Overdominance at the Gene Expression Level Plays a Critical Role in the Hybrid Root Growth of Brassica napus

Abstract

Despite heterosis contributing to genetic improvements in crops, root growth heterosis in rapeseed plants is poorly understood at the molecular level. The current study was performed to discover key differentially expressed genes (DEGs) related to heterosis in two hybrids with contrasting root growth performance (FO; high hybrid and FV; low hybrid) based on analysis of the root heterosis effect. Based on comparative transcriptomic analysis, we believe that the overdominance at the gene expression level plays a critical role in hybrid roots’ early biomass heterosis. Our findings imply that a considerable increase in up-regulation of gene expression underpins heterosis. In the FO hybrid, high expression of DEGs overdominant in the starch/sucrose and galactose metabolic pathways revealed a link between hybrid vigor and root growth. DEGs linked to auxin, cytokinin, brassinosteroids, ethylene, and abscisic acid were also specified, showing that these hormones may enhance mechanisms of root growth and the development in the FO hybrid. Moreover, transcription factors such as MYB, ERF, bHLH, NAC, bZIP, and WRKY are thought to control downstream genes involved in root growth. Overall, this is the first study to provide a better understanding related to the regulation of the molecular mechanism of heterosis, which assists in rapeseed growth and yield improvement.

Overdominant expression of genes plays a key role in root growth of tobacco hybrids

“…The application of transcriptome analysis in heterosis research has effectively revealed the molecular basis of heterosis in Arabidopsis ( Groszmann et al., 2015 ; Liu et al., 2021 ), rice ( Katara et al., 2020 ), corn ( Song et al., 2013 ; Guttikonda et al., 2020 ), cotton ( Shahzad et al., 2020 ), and soybean ( Zhang et al., 2017 ), but the molecular basis of heterosis in tobacco root growth has not been reported in the literature. In the early stage of tobacco growth, improved root development plays an important role in enhancing the absorption of nutrients and water by plants, promoting their growth and increasing their yield ( Zhang et al., 2020 ; Shalby et al., 2021 ). From this point of view, through comparative transcriptome analysis of roots, the genetic basis of root development heterosis of two strong heterosis hybrids and their parents was studied.…”

“…In most previous studies, heterosis is usually demonstrated in terms of biomass, yield, and stress resistance ( Fujimoto et al., 2018 ; Li et al., 2021 ). In recent years, however, some studies have shown that the level of heterosis in root traits may be higher than that in the overground part ( Ju et al., 2018 ; Dafna et al., 2021 ), and some efforts have been made to reveal the molecular mechanism of heterosis in root development ( Paschold et al., 2010 ; Shalby et al., 2021 ), which means that the root system may be the perfect organ to study the genetic basis of tobacco heterosis. Although there are several genetic models used to describe heterosis, including dominant, overdominant, and epistasis, but its molecular basis remains poorly understood ( Chen, 2013 ).…”

“…(2014) proposed two models of gene expression correlation: additive and non-additive expression patterns. In different crops, gene expression shows different additive and non-additive expression patterns ( Tian et al., 2018 ; Shahzad et al., 2020 ; Shalby et al., 2021 ). In recent years, a large number of transcriptome research advances have provided new insights into the molecular basis of heterosis in species such as Arabidopsis ( Fujimoto et al., 2012 ; Wang et al., 2019 ; Liu et al., 2020 ), rice ( Shao et al., 2019 ; Ren et al., 2020 ), maize ( Ko et al., 2016 ), and rape ( Xiong et al., 2022 ).…”

Comprehensive Analysis of NAC Genes Reveals Differential Expression Patterns in Response to Pst DC3000 and Their Overlapping Expression Pattern during PTI and ETI in Tomato

“…NAC (NAM, ATAF, and CUC) transcription factors (TFs), as one of the largest family of transcription factors in plants, comprise a complex plant-specific superfamily and presents in a wide range of species [ 4 , 6 ]. NAC TFs were found to function in various growth and development processes, including leaf or flower senescence [ 7 , 8 , 9 ], formation of cell wall [ 10 , 11 ], fruit ripening [ 12 , 13 , 14 ], root growth [ 15 ], etc. Besides, a large number of studies demonstrated that NAC TFs played important roles in abiotic and biotic stress responses, especially in crops.…”

Comparative transcriptomic reveals the molecular mechanism of maize hybrid Zhengdan538 in response to water deficit

“…With the development of high‐throughput nucleotide sequencing technology, transcriptome analysis has become an effective tool for studying crop heterosis and has been widely used to explore the molecular processes of hybrid vigor at the transcript regulation aspect in Arabidopsis thaliana , rice, maize, and other crops (Fu et al, 2022; Liu et al, 2020; Ma et al, 2018; Shalby et al, 2021; Sinha et al, 2020; Zhao et al, 2019). Recently, Shalby et al (2021) found that the overdominance at the gene expression level plays a critical role in hybrid roots early biomass heterosis of Brassica napus . Ma et al (2018) identified four important genes that were related to maize heterosis and high planting density by transcriptome analyses.…”