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The University of Tokyo discovers gene involved in improved nutrient uptake and utilization efficiency of rice plants


A research group led by Associate Professor Yoshihiro Ohmori, Special Researcher Nobuhiro Tanaka (at the time of research; currently, Senior Scientist at the National Agriculture and Food Research Organization), Project Lecturer Kiyoshi Yamazaki, and Professor Toru Fujiwara of the Graduate School of Agricultural and Life Sciences at the University of Tokyo announced their discovery that the rice transcription factor OsbZIP1 gene regulates nutrient uptake and utilization efficiency in rice plants. Phenotypic and gene expression analyses using rice mutants revealed that 88n, the which is an OsbZIP1 mutant, exhibits superior initial growth with increased efficiency in the uptake and utilization of nitrogen and inorganic phosphorus, two of the three fertilizer elements. As 88n has a higher ear weight, manipulation of the OsbZIP1 gene is expected to contribute to the creation of crop lines that are tolerant to low fertilizer input. The study results were published in the January 11, 2024 issue of The Plant Journal.

Figure 1: Root phenotypes of osbzip1 mutants.
(a) Wild type (WT), osbzip1 mutant (88n), OsbZIP1 genome-edited line (CRISPR) and complementary lines with OsbZIP1 gene introduced into 88n (Comple_1,_2) grown under low phosphorus conditions.
(b) Root length under low phosphorus and low nitrogen conditions; lines without OsbZIP1 function showed enhanced root elongation; tested by method; different alphabets indicate significant differences.
(c) Root angles of wild type and 88n. 88n has more open roots and more roots close to the soil surface. Roots at the ground surface are especially effective for phosphorus fertilizer absorption. t-test with t-test* indicates significant difference.
Provided by the University of Tokyo Graduate School of Agricultural and Life Sciences and Faculty of Agriculture

The production of nitrogen fertilizers consumes large amounts of fossil fuels, and there are limited reserves of phosphorus ore, the raw material for phosphorus fertilizers. Both issues are global environmental problems that extend well beyond planetary boundaries.

By modifying the OsbZIP1 gene discovered in this study, the following three effects can be achieved.

1) Compared with the wild-type rice strain, the phenotype of 88n (OsbZIP1 mutant) is characterized by a shallower root angle and, especially under low nitrogen and phosphorus conditions, a longer root.Therefore, modification of the OsbZIP1 gene is expected to increase the efficiency of soil nutrient uptake by crops.

2) Elemental analysis results showed that in 88n, the aboveground phosphorus concentration increased, and the nitrogen concentration decreased. Therefore, modification of the OsbZIP1 gene altered the expression of phosphorus and nitrogen transporters, resulting in improved efficiency in the uptake and utilization of these two nutrients by crops.

3) In strain 88n, both the number of seeds per ear and the ear weight per unit area were higher than those of the wild-type plant. Thus, by modifying the OsbZIP1 gene, the efficiency of nutrient uptake and utilization can be increased, and an increase in ear weight can be achieved.

Tanaka said, "By modifying the OsbZIP1 gene discovered in this research, we expect to realize crop cultivation with reduced fertilizer input. Such low-input cultivation contributes to a sustainable and stable food supply. In the future, we will conduct cultivation trials in different regions and under different conditions to utilize the OsbZIP1 gene, with the aim of achieving cultivation with low fertilizer input."

Journal Information
Publication: The Plant Journal
Title: OsbZIP1 regulates phosphorus uptake and nitrogen utilization, contributing to improved yield
Authors: Nobuhiro Tanaka, Saki Yoshida, Md. Saiful Islam, Kiyoshi Yamazaki, Toru Fujiwara, Yoshihiro Ohmori
DOI: 10.1111/tpj.16598

This article has been translated by JST with permission from The Science News Ltd. ( Unauthorized reproduction of the article and photographs is prohibited.

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