Search

Trichomes are specialized epidermal cells that play multiple roles in plant development. However, knowledge about the molecular mechanism of trichome development in rice is limited. In this study, a hairy leaf locus HL6 SWWR of rice variety Suwangwanger (SWWR) was identified by map-based cloning. Transgenic complementation and knock-out mutation demonstrated that HL6SWWR regulated trichomes on leaves and expression levels of HL6SWWR affected trichome elongation. Transgenic experiments of PROSWWR:HL6NIP and PRONIP:HL6SWWR indicated that the promoter and coding sequences of HL6SWWR were indispensable for trichome regulation. Sequencing alignment of the promoter and coding regions of HL6 in 22 varieties showed that some cis-binding elements in the promoter region may be related to trichome development, while no decisive variation was found in the coding sequence. Furthermore, RNA-sequencing analysis revealed that 1 415 differential expression genes (DEGs) were detected in hl6SWWR mutant vs wild type and that 1 010 DEGs were found in HL6SWWR complementary transgenic line vs wild type. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that most of the DEGs were involved in metabolite pathway, secondary metabolite biosynthesis, plant pathogen interaction and phytohormone signal transduction in both the two groups. The results indicated that these enhanced pathways are critical during trichome development in rice. Taken together, our results provided new views into the regulatory mechanism of trichome formation in rice.

Rice blast is one of the most devastating diseases, causing a significant reduction in global rice production. Developing and utilizing resistant varieties has proven to be the most efficient and cost-effective approach to control blasts. However, due to environmental pressure and intense pathogenic selection, resistance has rapidly broken down, and more durable resistance genes are being discovered. In this paper, a novel wall-associated kinase (WAK) gene, Pb4, which confers resistance to rice blast, was identified through a genome-wide association study (GWAS) utilizing 249 rice accessions. Pb4 comprises an N-terminal signal peptide, extracellular GUB domain, EGF domain, EGF-Ca2+ domain, and intracellular Ser/Thr protein kinase domain. The extracellular domain (GUB domain, EGF domain, and EGF-Ca2+ domain) of Pb4 can interact with the extracellular domain of CEBiP. Additionally, its expression is induced by chitin and polygalacturonic acid. Furthermore, transgenic plants overexpressing Pb4 enhance resistance to rice blast. In summary, this study identified a novel rice blast-resistant gene, Pb4, and provides a theoretical basis for understanding the role of WAKs in mediating rice resistance against rice blast disease. [ABSTRACT FROM AUTHOR]

Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance. [ABSTRACT FROM AUTHOR]

Identification of grain shape genes can facilitate breeding of rice cultivars with optimal grain shape and appearance quality. In this study, we selected two rice germplasms, namely Longliheinuo-dwarf (LH) and N643, with different grain shape, to construct a genetic population for quantitative trait locus (QTL) analysis. A major QTL (qGS7), controlling the ratio of grain length to grain width, was mapped on the chromosome 7 in a BC1F4 line. By high-resolution linkage analysis, qGS7 was delimited to a 52.8 kb region including eight predicted genes. Through sequence alignment and real-time PCR expression analysis of these ORFs, ORF3 (LOC_Os07g42410) was selected as the candidate gene for further analysis. Single nucleotide polymorphisms (SNP) diversity analysis of ORF3 revealed that a single nucleotide deletion in the 7th exon resulted in a frameshift in parent LH and the parent in which a premature stop codon was identified. It was a rare mutation that caused grain shape difference. Real-time PCR analyses showed that the expression characteristics of ORF3 was in accordance with the development of spikelets. Of the 18 agronomic traits investigation in qGS7 near isogenic lines (NILs) showed that qGS7 not only changed grain shape but also affected plant height, panicle curvature, panicle length, the length of second leaf from the top, and chalkiness. [ABSTRACT FROM AUTHOR]

Water managements are the most effective agricultural practices for restraining cadmium (Cd) uptake and translocation in rice, which closely correlated with rhizosphere assembly of beneficial microbiome. However, the role of the assemblage of specific microbiota in controlling root-to-shoot Cd translocation in rice remains scarcely clear. The aim of this study was to ascertain how water managements shaped rhizosphere microbiome and mediated root-to-shoot Cd translocation. To disentangle the acting mechanisms of water managements, we performed an experiment monitoring Cd uptake and transport in rice and changes in soil microbial communities in response to continuously flooding and moistening irrigation. Continuously flooding changed rhizosphere microbial communities, leading to the increased abundance of anaerobic bacteria such as Clostridium populations. Weighted gene co-expression network analysis (WGCNA) showed that a dominant OTU163, corresponding to Clostridium sp. CSP1, exhibited a strong negative correlation with root-to-shoot Cd translocation. An integrated analysis of transcriptome and metabolome further indicated that the Clostridium -secreted butyric acid was involved in the regulation of phenylpropanoid pathway in rice roots. The formation of endodermal suberized barriers and lignified xylems was remarkably enhanced in the Clostridium -treated roots, which led to more Cd retained in root cell wall and less Cd in the xylem sap. Collectively, our results indicate that the development of root apoplastic barriers can be orchestrated by beneficial Clostridium strains that are assembled by host plants grown under flooding regime, thereby inhibiting root-to-shoot Cd translocation. [Display omitted] • Flooding-induced rhizosphere assembly of Clostridium populations. • Clostridium sp. CSP1 triggered the development of root apoplastic barriers. • Clostridium sp. CSP1 inhibited root-to-shoot Cd translocation. [ABSTRACT FROM AUTHOR]