Representational image: The discovery could help improve crop yield. iStock
Turns out that even with all the research done over the years, plant seed formation still holds many secrets.
Japan’s Nagoya University researchers have recently identified a completely new plant tissue, something that has eluded observation for 160 years.
Interestingly, this novel rabbit-shaped tissue is the first new plant tissue discovered since the mid-19th century.
The significance of this discovery lies in its potential to enhance seeds and boost crop yields worldwide. In fact, the team says that they have already shown practical results, increasing yields of rice.
Callose deposition is decreased from A to C but increased from D to E. Credit: Ryushiro Kasahara
Rabbit-shaped tissue
Successful fertilization is crucial for the developing seed. Specifically, the hypocotyl, which forms the seedling’s stem and root, needs fertilization to receive vital nutrients from the mother plant.
Knowing how plants sense successful fertilization is highly important for improving crop yields.
The breakthrough came unexpectedly, thanks to the keen observation of Ryushiro Kasahara and Michitaka Nodaguchi.
While staining seeds to track callose – a waxy substance linked to fertilization – Dr. Kasahara noticed something peculiar.
“Plants fertilize by the insertion of a pollen tube, so most scientists are only interested in the place where this occurs. However, we found signals on the opposite side too,” he said.
“Nobody was looking where I was looking. I remember being surprised, especially when we realized that this signal was particularly strong when fertilization failed.”
His unconventional perspective led to the identification of a distinct, rabbit-shaped tissue structure. Through further examination, the team found that this tissue structure operated as a gateway. This newly identified plant structure has been named the “Kasahara Gateway” in honor of the person who found it.
Larger seeds
The signal Dr. Kasahara observed was the accumulation of callose. This waxy substance acts like a gatekeeper.
When fertilization fails, the Kasahara Gateway enters a “closed state,” with callose blocking the flow of essential nutrients and hormones, leading to the demise of the unfertilized seed.
On the other hand, when fertilization is successful, the hypocotyl detects this and triggers the dissolution of callose, opening the “gateway” and allowing nourishment to flow in, enabling the seed to grow.
“When the flow of nutrients was compared between successfully fertilized and unsuccessful embryos, it was found that the inflow of nutrients was observed only in the successful embryos, whereas it was completely blocked in the unsuccessful ones. This limits the amount of resources wasted on unviable seeds,” Kasahara explained.
The Kasahara Gateway’s ability to open and close hinted at genetic control.
Researchers studied fertilized hypocotyls and found a gene, AtBG_ppap, that was only active in them and responsible for breaking down callose. By making hypocotyls produce more AtBG_ppap, they kept the gateway permanently open, leading to increased nutrient absorption.
Kasahara stated that keeping the Kasahara Gateway permanently open could lead to larger seeds. Testing this on rice resulted in 9% larger seeds, and other species saw increases as high as 16.5%.
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This new discovery opens up an entirely new field of research in plant biology and holds immense practical applications for agriculture.
Maintaining a permanently open Kasahara Gateway could significantly increase the yields of vital crops, contributing to global food security.
The findings were published in the journal Current Biology.
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