MicroRNA transcriptomic analysis of the sixth leaf of maize (Zea mays L.) revealed a regulatory mechanism of jointing stage heterosis

Abstract

Background Zhengdan 958 (Zheng 58 × Chang 7–2), a commercial hybrid that is produced in a large area in China, is the result of the successful use of the heterotic pattern of Reid × Tang-SPT. The jointing stage of maize is the key period from vegetative to reproductive growth, which determines development at later stages and heterosis to a certain degree. MicroRNAs (miRNAs) play vital roles in the regulation of plant development, but how they function in the sixth leaf at the six-leaf (V6) stage to influence jointing stage heterosis is still unclear. Result Our objective was to study miRNAs in four hybrid combinations developed in accordance with the Reid × Tang-SPT pattern, Zhengdan 958, Anyu 5 (Ye 478 × Chang 7–2), Ye 478 × Huangzaosi, Zheng 58 × Huangzaosi, and their parental inbred lines to explore the mechanism related to heterosis. A total of 234 miRNAs were identified in the sixth leaf at the V6 stage, and 85 miRNAs were differentially expressed between the hybrid combinations and their parental inbred lines. Most of the differentially expressed miRNAs were non-additively expressed, which indicates that miRNAs may participate in heterosis at the jointing stage. miR164, miR1432 and miR528 families were repressed in the four hybrid combinations, and some miRNAs, such as miR156, miR399, and miR395 families, exhibited different expression trends in different hybrid combinations, which may result in varying effects on the heterosis regulatory mechanism. Conclusions The potential targets of the identified miRNAs are related to photosynthesis, the response to plant hormones, and nutrient use. Different hybrid combinations employ different mature miRNAs of the same miRNA family and exhibit different expression trends that may result in enhanced or repressed gene expression to regulate heterosis. Taken together, our results reveal a miRNA-mediated network that plays a key role in jointing stage heterosis via posttranscriptional regulation.

Gene Expression Variation Explains Maize Seed Germination Heterosis

“…Gene expression divergence of mRNAs, miRNAs, and tRFs were shown to explain the superior vigor in hybrids compared to their parental lines [43,44]. It is interesting to nd that most differently expressed mRNAs were higher expressed in hybrids, wherever miRNAs were largely repressed [36].…”

Gene expression variation explains maize seed germination heterosis

“…Gene expression divergence of mRNAs and miRNAs were shown to explain the superior vigor in hybrids compared to their parental lines [ 44 , 45 ]. It is interesting to find that most differently expressed mRNAs were higher expressed in hybrids, wherever miRNAs were largely repressed [ 37 ].…”

Non-coding RNA expression analysis revealed the molecular mechanism of flag leaf heterosis in inter-subspecific hybrid rice

“…In recent years, several ncRNAs and their corresponding regulatory networks have been proved to play important roles in plant growth and development ( Ohtani, 2017 ; Yuan et al, 2018 ; Luan et al, 2019 ; Wang et al, 2020 ; Zhai et al, 2020 ; Chand Jha et al, 2021 ; Qiao et al, 2021 ). However, there are few studies on the role of ncRNA in plant heterosis so far, which have been conducted in maize and cabbage ( Crisp et al, 2020 ; Hou et al, 2020 ; Li et al, 2021 ). As a hybrid rice with high yield potential, indica × japonica hybrid rice has always been an important material for heterosis research ( Xiong et al, 2021 ; Zhang, 2022 ).…”

“…Analysis of miRNA expression profiles in maize and Chinese cabbage suggested the potential contribution of miRNA-mediated regulatory networks to heterosis ( Hou et al, 2020 ; Li et al, 2021 ). Regrettably, there are few studies on the molecular mechanism of miRNA-mediated regulatory networks and rice heterosis.…”