Transcriptional dynamics of maize leaves, pollens and ovules to gain insights into heat stress-related responses

Abstract

Heat stress (HS) is one of the alarming issues today due to global warming and is the foremost detrimental to crop production. Maize is one of the versatile crops grown over different agro-climatic conditions. However, it is significantly sensitive to heat stress, especially during the reproductive phase. The heat stress tolerance mechanism is yet to be elucidated at the reproductive stage. Thus, the present study focused on identifying transcriptional changes in two inbreds, LM 11 (sensitive to HS) and CML 25 (tolerant to HS), under intense heat stress at 42°C during the reproductive stage from three tissues viz. flag leaf, tassel, and ovule. Samples from each inbred were collected after 5 days of pollinations for RNA isolation. Six cDNA libraries were constructed from three separate tissues of LM 11 and CML 25 and sequenced using an Illumina HiSeq2500 platform. A total of 2,164 (1127 up-regulated and 1037 down-regulated) differentially expressed genes (DEGs) were identified with 1151, 451, and 562 DEGs in comparisons of LM 11 and CML 25, corresponding to a leaf, pollen, and ovule, respectively. Functional annotated DEGs associated with transcription factors (TFs) viz. AP2, MYB, WRKY, PsbP, bZIP, and NAM, heat shock proteins (HSP20, HSP70, and HSP101/ClpB), as well as genes related to photosynthesis (PsaD & PsaN), antioxidation (APX and CAT) and polyamines (Spd and Spm). KEGG pathways analyses showed that the metabolic overview pathway and secondary metabolites biosynthesis pathway, with the involvement of 264 and 146 genes, respectively, were highly enriched in response to heat stress. Notably, the expression changes of the most common HS-responsive genes were typically much more significant in CML 25, which might explain why CML 25 is more heat tolerant. Seven DEGs were common in leaf, pollen, and ovule; and involved in the polyamines biosynthesis pathway. Their exact role in maize heat stress response would warrant further studies. These results enhanced our understanding to heat stress responses in maize.

Integrated Transcriptomic and Metabolomic Analysis Reveals the Mechanism of Gibberellic Acid Regulates the Growth and Flavonoid Synthesis in Phellodendron chinense Schneid Seedlings

“…The PsaD/N are crucial for PSI function. The former associates with PsaC/E polypeptides to form a stromal ridge that regulates the thioredoxin-mediated photoreduction of NADP + , the latter combines with PsaG/F polypeptides to form trimer that regulating the plastocyanin function, subsequently improving photosynthetic efficiency and biomass in plants [43][44][45][46]. Therefore, our results indicated that GA 3 promoted growth by improving the relative expression levels of key genes in photosynthesis in the leaves of P. chinense Schneid seedlings.…”

“…Meanwhile, the cluster and class heatmaps showed the similarity of components among biological repeats and the difference of components among the two treatment groups, suggesting that GA 3 strongly influenced the metabolite profiles in the stem bark of P. chinense Schneid seedlings (Figure S4b). In this present study, a total of 443 metabolites in stem bark samples from CK and GA 3 treatment groups were identified and divided into 11 categories, which mainly included flavonoid (90), phenolic acid (62), lipid (59), amino acid and derivative (46), alkaloid (45), organic acid (31), nucleotide and derivative (30), and lignan and coumarin (20) (Figure S4c).…”

Integrated Transcriptomics and Metabolomics Analysis of Two Maize Hybrids (ZD309 and XY335) under Heat Stress at the Flowering Stage

“…The flowering stage is one of the critical phases in maize that account for most of the yield losses due to heat stress [6]. Pollen formation, pollen development, and tassel development are extremely susceptible to heat stress [14,20,33]. Different genotypes of maize exhibit differences in heat tolerance.…”

“…Presently, the transcriptomic responses of maize to high temperature stress have been reported in a few studies. Most of them were focused on seedling-stage gene expression changes [20]. In this study, two commercial maize hybrids, ZD309 and XY335, were selected from four main planted maize hybrids in the Huang-Huai-Hai area of China based on high temperature resistance levels.…”

Transcriptomic Determination of the Core Genes Regulating the Growth and Physiological Traits of Quercus mongolica Fisch. ex Ledeb

“…The correlations of different modules with target traits and phenotypes can thus be analyzed, and specific modules containing the target traits and core genes can be identified. A co-expression regulatory network is then constructed based on the results of gene clustering and association analyses [15]. WGCNA, as a systems biology tool [16], has been used widely to assess specific biological processes, abiotic stresses, and disease resistance, among other topics in biology [17].…”