twenty or thirty.

There is also a disease similar to the human "gigantism" in rice, which is called "evil seedling disease". Rice with "seedling disease" grows wildly, the stalks grow very tall, but the rice harvest is reduced by more than 70%, and the quality of the rice is not good. Unlike gigantism in humans, rice disease is also contagious and can be transmitted from rice to rice. Therefore, "seedling disease" is a very serious crop disease, once it breaks out, a large area of fertile land is almost unharvested.

At first, people did not know what caused rice to suffer from "bad seedling disease" until 1898, when Japanese scientists confirmed that "bad seedling disease" was caused by a fungal infection; It took decades for researchers to discover that the fungus was gibberell. After inoculating normally growing rice with gibberella, they found that the rice would grow stems and leaves like crazy, showing symptoms similar to "bad seedling disease". Even if the active gibberella is removed and only the culture medium that has been cultured is treated, similar symptoms will still occur in the rice. This indicates that the active gibberella secretes certain substances in the culture medium, and these substances have the function of promoting plant elongation. Later, a class of compounds produced by gibberella that promote the growth of seedlings was called gibberellin

In fact, it is related to gibberellin. Gibberellin in plants is like a commander, it communicates to plants through signal transduction to command them to grow high. In dwarf varieties, either gibberellin does not give the order normally, or the "communicator" does not give the order normally. In this way, the plants that do not receive the instructions do not consume too much nutrients to grow taller, but can save most of the nutrients to bear fruit, so they become high-yielding varieties. This is also the reason why Brauger improved dwarf varieties such as wheat and corn.

Gibberellin is a class of plant hormones that belong to the diterpenoids. Erythroxin plays an important regulatory role in the life cycle of higher plants, and it is involved in the regulation of seed germination, hypocotyl and stem elongation, leaf elongation, epidermal trichome development, flowering time, flower organ development and fruit ripening. More than 100 well-defined erythoxins have been identified from different species, and they have been named GA1-GA136 in chronological order of discovery. However, studies have found that only a few species of gibberellin have the effect of regulating plant growth, such as GA1, GA3, GA4, GA7, etc.

The "Green Revolution" of the 20th century played an important role in agricultural production, especially high-yield breeding, and the use of dwarf varieties of crops was caused by mutations in gibberellin synthesis or response. The dwarf characteristics caused by gibberellin abnormalities lead to reduced nutrient distribution to stem elongation and increased nutrient distribution to seed growth, thereby increasing crop yields. At the same time, the dwarf trait also makes the crop easy to cultivate and manage, and reduces the loss caused by crop lodging.

Crops do not listen to gibberellin normally, creating high-yielding varieties; High-yielding varieties in turn ensure that there is enough food to eat. The little gibberellin has such a big credit, it really can't be underestimated its existence!