Identification, Analysis, and Confirmation of Seed Storability-Related Loci in Dongxiang Wild Rice (Oryza rufipogon Griff.)

Dongxiang wild rice (Oryza rufipogon Griff.) (DXWR) has strong seed storability and identifying its elite gene resources may facilitate genetic improvements in rice seed storability. In this study, we developed two backcross inbred lines (BILs) populations, with DXWR as a common donor parent and two rice varieties (F6 and R974) as recipient parents. Bulked segregant analysis via whole genome sequencing (BSA-seq) was used to identify seed storability-related loci in the DXWR and F6 population. Two main genomic regions containing 18,550,000–20,870,000 bp on chromosome 4 and 7,860,000–9,780,000 bp on chromosome 9 were identified as candidate loci of DXWR seed storability; these overlapped partially with seed storability-related quantitative trait loci (QTLs) discovered in previous studies, suggesting that these loci may provide important regions for isolating the responsible genes. In total, 448 annotated genes were predicted within the identified regions, of which 274 and 82 had nonsynonymous and frameshift mutations, respectively. We detected extensive metabolic activities and cellular processes during seed storability and confirmed the effects of the seed storability-related candidate loci using four BILs from DXWR and R974. These results may facilitate the cloning of DXWR seed storability-related genes, thereby elucidating rice seed storability and its improvement potential.

Identification, analysis, and confirmation of seed storability-related loci in Dongxiang wild rice (Oryza rufipogon Griff.)

Dongxiang wild rice (Oryza rufipogon Griff.) (DXWR) has strong seed storability and identifying its elite gene resources may facilitate genetic improvements in rice seed storability. In this study, we developed two backcross inbred lines (BILs) populations, with DXWR as a common donor parent and two rice varieties (F6 and R974) as recipient parents. Bulked segregant analysis via whole genome sequencing (BSAseq) was used to identify seed storability related loci in the DXWR and F6 population. Two main genomic regions containing 18,550,000 to 20,870,000 bp on chromosome 4 and 7,860,000 to 9,780,000 bp on chromosome 9 were identified as candidate loci of DXWR seed storability; these overlapped partially with seed storability related quantitative trait loci (QTLs) discovered in previous studies, suggesting that these loci may provide important regions for isolating the responsible genes. In total, 448 annotated genes were predicted within the identified regions, of which 274 and 82 had nonsynonymous and frameshift mutations, respectively. We detected extensive metabolic activities and cellular processes during seed storability and confirmed the effects of the seed storability related candidate loci using four BILs from DXWR and R974. These results may facilitate the cloning of DXWR seed storability-related genes, thereby elucidating rice seed storability and its improvement potential.

Development and verification of SSR markers from drought stress-responsive miRNAs in common wild rice

PREMISE: Dongxiang wild rice (Oryza rufipogon Griff., DXWR) is the northernmost common wild rice found in the world, which possesses abundant elite genetic resources. We developed a set of drought stress-responsive microRNA (miRNA)-based single sequence repeat (SSR) markers for DXWR, which will help breed drought stress-resistant rice varieties. METHODS AND RESULTS: Ninety-nine SSR markers were developed from the drought stress-responsive miRNAs of DXWR. The SSR loci were distributed in all 12 rice chromosomes and most were in chromosomes 2 and 6, with di- and trinucleotides being the most abundant repeat motifs. Nine out of ten synthesized SSR markers were displayed high levels of genetic diversity in the genomes of DXWR and 41 modern rice varieties worldwide. The number of alleles per locus ranged from 2 to 6, and the observed and expected heterozygosity ranged from 0.000 to 0.024 and 0.461 to 0.738, respectively. CONCLUSIONS: These SSR markers developed from drought stress-responsive miRNAs in DXWR could be additional tools for elite genes mapping and useful for drought stress-resistant rice breeding.

Diversity of Grass Species from Sendhwa Dist. Barwani (M.P.), India

The present study was aimed to determining Diversity of grass species of Sendhwa Dist. Barwani, Madhya Pradesh, India. Sendhwa is bestowed with unique diversity of ethnic culture and natural resource. The present study is based on diversity of grass species in Satpura region of Sendhwa Dist. Barwani, of Madhya Pradesh, India during the period of 2017-2020. This area is the representative of climax vegetation and rich in grass biodiversity. On the basis of grass utility three species are abundantly found along with 38 genera and 45 species are frequently occurred in Sendhwa dist. Barwani. The data from the primary and secondary sources resulted in the documentation of 45 species belonging to 38 genera. The study area has a rich species diversity of grasses. Present study observes some wild economically important grasses which are Brachiaria reptans (L.) Gard. & Hubb., Echinochloa colonum (L.) Link., Oryza rufipogon Griff., Pennesetum pedicelatum Trin. , Phragmites karka (Retz.) trin ex. Steud., Sporobolus capillaries Miq., Sorghum halepense (L.) Kuntz., Urochloa panicoides P.Beauv. This documentation will be helpful to the staff of Forest department and for better management of grasslands with special reference to wildlife habitat.

New Helvolic Acid Derivatives with Antibacterial Activities from Sarocladium oryzae DX-THL3, an Endophytic Fungus from Dongxiang Wild Rice (Oryza rufipogon Griff.)

Three new helvolic acid derivatives (named sarocladilactone A (1), sarocladilactone B (2) and sarocladic acid A (3a)), together with five known compounds (6,16-diacetoxy-25-hy- droxy-3,7-dioxy-29-nordammara-1,17(20)-dien-21-oic acid (3b), helvolic acid (4), helvolinic acid (5), 6-desacetoxy-helvolic acid (6) and 1,2-dihydrohelvolic acid (7)), were isolated from the endophytic fungus DX-THL3, obtained from the leaf of Dongxiang wild rice (Oryza rufipogon Griff.). The structures of the new compounds were elucidated via HR-MS, extensive 1D and 2D NMR analysis and comparison with reported data. Compounds 1, 2, 4, 5, 6 and 7 exhibited potent antibacterial activities. In particular, sarocladilactone B (2), helvolinic acid (5) and 6-desacetoxy-helvolic acid (6) exhibited strongly Staphylococcus aureus inhibitory activity with minimum inhibitory concentration (MIC) values of 4, 1 and 4 μg/mL, respectively. The structure–activity relationship (SAR) of these compounds was primarily summarized.

Isolation of Antimicrobial Genes from Oryza rufipogon Griff by Using a Bacillus subtilis Expression System with Potential Antimicrobial Activities

Antimicrobial genes are distributed in all forms of life and provide a primary defensive shield due to their unique broad-spectrum resistance activities. To better isolate these genes, we used the Bacillus subtilis expression system as the host cells to build Oryza rufipogon Griff cDNA libraries and screen potential candidate genes from the library at higher flux using built-in indicator bacteria. We observed that the antimicrobial peptides OrR214 and OrR935 have strong antimicrobial activity against a variety of Gram-positive and Gram-negative bacteria, as well as several fungal pathogens. Owing to their high thermal and enzymatic stabilities, these two peptides can also be used as field biocontrol agents. Furthermore, we also found that the peptide OrR214 (MIC 7.7–10.7 μM) can strongly inhibit bacterial growth compared to polymyxin B (MIC 5–25 μM) and OrR935 (MIC 33–44 μM). The cell flow analysis, reactive oxygen burst, and electron microscopy (scanning and transmission electron microscopy) observations showed that the cell membranes were targeted by peptides OrR214 and OrR935, which revealed the mode of action of bacteriostasis. Moreover, the hemolytic activity, toxicity, and salt sensitivity experiments demonstrated that these two peptides might have the potential to be used for clinical applications. Overall, OrR214 and OrR935 antimicrobial peptides have a high-throughput bacteriostatic activity that acts as a new form of antimicrobial agent and can be used as a raw material in the field of drug development.