Search Results (29)

The glycemic index (GI) of rice is a complex trait, affected by amylose content (AC), size, and packaging of starch granules (SGs). In this study, the electron microscopy results of starch morphology of nine rice genotypes showed varying AC (6.93–36.9%), and the predicted GI (pGI: 41.07–82.46) in relation to genetic factors revealed that smaller SG surface area (20.06 µm²) and irregular morphology (Hap 3-3 P-11, pGI = 41.07) were associated with a lower pGI, while larger SG surface area (47.68 µm²) and spherical structure were associated with a higher pGI (NON-HAI, pGI = 82.46). The expression of starch biosynthesis and packaging-related genes (OsSSIIb, OsSSIIc, OsSBEIIa, OsISA1, OsISA3, OsGBP, OsFLO6, and OsBT1) revealed downregulation of OsGBP and OsISA3 genes in low pGI lines IRRI-147 (pGI = 56.2) and Hap 3-1-p-18 (pGI = 41.79), respectively, while higher levels of expression of the OsBT1 gene in Makro (pGI = 59.06) and OsSSIIb in Swarna (pGI = 58.06) were observed. All these genotypes had similar AC (~30%), but the difference in expression pattern was correlated with starch granule morphology, suggesting its role in influencing pGI. Further, analysis of allelic variation in eight starch-related genes across 20 rice genotypes showed that allelic variants of only OsGBP were correlated with AC, where allele group 2 showed lower AC (9.62%), while all other allele groups showed consistently high AC (22–24%). These findings underscore the critical role of starch granule morphology and OsGBP allelic variation in determining AC and GI, providing actionable insights for developing low GI rice varieties using tools like CRISPR. Full article

The development of a new salt–alkaline-tolerant hybrid japonica rice is crucial for enhancing japonica rice supply and ensuring national food security. Utilizing molecular marker-assisted selection (MAS) technology combining Kompetitive Allele-Specific PCR (KASP) markers and a gene breeding chip, the salt-tolerant gene SKC1 was introgressed into a rice genotype Fan 14. This led to the development of Shenyanhui 1, a new high-quality, strongly heterotic, and salt-tolerant japonica restorer line. Subsequently, the high-quality, salt-tolerant japonica three-line hybrid rice variety Shenyanyou 1 was developed by crossing the BT-type japonica cytoplasmic male sterile (CMS) line Shen 21A with the restorer line Shenyanhui 1. Shenyanyou 1 carries the major salt tolerance gene SKC1, exhibiting excellent salt tolerance with seedling stage salt tolerance reaching level 5. Under precise salt tolerance evaluation throughout its growth cycle, Shenyanyou 1 achieved a yield of 3640.5 kg/hm², representing an extremely significant increase of 20.7% over the control variety Yandao 21. Shenyanyou 1 exhibits superior grain quality, meeting the Grade 3 high-quality rice standards issued by the Ministry of Agriculture. Shenyanyou 1 has good comprehensive resistance, aggregating rice blast resistance genes such as Pi2, Pita, Pizt and LHCB5, bacterial blight resistance genes Xa26/Xa3, stripe blast resistance gene STV11, semi-dwarf gene Sdt97, nitrogen-efficient utilization gene NRT1.1B, the light repair activity enhancement gene qUVR-10, the cold resistance gene qLTG3-1, and the iron tolerance gene OsFRO1. It has good resistance to biotic and abiotic stresses. This paper details the breeding process, key agronomic traits, salt tolerance, yield performance, and grain quality characteristics of Shenyanyou 1. Full article

The combination of Chinsurah Boro II (BT)-type cytoplasmic male sterility (CMS) and Rf1, the main fertility restorer gene (Rf) for CMS-BT, has been extensively utilized for the production of three-line commercial japonica hybrid seeds. The identification of new Rf genes holds significance for the breeding of BT-type restorer lines, aiming to enhance the heterosis level of BT-type japonica hybrids. In the present study, ‘02428’, a wide-compatibility japonica variety, was observed to partially restore fertility to BT-type CMS lines. Genetic analysis revealed that ‘02428’ carries a dominant Rf gene, Rf21(t), responsible for the fertility restoration of BT-type CMS lines. Leveraging bulked segregant analysis (BSA) resequencing technology and molecular markers, the Rf21(t) locus was identified, and mapped within a candidate interval of 6–12.5 Mb on chromosome 2. Using the iso-cytoplasmic restorer populations, Rf21(t) was ultimately mapped to an interval of approximately 77 kb, encompassing 12 predicted genes, including LOC_Os02g17360, encoding a PPR-domain-containing protein and LOC_Os02g17380 (Rf2), a cloned Rf for Lead-rice-type CMS. A comparative sequence analysis, gene expression profiling and gene knockout experiments confirmed that LOC_Os02g17360 and LOC_Os02g17380 are the most likely candidates of Rf21(t). Furthermore, Rf21(t) showed the dosage effect on the fertility restoration of BT-type CMS lines. This newly identified Rf21(t) represents a valuable genetic resource for the breeding of BT-type japonica restorer lines. Our findings offer practical insights for breeders interested in advancing BT-type japonica hybrid development. Full article

Weak seedlings and poor growth uniformity affect the mechanical transplanting of densely sown rice seedlings. To address these issues, seedlings of the conventional japonica rice “Zhehexiang 2” were grown in a traditional flat tray (control), pot-mat tray (26 × 52 bowls; BT(26)), and pot-mat tray (30 × 58 bowls; BT(30)) to compare the effects of different specifications of pot-mat trays (BTs) on the growth and quality of mechanical transplanting of densely sown rice seedlings with 250 g/tray. The BT-raised seedlings showed improved seedling quality, with increases in the shoot and root dry weights by 7.44% and 20.11%, respectively, compared to the flat tray. Under the dense sowing rate, the plant height uniformity of the BT(26) and BT(30) treatments was significantly increased by 6.95% and 3.43%, and the root entwining force of the seedlings was 14.28% and 10.21% higher, respectively, compared with those of the control. The missing hill rate for BT-raised seedlings after mechanical transplanting was significantly reduced by 53.15%. The loss of roots during mechanical transplanting was reduced. Compared with the control, the root length, root surface area, and root number were increased, and a greater number of large roots were retained, which promoted the early development of seedlings after mechanical transplanting. The proportion of holes with two to five seedlings was higher after mechanical transplanting. The pot-mat tray divided the root growth area of seedlings, promoted the growth of the seedlings, and reduced the root loss and missing hill rate under the high sowing rate. Thus, the quality of mechanical transplanting of densely sown seedlings was improved. Full article

The incorporation of Bacillus thuringiensis (Bt) rice straw into fields may influence the growth of subsequent crops, but its ecological risks for winter vegetables remain largely unreported. Investigating the effects of Bt rice straw extracts on the seed germination and plant growth of pakchoi (Brassica campestris L. ssp. Chinensis Makino var. communis Tsen et Lee) can provide a theoretical foundation for ecological risk assessments. In this study, straw extracts from non-Bt rice (Tianyouhuazhan), homozygous Bt rice (T775), and heterozygous Bt rice (F₁ of T775 hybrid) were used as experimental materials at concentrations of 10, 20, and 40 g·L⁻¹. Results showed that, compared to non-Bt extract, 40 g·L⁻¹ homozygous Bt extract increased seedling height and leaf peroxidase (POD) activity but inhibited catalase (CAT) and root superoxide dismutase (SOD) activities. The 20 g·L⁻¹ extract boosted root CAT activity yet suppressed leaf CAT and POD activities. The 10 g·L⁻¹ extract enhanced root length but reduced leaf CAT and POD activities. The 40 g·L⁻¹ heterozygous Bt extract increased leaf and root POD activity but inhibited germination rate and leaf SOD activity. The 10 g·L⁻¹ extract promoted root length and seedling POD activity but suppressed leaf POD activity. In plant growth assessments, the 10 g·L⁻¹ homozygous Bt extract reduced underground dry weight, and the 10 g·L⁻¹ heterozygous Bt extract inhibited both above and underground dry weight, while the 20 g·L⁻¹ heterozygous Bt extract increased aboveground dry weight. In conclusion, the effects of homozygous and heterozygous Bt rice straw extracts on pakchoi varied with concentration and physiological indices, showing no clear pattern. Optimizing straw return concentrations based on Bt rice variety differences is essential to mitigate ecological risks. Full article

Food grain production has multiplied over the last two decades in India, but natural resources are overexploited in modern farming. Farmers, especially those with small and marginal holdings, are suffering losses more often than not, the cost of production is increasing year after year, and profits are not up to the necessary levels. To address such challenges, there has been a broad recognition of the importance of employing farming system approaches in research. The cultivation of cropping systems with orchard crops and livestock components can play a significant role in the optimal utilization of resources, enhancing energy use efficiency as well as the eco-efficiency index, and reducing carbon footprints. This study was carried out to create a suitable IFS model with high economic and energy efficiency for small-holder farmers in India’s southern plateau and hills with a negligible impact on the environment. The following were the seven models: M₁: Rice − Groundnut; M₂: Rice − Groundnut, Pigeonpea + Sweetcorn (1:3) − Bajra, Bt cotton + Greengram (1:2) − Maize; M₃: Rice − Groundnut, Pigeonpea + Sweetcorn (1:3) − Bajra, Pigeonpea + Maize (1:3) − Sunhemp; Napier grass, Sheep (5 + 1); M₄: Rice − Groundnut, Pigeonpea + Sweetcorn (1:3) − Bajra, Bt cotton + Greengram (1:2) − Maize, Pigeonpea + Maize (1:3) − Sunhemp, Poultry unit; M₅: Guava, Hedge Lucerne, Napier grass, Bt cotton + Greengram (1:2) − Maize, Sheep (5 + 1); M₆: Guava, Bt cotton + Greengram (1:2) − Maize, Rice − Groundnut, Poultry; M₇: Rice − Groundnut, Pigeonpea + Sweetcorn (1:3) − Bajra, Pigeonpea + Maize (1:3) − Sunhemp; Napier grass, Hedge lucerne, Poultry (100), Sheep (5 + 1). Model M₁ was used to represent the local region, and the other models were compared in terms of economics, energetics, greenhouse gas emissions, and employment creation. The M₇ and M₃ models, according to the results, have higher economic efficiency (₹342.3 day⁻¹, ₹263.7 day⁻¹), increase output energy (228,529 and 183,231 MJ) net energy (258,184 and 198,920 MJ), produce net negative emissions (−2842 and −2399 kg CO₂ eq.), and create jobs year-round (112.5 and 110.5 man days year⁻¹), respectively. This is primarily because they have multiple highly efficient components that make them viable for Telangana’s small and marginal farmers. Full article

Plants significantly shape root-associated microbiota, making rhizosphere microbes useful environmental indicator organisms for safety assessment. Here, we report the pyrosequencing of the bacterial 16S ribosomal RNA in rhizosphere soil samples collected from transgenic cry1Ab/cry1Ac Bt rice Huahui No. 1 (GM crop) and its parental counterpart, Minghui63. We identified a total of 2579 quantifiable bacterial operational taxonomic units (OTUs). Many treatment-enriched microbial OTUs were identified, including 14 NonGM-enriched OTUs and 10 GM-enriched OTUs. OTUs belonging to the phyla Proteobacteria, Actinobacteria, Acidobacteria, Firmicutes, Nitrospirae, Chlorobi and GN04 were identified as statistically different in abundance between GM and the other two treatments. Compared with the different impacts of different rice varieties on microbiota, the impact of rice planting on microbiota is more obvious. Furthermore, Huahui No. 1 transgenic Bt rice had a greater impact on the rhizosphere bacterial communities than Minghui63. Early developmental stages of the transgenic Bt rice had a significant impact on many Bacillaceae communities. Soil chemical properties were not significantly altered by the presence of transgenic Bt rice. The peak concentration level of Bt protein products was detected during the seedling stage of transgenic Bt rice, which may be an intriguing factor for bacterial diversity variations. Based on these findings, we conclude that transgenic Bt rice has a significant impact on root-associated bacteria. This information may be leveraged in future environmental safety assessments of transgenic Bt rice varieties. Full article

Excessive nitrogen application is a common phenomenon in rice production in China, which will lead to a low nitrogen utilization rate and increase farmers’ production costs. In Jingzhou, Hubei Province, for two consecutive years (2021, 2022), rice was planted with nursery-box total fertilization (NBTF) technology to provide technical support for rice seedling box contact fertilization technology. The results showed that, compared with the conventional treatment, the seedling emergence rate decreased by 7.70–11.87%, but the seedling quality significantly improved and the plant height significantly increased by 4.38–6.06% in the full-heading stage after the aforementioned treatments. The leaf area index significantly increased by 16.75–34.55%, 10.04–19.30%, and 12.13–18.60% in the tiller, booting, and full-heading stages, respectively, whereas the photosynthetic rate significantly increased by 3.80–5.25% in the booting stage. The rice yield under the 50% CRU and 50% CRU + S treatments was the same as that under the FFP treatment. The rice yield under 50% CRU + BT and 50% CRU + BT + S treatments was 7.50–10.61% higher than that under the FFP treatment; nitrogen partial factor productivity increased by 96.15–123.63%. NBTF combined with Boxingtanzhuang (in Chinese) seedling trays showed an increase in yield, whereas normal seedling trays showed a stable yield. It is suggested that the seedling tray and fertilizer should be specialized in the rice seedling box, and the height of the seedling tray should be increased by 3–5 cm. At the same time, special controlled-release urea should be selected to ensure less N release before emergence and improve the seedling emergence rate so as to popularize NBTF technology in a large area. Full article

Transgenic Bt rice (abbr. Bt rice) has provided a powerful tactics to control the striped stemborer Chilo suppressalis as one key lepidopteran pest in the paddyfields of China. Globally rising carbon dioxide (i.e., CO₂) concentration has been predicted to affect the Cry protein contents in plant tissues of Bt rice and thus might affect its control efficiency to target insect pests. To reveal the resistance ability and the corresponding mechanism of C. suppressalis to Bt rice during different growth stage under elevated CO₂ (eCO₂), we carried out this experiment to measure the Bt toxin contents in Bt rice stems grown under ambient CO₂ (aCO₂) (400 ppm) and eCO₂ (800 ppm) at seedling, tillering and heading stages, and to observe the larval mortality and bioassay the activity of midgut protease and the expression levels of Bt-toxin-receptor genes, aminopeptidases (APNs) in C. suppressalis larvae. Compared with aCO₂, eCO₂ increased the Bt-toxin content of Bt rice at seedling stage (+6.66%), and decreased that at heading stages (−13.99%), and significantly reduced the Bt-toxin content at tillering stage (−15.21%). And the larval mortality of C. suppressalis was lower as reared with Bt rice stems during tillering stage grown under eCO₂ in contrast to aCO₂. In addition, eCO₂ significantly increased the activity of total protease, tryptase-like enzyme and aminopeptidase of C. suppressalis larvae fed on Bt rice during seedling stage, and significantly reduced the activity of tryptase-like enzyme and aminopeptidase of C. suppressails larvae fed on Bt rice during tillering and heading stages respectively. Moreover, eCO₂ significantly increased the expression level of APN1 and APN5 of C. suppressails larvae fed on Bt rice during seedling stage, and significantly reduced the expression level of APN5 of C. suppressalis larvae fed on Bt rice during tillering and heading stages respectively. In summary, the control efficiency of Bt rice to target insect pests under eCO₂ showed a downward trend during tillering and heading stages, and especially during tillering stage. Full article

The safety and unintended effects of genetically modified (GM) crops have been the focus of public attention. Transcriptome analysis is a powerful tool to assess the potential impact of genetic modification on plant genomes. In this study, three transgenic (KMD, KF6, and TT51-1) and three non-transgenic (XS11, MH86, and MH63) rice varieties were assessed at the genomic and protein levels. The results of polymerase chain reaction (PCR) and Cry1Ab/1Ac speed test strips showed that the Bt gene was successfully expressed in transgenic rice. The results of RNA-seq analysis to analyze the unintended effects of transgenic Bt rice showed fewer differentially expressed genes (DEGs) between the transgenic and non-transgenic rice varieties than among the different varieties. Meanwhile, the results of principal component analysis and cluster analysis found no significant genetic variation between the transgenic and non-transgenic rice varieties, except for the presence of Bt in transgenic rice. There were only two co-upregulated DEGs and no co-downregulated DEGs among three comparison groups. Although there were various DEGs among the groups, the two co-upregulated DEGs were not related to any significantly enriched gene ontology (GO) term or Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, indicating that the differences among the subgroups were more likely caused by complex environmental or genetic factors, rather than unintended effects due to Bt expression. This study provides useful information to further explore the unexpected effects and safety of GM rice. Full article

Rice (Oryza sativa L.), one of the most important commodities and a primary food source worldwide, can be affected by adverse environmental factors. The chromosome segment substitution line 16 (CSSL16) of rice is considered salt-tolerant. A comparison of the transcriptomic data of the CSSL16 line under normal and salt stress conditions revealed 511 differentially expressed sequence (DEseq) genes at the seedling stage, 520 DEseq genes in the secondary leaves, and 584 DEseq genes in the flag leaves at the booting stage. Four BTB genes, OsBTBZ1, OsBTBZ2, OsBTBN3, and OsBTBN7, were differentially expressed under salt stress. Interestingly, only OsBTBZ1 was differentially expressed at the seedling stage, whereas the other genes were differentially expressed at the booting stage. Based on the STRING database, OsBTBZ1 was more closely associated with other abiotic stress-related proteins than other BTB genes. The highest expression of OsBTBZ1 was observed in the sheaths of young leaves. The OsBTBZ1-GFP fusion protein was localized to the nucleus, supporting the hypothesis of a transcriptionally regulatory role for this protein. The bt3 Arabidopsis mutant line exhibited susceptibility to NaCl and abscisic acid (ABA) but not to mannitol. NaCl and ABA decreased the germination rate and growth of the mutant lines. Moreover, the ectopic expression of OsBTBZ1 rescued the phenotypes of the bt3 mutant line and enhanced the growth of wild-type Arabidopsis under stress conditions. These results suggest that OsBTBZ1 is a salt-tolerant gene functioning in ABA-dependent pathways. Full article

As pests are an important factor in reducing crop yields, pest control is an important measure in preventing reductions in crop yields. With the aim of ending the use of chemical pesticides, biological control and genetically modified methods are now considered more reasonable pest control strategies. The bacterium Bacillus thuringiensis (Bt) can produce crystal proteins that have specific toxicity to lepidopteran insects, and so it has been applied as a microbial insecticide in the control of crop pests for several decades. With the development of plant genetic engineering, Bt genes encoding insecticidal crystal protein have been introduced into many crop species for pest control. This article indicates that, after years of experiments and research, Bt transgenic rice is close to becoming a commercial insect-resistant rice, and many studies have shown that transgenic rice has pronounced abilities in the control of pests such as yellow stem borers (Scirpophaga incertulas, YSB), striped stem borers (Chilo suppressalis, SSB), and rice leaf rollers (Cnaphalocrocis medinalis, RLR); moreover, it does not obviously differ from non-transgenic rice in terms of safety. This paper suggests that transgenic Bt rice has application potential and commercial value. Full article

The Magnaporthe oryzae Triticum (MoT) pathotype is the causal agent of wheat blast, which has caused significant economic losses and threatens wheat production in South America, Asia, and Africa. Three bacterial strains from rice and wheat seeds (B. subtilis BTS-3, B. velezensis BTS-4, and B. velezensis BTLK6A) were used to explore the antifungal effects of volatile organic compounds (VOCs) of Bacillus spp. as a potential biocontrol mechanism against MoT. All bacterial treatments significantly inhibited both the mycelial growth and sporulation of MoT in vitro. We found that this inhibition was caused by Bacillus VOCs in a dose-dependent manner. In addition, biocontrol assays using detached wheat leaves infected with MoT showed reduced leaf lesions and sporulation compared to the untreated control. VOCs from B. velezensis BTS-4 alone or a consortium (mixture of B. subtilis BTS-3, B. velezensis BTS-4, and B. velezensis BTLK6A) of treatments consistently suppressed MoT in vitro and in vivo. Compared to the untreated control, VOCs from BTS-4 and the Bacillus consortium reduced MoT lesions in vivo by 85% and 81.25%, respectively. A total of thirty-nine VOCs (from nine different VOC groups) from four Bacillus treatments were identified by gas chromatography–mass spectrometry (GC–MS), of which 11 were produced in all Bacillus treatments. Alcohols, fatty acids, ketones, aldehydes, and S-containing compounds were detected in all four bacterial treatments. In vitro assays using pure VOCs revealed that hexanoic acid, 2-methylbutanoic acid, and phenylethyl alcohol are potential VOCs emitted by Bacillus spp. that are suppressive for MoT. The minimum inhibitory concentrations for MoT sporulation were 250 mM for phenylethyl alcohol and 500 mM for 2-methylbutanoic acid and hexanoic acid. Therefore, our results indicate that VOCs from Bacillus spp. are effective compounds to suppress the growth and sporulation of MoT. Understanding the MoT sporulation reduction mechanisms exerted by Bacillus VOCs may provide novel options to manage the further spread of wheat blast by spores. Full article

In this study, Xiushui 134Bt, a highly insect-resistant rice transgenic material with stable expression of CryIAc1 gene in rice plants and no significant changes in main agronomic traits, was obtained by means of Agrobacterium-mediated transformation method using japonica rice Xiushui 134 as receptor material. Biosecurity of the transgenic rice Xiushui 134Bt was assessed by rat feeding experiments. Wistar rats were fed a nutritionally balanced diet supplemented with 35% Genetically Modified (LGM) or 70% Genetically Modified (HGM) Xiushui 134Bt, respectively, for 90 days. Compared with the wild-type group (Xiushui 134), there were no significant differences in body weight, total food intake, food conversion rate, relative organ weight, blood routine, blood physiological or biochemical parameters, or histopathological examination between LGM and HGM Bt groups (p > 0.05). These results indicate that the transgenic rice Xiushui 134Bt is non-toxic in laboratory animals and provide guidance for the future commercial release of the transgenic rice Xiushui 134Bt in China. Full article

Climate change is a very serious threat to the agricultural sector and potentially brings new problems to the sustainability of agricultural production systems. This paper aims to know how to improve crop yield by changing the nitrogen application ratio and sowing time under future climate change conditions based on the CERES-Rice model. The CERES-Rice model was calibrated and validated with a three-year field experiment (2018–2020), which was coupled with four N rates (50, 100, 150, and 200 kg/ha) and three different N ratios (B:T:S = 3:1:0; B:T:S = 5:3:2; B:T:S = 6:3:1). The results showed that the CERES-Rice model had better simulation effect on the phenophase (n-RMSE < 15%, d > 0.9 and R² = 0.978) and yield (n-RMSE < 10%, d > 0.9 and R² = 0.910) of double-harvest rice. The calibrated model was used to evaluate the growth period and yield of double-harvest rice under the RCP4.5 climate scenario and the results revealed that future yields of double-harvest rice in Nanchang are lower than those in experimental years, especially for early rice. Adjusting the nitrogen application ratio and sowing time can improve the yield of double-harvest rice to a certain extent, and the nitrogen application ratio of 5:3:2 has the best effect. In 2021–2035, the best yield of double-harvest rice can be obtained when the sowing date of early rice is about 15 days earlier and the sowing date of late rice is about 10 days earlier than the experiment year. From 2035 to 2050, the sowing date of early rice and late rice will be advanced by about 10 days, and the total yield of double-harvest rice will be higher. In 2050–2070, the total yield of double-harvest rice may reach the best when the sowing date is delayed by 10–15 days. Therefore, reasonably changing the sowing date of double-harvest rice and the nitrogen application regime of early rice can be used as a possible adaptive strategy to cope with the yield reduction in double-harvest rice in future climate scenarios. Full article