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【Objective】Rice blast is an important limiting factor in rice production. Exploring and utilizing resistant genes is an important guarantee for achieving high and stable yield of rice. Previous studies have shown that rice blast resistance-related microRNA osa-miR-21 may regulate rice blast resistance by targeting the polyamine oxidase gene OsPAO4. However, the function of Polyamine Oxidases (PAOs) in rice disease resistance has not been reported. In order to further explore the possible biological function of OsPAO4 gene in rice disease resistance, the CRISPR/Cas9 editing technology was used for site-specific editing of ospao4 gene mutants and the edited offspring were also analyzed.【Method】A 20-bp editing target was designed in the second exon of OsPAO4, and the nucleotide fragments of the target was cloned into pRGEB32 vector to obtain OsPAO4 editing vector. Then, the rice Pik-H4 NIL callus was transformed by Agrobacterium-mediated method. Positive transgenic plants were obtained by regeneration culture and hygromycin detection, PCR and sequence analysis were performed on the DNA sequences near the target site in the T0 generation plants.【Result】The results show that the OsPAO4 gene was successfully edited and finally 25 transgenic-positive plants were obtained, and various mutation types were produced in the T0 generation, including 3 homozygous mutants, 18 heterozygous mutants and 4 nonedited plants. In addition, the glume color of the heterozygous mutation ospao4-8 of the T0 generation changed from purple to dark gray, and the activity of catalase (CAT) in the mutants was increased. It was predicted that OsPAO4 might participate in the basis immunization process.【Conclusion】A variety of ospao4 mutants were created in this study, and it was preliminarily determined that OsPAO4 might participate in the regulation of rice immune process, which laid an important foundation for further revealing the specific biological function and molecular regulation mechanism of OsPAO4 gene.

【Objective】IQD gene family proteins are plant specific calmodulin-binding target proteins, which play an important role in plant defense and development regulation. The interaction between Pik-H4 and OsIQD1 was found in the yeast double hybrid screening experiment in laboratory. In order to reveal the specific biological functions of OsIQD1 in rice blast resistance, OsIQD1 gene was edited by using CRISPR/Cas9 editing technique.【Method】OsIQD1 was obtained by sequence alignment. Two 20 bp editing targets were designed in exon 1 and exon 5 of OsIQD1 (DUF4005 domain), and the nucleotide fragments of the two targets were cloned into pRGEB32 vector to obtain pRGEB32-OsIQD1 -gRNA vector. The rice Pik-H4 NIL callus was transformed by agrobacterium-mediated method. Transgenic positive plants were obtained by regeneration culture and hygromycin resistance screening. PCR and sequencing were performed on the target region sequences of transgenic plants of T0 generation to analyze the mutation types of osiqd1.【Result】The transgenic regenerated plants were identified by PCR with hygromycin resistance gene HPT Ⅱ, and 30 positive lines were obtained. Sequencing analysis of the sequences near the target site of T0 generation plants showed that OsIQD1 gene was successfully edited, and the editing efficiency of the two sites was 21.67% and 26.67%, respectively. There was one homozygous mutant line in target 2 region.【Conclusion】The study results provide genetic material for further studies on the mechanism of osiqd1 mutation involved in calcium ion/calmodulin signaling pathway, and OsIQD1 is preliminarily presumed to be involved in the basic immune response of plants.

Bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is a bacterial disease affecting rice production in Asia and Africa, whose severity is expected to increase with climate change. Identification of new quantitative-trait loci (QTL) or resistance genes for BLS resistance is essential for developing resistant rice. A genome-wide association study to identify QTL associated with BLS resistance was conducted using phenotypic and genotypic data from 429 rice accessions. Of 47 QTL identified, 45 were novel and two co-localized with previously reported QTL or genes conferring BLS resistance. qBLS6.2 on chromosome 6 explained the greatest phenotypic variation. Combined analysis of differential expression and annotations of predicted genes near qBLS6.2 based on haplotype and disease phenotype identified OsBLS6.2 (LOC_Os06g02960) as a candidate gene for qBLS6.2. OsBLS6.2 knockout plants showed higher resistance to Xoc than wild-type plants. Many other candidate genes for resistance to Xoc were identified. [ABSTRACT FROM AUTHOR]