Plant transformation and regeneration have been continuously developed for the past four decades. In rice (Oryza sativa L.), Agrobacterium-mediated transformation has high efficiency in japonica and some indica cultivars using mature seeds and immature embryos. However, these protocols have low transformation efficiency in the latest indica cultivar that has been developed in South China since 2010. Here, we explored plant culture regeneration of the high-quality and high-yield indica cultivar Nanguizhan (NGZ) through CRISPR/Cas-based genome editing and traditional overexpression transformations. We compared transformation efficiency in this cultivar to four other widely-used indica cultivars and one japonica cultivar using mature seeds and the gene Grain Size and Number 1 (GSN1) as a case study. We observed universe smaller grain size in overexpression lines and bigger grain size in gene-editing lines among different cultivars. NGZ phenotypes make it an excellent model in which to investigate gene functions. We also examined the single nucleotide polymorphism (SNP) distribution and differences in expression levels of regeneration-related genes in calli, possibly revealing the source of NGZ's advantages in Agrobacterium-mediated transformation. These results shed light on the advanced application of NGZ in gene editing and overexpression transformation related to grain improvement, contributing to the "rice breeding 4.0 era".

This paper aims to review the research progress on the processing and utilization of functional rice and explore its potential to enhance human health. The research progress in the processing and utilization of colored rice, low-protein rice, high-resistant starch rice, micronutrient-enriched rice, and bioreactor rice was systematically analyzed through a comprehensive literature review. The impact of various processing techniques on the retention of nutritional components in functional rice was also discussed. This study found that functional rice exhibits great potential in terms of nutritional value, health effects, and market demand. However, issues such as the loss of bioactive components during processing, the maintenance of specific agronomic traits, and market acceptance still need to be addressed. The research and development of functional rice are significant for enriching people’s dietary choices and addressing global malnutrition and chronic disease problems. Future efforts should focus on further optimizing processing techniques and utilizing genetic engineering and molecular breeding technologies to enhance the nutritional value and agronomic traits of functional rice, thus meeting market demands and health objectives.

This study investigated metabolite changes in three pomelo cultivars during postharvest senescence using ¹H NMR-based metabolic profiling. Three pomelo cultivars, ‘Hongroumiyou’, ‘Bairoumiyou’ and ‘Huangroumiyou’, abbreviated as “R”, “W” and “Y” according to the color of their juice sacs, were stored at 25 °C for 90 days, and NMR was applied to determine the metabolite changes in juice sacs during storage. Fifteen metabolites were identified, including organic acids, sugars, amino acids, fatty acids, phenols and naringin. Partial least squares discriminant analysis (PLS-DA) was used to screen the significant metabolites according to the variable importance for the projection (VIP) scores in three pomelo cultivars during 90 days of storage. Additionally, eight metabolites, naringin, alanine, asparagine, choline, citric acid, malic acid, phosphocholine and β-D-glucose, were screened to be the crucial biomarkers with VIP > 1. The undesirable flavor of “bitter and sour” during the 60 days of storage was mainly attributed to the naringin, citric acid and sugars. According to the correlation analysis, the citric acid content determined by NMR showed a significantly positive relationship with that analyzed by HPLC. These findings suggested that NMR technology was accurate and efficient for metabolomic analysis of pomelo fruit, and the ¹H NMR-based metabolic profiling can be efficient during quality evaluation and useful for improving the fruit flavor quality during postharvest storage.

Hybrid sterility is the major obstacle to the utilization of inter-subspecific heterosis in hybrid rice breeding. The S5 locus, composed of three adjacent genes ORF3, ORF4, and ORF5, plays a crucial role in regulating indica/japonica hybrids’ female sterility. Through a series of crosses involving 38 parents, three alleles of S5, ORF3+ORF4−ORF5n, ORF3+ORF4+ORF5n, and ORF3−/ORF4−/ORF5n, all could be regarded as wide-compatibility alleles, and when crossed with indica or japonica rice, they all showed significantly high fertility. Then, in order to explore the genes’ function, we further knocked out genes by using CRISPR/Cas9-based genome editing. Our results demonstrate that the ORF3+ was not just the protector in the killer-protector system, and knocking out ORF3 of the indica allele seriously affected the rice’s normal development. We observed the concrete enhancing hybrid spikelet fertility from the crosses between the ORF4+ knockout japonica materials with indica varieties. By conducting the comparative RNA-Seq analysis of young spikelets, we found that the ORF4+/ORF4− could modulate the hybrid fertility by affecting the expressions of genes related to the function of the Golgi apparatus. This study indicated that knocking out the ORF4+ of the japonica allele or using the alleles carrying ORF5n would provide effective approaches to overcome indica/japonica hybrid female sterility in rice breeding.

A polysaccharide with water solubility named RRBP was extracted from red rice bran (Oryza sativa L.), and its structural characterization was analyzed. The polysaccharide exhibited a monodisperse molecular weight distribution with an average of 51.4 kDa, and also comprised glucose (98.1%, w/w) and small amounts of arabinose, galactose, xylose, and mannose. Structural investigations using methylation analysis combined with UV and FT-IR spectroscopy demonstrated that RRBP is a structurally complex hyperbranched glucan characterized by an extensive branch with “→4)-α-d-Glcp-(1“→linkages constituting 30.6% of the backbone. RRBP demonstrated concentration-dependent stimulation of nitric oxide (NO) generation along with elevated secretion levels of IL-6 and TNF-α but showed minimal effect on IL-12 production in assays with RAW264.7 macrophage cells. Gene expression profiling verified the enhanced transcription of genes encoding iNOS and pro-inflammatory cytokines including IL-6, TNF-α, and IL-12 following RRBP treatment. Moreover, it is important to note that RRBP was able to promote M1 macrophage activation and exhibited no cytotoxicity, and this implied that RRBP could serve as a biocompatible pro-inflammatory immunostimulant. In summary, these findings suggested that RRBP is a distinctive glucan that possesses selective immunomodulatory properties and could be applied in the development of functional food products designed for targeted immune system modulation.