Explore the vast range of titles available.

Plant architecture is the key factor affecting overall yield in many crops. The genetic basis underlying plant architecture in rapeseed (Brassica napus), a key global oil crop, is elusive. We characterized an ethyl methanesulfonate (EMS)-mutagenized rapeseed mutant, sca, which had multiple phenotypic alterations, including crinkled leaves, semi-dwarf stature, narrow branch angles and upward-standing siliques. We identified the underlying gene, which encodes an Aux/IAA protein (BnaA3.IAA7). A Gto-A mutation changed the glycine at the 84th position to glutamic acid (G84E), disrupting the conserved degron motif GWPPV and reducing the affinity between BnaA3.IAA7 and TIR1 (TRANSPORT INHIBITOR RESPONSE 1) in an auxin dosage-dependent manner. This change repressed the degradation of BnaA3.IAA7 and therefore repressed auxin signaling at low levels of auxin that reduced the length of internodes. The G84E mutation reduced branch angles by enhancing the gravitropic response. The heterozygote +/sca closely resembled a proposed ideal plant architecture, displaying strong yield heterosis through single-locus overdominance by improving multiple component traits. Our findings demonstrate that a weak gain-of-function mutation in BnaA3.IAA7 contributes to yield heterosis by improving plant architecture and would be valuable for breeding superior rapeseed hybrid cultivars and such a mutation may increase the yield in other Brassica crops.

The mechanisms underlying heterosis have long remained a matter of debate, despite its agricultural importance. How changes in transcriptional networks during plant development are relevant to the continuous manifestation of growth vigor in hybrids is intriguing and unexplored. Here, we present an integrated high-resolution analysis of the daily dynamic growth phenotypes and transcriptome atlases of young Arabidopsis seedlings (parental ecotypes [Col-0 and Per-1] and their F₁ hybrid). Weighted gene coexpression network analysis uncovered divergent expression patterns between parents of the network hub genes, in which genes related to the cell cycle were more highly expressed in one parent (Col-0), whereas those involved in photosynthesis were more highly expressed in the other parent (Per-1). Notably, the hybrid exhibited spatiotemporal high-parent–dominant expression complementation of network hub genes in the two pathways during seedling growth. This suggests that the integrated capacities of cell division and photosynthesis contribute to hybrid growth vigor, which could be enhanced by temporal advances in the progression of leaf development in the hybrid relative to its parents. Altogether, this study provides evidence of expression complementation between fundamental biological pathways in hybrids and highlights the contribution of expression dominance in heterosis.

Due to technological limitations for the development of onion hybrids, first-cycle synthetic varieties (Syn1-SV) could be an alternative to partially explore heterotic vigor. The growing areas of onion hybrids in Brazilare mainly defined by bulb yield and uniformity. From this perspective, the present study aimed to developtropical onion Syn1-SV and estimate mid-parent heterosis (Hm), heterobeltiosis (Hp), and standard heterosis(Hs) as an alternative to hybrid development. Six Syn1-SVs, eight open-pollinated (OP) populations, and onecommercial hybrid were evaluated in a randomized block design with three replications, in two semesters, forthe commercial bulb yield (CBY) and days to bulb harvest (DBH). Significant differences were observed fortreatments (T), semesters (S) and the T*S interaction for both variables (p-value<0.05). The OPs ‘Alfa SF RT’ inthe first semester and ‘IPA11’ in the second semester were the most precocious treatments. The highest CBYwas estimated in the commercial hybrid (105.8 t ha-1) and in ‘Alfa SF RT’ (45.5 t ha-1) in the first and secondsemesters, respectively. Three Syn1-SVs showed positive Hm values, ranging from 2.0% to 6.3% for CBY. ThreeSyn1-SV showed positive Hp values in the first semester, ranging from 3.0% to 5.2%, for CBY. Only the Syn1-SV ‘AlfaSF RT’ × ‘BRS Alfa São Francisco’ (48.9 t ha-1) showed positive Hs values, surpassing by a small value the controlOP population ‘IPA11’ (48.0 t ha-1), indicating the potential of Syn1-SV as an option for onion hybrids.

Heterosis, or hybrid vigor, describes the superior performance of F 1 hybrids relative to their parents. Despite its significant importance in crop breeding, the molecular mechanisms underlying heterosis remain debated, mainly attributable to discrepancies across genotypes, traits, tissues, populations, developmental stages, growth environments, and species. This study systematically identifies heterosis‐associated genes and metabolites from parental molecular differences and functionally validates three genes to heterosis for seedling length in rice. The predominant inheritance patterns of these molecules are additive and partially dominant effects, namely at mid‐parent levels or values between mid‐parent and parental levels, respectively. These two genetic effects contribute to heterosis of 17 agronomic traits in rice, including grain yield and plant height across developmental stages. They also explain yield heterosis in diverse hybrid populations and distinct growth environments in both rice and maize, as well as biomass heterosis in Arabidopsis . Notably, additive and partially dominant effects are associated with parental genomic variants, and the number of these variants correlates significantly with heterosis. Unlike classical heterosis models primarily focused on genomic sequence variation, these findings provide quantitative insights from genomic downstream information into the molecular mechanisms of plant heterosis, highlighting their potential for improving breeding efficiency of hybrid crops.

Heterosis (or hybrid vigor) is a natural phenomenon whereby hybrid offspring of genetically diverse individuals display improved physical and functional characteristics relative to their parents. Heterosis has been increasingly applied in crop production for nearly a century, with the aim of developing more vigorous, higher yielding and better performing cultivars. In this review we present and compare three categories of crop heterosis utilization: intraspecific heterosis, intersubspecific heterosis and wide-hybridization heterosis, with particular focus on polyploid species. Different pollination-control systems used to breed for heterosis are also comparatively analyzed. Finally, we highlight problems involved in heterosis research and crop improvement. We aim to provide insight into best practices for amplifying heterosis potential.

The utilization of heterosis is a successful strategy in increasing yield for many crops. However, it consumes tremendous manpower to test the combining ability of the parents in fields. Here, we applied the genomic-selection (GS) strategy and developed models that significantly increase the predictability of heterosis by introducing the concept of a regional parental genetic-similarity index (PGSI) and reducing dimension in the calculation matrix in a machine-learning approach. Overall, PGSI negatively affected grain yield and several other traits but positively influenced the thousand-seed weight of the hybrids. It was found that the C subgenome of rapeseed had a greater impact on heterosis than the A subgenome. We drew maps with overviews of quantitative-trait loci that were responsible for the heterosis (h-QTLs) of various agronomic traits. Identifications and annotations of genes underlying high impacting h-QTLs were provided. Using models that we elaborated, combining abilities between an Ogu-CMS-pool member and a potential restorer can be simulated in silico, sidestepping laborious work, such as testing crosses in fields. The achievements here provide a case of heterosis prediction in polyploid genomes with relatively large genome sizes.

Heterosis is most frequently manifested by the substantially increased vigorous growth of hybrids compared with their parents. Investigating genomic variations in natural populations is essential to understand the initial molecular mechanisms underlying heterosis in plants. Here, we characterized the genomic architecture associated with biomass heterosis in 200 Arabidopsis hybrids. The genome-wide heterozygosity of hybrids makes a limited contribution to biomass heterosis, and no locus shows an obvious overdominance effect in hybrids. However, the accumulation of significant genetic loci identified in genomewide association studies (GWAS) in hybrids strongly correlates with better-parent heterosis (BPH). Candidate genes for biomass BPH fall into diverse biological functions, including cellular, metabolic, and developmental processes and stimulus-responsive pathways. Important heterosis candidates include WUSCHEL, ARGOS, and some genes that encode key factors involved in cell cycle regulation. Interestingly, transcriptomic analyses in representative Arabidopsis hybrid combinations reveal that heterosis candidate genes are functionally enriched in stimulus-responsive pathways, including responses to biotic and abiotic stimuli and immune responses. In addition, stimulus-responsive genes are repressed to low-parent levels in hybrids with high BPH, whereas middle-parent expression patterns are exhibited in hybrids with no BPH. Our study reveals a genomic architecture for understanding the molecular mechanisms of biomass heterosis in Arabidopsis, in which the accumulation of the superior alleles of genes involved in metabolic and cellular processes improve the development and growth of hybrids, whereas the overall repressed expression of stimulus-responsive genes prioritizes growth over responding to environmental stimuli in hybrids under normal conditions.

Spider plant (Gynandropsis gynandra) is a leafy vegetable rich in micronutrients, including minerals, vitamins, and secondary metabolites, making it a valuable opportunity crop for combating hidden hunger and promoting human health. However, knowledge of the inheritance of mineral content is limited, which hinders the development of improved cultivars for wider cultivation. To address this, 118 F.sub.1 experimental hybrids involving 26 parental lines were generated from a North Carolina mating design II. The F.sub.1 s and their parents were evaluated across two years (2019 and 2020) for gene action, combining ability effects and heterosis of leaf mineral (zinc, copper, manganese, calcium, magnesium, sodium, phosphorus, and potassium) content. Significant differences (p < 0.001) were observed among and between hybrids and parents for iron, zinc, copper, manganese, calcium, magnesium, sodium, phosphorus, and potassium contents. The genotype x year interaction was also significant, with variance greater than the genotypic variance. Significant general and specific combining ability effects, together with variance components analysis, revealed that both additive and nonadditive gene action controlled mineral content, with a predominance of nonadditive gene action. Mid- and best-parent heterosis ranged from -80.4% to 389.5% for mineral content. Parents with good general combining ability were identified, as well as crosses with high specific combining ability and heterosis. There were significant and moderate to strong correlations between mean hybrid performance, specific combining ability effects, and heterosis levels, and low to moderate correlations between general combining ability and the performance of the mean parents. We conclude that hybridization in G. gynandra contributes to improving the mineral content. G. gynandra can be used as a model crop to study the genetic mechanism underlying heterosis in leafy vegetables.

Global food security demands the development and delivery of new technologies to increase and secure cereal production on finite arable land without increasing water and fertilizer use. There are several options for boosting wheat yields, but most offer only small yield increases. Wheat is an inbred plant, and hybrids hold the potential to deliver a major lift in yield and will open a wide range of new breeding opportunities. A series of technological advances are needed as a base for hybrid wheat programmes. These start with major changes in floral development and architecture to separate the sexes and force outcrossing. Male sterility provides the best method to block self-fertilization, and modifying the flower structure will enhance pollen access. The recent explosion in genomic resources and technologies provides new opportunities to overcome these limitations. This review outlines the problems with existing hybrid wheat breeding systems and explores molecular-based technologies that could improve the hybrid production system to reduce hybrid seed production costs, a prerequisite for a commercial hybrid wheat system.