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.
Highlights
The plant embryogenic callus is an irregular embryogenic cell mass with strong regenerative ability
Auxin and Cytokinin Play an Important Role in Drumstick embryogenic callus (EC) Formation
It is known that auxin activates the expression of three major families of primary response genes: the Aux/IAA genes, the GH3 genes, and the SAUR genes [24]
Summary
The plant embryogenic callus is an irregular embryogenic cell mass with strong regenerative ability. Embryogenic callus cultured in vitro can regenerate into adventitious buds or form complete plants after somatic embryogenesis [1]. In addition to its frequent use for propagating various economically important species, embryogenic callus-based genetic transformation has emerged as the most successful plant transformation system in the last decade [2,3,4]. Embryogenic callus formation is generally induced by optimizing the ratio of hormones in the medium [5,6,7]. Hormones play central roles in embryogenic callus induction, this non-genetic method of optimizing culture conditions cannot provide culture schemes suitable for all genotypes [8,9].
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