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This study was conducted on the lesion-mimic mutant lm5, which was produced by mutagenesis of WYJ21 (WT) using ethyl methane sulfonate (EMS). The mutant lm5 was short in the seedling stage and displayed yellowish-brown disease-like spots on leaves that were yellowish-brown when the plant was at the tillering stage. The disease-like spots gradually grew larger as the plant grew until it reached maturity. Compared to WT, lm5 had considerably reduced the plant height, ear panicle length, tiller number, and 1000-grain weight. A single recessive gene was found to be in control of lm5, according to a genetic study. It was physically located 245 kb apart between the RM21160 and RM180 markers on chromosome 7. Using RiceData and other websites, analyze and sequence potential gene candidates. Exon 7 of LOC_Os07g10390 (OsLM5) was identified to have a mutation that changed the 1560 base from G to A, changing the 788 amino acids from Arg to Lys. The OsLM5 gene was found to be a new allele of the SPL5 gene, encoding the protein shear factor SF3b3. Studies showed that OsLM5 was localized in the nucleus, and OsLM5 was significantly expressed in leaves. Reactive oxygen species (ROS) accumulation occurred in the leaves and roots of mutant lm5, and qPCR results showed abnormal expression of genes related to chloroplast development as well as significantly increased expression of genes related to aging and disease course. The OsLM5 gene may have a significant impact on the regulation of apoptosis in rice cells. [ABSTRACT FROM AUTHOR]

Extreme weather and global warming are drastic agricultural issues causing water scarcity. Under these conditions, it is vital to select drought-tolerant hybrid super rice breeds to enhance the rice yield in dry areas. In the current study, a dry-shed experiment was carried out in 2019–2020 to analyze the root growth, gene expression, and enzyme activity of hybrid rice Deyou4727, its parent (Dexiang074B * Chenghui727), taking IR64 as a universal control. Results showed that Deyou4727 and its maintainer line Dexiang074B produced more roots (30–50 cm soil) and higher enzymatic activity than IR64 during the drought stress period, indicating a good drought-tolerant capacity for Deyou4727. The distribution and morphology of the root system in Deyou4727 were inherited by the maintainer line Dexiang074B, which was confirmed by the high upregulation of DRO1 and OsPIN1b gene expression and the sharing of the same ORF region in both the hybrid rice varieties. However, the DRO1 gene ORF study showed that, in the case of the control IR64, 'A' was missing at the 4th exon of the DRO1 gene, which may explain the shallow and weak root architecture system of IR64. The drought-tolerance capacity of Deyou4727 can be used in the future as a drought-resistant germplasm for breeding more drought-tolerant hybrid rice varieties. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most important cereal crops in the world. The identification of sd1 mutants in rice resulted in a semi-dwarf phenotype that was used by breeders to improve yields. Investigations of sd1 mutants initiated the "green revolution" for rice and staved off famine for many people in the 1960s. The smaller plant height conferred by sd1 allele gives the plants lodging resistance even with a high amount of nitrogen fertilizer. Guang-chang-ai-carrying sd1 was the first high-yielding rice variety that capitalized on the semi-dwarf trait, aiming to significantly improve the rice yield in China. IR8, known as the miracle rice, was also bred by using sd1. The green revolution gene sd1 in rice has been used for decades, but was not identified for a long time. The SD1 gene encodes the rice Gibberellin 20 oxidase-2 (GA20ox2). As such, the SD1 gene is instrumental in uncovering the molecular mechanisms underlying gibberellin biosynthesis There are ten different alleles of SD1. These alleles are identified by genome sequencing within several donor lines in breeding for semi-dwarf rice. Apart from breeding applications and the molecular mechanism of GA biosynthesis, the SD1 gene is also involved in the molecular regulation of other important agronomic traits, like nitrogen fertilizer utilization. The dentification of new alleles of SD1 can be obtained by mutagenesis and genome editing. These new alleles will play an important role in improving the resource diversity of semi-dwarf breeding in the future. [ABSTRACT FROM AUTHOR]

Incorporating oilseed-rape straw in soil is one of the effective methods for enhancing the use efficiency of agricultural resources in the rape-rice rotation system. However, the impacts of oilseed-rape straw incorporation on root growth and dynamic changes in soil are still unclear. In order to provide a deeper understanding of the oilseed rape straw return on rice growth and productivity, the experiment was conducted in the field and in a specially-designed pots system from 2016 to 2017 by means of two straw returning methods and four straw returning amounts. In the early stage of rice growth (0–36 days after rice transplanting) the straw returning treatments decreased 1.0–8.6 mg/plant in bleeding density and 0.10–6.11, 0.06–0.31, and 0.52–0.84 μmol/(g h) in the activity of glutamine synthetase (GS), glutamic-oxalacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT), respectively. Oilseed rape straw returned by mulching induced negative impacts on new germinating roots in 0–10 cm of soil, while the negative impacts were observed on roots in 10–30 cm of soil for straw returned by plowing. In the later stage of rice growth (56–75 days after rice transplanting), oilseed rape straw returning produced some positive impacts on rice roots, which enhanced the yield of rice. Conclusively, our findings suggested that dynamic root growth and the activity of root enzymes are two major factors behind the slow reviving of rice after transplanting in the straw returning field. Plowing is a more appropriate method of straw returning than mulching in the rape-rice rotation system in the Sichuan basin area, with a straw incorporation rate of 3.0 t/hm2. [ABSTRACT FROM AUTHOR]

Light is one of the most important environmental factors that affect many aspects of plant growth, including chlorophyll (Chl) synthesis and flowering time. Here, we identified a rice mutant, yellow leaf and early flowering (ye1), and characterized the gene YE1 by using a map-based cloning method. YE1 encodes a heme oxygenase, which is localized to the chloroplasts. YE1 is expressed in various green tissues, especially in leaves, with a diurnal-rhythmic expression pattern, and its transcripts is also induced by light during leaf-greening. The mutant displays decreased Chl contents with less and disorderly thylakoid lamellar layers in chloroplasts, which reduced the photosynthesis rate. The early flowering phenotype of ye1 was not photoperiod-sensitive. Furthermore, the expression levels of Chl biosynthetic genes were downregulated in ye1 seedlings during de-etiolation responses to light. We also found that rhythmic expression patterns of genes involved in photoperiodic flowering were altered in the mutant. Based on these results, we infer that YE1 plays an important role in light-dependent Chl biogenesis as well as photoperiodic flowering pathway in rice. [ABSTRACT FROM AUTHOR]