Rice has been a staple diet for more than half of the world's population for many years. To increase awareness and encourage action to protect and advance the crop for a rapidly rising population, the United Nations named 2004 the International Year of Rice.
More recently, the United Nations and the International Rice Research Institute (IRRI) jointly organized the Sustainable Rice Platform to bring together stakeholders from all sectors with the goal of producing more rice in a sustainable and cost-effective manner.
Research Insights:
Rice has been around for 10,000 years, according to archaeological findings. Modern crops have been designed over time to increase yield and resiliency, based on farmer experience and researchers' scientific understanding. The research findings were published in the journal ‘Development.’
Rice's genetic direction for growth and reproduction, on the other hand, is still a mystery. Now, a Japanese study team is learning more, including how important one gene is for the plant to generate rice grains that serve as both seeds and food.
"Plants have a unique ability to create lateral organs, such as leaves and floral organs, continually throughout their lifecycle," said Wakana Tanaka, an assistant professor at Hiroshima University's Graduate School of Integrated Sciences for Life's Program of Food and AgriLife Science.
"This ability is reliant on the activity of pluripotent stem cells, which self-renew to maintain a consistent quantity in tandem with organ differentiation in the plant." In the thale cress plant, another model plant, we were getting a better understanding of the mechanisms behind stem cell maintenance, but we didn't know enough about them in rice."
The pistil, which houses the flower's ovary, is one of the floral organs found in rice flowers. The flower's ovules are buried in the ovary at the base of the bloom, where they mature into rice seeds when pollinated.
"Because all floral organs are created from stem cells, which are present in young flower buds," Tanaka explained, "the stem cells must be kept in a consistent amount until the last floral organ -the ovule -is formed."
TAB1 Gene:
A gene called WUS is required for stem cell maintenance in thale cress during the early stages of flower development when the pistil and stamens form. A rice plant lacking the corresponding gene, known as TAB1, was previously isolated from a population of mutant rice plants by the researchers. They investigated the mutant lacking TAB1 (tab1 mutant) in this investigation and discovered it lacked ovules.
"The tab1 mutant did not produce any fertile rice grains without ovules, implying that the TAB1 gene is required for rice grain development," Tanaka said.
The researchers discovered that stem cells were present during the production of early floral organs in the tab1 mutant, but had vanished by the time ovules matured.
"This finding suggests that the TAB1 gene is necessary for the robust preservation of stem cells until flower development's final stages," Tanaka added. "The TAB1 gene is involved in the maintenance of stem cells during ovule production, which finally leads to the formation of seeds." This direct requirement for stem cell activity in ovule production is not apparent in thale cress, hence it appears to be a rice-specific feature."
The researchers intend to look into the genes involved in the creation of other floral organs in the future. "By elucidating the gene, we want to explain the mechanisms of stem cell maintenance during flower development," Tanaka added. "Using the mechanisms we've discovered, we aim to contribute to rice breeding in the future."
(Source: Hiroshima University)
