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The OsSPL16 (SQUAMOSA promoter-binding protein like 16) or GW8(Grain Width 8) gene is expressed specifically in developing seeds and positively controls grain width and weight by modulating cell proliferation and enlargement in the spikelet hull of rice. OsSPL16acts as the direct upstream suppressor of GW7(Grain Width 7), a gene responsible for grain slenderness. The down-regulation of the OsSPL16gene will effectively disrupt its interaction with the GW7gene, leading to the development of slender rice grains. In our investigation, we introduced grain slenderness to a bold grain-type rice cultivar, ASD16, by employing the CRISPR/Cas9 system to knock-out the function of the OsSPL16gene. Molecular analysis of spl16mutants unveiled the existence of mutations within the first exon of OsSPL16, which included in-frame and frame-shift mutations. Our results demonstrated that inducing frame-shift mutations in the coding sequence of the OsSPL16gene could effectively impart grain slenderness in bold grain varieties.

The thermosensitive genic male sterility (TGMS) system is widely used for hybrid rice cultivation. Male sterile lines are sensitive to temperature and this trait is controlled by the TMS5gene, encoding a nuclear ribonuclease Z (RNase ZS1) enzyme, which is involved in the degradation of ubiquitin fusion ribosomal protein L40 (UbL40) mRNAs. Mutation in the TMS5gene will lead to loss of function of RNase ZS1,resulting in accumulation of high levels of UbL40mRNAs, thereby causing male sterility. We developed tms5mutants through targeted mutagenesis of the TMS5gene via CRISPR/Cas9 technology in three rice genetic backgrounds, viz., CO51, ADT39, and ASD16. The tms5mutants exhibited pollen sterility percentages ranging from 2.05 to 91.1% and seed setting rates between 1.14 and 97.36% under restrictive temperature. This indicates that the mutants possess traces of fertile pollen due to incomplete suppression of RNase ZS1, resulting in partial fertility even under restrictive temperature. Hence, we conclude that the complete suppression of RNase ZS1activity in tms5mutants is necessary for using them as female parents in hybrid rice breeding programs.

Background: The rising demand for food production along with the concerns regarding the injudicious use of chemicals in pest management has paved way for the alternatives that could promise sustainable pest management. Bacillus thuringiensisBerliner (Bt), a soil bacterium, is a potential biopesticide with its ability to produce crystal toxins that are insecticidal in nature. Main body: This article provides an insight into the diverse Bttoxins and their applications as biopesticides in pest management. The selective action of Bttowards target organism is based on its specific interactions with the insect gut receptors. The significance of Btin the management of lepidopteran, coleopteran, hemipteran, dipteran and nematode pests of crops and livestock through its mode of action is extensively reviewed. Conclusion: Besides being a promising pest control option, the challenges faced through resistance development, variation in susceptibility across species and non-target effects of Btare also discussed. Proactive approaches and multiple modes of action can mitigate this issue.

Rice tungro disease (RTD) is caused by the joint infection of rice tungro bacilliform virus and rice tungro spherical virus (RTSV) and is the most important viral disease that limits rice production and productivity in major rice growing regions of South and Southeast Asia. Cultivars with RTSV resistance alone could significantly reduce RTD incidence in the fields. RTSV resistance is conferred by in-frame mutations in SVLFPNLAGKSYVV motif (mainly NL and YV residue) in translation initiation factor 4 gamma (eIF4G) gene. Here, we report CRISPR/Cas9-mediated genome editing to create novel in-frame mutations targeting this residue in indicarice. An average mutation efficiency of 46.19% was observed and 30 T0independent events had in-frame mutations in one of the alleles of eIF4Ggene. Twenty events with homozygous in-frame mutations were identified in T1generation. These mutations were faithfully inherited to T2generation. Bioassay on transgene-free homozygous T2mutants suggested that mutations specifically affecting the target residue could successfully confer resistance to RTD. These homozygous mutants did not have any unintended off-target editing and were agronomically similar in performance to their wild type counterpart.

A full-length cDNA of phyAgene of Aspergillus niger, encoding phytase enzyme, was cloned and expressed in E. coliBL21 cells and assayed for its activity. The phyA cDNA consisted of 1404 bp, which encoded 467 amino acid residues. The phytase activity of purified phytase was 826.33 U/mL. The phyAgene under the control of endosperm-specific promoters was transformed into an Indian maize inbred line, UMI29, using particle bombardment-mediated transformation method to generate transgenic maize plants over-expressing phytase in seeds. PCR and GUS analyses demonstrated the presence of transgenes in T0transgenic plants and their stable inheritance in the T1progenies. Three transgenic events expressing detectable level of A. nigerphytase were characterized by western blot analysis. Phytase activity of 463.158 U/kg of seed was observed in one of the events, JB-UMI29-Z17/2. The phytase activity of transgenic maize seeds was 5.5- to 7-fold higher than the wild-type UMI29 seeds and, consequently, the seeds had 0.6- to 5-fold higher inorganic phosphorus content.