New insights into light spectral quality inhibits the plasticity elongation of maize mesocotyl and coleoptile during seed germination

Abstract

The plastic elongation of mesocotyl (MES) and coleoptile (COL), which can be repressed by light exposure, plays a vital role in maize seedling emergence and establishment under adverse environmental conditions. Understanding the molecular mechanisms of light-mediated repression of MES and COL elongation in maize will allow us to develop new strategies for genetic improvement of these two crucial traits in maize. A maize variety, Zheng58, was used to monitor the transcriptome and physiological changes in MES and COL in response to darkness, as well as red, blue, and white light. The elongation of MES and COL was significantly inhibited by light spectral quality in this order: blue light > red light > white light. Physiological analyses revealed that light-mediated inhibition of maize MES and COL elongation was closely related to the dynamics of phytohormones accumulation and lignin deposition in these tissues. In response to light exposure, the levels of indole-3-acetic acid, trans-zeatin, gibberellin 3, and abscisic acid levels significantly decreased in MES and COL; by contrast, the levels of jasmonic acid, salicylic acid, lignin, phenylalanine ammonia-lyase, and peroxidase enzyme activity significantly increased. Transcriptome analysis revealed multiple differentially expressed genes (DEGs) involved in circadian rhythm, phytohormone biosynthesis and signal transduction, cytoskeleton and cell wall organization, lignin biosynthesis, and starch and sucrose metabolism. These DEGs exhibited synergistic and antagonistic interactions, forming a complex network that regulated the light-mediated inhibition of MES and COL elongation. Additionally, gene co-expression network analysis revealed that 49 hub genes in one and 19 hub genes in two modules were significantly associated with the elongation plasticity of COL and MES, respectively. These findings enhance our knowledge of the light-regulated elongation mechanisms of MES and COL, and provide a theoretical foundation for developing elite maize varieties with improved abiotic stress resistance.

Genetic Parameters in Mesocotyl Elongation and Principal Components for Corn in High Valleys, Mexico

“…Therefore, it can be said that the elongation of the mesocotyl of some crosses was positively associated, while others were not, with the expression of some traits, such as the number and weight of grain per cob and the production of dry matter in seedling and adult plants. In this regard, studies, such as [61], indicate that some genotypes show different genetic capacities for mesocotyl elongation in deep sowing while others do not, which leads to low emergence percentages and population density, with "re-sowing" being necessary, which increases production costs and negatively affects the grain yield [62]. This could be due to the darkness that persists in deep sowing and inhibits the LM of some seedlings from emerging, so some lines of corn within each sub-population are heterogeneous concerning their response patterns in the dark and light [61].…”

Integrated QTL Mapping, Meta-Analysis, and RNA-Sequencing Reveal Candidate Genes for Maize Deep-Sowing Tolerance

“…The physical map of all major QTLs, MQTLs, and candidate genes was constructed using MapInspect 1.0 ( ; accessed on 20 December 2022), and the physical length of each chromosome was obtained through B73 RefGen_v3 genome ( ; accessed on 20 December 2022). The expression profiles of candidate genes were performed using TBtools software ( ; accessed on 21 December 2022) [ 73 , 74 ].…”

“…The physical map of all major QTLs, MQTLs, and candidate genes was constructed using MapInspect 1.0 (https://mapinspect.software.informer.com/; accessed on 20 December 2022), and the physical length of each chromosome was obtained through B73 RefGen_v3 genome (https://www.maizegdb.org/genome/assembly/B73% 20RefGen_v3; accessed on 20 December 2022). The expression profiles of candidate genes were performed using TBtools software (https://github.com/CJ-Chen/TBtools/releases; accessed on 21 December 2022) [73,74]. 4.6. qRT-PCR Analysis 0.5 µg RNA was reverse-transcribed to synthesise first-stand cDNA using HiScript ® Q RT SuperMix for qPCR (Vazyme, China), according to the manufacturer's protocol.…”

The Mechanism of Exogenous Salicylic Acid and 6-Benzylaminopurine Regulating the Elongation of Maize Mesocotyl

“…Salicylic acid (SA) is a naturally occurring phenolic compound and a key signaling molecule that regulates various physiological and morphological responses in plants [19]. 6-benzylaminopurine (6-BA) is a synthetic cytokinin growth regulator, which plays an important regulatory role in plant growth and development and resistance to environmental stresses, such as drought, high temperature, low temperature, waterlogging and salt [20]. At present, the effects of exogenous SA and 6-BA on maize mesocotyls have not been reported.…”

“…Studies indicate that mesocotyl length is influenced by both genetic background and the external environment, with a complex genetic mechanism at play [ 5 ]. Some scholars suggest that light is an important environmental factor in the regulation of plant growth and development, and the length of the mesocotyl is related to light stimulation [ 6 ]. Light treatment can increase the activity of phytochrome-mediated PAO (polyamine oxidase) in maize mesocotyls, which in turn causes an increase in H 2 O 2 content, resulting in a decrease in cell wall ductility and inhibition of mesocotyl elongation [ 7 ].…”