How have breeders adapted rice flowering to the growing region?

Flowering time is a crucial rice trait that influences its adaptation to various environments, cropping schedules, and agronomic characteristics. Rice breeders have exploited spontaneous mutations in heading date genes to regulate the flowering time. In the present study, we investigated how breeders in Fukui Prefecture regulated days to heading while developing promising rice varieties.

Redefining awn development in rice through the breeding history of Japanese awn reduction.

The study challenges the conventional understanding of awn loss as a domestication syndrome, showing instead that many awned varieties continued to be widely grown in Japan until the early twentieth century and that selection for awn reduction was active at that time, demonstrating that awn loss is not a domestication syndrome but "a trait that emerged during crop improvement". Although selection for awnless mutants was carried out independently using different types of awned cultivars in the early twentieth century in Japan, awn loss was caused by the mutation in This suggests that a single mutant haplotype of was conserved in the genomes of different cultivars and subsequently selected within each line to meet the demand for awnless varieties. The study also conducts phylogenetic analyses of in 48 grass plants, revealing its unique involvement in awn formation in rice while potentially playing a different role in the domestication of other grass plants.

Low mutation rate of spontaneous mutants enables detection of causative genes by comparing whole genome sequences.

In the early 1900s, mutation breeding to select varieties with desirable traits using spontaneous mutation was actively conducted around the world, including Japan. In rice, the number of fixed mutations per generation was estimated to be 1.38-2.

Effective use of legacy data in a genome-wide association studies improves the credibility of quantitative trait loci detection in rice.

Genome-wide association studies (GWASs) are used to detect quantitative trait loci (QTL) using genomic and phenotypic data as inputs. While genomic data are obtained with high throughput and low cost, obtaining phenotypic data requires a large amount of effort and time. In past breeding programs, researchers and breeders have conducted a large number of phenotypic surveys and accumulated results as legacy data.

The allele from a large-grain rice cultivar, Akita 63, increases yield and improves nitrogen-use efficiency.

The Green Revolution allowed a large amount of nitrogen (N) fertilization to increase crop yield but has led to severe environmental pollution. Therefore, increasing the crop grain yield must be achieved without such considerable input of N fertilization. A large-grain rice cultivar, Akita 63, significantly increased grain yield and improved N-use efficiency (NUE) for yield per amount of N absorbed by plants.

Expression of flavodiiron protein rescues defects in electron transport around PSI resulting from overproduction of Rubisco activase in rice.

Fragility of photosystem I has been observed in transgenic rice plants that overproduce Rubisco activase (RCA). In this study, we examined the effects of RCA overproduction on the sensitivity of PSI to photoinhibition in three lines of plants overexpressing RCA (RCA-ox). In all the RCA-ox plants the quantum yield of PSI [Y(I)] decreased whilst in contrast the quantum yield of acceptor-side limitation of PSI [Y(NA)] increased, especially under low light conditions.

Manganese toxicity disrupts indole acetic acid homeostasis and suppresses the CO assimilation reaction in rice leaves.

Despite the essentiality of Mn in terrestrial plants, its excessive accumulation in plant tissues can cause growth defects, known as Mn toxicity. Mn toxicity can be classified into apoplastic and symplastic types depending on its onset. Symplastic Mn toxicity is hypothesised to be more critical for growth defects.

Co-overproducing Rubisco and Rubisco activase enhances photosynthesis in the optimal temperature range in rice.

Rubisco limits C3 photosynthesis under some conditions and is therefore a potential target for improving photosynthetic efficiency. The overproduction of Rubisco is often accompanied by a decline in Rubisco activation, and the protein ratio of Rubisco activase (RCA) to Rubisco (RCA/Rubisco) greatly decreases in Rubisco-overproducing plants (RBCS-ox). Here, we produced transgenic rice (Oryza sativa) plants co-overproducing both Rubisco and RCA (RBCS-RCA-ox).

Overproduction of Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase Improves Photosynthesis Slightly under Elevated [CO2] Conditions in Rice.

Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) limits the regeneration of ribulose 1,5-bisphosphate (RuBP) in the Calvin-Benson cycle. However, it does not always limit the rate of CO2 assimilation. In the present study, the effects of overproduction of GAPDH on the rate of CO2 assimilation under elevated [CO2] conditions, where the capacity for RuBP regeneration limits photosynthesis, were examined in transgenic rice (Oryza sativa).

Effects of Overproduction of Rubisco Activase on Rubisco Content in Transgenic Rice Grown at Different N Levels.

It has been reported that overproduction of Rubisco activase (RCA) in rice ( L.) decreased Rubisco content, resulting in declining photosynthesis. We examined the effects of RCA levels on Rubisco content using transgenic rice with overexpressed or suppressed under the control of different promoters of the and Rubisco small subunit () genes.

Transgenic rice overproducing Rubisco exhibits increased yields with improved nitrogen-use efficiency in an experimental paddy field.

The green revolution's breeding of semi-dwarf rice cultivars in the 1960s improved crop yields, with large increases in the use of nitrogen (N) fertilizer. However, excess N application has caused serious environmental problems, including acid rain and the eutrophication of rivers and oceans. To use N to improve crop yields, while minimizing the associated environmental costs, there is a need to produce crops with higher N-use efficiency and higher yield components.