The high-yield and quality improvement of rice starts from the "source"

The high-yield and quality improvement of rice starts from the "source"

High-yield and high-quality rice starts from the "source".

Photo courtesy of Yangzhou University

 Photo courtesy of Yangzhou University

The formation of crop yield depends on photosynthesis on the one hand, and storage capacity on the other
.

The organs that produce and output photosynthetic products are called source organs, such as leaves, and the organs that receive and store photosynthetic products are called sink organs, such as seeds

Liu Qiaoquan, a professor at the School of Agriculture of Yangzhou University, told China Science Daily that improving the photosynthetic efficiency of source organs and the storage capacity of sink organs to improve the overall agronomic traits of crops is currently the main application of the "source-sink theory" widely recognized by scientists
.

Recently, "Journal of Plant Biotechnology" published online the latest research results of Liu Qiaoquan's group
.

They confirmed for the first time that a key source gene, rice glucan hydration dikinase 1 (GWD1), which can coordinate the source-sink relationship, can simultaneously improve the yield and quality traits of rice under reasonable regulation, which has great potential for application

Find the direction from the "source"

Find the direction from the "source"

"The relationship between source organs and sink organs is the core that determines the overall agronomic traits of crops
.

" Li Qianfeng, the corresponding author of the paper and a professor at the School of Agriculture of Yangzhou University, told the China Science Daily.

Liu Qiaoquan said that cloning and identifying specific genes related to "source-sink" and clarifying their molecular functions are of great significance for elucidating the mechanism of "source-sink" and promoting crop yields in production practices
.

Rice is one of the important food crops for the population of China and even the world.
To ensure food security, research on the "quality" and "quantity" of rice is becoming more and more important
.

"Currently discovered genes affecting the'source-sink relationship' of rice are mostly related to specific traits of the sink organization, such as grain length, grain width, grain weight, etc.

However, there are still few related studies on source genes, especially lack of potential applications.

"The source gene of the source gene

For this reason, after many years of basic research, a key enzyme gene that regulates starch metabolism in the leaves of the source organ-glucan water dikinase 1 (GWD1) has entered the field of view of the team's research
.

Accelerate the "out of circle" expression of key source genes

Accelerate the "out of circle" expression of key source genes

Scientists have discovered that leaf photosynthesis will produce instantaneous starch, and its conversion efficiency to storage starch has an important impact on the formation of final crop yields.
At the same time, proper starch phosphorylation can also improve quality
.

Studies have confirmed that dextran water dikinase 1 is involved in the metabolic regulation of transient starch in the leaves of the source organs, but the current evolutionary pathways and enzyme functions, especially the effects on important traits related to seeds, are still largely unknown
.

In order to clarify these problems, the team used CRISPR/Cas9 genome editing technology to create a weak mutant that down-regulated the expression of dextran water dikinase 1
.

At the same time, by driving the overexpression of the glucan water dikinase 1 gene in rice leaf tissues, overexpressed transgenic rice was obtained

"During this process, we discovered that the glucan water dikinase 1 gene expression site is mainly in the leaves.
If it can specifically enhance its expression in the leaves, it can avoid or reduce the impact on other rice tissues and promote The instantaneous starch metabolism efficiency in the leaves can better provide raw materials for the synthesis of stored substances in the reservoir organs
.

" said Wang Zhen, the first author of the paper and a master student in the School of Agriculture of Yangzhou University

In order to make the glucan water dikinase 1 gene "out of circle" expression in the leaves, the team spent a lot of time and finally screened out a promoter called Osl2, which can not only "help" glucan water dikinase 1 The gene is highly expressed in the leaves, and the efficiency will not decrease with the senescence of the leaves
.

Further analysis confirmed that the overexpression of glucan water dikinase 1 rice driven by the Osl2 promoter has significantly improved rice yield, quality, germination characteristics and stress resistance, but has no obvious negative effects on other major agronomic traits
.

Dig deeper into the regulatory mechanism of the source gene

Dig deeper into the regulatory mechanism of the source gene

So, as the source gene, what kind of regulatory mechanism does the glucan water dikinase 1 gene have in the process of increasing rice yield and improving quality?

"We have proved through leaf iodine staining experiments that inhibiting or reducing the expression of this gene will increase the instantaneous starch content of the leaves, which means that the conversion rate will be reduced
.

On the contrary, increasing the expression of this gene can promote the transformation of instantaneous starch and increase the final grain yield

He explained to reporters that this may be due to the increase in the instantaneous starch conversion rate in the leaves, resulting in a corresponding increase in the soluble sugar transported to the seeds through the stem, which not only promotes the increase in plant height, but also promotes the corresponding increase in the starch content accumulated in the grain.
Promote the increase in production
.

At the same time, the team also found that up-regulating the expression of this gene can significantly improve a number of important agronomic traits, including rice grain shape, rice quality, seed germination and stress resistance characteristics
.

This indicates that the gene not only participates in the instantaneous starch degradation process in the leaves of the source organs, but also can effectively improve many important characteristics of the seeds of the sink organs
.
This also means that in the future, the glucan water dikinase 1 gene can become an ideal target gene for synergistically improving rice yield and quality using biotechnology
.

"This work has laid an important foundation for methods, genes and materials for the collaborative improvement of rice yield and quality
.
" Liu Qiaoquan said, "The era of just'taking output as a hero' has passed, and'high-yield and high-quality' has become a new vane, which is urgently needed.
The integration of good seeds, good methods, and advanced equipment and technology will consolidate the foundation for the high-quality development of China’s rice industry
.
” (Source: China Science News Li Chen Wang Yifan)

Related paper information: https://doi.
org/10.
1111/pbi.
13686

https://doi.
org/10.
1111/pbi.
13686