Global Transcriptomic Analysis Reveals Differentially Expressed Genes Involved in Embryogenic Callus Induction in Drumstick (Moringa oleifera Lam.)

Abstract

The plant embryogenic callus (EC) is an irregular embryogenic cell mass with strong regenerative ability that can be used for propagation and genetic transformation. However, difficulties with EC induction have hindered the breeding of drumstick, a tree with diverse potential commercial uses. In this study, three drumstick EC cDNA libraries were sequenced using an Illumina NovaSeq 6000 system. A total of 7191 differentially expressed genes (DEGs) for embryogenic callus development were identified, of which 2325 were mapped to the KEGG database, with the categories of plant hormone signal transduction and Plant-pathogen interaction being well-represented. The results obtained suggest that auxin and cytokinin metabolism and several embryogenesis-labeled genes are involved in embryogenic callus induction. Additionally, 589 transcription factors from 20 different families were differentially expressed during EC formation. The differential expression of 16 unigenes related to auxin signaling pathways was validated experimentally by quantitative real time PCR (qRT-PCR) using samples representing three sequential developmental stages of drumstick EC, supporting their apparent involvement in drumstick EC formation. Our study provides valuable information about the molecular mechanism of EC formation and has revealed new genes involved in this process.

Genome-Wide Identification and Expression Analysis of the Aux/IAA Gene Family of the Drumstick Tree (Moringa oleifera Lam.) Reveals Regulatory Effects on Shoot Regeneration

“…There is a population of stem cells in the primordia that can be induced to differentiate by inducing changes in gene expression [ 47 ]. Several phytohormones deliver a specific molecular signal and play key roles in plant cell division and differentiation [ 7 ]. Auxin works by directly binding to the nuclear receptor of TIR1/AFB proteins; the auxin-TIR1/AFB co-receptors inhibit the Aux/IAA transcriptional repressors.…”

“…ARFs activate the initiation of the LRP by activating the transcription factor of LBDs (Lateral Organ Boundaries Domains), while ARFs are negatively regulated by Aux/IAAs . The MoLBD gene family was found to be differently expressed at the callus differentiation stage in our previous study [ 7 ]. ARF7 activates SAUR19 expression by binding its promoter directly, and several SAUR genes have been found to exhibit highly increased expression across the coffee somatic embryogenesis process [ 48 ].…”

“…ACP2 was amplified as a reference gene [ 55 ]. Gene expression was detected with RT-qPCR, and the relative expression level for each gene was estimated using 2 −ΔΔCT [ 7 ].…”

“…A study of auxin early response genes has revealed that the Aux/IAA (Auxin/Indole-3-Acetic) , ARF (Auxin Response Factor) , GH3 (Gretchen Hagen 3), and SAUR (Small Auxin Up-regulated RNA) family genes are closely involved in the embryogenic transformation of upland cotton callus; Aux/IAAs, in particular, display a high level of expression [ 6 ]. Global transcriptomic analysis implied that Aux/IAA gene family is involved in the molecular regulatory network during drumstick tree shoot regeneration in our previous research [ 7 ].…”

Miracle Tree Moringa oleifera: Status of the Genetic Diversity, Breeding, In Vitro Propagation, and a Cogent Source of Commercial Functional Food and Non-Food Products

“…Several other molecular markers, e.g., allele-specific associated primer (ASAP), cleaved amplified polymorphic sequence (CAPS), directed amplification of minisatellite DNA (DAMD), diversity array technology (DArT), randomly amplified microsatellite polymorphisms (RAMPO), restriction landmark genomic scanning (RLGS), sequence tagged microsatellite (STM), single nucleotide polymorphisms (SNPs), and single-strand conformation polymorphism (SSCP) [36] could also be potentially useful for elucidating the genetic diversity among the MO accessions and thus merit detailed investigations. Identification of elite accessions of MO would provide a much-needed fillip towards generating them for desirable agronomic traits by conventional methods and/or molecular breeding complemented by significant advances in whole-genome assembly and a global transcriptomic analysis [150,151] (Figure 6). It is anticipated that superior MO accessions would have a commensurate influence on their repertoire of commercially viable functional food and non-food products for trade and commerce.…”