The integration of leaf-derived signals sets the timing of vegetative phase change in maize, a process coordinated by epigenetic remodeling

Comparison of meiotic transcriptomes of three maize inbreds with different origins reveals differences in cell cycle and recombination

Background

Cellular events during meiosis can differ between inbred lines in maize. Substantial differences in the average numbers of chiasmata and double-strand breaks (DSBs) per meiotic cell have been documented among diverse inbred lines of maize: CML228, a tropical maize inbred line, B73 and Mo17, temperate maize lines. To determine if gene expression might explain these observed differences, an RNA-Seq experiment was performed on CML228 male meiocytes which was compared to B73 and Mo17 male meiocytes, where plants were grown in the same controlled environment.

Results

We found that a few DSB-repair/meiotic genes which promote class I crossovers (COs) and the Zyp1 gene which limits newly formed class I COs were up-regulated, whereas Mus81 homolog 2 which promotes class II COs was down-regulated in CML228. Although we did not find enriched gene ontology (GO) categories directly related to meiosis, we found that GO categories in membrane, localization, proteolysis, energy processes were up-regulated in CML228, while chromatin remodeling, epigenetic regulation, and cell cycle related processes including meiosis related cell cycle processes were down-regulated in CML228. The degree of similarity in expression patterns between the three maize lines reflect their genetic relatedness: B73 and Mo17 had similar meiotic expressions and CML228 had a more distinct expression profile.

Conclusions

We found that meiotic related genes were mostly conserved among the three maize inbreds except for a few DSB-repair/meiotic genes. The findings that the molecular players in limiting class I CO formation (once CO assurance is achieved) were up-regulated and those involved in promoting class II CO formation were down-regulated in CML228 agree with the lower chiasmata number observed in CML228 previously. In addition, epigenetics such as chromatin remodeling and histone modification might play a role. Transport and energy-related processes was up-regulated and Cyclin13 was down-regulated in CML228. The direction of gene expression of these processes agree with that previously found in meiotic tissues compared with vegetative tissues. In summary, we used different natural maize inbred lines from different climatic conditions and have shown their differences in expression landscape in male meiocytes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08922-w.

The translatability of genetic networks from model to crop species: lessons from the past and perspectives for the future

Comparative analyses of growth-regulatory mechanisms between Arabidopsis and maize revealed that even when the gene space is conserved, the translation of knowledge from model species to crops is not trivial. Based on these insights, we formulate future opportunities to improve the interpretation of curiosity-driven research towards crop improvement.

LEAFY COTYLEDONs: Connecting different stages of plant development

The life of higher plants progresses successively through embryonic, juvenile, adult, and reproductive stages. LEAFY COTYLEDON (LEC) transcription factors, first discovered in Arabidopsis thaliana several decades ago, play a key role in regulating plant embryonic development, seed maturation, and subsequent growth. Existing studies have demonstrated that LECs together with other transcription factors form a huge and complex regulatory network to regulate many aspects of plant growth and development and respond to environmental stresses. Here, we focus on the role that has received little attention about the LECs linking different developmental stages and generational cycles in plants. We summarize the current fragmented research progress on the LECs role and molecular mechanism in connecting embryonic and vegetative growth periods and the reproductive stage. Furthermore, the possibility of LECs controlling the maintenance and transition of plant growth stages through epigenetic modifications is discussed.