Breeding Science最新文献

To counteract the growing population and climate changes, resilient varieties adapted to regional environmental changes are required. Landraces are valuable genetic resources for achieving this goal. Recent advances in sequencing technology have enabled national seed/gene banks to share genomic and genetic information from their collections including landraces, promoting the more efficient utilization of germplasms. In this study, we developed genomic and genetic resources for Myanmar rice germplasms. First, we assembled a diversity panel consisting of 250 accessions representing the genetic diversity of Myanmar indica varieties, including an elite lowland variety, Inn Ma Yebaw (IMY). Our population genetic analyses illustrated that the diversity panel represented Myanmar indica varieties well without any apparent population structure. Second, de novo genome assembly of IMY was conducted. The IMY assembly was constructed by anchoring 2888 contigs, which were assembled from 30× coverage of long reads, into 12 chromosomes. Although many gaps existed in the IMY genome assembly, our quality assessments indicated high completeness in the gene-coding regions, identical to other near-gap-free assemblies. Together with dense variant information, the diversity panel and IMY genome assembly will facilitate deeper genetic research and breeding projects that utilize the untapped Myanmar rice germplasms.

Starch properties are the major determinants of grain quality and food characteristics in rice (Oryza sativa L.). Understanding the interactions between genetic regions responsible for starch properties will lead to the development of rice cultivars with desirable characteristics. This study investigated the genetic effect and interaction between qAC9.3, a low-amylose quantitative trait locus (QTL), and the genetic region around Starch branching enzyme IIb (SbeIIb). Both these factors are responsible for the starch properties of the Hokkaido breeding population. The amylose content, pasting temperature, and amylopectin chain-length distribution were compared using F₅ lines derived from the cross between the lower amylose content and lower pasting temperature strain 'Hokkai332 (qAC9.3, SbeIIb)' and the higher amylose content and higher pasting temperature variety 'Kitagenki (-, SbeIIb^sr )'. The qAC9.3 genotype exhibited low amylose content and reduced the hardness of boiled rice but increased the ratio of amylopectin long chains and did not alter the pasting temperature. In contrast, the SbeIIb genotype was associated with pasting temperature but did not affect the amylose content and hardness of boiled rice. It was suggested that appropriately selecting genotypes of these genetic regions and QTL would allow the fine-tuning of starch properties of cooked rice suitable for future demand.

Sweetpotato (Ipomoea batatas) includes diverse cultivars with flesh textures ranging from dry to moist. Moist-fleshed cultivars often contain starch with a lower gelatinization temperature (GT). To elucidate the genetic determinants of flesh texture and starch GT, we conducted a QTL analysis using F₁ progenies obtained from a cross between dry-fleshed and moist-fleshed cultivars, 'Benikomachi' (BK) and 'Amahazuki' (AH), by using an updated polyploid QTL-seq pipeline. Flesh texture was assessed based on the wet area ratio (WAR) observed on the cut surface of steamed tubers, as progenies with dry and moist flesh exhibited low and high WAR values, respectively, demonstrating a strong correlation. Three QTLs were found to regulate the WAR. Notably, two AH-derived alleles at 4.30 Mb on Itr_chr05 and 21.01 Mb on Itr_chr07, along with a BK-derived allele at 2.89 Mb on Itr_chr15, were associated with increased WAR. Starch GT, which displayed no correlation with either flesh texture or WAR, was distinctly influenced by two QTLs: a GT-increasing BK-derived allele at 1.74 Mb on Itr_chr05 and a GT-decreasing AH-derived allele at 30.16 Mb on Itr_chr12. Consequently, we developed DNA markers linked to WAR, offering a promising avenue for the targeted breeding of sweetpotato with the desired flesh textures.

Vigna nakashimae is a wild species closely related to the azuki bean (V. angularis), with salt-tolerance abilities. The present study aimed to explore the genetic and salt tolerance diversity within the species, by evaluating the phylogenetic relationships of 55 accessions of V. nakashimae including 25 newly collected from the Gotō Islands and Iki in Nagasaki Prefecture, Japan. We conducted salt-tolerance analysis for 48 of the accessions, including 18 of the newly collected accessions. Phylogenetic analysis based on single-nucleotide polymorphisms obtained from MIGseq and RADseq analyses revealed the genetic diversity of V. nakashimae to reflect the geographic arrangement of the habitat islands. Korean accessions formed one clade, while Japanese accessions predominantly grouped into Uku Island and Fukue Island subclades. Within this population, we identified "G4-2" (JP248291) as the most salt tolerant, surpassing even the previously reported "Ukushima" accession. Both accessions collected from Uku Island, with accessions belonging to the Uku Island subclade exhibiting a strong trend of salt tolerance. Our results strongly suggest the occurrence of genetic mutations conferring enhanced salt tolerance in specific clade and region. This study highlights the potential of genetic analyses for identifying regions suitable for collecting valuable genetic resources for stress tolerance.

The success or failure of food technologies in society depends to a large extent on the public interest, concerns, images, and expectations surrounding them. This paper delves into the landscape of public attitudes towards gene-edited foods in Japan, exploring the reasons behind the acceptance or rejection of these products. A literature review and preliminary findings from a survey conducted in Japan in 2022, aim to identify key issues crucial for evaluating societal acceptance of gene-edited foods. The study showed that the public view gene-edited foods as somewhat unnatural, but upon closer examination, significant variation in attitudes was observed among respondents. Some respondents expressed a favorable perception towards gene-edited foods, particularly those that benefit consumers, while others expressed concerns about its perceived artificiality. Moreover, a significant number of respondents displayed indifference or lack of clear perspective regarding gene-edited foods. These findings reflect the complex relationship between public attitudes, naturalness, and social acceptance of gene-edited foods. Furthermore, the study indicates the importance of paying close attention to those who refrain from expressing their viewpoints in the survey. This nuanced landscape warrants further exploration.

There is a need to introduce new regulations regarding genome editing technology and its application to agriculture and food. Regulations are different among countries and sometimes inconsistent. Here, we summarize the current regulations regarding the use of genome editing technology in agriculture and food in various countries around the world. We also discuss the main regulatory developments expected to occur in the future.

The advent of CRISPR/Cas9 has had a disruptive impact on the world by bringing about dramatic progress and rapid penetration of genome editing technology. However, even though gene disruption can be easily achieved, there has been a challenge in freely changing the sequence. To solve this problem, various novel technologies have emerged in recent years to realize free rewriting of genome sequences. In this review, scarless editing by two-step HDR, a technology that can freely rewrite genomes from a single nucleotide to more than several thousand nucleotides, will be introduced.

Plant factories with artificial light are less affected than open-air areas to environmental factors in crop cultivation and are attracting attention as one of the solutions to the world's food problems. However, the cost of cultivation in plant factories is higher than open-air cultivation, and currently, profitable factory-grown crop varieties are limited to those that are small or have a short growing period. Tomatoes are one of the main crops consumed around the world, but due to their large plant height and width, they are not yet suitable for mass production in plant factories. In this study, the DWARF (D) and SELF-PRUNING (SP) genes of the GABA hyperaccumulating tomato variety #87-17 were genome-edited by the CRISPR-Cas9 method to produce dwarf tomato plants. The desired traits were obtained in the T₁ genome-edited generation, and the fruit traits were almost the same as those of the original variety. On the other hand, the F₂ cross between #87-17 and Micro-Tom containing the d and sp mutations was dwarfed, but the fruit phenotype was a mixture of the traits of the two varieties. This indicates that genome editing of these two genes using CRISPR-Cas9 can efficiently impart traits suitable for plant factory cultivation while retaining the useful traits of the original cultivar.

Food shortages due to population growth and climate change are expected to occur in the near future as a problem that urgently requires solutions. Conventional breeding techniques, notably crossbreeding and mutation breeding, are known for being inefficient and time-consuming in obtaining seeds and seedlings with desired traits. Thus, there is an urgent need for novel methods for efficient plant breeding. Breeding by genome editing is receiving substantial attention because it can efficiently modify the target gene to obtain desired traits compared with conventional methods. Among the programmable sequence-specific nucleases that have been developed for genome editing, CRISPR-Cas12a and CRISPR-MAD7 nucleases are becoming more broadly adopted for the application of genome editing in grains, vegetables and fruits. Additionally, ST8, an improved variant of MAD7, has been developed to enhance genome editing efficiency and has potential for application to breeding of crops.