Network Analysis of Different Exogenous Hormones on the Regulation of Deep Sowing Tolerance in Maize Seedlings

Abstract

The planting method of deep sowing can make the seeds make full use of water in deep soil, which is considered to be an effective way to respond to drought stress. However, deep sowing will affect the growth and development of maize (Zea mays L.) at seedling stage. To better understand the response of maize to deep sowing stress and the mechanism of exogenous hormones [Gibberellin (GA3), Brassinolide (BR), Strigolactone (SL)] alleviates the damaging effects of deep-sowing stress, the physiological and transcriptome expression profiles of seedlings of deep sowing sensitive inbred line Zi330 and the deep-tolerant inbred line Qi319 were compared under deep sowing stress and the conditions of exogenous hormones alleviates stress. The results showed that mesocotyl elongated significantly after both deep sowing stress and application of exogenous hormones, and its elongation was mainly through elongation and expansion of cell volume. Hormone assays revealed no significant changes in zeatin (ZT) content of the mesocotyl after deep sowing and exogenous hormone application. The endogenous GA3 and auxin (IAA) contents in the mesocotyl of the two inbred lines increased significantly after the addition of exogenous GA3, BR, and SL under deep sowing stress compared to deep sowing stress, while BR and SL decreased significantly. Transcriptome analysis showed that the deep seeding stress was alleviated by GA3, BR, and SLs, the differentially expressed genes (DEGs) mainly included cellulose synthase, expansin and glucanase, oxidase, lignin biosynthesis genes and so on. We also found that protein phosphatase 2C and GA receptor GID1 enhanced the ability of resist deep seeding stress in maize by participating in the abscisic acid (ABA) and the GA signaling pathway, respectively. In addition, we identified two gene modules that were significantly related to mesocotyl elongation, and identified some hub genes that were significantly related to mesocotyl elongation by WGCNA analysis. These genes were mainly involved in transcription regulation, hydrolase activity, protein binding and plasma membrane. Our results from this study may provide theoretical basis for determining the maize deep seeding tolerance and the mechanism by which exogenous hormones regulates deep seeding tolerance.

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

“…In this study, the root length, seedling length, mesocotyl length, coleoptile length and the sum of the mesocotyl and coleoptile lengths of the maize inbred lines Qi319 and Zi330 under deep-sowing conditions all changed to varying degrees, among which mesocotyl elongation was the most significant. Studies have shown that exogenous IAA [ 24 ], GA 3 [ 25 ], BR, SL (strigolactone) [ 26 ], EBR (2,4-Epibrassinolide Solution) [ 27 ], etc., promote the elongation of mesocotyls under deep-sowing conditions. In this study, we found that exogenous SA significantly promoted the elongation of the mesocotyl, exogenous 6-BA significantly inhibited the elongation of the mesocotyl, and the SA–6-BA combined treatment also showed an inhibitory effect, but the inhibitory effect was weaker, indicating that there may be an interaction between these two hormones; exogenous SA partially alleviated the inhibitory effect of exogenous 6-BA on mesocotyl elongation.…”

Study on ZmRPN10 Regulating Leaf Angle in Maize by RNA-Seq

“…Transcriptome sequencing can quickly and comprehensively obtain gene expression changes in different tissues or organs under specific conditions, and differential gene analysis is helpful to analyze gene regulatory networks [31]. Transcriptome sequencing of B73 and lpa1 plays an important role in mining functional genes related to different traits [32].…”

“…During the maize powder stage, paraffin sections were prepared using the lower lobe ear site of B73 and rpn10 plants. The experimental procedure is described by Chen et al [31]. The images were observed using a LEICA DM500 optical microscope and the ToupView camera system was used to take pictures.…”

Transcriptome-Based Weighted Correlation Network Analysis of Maize Leaf Angle Regulation by Exogenous Brassinosteroid

“…The total RNA concentration and quality were assessed using Agilent 2100 Bioanalyzer (Agilent Technologies, Santa Clara, CA, USA) and NanoDrop (IMPLEN, Westlake Village, CA, USA). The total RNA of each treated sample was taken for the construction of the RNA-seq library as described by Chen et al [26]. Then, the cDNA libraries were sequenced with the BGISEQ-500 sequencing platform and 150 bp paired-end reads were generated.…”

“…A new study shows there are significant biological metabolic differences in different parts of maize leaves or at different developmental transition states [41]. WGCNA analysis can analyze gene co-expression network through cluster analysis, and combine samples phenotype detection of expression patterns associated with phenotype, to mine key genes associated with phenotype [26]. Studies have shown that leaf occipital plays an important role in the regulation of leaf angle.…”