Weakening of gene function of OsTB1 by genome editing improves rice productivity under phosphorus deficiency
Country
Madagascar
Description
Tillering is an important trait that determines shoot architecture and yield in rice. Many genes are involved in tillering in rice, and among them, rice TEOSINTE BRANCED1 (OsTB1) is a key gene that suppresses tillering. On the other hand, phosphorus, a soil nutrient, is one of the most important environmental factors involved in tillering. Phosphorus deficiency leads to reduced tiller number and is a major constraint on rice production in sub-Saharan Africa. In this study, we generate mutants for OsTB1 using the CRISPR/Cas9 system in X265, which is a major rice cultivar in Madagascar, and then investigate tillering and productivity under phosphorus deficiency in the resultant mutants.The CRISPR/Cas9 system has generated two types of mutant lines: an in-frame mutant line with 30-bp deletion (#29418) and a frameshift mutant line with 1-bp insertion (#29430) (Fig. 1). The in-frame mutant line #29418 has 1.2 times more tillers than the background cultivar X265 (WT) at just before heading stage (Fig. 1). On the other hand, the frameshift mutant line #29430 produces 3.4 times more tillers than WT (Fig. 1). This means that OsTB1 weakens its tillering suppression function through the in-frame mutation, while the frameshift mutation loses its tillering suppression function. The expression level of the OsTB1 gene in #29418 is comparable to that of WT (Fig. 2). The OsGT1 gene, which is directly regulated by OsTB1 to suppress tillering, is down-regulated in #29430 (Fig. 2). The expression level of OsGT1 in #29418 is intermediate between those of WT and #29430 (Fig. 2), revealing that the modified OsTB1 expressed in the in-frame mutant line #29418 has a moderate function in the regulation of OsGT1. The grain yield of #29418 under phosphorus deficiency is higher than that of WT under low phosphorus application levels: #29418 has approximately 40% higher grain yield than WT under 0 mg/kg phosphorus application (Fig. 3A). The number of panicles, spikelets, and filled grains of #29418 was higher than those of WT, and the 1,000-grain weight was lower than that of WT (Fig. 3B). The gain in filled grain numbers more than compensates for the reduced 1,000-grain weight. On the other hand, the frameshift mutant line #29430 has more filled grains than WT, but it does not improve yields because the gain in filled grain numbers does not compensate for its decreased 1,000-grain weight.
Our study demonstrates that genome editing of OsTB1 can modify tillering in rice and suggests that the breeding of rice cultivars that have a moderately higher number of tillers may effectively improve rice productivity in areas suffering from phosphorus deficiency.
Figure, table
- Research project
- Program name
- Term of research
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2018-2022
- Responsible researcher
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Ishizaki Takuma ( Tropical Agriculture Research Front )
Ueda Yoshiaki ( Crop, Livestock and Environment Division )
ORCID ID0000-0002-4304-368XKAKEN Researcher No.: 70835181Takai Toshiyuki ( Crop, Livestock and Environment Division )
Tsujimoto Yasuhiro ( Crop, Livestock and Environment Division )
KAKEN Researcher No.: 20588511Maruyama Kyounoshin ( Biological Resources and Post-harvest Division )
- ほか
- Publication, etc.
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Ishizaki et al. (2023) Plant Science 330: 111627https://doi.org/10.1016/j.plantsci.2023.111627
- Japanese PDF
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2023_B08_ja.pdf1.02 MB
- English PDF
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2023_B08_en.pdf518.36 KB
＊ Affiliation at the time of implementation of the study.