Uncovering early transcriptional regulation during adventitious root formation in Medicago sativa

Abstract

Background Alfalfa (Medicago sativa L.) as an important legume plant can quickly produce adventitious roots (ARs) to form new plants by cutting. But the regulatory mechanism of AR formation in alfalfa remains unclear. Results To better understand the rooting process of alfalfa cuttings, plant materials from four stages, including initial separation stage (C stage), induction stage (Y stage), AR primordium formation stage (P stage) and AR maturation stage (S stage) were collected and used for RNA-Seq. Meanwhile, three candidate genes (SAUR, VAN3 and EGLC) were selected to explore their roles in AR formation. The numbers of differentially expressed genes (DEGs) of Y-vs-C (9,724) and P-vs-Y groups (6,836) were larger than that of S-vs-P group (150), indicating highly active in the early AR formation during the complicated development process. Pathways related to cell wall and sugar metabolism, root development, cell cycle, stem cell, and protease were identified, indicating that these genes were involved in AR production. A large number of hormone-related genes associated with the formation of alfalfa ARs have also been identified, in which auxin, ABA and brassinosteroids are thought to play key regulatory roles. Comparing with TF database, it was found that AP2/ERF-ERF, bHLH, WRKY, NAC, MYB, C2H2, bZIP, GRAS played a major regulatory role in the production of ARs of alfalfa. Furthermore, three identified genes showed significant promotion effect on AR formation. Conclusions Stimulation of stem basal cells in alfalfa by cutting induced AR production through the regulation of various hormones, transcription factors and kinases. This study provides new insights of AR formation in alfalfa and enriches gene resources in crop planting and cultivation.

Insight into regulation of adventitious root formation by arbuscular mycorrhizal fungus and exogenous auxin in tea plant (Camellia sinensis L.) cuttings

“…SAUR15 can promote adventitious root development of Arabidopsis via auxin accumulation by activating auxin biosynthesis genes ( Yin et al., 2020 ). Previous research also found that in the induction phase of AR production, SAUR was mainly up-regulated, but down-regulated in the root primordium formation stage ( Ai et al., 2023 ), and we screened out a SAUR gene ( auxin-responsive protein SAUR32-like , LOC114266460 ) in CS0 vs. TS0. SAUR71 ( LOC114290786 ) also found at S2 stage may indicate the existence of root primordium induction process triggered by AMF.…”

Integrated Transcriptomics and Metabolomics Analysis Promotes the Understanding of Adventitious Root Formation in Eucommia ulmoides Oliver

“…The heterologous overexpression of LkWOX4 from Larix kaempferi in 84 K poplar altered the number and length of AR as well as remodeled the transcriptome, and the expressions of phytohormone-signaling genes ( ARF2 , ARF3 , ARF7 , and ARF18 ), rooting-associated transcription factors ( WOX5 , LBD29 , and SCR ), and root development-associated genes ( CYCD3 , GRF1 , and TAA1 ) were modulated [ 32 ]. In addition, transcription factors, such as MYB , NAC , MADS-box , WRKY , bHLH , bZIP , and GRAS families, have also been found to mediate AR formation [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. The phenylpropanoid metabolism plays a significant role in plant development and stress tolerance, and it is regulated by various plant hormones, including auxins, ethylene, JA, strigolactones (SL), and gibberellins (GA) [ 40 , 41 ].…”