The Cytokinins BAP and 2-iP Modulate Different Molecular Mechanisms on Shoot Proliferation and Root Development in Lemongrass (Cymbopogon citratus)

Abstract

The known activities of cytokinins (CKs) are promoting shoot multiplication, root growth inhibition, and delaying senescence. 6-Benzylaminopurine (BAP) has been the most effective CK to induce shoot proliferation in cereal and grasses. Previously, we reported that in lemongrass (Cymbopogon citratus) micropropagation, BAP 10 µM induces high shoot proliferation, while the natural CK 6-(γ,γ-Dimethylallylamino)purine (2-iP) 10 µM shows less pronounced effects and developed rooting. To understand the molecular mechanisms involved, we perform a protein–protein interaction (PPI) network based on the genes of Brachypodium distachyon involved in shoot proliferation/repression, cell cycle, stem cell maintenance, auxin response factors, and CK signaling to analyze the molecular mechanisms in BAP versus 2-iP plants. A different pattern of gene expression was observed between BAP- versus 2-iP-treated plants. In shoots derived from BAP, we found upregulated genes that have already been demonstrated to be involved in de novo shoot proliferation development in several plant species; CK receptors (AHK3, ARR1), stem cell maintenance (STM, REV and CLV3), cell cycle regulation (CDKA-CYCD3 complex), as well as the auxin response factor (ARF5) and CK metabolism (CKX1). In contrast, in the 2-iP culture medium, there was an upregulation of genes involved in shoot repression (BRC1, MAX3), ARR4, a type A-response regulator (RR), and auxin metabolism (SHY2).

Effects of seed soaking with plant growth regulators combination on the aggregation ability of shallot from seeds

“…Yamazaki et al (2015) showcased the influence of gibberellins on increasing tiller formation in spring onions (Allium fistulosum) by watering with 40 ppm GA₃ with 10 mL per plant. Aquino et al (2023) stated that the most effective cytokinin for inducing shoot proliferation in cereals and grasses was 6-benzyl amino purine (BAP). NAA application at 50 ppm was reported to augment leaf area and leaf area index in pumpkins (Arvindkumar et al, 2014), while NAA at 100 ppm proved to be the optimal treatment for increasing the number of fruit and grape yield per plant (Ghani et al, 2013).…”