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    28 May 2023, Volume 30 Issue 3 Previous Issue    Next Issue

    Research Paper
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    Additive Effects of QTLs/Genes on Rice Grain Size Traits Revealed by Genetic Comparisons
    HE Lei, LIANG Wenhua, HU Jiang, ZHAO Chunfang, YAO Shu, CHEN Tao, ZHU Zhen, ZHAO Qingyong, LU Kai, ZHAO Ling, ZHOU Lihui, QIAN Qian, WANG Cailin, ZHANG Yadong
    2023, 30(3): 171-175.  DOI: 10.1016/j.rsci.2023.03.001
    Abstract ( )   PDF (1021KB) ( )  

    Grain size is controlled by many QTLs and/or genes. Despite intensive study, the genetic interactions between these QTLs/ genes remain largely unclear. We previously found that the japonica large-grain rice cultivar TD70 with 1000-grain weight of 68.6 g carries superior alleles at the loci GW2, GS3, qGL3, GS5 and GW8, all of which are known to control grain size, while the indica rice variety Kasalath with 1000-grain weight of 19.1 g has normal alleles at these loci. In this study, molecular markers corresponding to the above five grain size genes were used to genotype recombinant inbred lines (RILs) generated from a cross between TD70 and Kasalath, and the grain size traits were evaluated in different combinations of these alleles. We found that the more TD70-derived alleles present, the larger the grains are in the corresponding plants, indicating that the five grain size genes had additive effects on this trait, with GW2, GS3 and qGL3 having the largest effects. Moreover, we constructed six near-isogenic lines (NILs), NIL-GW2TD70, NIL-GS3TD70, NIL-qGL3TD70, NIL-GW2TD70/GS3TD70, NIL-GW2TD70/qGL3TD70 and NIL-GS3TD70/qGL3TD70, in the genetic background of Kasalath to investigate the effects of these gene combinations on grain size, and the results further confirmed their additive effects. Our findings provide more insights into the molecular mechanisms regulating rice grain size and can provide a reference for the precise molecular design of rice breeding.

    Development and Application of a Novel Functional Marker for Fragrance in Rice
    SUN Pingyong, ZHANG Wuhan, ZHANG Li, SHU Fu, HE Qiang, XU Na, PENG Zhirong, ZENG Jia, FANG Pengpeng, DENG Huafeng
    2023, 30(3): 176-180.  DOI: 10.1016/j.rsci.2023.03.002
    Abstract ( )   PDF (1012KB) ( )  

    Fragrant rice is favored worldwide by consumers and rice breeders, due to its full aroma and high nutritional value. Loss of function of the betaine aldehyde dehydrogenase gene (OsBADH2) leads to aroma in rice. Our previous sequencing results showed that fragrant rice Chuan 7 belongs to badh2-E14 type, with a 1 bp insertion mutation in exon 14 (Sun et al, 2021), and this allele mutation is mainly distributed in Nepal and India (Kovach et al, 2009). Based on the badh2-E14 variation, a novel KASP (Kompetitive allele-specific PCR) functional marker FM-E14 was designed. The badh2-E14 genotypes of 209 individual plants in 5 BC1F1 breeding populations were validated and identified by FM-E14. It was completely consistent with the sequencing result, and the accuracy rate of FM-E14 reached 100%, which was higher than that of the developed linkage marker L-E14 (99.04%). Identification of OsBADH2 by functional marker FM-E14 can omit the gel electrophoresis and enzyme digestion steps after PCR, and can accurately and rapidly identify the fragrance homozygous, non-fragrance homozygous and heterozygous genotypes according to the fluorescence signal. Therefore, it is safe, efficient, high-throughput and low-cost. The functional marker FM-E14 developed in this study greatly improves the selection efficiency of badh2-E14 and accelerates the breeding process, as well as enriches the genetic diversity of aromatic rice, to avoid serious homogenization. Therefore, FM-E14 has an important application value for the creation of aroma rice resources and the cultivation of new high-quality fragrant rice varieties.

    Cadmium Tolerance and Accumulation in Wild Rice Species
    Ayotunde A. ADEOSUN, Adam H. PRICE, Gareth J. NORTON
    2023, 30(3): 181-185.  DOI: 10.1016/j.rsci.2023.03.003
    Abstract ( )   PDF (532KB) ( )  
    When exposed to cadmium (Cd), rice (Oryza sativa L.) suffers a loss in biomass as well as an increased concentration of Cd within the plant. When looking for genes that can reduce Cd accumulation or increase Cd tolerance, the wild relatives of rice are under-utilised resources. In this study, a rapid hydroponic screening system was established using known tolerant and sensitive O. sativa accessions, and found that 10 µmol/L Cd concentration appeared to be the optimum for screening Cd tolerance of rice cultivars. Then, 18 wild rice accessions were screened for Cd tolerance and accumulation. Significant differences in percentage tolerance to Cd of the wild rice accessions were observed for root length, shoot length and shoot dry weight. Moreover, there were significant differences between the wild rice species for percentage tolerance to Cd and shoot Cd concentration in all plant growth traits (P-value < 0.05). O. longistaminata, a tolerant species, had 1.5- to 2.0-fold higher percentage tolerance in comparison with O. rufipogon, the most sensitive species, and had an almost 3-fold higher shoot Cd concentration compared with O. barthii. O. longistaminata accessions displayed high tissue-level tolerance to Cd. This data suggests a wide variation of these traits amongst the wild rice species.
    Adoption of Improved Rice Varieties in the Global South: A Review
    Julia CHECCO, Fathin Ayuni AZIZAN, Jaquie MITCHELL, Ammar Abdul AZIZ
    2023, 30(3): 186-206.  DOI: 10.1016/j.rsci.2023.03.004
    Abstract ( )   PDF (1304KB) ( )  
    Improved rice varieties (IRVs) play a significant role in establishing food security and improving livelihood in the Global South since its introduction in the 1960s. However, the adoption of new IRVs has remained relatively low. This low adoption poses a challenge to rice-producing and consuming countries as they are increasingly threatened by production shortages, malnutrition, and poor rice quality. Many empirical studies have attempted to identify the determinants influencing the adoption of IRVs by distinguishing the characteristics between adopters and non-adopters. This review showed a consensus on the important determinants influencing the adoption of IRVs in the Global South. Findings synthesized from 99 studies suggested that variables (farm size, education, information access and farm location) examined extensively are not necessarily the most important determinants of adoption when undertaking a weighted analysis. Terrain, source of seed and technology-related attributes (perceived yield, maturity, ease of use, marketability and technical efficiency) are more important determinants of adoption, with determinants changing according to adoption type (probability or intensity of adoption), variety type and region. The recommendations for future adoption studies include: incorporating more technology-specific variables, increasing research for overlooked regions and variety types, shifting away from predominant static analysis by capturing the dynamics of the adoption process, and considering the potential biases in analyses. This review will facilitate the development of targeted interventions and policies that promote IRV adoption in the Global South.
    Rice Storage Proteins: Focus on Composition, Distribution, Genetic Improvement and Effects on Rice Quality
    LONG Xinkang, GUAN Chunmin, WANG Lin, JIA Liting, FU Xiangjin, LIN Qinlu, HUANG Zhengyu, LIU Chun
    2023, 30(3): 207-221.  DOI: 10.1016/j.rsci.2023.03.005
    Abstract ( )   PDF (1086KB) ( )  
    Rice storage proteins (RSPs) are plant proteins with high nutritional quality. As the second largest type of storage substance in rice, it is the main source of protein intake for people who consume rice as a staple food. The content and type of RSPs affect the appearance, processing quality and eating quality of rice. These effects involve the distribution of RSPs in rice grains as well as the interactions of RSPs with other components such as starch in rice grains. In the past two decades, some progress has been made in the genetic improvement of RSPs. However, the determination mechanism of protein content and composition in rice is still unclear, and the mechanism of the effect of RSPs on rice quality has not been elucidated. In this review, the composition, biosynthesis and distribution of RSPs, and quantitative trait loci mapping and cloning of RSP genes are summarized, the research progress of the influence of RSPs and their components on rice quality are reviewed, and the research directions in the future are proposed.
    Research Paper
    OsAMT1.1 Expression by Nitrate-Inducible Promoter of OsNAR2.1 Increases Nitrogen Use Efficiency and Rice Yield
    JIANG Hongzhen, WANG Yamei, LAI Liuru, LIU Xintong, MIAO Changjian, LIU Ruifang, LI Xiaoyun, TAN Jinfang, GAO Zhenyu, CHEN Jingguang
    2023, 30(3): 222-234.  DOI: 10.1016/j.rsci.2023.03.006
    Abstract ( )   PDF (1646KB) ( )  
    Nitrate (NO3) and ammonium (NH4+) are two main inorganic nitrogen (N) sources during crop growth. Here, we enhanced the expression of OsAMT1.1, which encodes a NH4+ transporter, using the NO3-inducible promoter of OsNAR2.1 and an ubiquitin promoter in transgenic rice plants. Under field condition of 120 kg /hm2 N, agronomic N use efficiency, N recovery efficiency and N transport efficiency, and grain yield of the pOsNAR2.1:OsAMT1.1 transgenic lines were increased compared with those of the wild type (WT) and the pUbi:OsAMT1.1 transgenic plants. Under 2.0 mmol/L NO3 + 0.5 mmol/L NH4+ and 0.5 mmol/L NO3 + 2.0 mmol/L NH4+ conditions of hydroponic culture, compared with the WT, both biomass and total N content were increased in the pOsNAR2.1:OsAMT1.1 transgenic lines. However, biomass was significantly reduced in pUbi:OsAMT1.1 transgenic plants under 0.5 mmol/L NO3 + 2.0 mmol/L NH4+ condition. The lines expressing pOsNAR2.1:OsAMT1.1 exhibited increased OsAMT1.1 expression and 15NH4+ influx in roots under both 2.0 mmol/L NO3 + 0.5 mmol/L NH4+ and 0.5 mmol/L NO3 + 2.0 mmol/L NH4+ conditions. Our study showed that expression of OsAMT1.1 can be promoted when driven by the OsNAR2.1 promoter, especially under high-level nitrate condition, leading to enhancement of NH4+ uptake, N use efficiency and grain yield.
    Polyphosphate Accelerates Transformation of Nonstructural Carbohydrates to Improve Growth of ppk-Expressing Transgenic Rice in Phosphorus Deficiency Culture
    ZHU Jinling, WEI Ruping, WANG Xin, ZHENG Chaoqun, WANG Mengmeng, YANG Yicheng, YANG Liuyan
    2023, 30(3): 235-246.  DOI: 10.1016/j.rsci.2023.03.007
    Abstract ( )   PDF (966KB) ( )  
    Crop yield and quality are often limited by the amount of phosphate fertilizer added to infertile soils, a key limiting factor for sustainable development in modern agriculture. The polyphosphate kinase (ppk) gene -expressing transgenic rice with a single-copy line (ETRS) is constructed to improve phosphate fertilizer utilization efficiency for phosphorus resource conservation. To investigate the potential mechanisms of the increased biomass in ETRS in low phosphate culture, ETRS was cultivated in a low inorganic phosphate (Pi) culture medium (15 μmol/L Pi, LP) and a normal Pi culture medium (300 μmol/L Pi, CP), respectively. After 89 d of cultivation in different concentrations of phosphate culture media, the total phosphorus, polyphosphate (polyP), biomass, photosynthetic rate, nonstructural carbohydrate (NSC) contents, related enzyme activities, and related gene expression levels were analyzed. The results showed that ETRS had a high polyP amount to promote the photosynthetic rate in LP, and its biomass was almost the same as the wild type (WT) in CP. The NSC content of ETRS in LP was higher than that of WT in LP, but slightly lower than that of WT in CP. PolyP notably promoted the sucrose phosphate synthase activities of ETRS and significantly down-regulated the expression levels of sucrose transporter genes (OsSUT3 and OsSUT4), resulting in inhibiting the transport of sucrose from shoot to root in ETRS. It was concluded that polyP can stimulate the synthesis of NSCs in LP, which improved the growth of ETRS and triggered the biological activities of ETRS to save phosphate fertilizer. Our study provides a new way to improve the utilization rate of phosphate fertilizer in rice production.
    Improved Yield Prediction of Ratoon Rice Using Unmanned Aerial Vehicle-Based Multi-Temporal Feature Method
    ZHOU Longfei, MENG Ran, YU Xing, LIAO Yigui, HUANG Zehua, LÜ Zhengang, XU Binyuan, YANG Guodong, PENG Shaobing, XU Le
    2023, 30(3): 247-256.  DOI: 10.1016/j.rsci.2023.03.008
    Abstract ( )   PDF (792KB) ( )  
    Pre-harvest yield prediction of ratoon rice is critical for guiding crop interventions in precision agriculture. However, the unique agronomic practice (i.e., varied stubble height treatment) in rice ratooning could lead to inconsistent rice phenology, which had a significant impact on yield prediction of ratoon rice. Multi-temporal unmanned aerial vehicle (UAV)-based remote sensing can likely monitor ratoon rice productivity and reflect maximum yield potential across growing seasons for improving the yield prediction compared with previous methods. Thus, in this study, we explored the performance of combination of agronomic practice information (API) and single-phase, multi-spectral features [vegetation indices (VIs) and texture (Tex) features] in predicting ratoon rice yield, and developed a new UAV-based method to retrieve yield formation process by using multi-temporal features which were effective in improving yield forecasting accuracy of ratoon rice. The results showed that the integrated use of VIs, Tex and API (VIs & Tex + API) improved the accuracy of yield prediction than single-phase UAV imagery-based feature, with the panicle initiation stage being the best period for yield prediction (R2 as 0.732, RMSE as 0.406, RRMSE as 0.101). More importantly, compared with previous multi-temporal UAV-based methods, our proposed multi- temporal method (multi-temporal model VIs & Tex: R2 as 0.795, RMSE as 0.298, RRMSE as 0.072) can increase R2 by 0.020–0.111 and decrease RMSE by 0.020–0.080 in crop yield forecasting. This study provides an effective method for accurate pre-harvest yield prediction of ratoon rice in precision agriculture, which is of great significance to take timely means for ensuring ratoon rice production and food security.
    In Vitro Antifungal Activity of Dihydrochelerythrine and Proteomic Analysis in Ustilaginoidea virens
    WEI Qinghui, CUI Daizong, ZHENG Baojiang, ZHAO Min
    2023, 30(3): 257-266.  DOI: 10.1016/j.rsci.2023.03.009
    Abstract ( )   PDF (1064KB) ( )  
    Dihydrochelerythrine (DHCHE) is an isoquinoline compound, which has distinct antifungal activity and can induce apoptosis. The antifungal activity of DHCHE against five rice pathogenic fungi was studied in vitro. At the concentration of 7.5 mg/L, DHCHE exhibited the highest efficacy among tested compounds in inhibiting mycelium growth, with an inhibition rate of 68.8% in Ustilaginoidea virens, which was approximately 2.4 times of that of validamycin (28.7%). After exposure to DHCHE, transmission electron micrographs revealed spores showed incomplete organelles, malformed cell walls and nuclear membranes, as well as irregular lipid spheres. Reactive oxygen species accumulation in treated spores was markedly higher than that in control spores. DHCHE induced cell damage increased in a dose-dependent manner, as indicated by the decrease in mitochondrial membrane potential and initiation of apoptosis. The differences of expression levels of Fip1, ACP1, PMS2 and COX13 that are important for oxidative phosphorylation and mismatch repair pathway were significant, which may be some of the reasons for the induction of apoptosis in DHCHE-treated U. virens. The protein levels of Fip1, ACP1, PMS2 and COX13 agreed with protein fold change ratio from parallel reaction monitoring Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathway of differentially expressed proteins were further analyzed. These findings will help to elucidate the mechanisms associated with antifungal and pro-apoptotic effects of DHCHE on U. virens, thereby aiding the potential development of novel pesticides.