Comparison performance of the IPMA in the ten functions.

<p>This table shows performance of IPMA compared with other algorithms through the above indicators in 50 cycles.</p

Gene Ontology (GO) analysis of down- and up-regulated genes in the high-temperature group vs. the control group.

<p>GO terms belonging to biological process (BP), molecular function (MF), and cellular component (CC) groups are shown in red, green, and blue, respectively. (A and B) Up- and down-regulated genes in the stem tip, respectively. (C and D) Up- and down-regulated genes in leaves, respectively. GO terms are sorted based on their <i>p</i>-values.</p

Comparison of paraffin sections from different treatments.

<p>(A-C) Control shoot tip meristems on days 5, 7, and 9, respectively, which did not differentiate over time. (D-F) Treatment shoot tip meristems on days 5, 7, and 9, respectively, with gradual growth observed.</p

Transcriptomic analysis reveals the roles of gibberellin-regulated genes and transcription factors in regulating bolting in lettuce (<i>Lactuca sativa</i> L.)

<div><p>A cool temperature is preferred for lettuce cultivation, as high temperatures cause premature bolting. Accordingly, exploring the mechanism of bolting and preventing premature bolting is important for agriculture. To explore this relationship in depth, morphological, physiological, and transcriptomic analyses of the bolting-sensitive line S39 at the five-leaf stage grown at 37°C were performed in the present study. Based on paraffin section results, we observed that S39 began bolting on the seventh day at 37°C. During bolting in the heat-treated plants, GA3 and GA4 levels in leaves and the indoleacetic acid (IAA) level in the stem reached a maximum on the sixth day, and these high contents were maintained. Additionally, bolting begins in the fifth day after GA3 treatment in S39 plants, GA3 and GA4 increased and then decreased, reaching a maximum on the fourth day in leaves. Similarly, IAA contents reached a maximum in the stem on the fifth day. No bolting was observed in the control group grown at 25°C, and significant changes were not observed in GA3 and GA4 levels in the controls during the observation period. RNA-sequencing data implicated transcription factors (TFs) in regulating bolting in lettuce, suggesting that the high GA contents in the leaves and IAA in the stem promote bolting. TFs possibly modulate the expression of related genes, such as those encoding hormones, potentially regulating bolting in lettuce. Compared to the control group, 258 TFs were identified in the stem of the treatment group, among which 98 and 156 were differentially up- and down-regulated, respectively; in leaves, 202 and 115 TFs were differentially up- and down-regulated, respectively. Significant changes in the treated group were observed for C2H2 zinc finger, AP2-EREBP, and WRKY families, indicating that these TFs may play important roles in regulating bolting.</p></div

Comparison of visual morphology between high-temperature(37°C) and control groups(25°C).

<p>(A-C) Control plants on days 5, 7, and 9, respectively. (D-F) High-temperature treatment plants on days 5, 7, and 9, respectively.</p

Family assignment of transcription factors that showed differential expression in the high-temperature group vs. the control group.

<p>The number of genes assigned to each family is shown behind a comma. (A and C) Genes with higher expression and lower expression in the stem tip, respectively. (B and D) Genes with higher expression and lower expression in leaves, respectively.</p

Hormone contents in different parts of lettuce plants on different treatment days.

<p>(A and B) GA3 and GA4 contents in leaves, respectively. (C and D) IAA contents in leaves and stems exposed to different treatments, respectively. (E and F)ABA contents in leaves and stems exposed to different treatments, respectively. The solid line represents the changes of treatment group, and the dotted line represents the control group. Asterisks represent significant difference at <i>P</i> < 0.05 by student <i>t</i>-test.</p

Changes in hormone contents, morphology and stem length after treatment with exogenous hormones.

<p>Plants in the fifth-leaf stage were treated with the exogenous plant growth regulator GA3 or its biosynthetic inhibitor CCC in the same amount of water. There were four different treatment modes. Changes in stem length and endogenous hormone levels in leaves and stems were examined at the control temperature after the different treatments. (A and B) GA4 and GA3 contents in leaves. (C and D) IAA contents in leaves and stems. (E-H) The morphology of lettuce plants without any treatment or treated with water, GA or CCC, respectively. (I) Stem elongation in S39 plants after treatment with exogenous hormone for 18 days.</p

Verification of differentially expressed genes by RT-qPCR.

<p>Twenty genes were chosen for RT-qPCR validation. The white and black bars represent the relative expression levels of each gene in the control and high-temperature groups, as detected by RT-qPCR and RNA-Seq, respectively. To plot the RNA-Seq data, gene expression in the control group was set to be the same as that observed by RT-qPCR, and relative expression in the high-temperature group was calculated using the fold-change detected by RNA-Seq. The bars represent the standard deviation (n = 3); 1 represents the control temperature, and 2 represents the high temperature. Asterisks indicate that the gene transcriptions are significantly different between control and treatment group (unpaired t test, P< 0.05).</p

List of GA-related genes that were differentially expressed in the lettuce stem and leaf in the high-temperature group vs. the control group.

<p>List of GA-related genes that were differentially expressed in the lettuce stem and leaf in the high-temperature group vs. the control group.</p