A comprehensive dynamic immune acetylproteomics profiling induced by Puccinia polysora in maize.

Lysine-ε-acetylation (Kac) is a reversible post-translational modification that plays important roles during plant-pathogen interactions. Some pathogens can deliver secreted effectors encoding acetyltransferases or deacetylases into host cell to directly modify acetylation of host proteins. However, the function of these acetylated host proteins in plant-pathogen defense remains to be determined. Employing high-resolution tandem mass spectrometry, we analyzed protein abundance and lysine acetylation changes in maize infected with Puccinia polysora (P. polysora) at 0 h, 12 h, 24 h, 48 h and 72 h. A total of 7412 Kac sites from 4697 proteins were identified, and 1732 Kac sites from 1006 proteins were quantified. Analyzed the features of lysine acetylation, we found that Kac is ubiquitous in cellular compartments and preferentially targets lysine residues in the -F/W/Y-X-X-K (ac)-N/S/T/P/Y/G- motif of the protein, this Kac motif contained proteins enriched in basic metabolism and defense-associated pathways during fungal infection. Further analysis of acetylproteomics data indicated that maize regulates cellular processes in response to P. polysora infection by altering Kac levels of histones and non-histones. In addition, acetylation of pathogen defense-related proteins presented converse patterns in signaling transduction, defense response, cell wall fortification, ROS scavenging, redox reaction and proteostasis. Our results provide informative resources for studying protein acetylation in plant-pathogen interactions, not only greatly extending the understanding on the roles of acetylation in vivo, but also providing a comprehensive dynamic pattern of Kac modifications in the process of plant immune response.

Cloning southern corn rust resistant gene RppK and its cognate gene AvrRppK from Puccinia polysora.

Broad-spectrum resistance has great values for crop breeding. However, its mechanisms are largely unknown. Here, we report the cloning of a maize NLR gene, RppK, for resistance against southern corn rust (SCR) and its cognate Avr gene, AvrRppK, from Puccinia polysora (the causal pathogen of SCR). The AvrRppK gene has no sequence variation in all examined isolates. It has high expression level during infection and can suppress pattern-triggered immunity (PTI). Further, the introgression of RppK into maize inbred lines and hybrids enhances resistance against multiple isolates of P. polysora, thereby increasing yield in the presence of SCR. Together, we show that RppK is involved in resistance against multiple P. polysora isolates and it can recognize AvrRppK, which is broadly distributed and conserved in P. polysora isolates.

Hierarchically Hybrid Porous Co3O4@NiMoO4/CoMoO4 Heterostructures for High-Performance Electrochemical Energy Storage.

Hierarchical, ultrathin, and porous NiMoO4@CoMoO4 on Co3O4 hollow bones were successfully designed and synthesized by a hydrothermal route from the Co-precursor, followed by a KOH (potassium hydroxide) activation process. The hydrothermally synthesized Co3O4 nanowires act as the scaffold for anchoring the NiMoO4@CoMoO4 units but also show more compatibility with NiMoO4, leading to high conductivity in the heterojunction. The intriguing morphological features endow the hierarchical Co3O4@NiMoO4@CoMoO4 better electrochemical performance where the capacity of the Co3O4@NiMoO4@CoMoO4 heterojunction being 272 mA·h·g-1 at 1 A·g-1 can be achieved with a superior retention of 84.5% over 1000 cycles. The enhanced utilization of single/few NiMoO4@CoMoO4 shell layers on the Co3O4 core make it easy to accept extra electrons, enhancing the adsorption of OH- at the shell surface, which contribute to the high capacity. In our work, an asymmetric supercapacitor utilizing the optimized Co3O4@NiMoO4@CoMoO4 activated carbon (AC) as electrode materials was assembled, namely, Co3O4@NiMoO4@CoMoO4//AC device, yielding a maximum high energy density of 53.9 W·h·kg-1 at 1000 W·kg-1. It can retain 25.92 W·h·kg-1 even at 8100 W·kg-1, revealing its potential and viability for applications. The good power densities are ascribed to the porous feature from the robust architecture with recreated abundant mesopores on the composite, which assure improved conductivity and enhanced diffusion of OH- and also the electron transport. The work demonstrated here holds great promise for synthesizing other heterojunction materials M3O4@MMoO4@MMoO4 (M = Fe, Ni, Sn, etc).

The RppC-AvrRppC NLR-effector interaction mediates the resistance to southern corn rust in maize.

Southern corn rust (SCR), caused by the fungal pathogen Puccinia polysora, is a major threat to maize production worldwide. Efficient breeding and deployment of resistant hybrids are key to achieving durable control of SCR. Here, we report the molecular cloning and characterization of RppC, which encodes an NLR-type immune receptor and is responsible for a major SCR resistance quantitative trait locus. Furthermore, we identified the corresponding avirulence effector, AvrRppC, which is secreted by P. polysora and triggers RppC-mediated resistance. Allelic variation of AvrRppC directly determines the effectiveness of RppC-mediated resistance, indicating that monitoring of AvrRppC variants in the field can guide the rational deployment of RppC-containing hybrids in maize production. Currently, RppC is the most frequently deployed SCR resistance gene in China, and a better understanding of its mode of action is critical for extending its durability.

Genetic dissection of maize plant architecture using a novel nested association mapping population.

The leaf angle (LA), plant height (PH), and ear height (EH) are key plant architectural traits influencing maize (Zea mays L.) yield. However, their genetic determinants have not yet been well-characterized. Here, we developed a maize advanced backcross-nested association mapping population in Henan Agricultural University (HNAU-NAM1) comprised of 1,625 BC1 F4 /BC2 F4 lines. These were obtained by crossing a diverse set of 12 representative inbred lines with the common GEMS41 line, which were then genotyped using the MaizeSNP9.4K array. Genetic diversity and phenotypic distribution analyses showed considerable levels of genetic variation. We obtained 18-88 quantitative trait loci (QTLs) associated with LA, PH, and EH by using three complementary mapping methods, named as separate linkage mapping, joint linkage mapping, and genome-wide association studies. Our analyses enabled the identification of ten QTL hot-spot regions associated with the three traits, which were distributed on nine different chromosomes. We further selected 13 major QTLs that were simultaneously detected by three methods and deduced the candidate genes, of which eight were not reported before. The newly constructed HNAU-NAM1 population in this study will further broaden our insights into understanding of genetic regulation of plant architecture, thus will help to improve maize yield and provide an invaluable resource for maize functional genomics and breeding research.

High-quality genome assembly of Huazhan and Tianfeng, the parents of an elite rice hybrid Tian-you-hua-zhan.

High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding. Tian-you-hua-zhan has been a leading hybrid in China over the past decade. Here, de novo genome assembly strategy optimization for the rice indica lines Huazhan (HZ) and Tianfeng (TF), including sequencing platforms, assembly pipelines and sequence depth, was carried out. The PacBio and Nanopore platforms for long-read sequencing were utilized, with the Canu, wtdbg2, SMARTdenovo, Flye, Canu-wtdbg2, Canu-SMARTdenovo and Canu-Flye assemblers. The combination of PacBio and Canu was optimal, considering the contig N50 length, contig number, assembled genome size and polishing process. The assembled contigs were scaffolded with Hi-C data, resulting in two "golden quality" rice reference genomes, and evaluated using the scaffold N50, BUSCO, and LTR assembly index. Furthermore, 42,625 and 41,815 non-transposable element genes were annotated for HZ and TF, respectively. Based on our assembly of HZ and TF, as well as Zhenshan97, Minghui63, Shuhui498 and 9311, comprehensive variations were identified using Nipponbare as a reference. The de novo assembly strategy for rice we optimized and the "golden quality" rice genomes we produced for HZ and TF will benefit rice genomics and breeding research, especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.

Identification and fine-mapping of RppCML496, a major QTL for resistance to Puccinia polysora in maize.

Southern corn rust (SCR), which is caused by the fungal pathogen Puccinia polysora Underw, is a prevalent foliar disease in maize. Breeding for resistant cultivars is a desirable way for the efficient control of this disease. To identify quantitative trait loci (QTL) for conferring resistance to SCR, a recombinant inbred population including 138 lines (RILs) derived from the SCR-resistant line CML496 and susceptible line Lx9801 was evaluated for phenotypic reaction to SCR in three trials in two locations over 2 years. The population was genotyped with the maize 9.4K SNP Genotyping Array marker platform. A total of 3 QTL were mapped on chromosomes 6, 9 and 10, respectively. One major QTL on chromosome 10 (bin 10.00/10.01), RppCML496, was consistently detected across environments, which explained 43-78% of the total phenotypic variation. Using a fine mapping strategy, we delimited RppCML496 to an interval of 128 Kb. Genome mining of this region suggests two candidate genes, and a NBS-LRR gene is the promising one for RppCML496 against SCR. The tightly linked molecular markers developed in this study can be used for molecular breeding of resistance to SCR in maize.

Identification and Fine Mapping of qSCR4.01, a Novel Major QTL for Resistance to Puccinia polysora in Maize.

Southern corn rust (SCR) is a prevalent foliar disease that can lead to severe yield losses in maize. Growing SCR-resistant varieties is the most effective way to control the disease. To identify major quantitative trait loci (QTLs) for SCR resistance, a recombinant inbred line population derived from a cross between CIMBL83 (resistant) and Lx9801 (susceptible) was analyzed. The resistance to SCR had high heritability within the population, and a major QTL on chromosome 4 (qSCR4.01), which can explain 48 to 65% of the total phenotypic variation, was consistently detected across multiple environments. Using a progeny-based fine-mapping strategy, we delimited qSCR4.01 to an interval of ∼770 kb. In contrast to other major QTLs for SCR resistance previously reported on the short arm of chromosome 10, qSCR4.01 is a novel QTL and, therefore, a desirable source of SCR resistance in maize breeding programs.

New QTL for resistance to Puccinia polysora Underw in maize.

Southern corn rust (SCR) is a prevalent foliar disease in maize. Deployment of resistant cultivars is an effective way to control SCR. In this study, resistance to SCR was evaluated in a BC1RIL population comprising 118 lines grown under three different field conditions. Combined with a genetic map constructed from 1635 SNP markers obtained from the maize 9.4 K SNP Affymetrix® Axiom® Genotyping Array, single quantitative trait loci (QTL) were mapped on chromosomes 4, 9, and 10, respectively. The QTL on chromosome 4 (qSCR4.08) and chromosome 9 (qSCR9.04) were stable across multiple environments, and each explained more than 10% of the phenotypic variation. The stable QTL detected could be desirable sources of SCR resistance in maize-breeding programs.