Transcriptome Dynamics of Rooting Zone and Leaves during In Vitro Adventitious Root Formation in Eucalyptus nitens

Abstract

Wood properties and agronomic traits associated with fast growth and frost tolerance make Eucalyptus nitens a valuable forest alternative. However, the rapid age-related decline in the adventitious root (AR) formation (herein, meaning induction, initiation, and expression stages) limits its propagation. We analyzed transcriptomic profile variation in leaves and stem bases during AR induction of microcuttings to elucidate the molecular mechanisms involved in AR formation. In addition, we quantified expressions of candidate genes associated with recalcitrance. We delimited the ontogenic phases of root formation using histological techniques and Scarecrow and Short-Root expression quantification for RNA sequencing sample collection. We quantified the gene expressions associated with root meristem formation, auxin biosynthesis, perception, signaling, conjugation, and cytokinin signaling in shoots harvested from 2- to 36-month-old plants. After IBA treatment, 702 transcripts changed their expressions. Several were involved in hormone homeostasis and the signaling pathways that determine cell dedifferentiation, leading to root meristem formation. In part, the age-related decline in the rooting capacity is attributable to the increase in the ARR1 gene expression, which negatively affects auxin homeostasis. The analysis of the transcriptomic variation in the leaves and rooting zones provided profuse information: (1) To elucidate the auxin metabolism; (2) to understand the hormonal and signaling processes involved; (3) to collect data associated with their recalcitrance.

Application of Long-Chained Auxin Conjugates Influenced Auxin Metabolism and Transcriptome Response in Brassica rapa L. ssp. pekinensis

“…Due to the lack of literature describing transcriptome analyses after treatments with auxin conjugates, we cannot compare our data with others. However, there are some data on the effects of auxin treatment on the transcriptomes of Eucalyptus [ 38 ], A. thaliana [ 39 ] and B. napus [ 40 ]. IBA feeding experiments on Eucalyptus resulted in changes in the expression of 702 transcripts [ 38 ].…”

“…However, there are some data on the effects of auxin treatment on the transcriptomes of Eucalyptus [ 38 ], A. thaliana [ 39 ] and B. napus [ 40 ]. IBA feeding experiments on Eucalyptus resulted in changes in the expression of 702 transcripts [ 38 ]. This represents a high number of DEGs and is consistent with our data from the IBA-Ala treatment.…”

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

“…Auxin signal transduction controls the response of tissues and organs to auxin and is an important part of plant auxin research. The auxin responsive protein SAUR family, Aux/IAA family, auxin-binding protein (ABP) family, auxin response factor (ARF) family, crucial in the adventitious root formation, are key genes in the auxin signal transduction ( Della Rovere et al., 2015 ; Ayala et al., 2022 ). In our experiment, 4 ( LOC114302430 , LOC114260030 , LOC114302715 and LOC114269433 ) of 7 auxin-related DEGs, which were significantly positively correlated with AMF inoculation, were belong to auxin signal transduction pathway ( Figure 7 ), indicating the important role of auxin signal transduction in AM fungal regulation on the rooting of tea cuttings.…”

Expression of CsSCL1 and Rooting Response in Chestnut Leaves Are Dependent on the Auxin Polar Transport and the Ontogenetic Origin of the Tissues

“…The direct relationship between rooting ability and gene expression simplifies the molecular analysis and data interpretation. Expression of SCL1 homologs has also been related to the AR process in pine, black walnut and eucalyptus, suggesting its role as a marker of rooting ability in forest species [ 20 , 23 , 43 ]. The localized expression of CsSCL1 in the QC and stem cells also indicates the involvement of the gene in maintaining the radial patterning of the root.…”