Auxin plays a crucial role in all aspects of plant growth and development. Auxin can induce the rapid and efficient expression of some genes, which are named auxin early response genes (AERGs), mainly including the three families: auxin/indole‐3‐acetic acid (Aux/IAA), Gretchen Hagen 3 (GH3), and small auxin-up RNA (SAUR). Aux/IAA encodes the Aux/IAA protein, which is a negative regulator of auxin response. Aux/IAA and auxin response factor (ARF) form a heterodimer and participate in a variety of physiological processes through classical or non-classical auxin signaling pathways. The GH3 encodes auxin amide synthetase, which catalyzes the binding of auxin to acyl-containing small molecule substrates (such as amino acids and jasmonic acid), and regulates plant growth and stresses by regulating auxin homeostasis. SAURs is a class of small auxin up-regulated RNAs. SAUR response to auxin is complex, and the process may occur at the transcriptional, post-transcriptional and protein levels. With the development of multi-omics, significant progress has been made in the study of Aux/IAA, GH3, and SAUR genes, but there are still many unknowns. This review offers insight into the characteristics of Aux/IAA, GH3, and SAUR gene families, and their roles in roots, hypocotyls, leaves, leaf inclinations, flowers, seed development, stress response, and phytohormone crosstalk, and provides clues for future research on phytohormone signaling and the molecular design breeding of crops.

Maize (Zea mays L.) is a global cereal crop whose demand is projected to double by 2050. Along with worsening of farmland salinization, salt stress has become a major environmental threat to the sustainability of maize production worldwide. Accordingly, there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize. As salt tolerance is a complex trait regulated by multiple genes, and maize germplasm varies widely in salt tolerance, efforts have been devoted to the identification and application of quantitative-trait loci (QTL) for salt tolerance. QTL associated with ion regulation, osmotic tolerance, and other aspects of salt tolerance have been discovered using genome-wide association studies (GWAS), linkage mapping, and omics-based approaches. This review highlights recent advances in the molecular-level understanding of salt stress response in maize, in particular in (a) the discovery of salt-tolerance QTL, (b) the mechanisms of salt tolerance, (c) the development of salt-tolerant maize cultivars, and (d) current challenges and future prospects.

The Saccharum genus comprises species with large and variable chromosome numbers, leading to challenges in genomic studies and breeding improvement. Cytogenetics, including classical and molecular approaches, has played a central role in deciphering the genome structure, classification, and evolution of the genus Saccharum. The application of fluorescence in situ hybridization using oligonucleotide probes significantly improved our understanding of the complex genomes of Saccharum species. This paper reviews the application and progress of cytogenetic techniques in Saccharum. Future applications of cytogenetics are discussed, as they could benefit both genomic studies and breeding of sugarcane as well as other plants with complex genomes.

Plant glutamine synthetase (GS, EC6.3.1.2) catalyzes the synthesis of glutamine from glutamate and ammonium ions and acts as a key enzyme in the nitrogen metabolic pathway in organisms. Nitrogen is an essential element for plant growth and development and plays an important role in crop yield and quality formation. Therefore, GS is crucial in many physiological processes in plants. Currently, nitrogen regulation by GS in plants is well-studied in terms of its effect on plant growth and development. This article reviews the regulatory role of plant GS and its molecular mechanism in mitigating stress injury, such as low or high temperature, salinity, drought and oxidation. The function of plant GS in stress tolerance response is focused. The review aims to provide a reference for the utilization of plant GS in crop stress tolerance breeding.

Heterosis, which describes the superior vigor and yield of F₁ hybrids with respect to their parents, is observed in many rice hybrid crosses. The exploitation of heterosis is a great leap in the history of rice breeding. With advances in genomics and genetics, high-resolution mapping and functional identification of heterosis-associated loci have been performed in rice. Here we summarize advances in understanding the genetic basis of grain yield heterosis in hybrid rice and provide a vision for the genetic study and breeding application of rice heterosis in the future.

Plants and viruses coexist in the natural ecosystem for extended periods of time, interacting with each other and even coevolving, maintaining a dynamic balance between plant disease resistance and virus pathogenicity. During virus-host interactions, plants often exhibit abnormal growth and development. However, plants do not passively withstand virus attacks but have evolved sophisticated and effective defense mechanisms to resist, limit, or undermine virus infections. It is widely believed that the initial stage of infection features the most intense interactions between the virus and the host and the greatest variety of activated signal transduction pathways. This review describes the most recent findings in rice antiviral research and discusses a variety of rice antiviral molecular mechanisms, including those based on R genes and recessive resistance, RNA silencing, phytohormone signaling, autophagy and WUS-mediated antiviral immunity. Finally, we discuss the challenges and future prospects of breeding rice for enhanced virus resistance.

Flowering time is an important agronomic trait for soybean yield and adaptation. However, the genetic basis of soybean adaptation to diverse latitudes is still not clear. Four NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED 2 (LNK2) homeologs of Arabidopsis thaliana LNK2 were identified in soybean. Three single-guide RNAs were designed for editing the four LNK2 genes. A transgene-free homozygous quadruple mutant of the LNK2 genes was developed using the CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9). Under long-day (LD) conditions, the quadruple mutant flowered significantly earlier than the wild-type (WT). Quantitative real-time PCR (qRT-PCR) revealed that transcript levels of LNK2 were significantly lower in the quadruple mutant than in the WT under LD conditions. LNK2 promoted the expression of the legume-specific E1 gene and repressed the expression of FT2a. Genetic markers were developed to identify LNK2 mutants for soybean breeding. These results indicate that CRISPR/Cas9-mediated targeted mutagenesis of four LNK2 genes shortens flowering time in soybean. Our findings identify novel components in flowering-time control in soybean and may be beneficial for further soybean breeding in high-latitude environments.

The characterization of agronomically important genes has great potential for the improvement of wheat. However, progress in wheat genetics and functional genomics has been impeded by the high complexity and enormous size of the wheat genome. Recent advances in genome sequencing and sequence assembly have produced a high-quality genome sequence for wheat. Here, we suggest that the strategies used to characterize biological mechanisms in model species, including mutant preparation and characterization, gene cloning methods, and improved transgenic technology, can be applied to wheat biology. These strategies will accelerate progress in wheat biology and promote wheat breeding program development. We also outline recent advances in wheat functional genomics. Finally, we discuss the future of wheat functional genomics and the rational design-based molecular breeding of new wheat varieties to contribute to world food security.

This study was aimed at developing a protocol for increasing the number of generation cycles per year in chickpea (Cicer arietinum L.). Six accessions, two each from early (JG 11 and JG 14), medium (ICCV 10 and JG 16), and late (CDC-Frontier and C 235) maturity groups, were used. The experiment was conducted for two years under glasshouse conditions. The photoperiod was extended to induce early flowering and immature seeds were germinated to further reduce generation cycle time. Compared to control, artificial light caused a reduction in flowering time by respectively 8-19, 7-16, and 11-27 days in early-, medium-, and late-maturing accessions. The earliest stage of immature seed able to germinate was 20-23 days after anthesis in accessions of different maturity groups. The time period between germination and the earliest stage of immature seed suitable for germination was considered one generation cycle and spanned respectively 43-60, 44-64, and 52-79 days in early-, medium-, and late-maturing accessions. However, the late-maturing accession CDC-Frontier could not be advanced further after three generation cycles owing to the strong influence of photoperiod and temperature. The mean total number of generations produced per year were respectively 7, 6.2, and 6 in early-, medium-, and late-maturing accessions. These results have encouraging implications for breeding programs: rapid progression toward homozygosity, development of mapping populations, and reduction in time, space and resources in cultivar development (speed breeding).

Common wheat is the major cereal crop that underpins the food safety of China. Both winter wheat and spring wheat are grown on ~24?million?ha. This review aims to summarize the current status of wheat production and breeding progress in the northern wheat production areas of the country, and to review recently advanced technologies being applied in wheat breeding, including the use of dwarf-male-sterile (DMS) wheat, speed breeding and specialized wheat breeding SNP chips. Crossing is the initial step in most breeding programs. DMS wheat is a convenient tool for large scale production of hybrid seed. Speed breeding or accelerated generation turnover attempts to reduce the time taken in cultivar development. Several different SNP chips are high-throughput, genome-wide genotyping platforms for breeding and research.

Common wheat is an important and widely cultivated food crop throughout the world. Much progress has been made in regard to wheat genome sequencing in the last decade. Starting from the sequencing of single chromosomes/chromosome arms whole genome sequences of common wheat and its diploid and tetraploid ancestors have been decoded along with the development of sequencing and assembling technologies. In this review, we give a brief summary on international progress in wheat genome sequencing, and mainly focus on reviewing the effort and contributions made by Chinese scientists.