Huaiqing Hao

Sweet sorghum (Sorghum bicolor) displays an excellent potential to serve as a non-food bioenergy feedstock for bioethanol production in China due to its high potential yield on marginal lands. However, few studies have been conducted on the potential of sweet sorghum yield and appropriate industrial models in different marginal regions in China. This study explored the spatial distribution of potential sweet sorghum production using the Decision Support System for Agrotechnology Transfer (DSSAT) model and proposed three typical industrial models of sweet sorghum industry to calculate their economic and ecological benefits. The results indicate that considering the factors of land use, annual precipitation, soil salinity, soil pH, and accumulated temperature, approximately 32.23 million ha of marginal land are suitable for sweet sorghum cultivation in China, and 130 million tonnes (t) of ethanol can be produced. Further, the development of the sweet sorghum industry under the three models can generate 1425.49 billion CNY potential, approximately accounting for 3.57% of industrial added value in China if measured against 2023 levels, and reduce CO2 emissions by 4.68 million t. This study provides an innovative perspective for the multi-industry large-scale promotion of sweet sorghum in different marginal lands based on the high spatial resolution Geographic Information System (GIS) data by the DSSAT model with a Life Cycle Assessment (LCA) method, and this applies not only to China but also to the worldwide and other types of energy plants.

Darkness is often used as an effective measure to induce leaf senescence. Although many senescence-related genes in rice have been reported, the genome-wide genetic architecture underlying leaf senescence remains poorly understood. In our study, indica and japonica rice showed contrasting responses to dark-induced leaf senescence (DILS). Genome-wide association studies (GWAS) combined with transcriptomic analyses revealed 57, 97, and 48 loci involved in the regulation of the onset, progression, and ending of DILS, respectively. Haplotype analyses showed that the senescence-related loci differentially accumulated in indica and japonica accessions and functioned additively to regulate DILS. A total of 357 candidate genes were identified that are involved in various senescence-related processes such as lipid and amino acid catabolism, photosynthesis, response to reactive oxygen species, and regulation of defense response. In addition, functional analyses of the two candidate genes, OsMYB21 and OsSUB1B, revealed that OsMYB21 positively regulates the onset of DILS, while OsSUB1B negatively regulates its progression. Thus, our results provide new insights into the genetic regulation of DILS in rice.

Aerial root mucilage can enhance nitrogen fixation by providing sugar and low oxygen environment to the rhizosphere microbiome in Sierra Mixe maize. Aerial root mucilage has long been documented in sorghum (Sorghum bicolor), but little is known about the biological significance, genotypic variation, and genetic regulation of this biological process. In the present study, we found that a large variation of mucilage secretion capacity existed in a sorghum panel consisting of 146 accessions. Mucilage secretion occurred primarily in young aerial roots under adequately humid conditions but decreased or stopped in mature long aerial roots or under dry conditions. The main components of the mucilage-soluble were glucose and fructose, as revealed by sugar profiling of cultivated and wild sorghum. The mucilage secretion capacity of landrace grain sorghum was significantly higher than that of wild sorghum. Transcriptome analysis revealed that 1844 genes were upregulated and 2617 genes were downregulated in mucilage secreting roots. Amongst these 4461 differentially expressed genes, 82 genes belonged to glycosyltransferases and glucuronidation pathways. Sobic.010G120200, encoding a UDP-glycosyltransferase, was identified by both GWAS and transcriptome analysis as a candidate gene, which may be involved in the regulation of mucilage secretion in sorghum through a negative regulatory mechanism.

Key message Leaf senescence in sorghum is primarily controlled by the progression, but not by the onset of senescence. The senescence-delaying haplotypes of 45 key genes accentuated from landraces to improved lines. Abstract Leaf senescence is a genetically programmed developmental process and plays a central role for plant survival and crop production by remobilising nutrients accumulated in senescent leaves. In theory, the ultimate outcome of leaf senescence is determined by the onset and progression of senescence, but how these two processes contribute to senescence is not fully illustrated in crops and the genetic basis for them is not well understood. Sorghum (Sorghum bicolor), which is known for the remarkable stay-green trait, is ideal for dissecting the genomic architecture underlying the regulation of senescence. In this study, a diverse panel of 333 sorghum lines was explored for the onset and progression of leaf senescence. Trait correlation analysis showed that the progression of leaf senescence, rather than the onset of leaf senescence, significantly correlated with variations of the final leaf greenness. This notion was further supported by GWAS, which identified 31 senescence-associated genomic regions containing 148 genes, of which 124 were related to the progression of leaf senescence. The senescence-delaying haplotypes of 45 key candidate genes were enriched in lines with extremely prolonged senescence duration, while senescence-promoting haplotypes in those with extremely accelerated senescence. Haplotype combinations of these genes could well explain the segregation of the senescence trait in a recombinant inbred population. We also demonstrated that senescence-delaying haplotypes of candidate genes were under strong selection during sorghum domestication and genetic improvement. Together, this research advanced our understanding of crop leaf senescence and provided a suite of candidate genes for functional genomics and molecular breeding.

Background: As the fifth major cereal crop originated from Africa, sorghum (Sorghum bicolor) has become a key C₄ model organism for energy plant research. With the development of high-throughput detection technologies for various omics data, much multi-dimensional and multi-omics information has been accumulated for sorghum. Integrating this information may accelerate genetic research and improve molecular breeding for sorghum agronomic traits. Results: We updated the Sorghum Genome SNP Database (SorGSD) by adding new data, new features and renamed it to Sorghum Genome Science Database (SorGSD). In comparison with the original version SorGSD, which contains SNPs from 48 sorghum accessions mapped to the reference genome BTx623 (v2.1), the new version was expanded to 289 sorghum lines with both single nucleotide polymorphisms (SNPs) and small insertions/deletions (INDELs), which were aligned to the newly assembled and annotated sorghum genome BTx623 (v3.1). Moreover, phenotypic data and panicle pictures of critical accessions were provided in the new version. We implemented new tools including ID Conversion, Homologue Search and Genome Browser for analysis and updated the general information related to sorghum research, such as online sorghum resources and literature references. In addition, we deployed a new database infrastructure and redesigned a new user interface as one of the Genome Variation Map databases. The new version SorGSD is freely accessible online at http://ngdc.cncb.ac.cn/sorgsd/. Conclusions: SorGSD is a comprehensive integration with large-scale genomic variation, phenotypic information and incorporates online data analysis tools for data mining, genome navigation and analysis. We hope that SorGSD could provide a valuable resource for sorghum researchers to find variations they are interested in and generate customized high-throughput datasets for further analysis.

Key message Twelve QTL for flowering and leaf number were detected. The ZmWRKY14^Hap4 could increase leaf number, flowering time and biomass yield which are promising for silage maize breeding. Abstract Silage maize, one of the most important feedstock for ruminants, is widely grown from temperate regions to the tropics. Flowering time and leaf number are two significantly correlated traits and important for the quality, adaptation and biomass yield of silage maize. In this study, a recombinant inbred line population consisting of 215 individuals and an association panel of 369 inbred lines were analysed in field conditions in three locations for 2 consecutive years, and five, four and three quantitative trait loci for the total leaf number, days to anthesis (DTA) and silking (DTS) were detected, which could explain 48.55, 35.37 and 34.22% of total phenotypic variation, respectively. Association analysis of qLN10 on chromosome 10 found that ZmWRKY14 was the candidate gene for leaf number, whose expression level was negatively correlated with the leaf number. There are five haplotypes for ZmWRKY14, and haplotype 4 could significantly increase flowering time, leaf number and biomass yield, but has no obvious influence on ear weight. The optimal allelic combination of ZmWRKY14 and ZCN8 could further increase leaf number and biomass yield. The results will provide important genetic information for silage maize breeding.

BackgroundAs the fifth major cereal crop originated from Africa, sorghum (Sorghum bicolor) has become a key C₄ model organism for energy plant research. With the development of high-throughput detection technologies for various omics data, much multi-dimensional and multi-omics information has been accumulated for sorghum. Integrating this information may accelerate genetic research and improve molecular breeding for sorghum agronomic traits.ResultsWe updated the Sorghum Genome SNP Database (SorGSD) by adding new data, new features and renamed it to Sorghum Genome Science Database (SorGSD). In comparison with the original version SorGSD, which contains SNPs from 48 sorghum accessions mapped to the reference genome BTx623 (v2.1), the new version was expanded to 289 sorghum lines with both single nucleotide polymorphisms (SNPs) and small insertions/deletions (INDELs), which were aligned to the newly assembled and annotated sorghum genome BTx623 (v3.1). Moreover, phenotypic data and panicle pictures of critical accessions were provided in the new version. We implemented new tools including ID Conversion, Homologue Search and Genome Browser for analysis and updated the general information related to sorghum research, such as online sorghum resources and literature references. In addition, we deployed a new database infrastructure and redesigned a new user interface as one of the Genome Variation Map databases. The new version SorGSD is freely accessible online at https://bigd.big.ac.cn/sorgsd/.ConclusionsSorGSD is a comprehensive integration with large-scale genomic variation, phenotypic information and incorporates online data analysis tools for data mining, genome navigation and analysis. We hope that SorGSD could provide a valuable resource for sorghum researchers to find variations they are interested in and generate customized high-throughput datasets for further analysis.

Leaf senescence is important for crop yield as delaying it can increase the average yield. In this study, population genetics and transcriptomic profiling were combined to dissect its genetic basis in maize. To do this, the progenies of an elite maize hybrid Jidan27 and its parental lines Si-287 (early senescence) and Si-144 (stay-green), as well as 173 maize inbred lines were used. We identified two novel loci and their candidate genes, Stg3 (ZmATG18b) and Stg7 (ZmGH3.8), which are predicted to be members of autophagy and auxin pathways, respectively. Genomic variations in the promoter regions of these two genes were detected, and four allelic combinations existed in the examined maize inbred lines. The Stg3^Si-144/Stg7^Si-144 allelic combination with lower ZmATG18b expression and higher ZmGH3.8 expression could distinctively delay leaf senescence, increase ear weight and the improved hybrid of NIL-Stg3Si-144/Stg7Si-144 × Si-144 significantly reduced ear weight loss under drought stress, while opposite effects were observed in the Stg3^Si-287/Stg7^Si-287 combination with a higher ZmATG18b expression and lower ZmGH3.8 expression. Thus, we identify a potential interaction between autophagy and auxin which could modulate the timing of maize leaf senescence.

Key message The importance and potential of the multi-purpose crop sorghum in global food security have not yet been fully exploited, and the integration of the state-of-art genomics and high-throughput technologies into breeding practice is required. Abstract Sorghum, a historically vital staple food source and currently the fifth most important major cereal, is emerging as a crop with diverse end-uses as food, feed, fuel and forage and a model for functional genetics and genomics of tropical grasses. Rapid development in high-throughput experimental and data processing technologies has significantly speeded up sorghum genomic researches in the past few years. The genomes of three sorghum lines are available, thousands of genetic stocks accessible and various genetic populations, including NAM, MAGIC, and mutagenised populations released. Functional and comparative genomics have elucidated key genetic loci and genes controlling agronomical and adaptive traits. However, the knowledge gained has far away from being translated into real breeding practices. We argue that the way forward is to take a genome-based approach for tailored designing of sorghum as a multi-functional crop combining excellent agricultural traits for various end uses. In this review, we update the new concepts and innovation systems in crop breeding and summarise recent advances in sorghum genomic researches, especially the genome-wide dissection of variations in genes and alleles for agronomically important traits. Future directions and opportunities for sorghum breeding are highlighted to stimulate discussion amongst sorghum academic and industrial communities.