Auxin Signal Transduction Pathway Research Articles

NnARF17 and NnARF18 from lotus promote root formation and modulate stress tolerance in transgenic Arabidopsis thaliana

Auxin response factors (ARFs) play a crucial role in regulating gene expression within the auxin signal transduction pathway, particularly during adventitious root (AR) formation. In this investigation, we identified full-length sequences for ARF17 and ARF18, encompassing 1,800 and 2,055 bp, encoding 599 and 684 amino acid residues, respectively. Despite exhibiting low sequence homology, the ARF17- and ARF18-encoded proteins displayed significant structural similarity and shared identical motifs. Phylogenetic analysis revealed close relationships between NnARF17 and VvARF17, as well as NnARF18 and BvARF18. Both ARF17 and ARF18 demonstrated responsiveness to exogenous indole-3-acetic acid (IAA), ethephon, and sucrose, exhibiting organ-specific expression patterns. Beyond their role in promoting root development, these ARFs enhanced stem growth and conferred drought tolerance while mitigating waterlogging stress in transgenic Arabidopsis plants. RNA sequencing data indicated upregulation of 51 and 75 genes in ARF17 and ARF18 transgenic plants, respectively, including five and three genes associated with hormone metabolism and responses. Further analysis of transgenic plants revealed a significant decrease in IAA content, accompanied by a marked increase in abscisic acid content under normal growth conditions. Additionally, lotus seedlings treated with IAA exhibited elevated levels of polyphenol oxidase, IAA oxidase, and peroxidase. The consistent modulation of IAA content in both lotus and transgenic plants highlights the pivotal role of IAA in AR formation in lotus seedlings.

Integrated physiological, transcriptomic, and metabolomic analyses of drought stress alleviation in Ehretia macrophylla Wall. seedlings by SiO2 NPs (silica nanoparticles).

With environmental problems such as climate global warming, drought has become one of the major stress factors, because it severely affects the plant growth and development. Silicon dioxide nanoparticles (SiO2 NPs) are crucial for mitigating abiotic stresses suffered by plants in unfavorable environmental conditions and further promoting plant growth, such as drought. This study aimed to investigate the effect of different concentrations of SiO2 NPs on the growth of the Ehretia macrophylla Wall. seedlings under severe drought stress (water content in soil, 30-35%). The treatment was started by starting spraying different concentrations of SiO2 NPs on seedlings of Ehretia macrophyla, which were consistently under normal and severe drought conditions (soil moisture content 30-35%), respectively, at the seedling stage, followed by physiological and biochemical measurements, transcriptomics and metabolomics analyses. SiO2 NPs (100 mg·L-1) treatment reduced malondialdehyde and hydrogen peroxide content and enhanced the activity of antioxidant enzymes under drought stress. Transcriptomic analysis showed that 1451 differentially expressed genes (DEGs) in the leaves of E. macrophylla seedlings were regulated by SiO2 NPs under drought stress, and these genes mainly participate in auxin signal transduction and mitogen-activated protein kinase signaling pathways. This study also found that the metabolism of fatty acids and α-linolenic acids may play a key role in the enhancement of drought tolerance in SiO2 NP-treated E. macrophylla seedlings. Metabolomics studies indicated that the accumulation level of secondary metabolites related to drought tolerance was higher after SiO2 NPs treatment. This study revealed insights into the physiological mechanisms induced by SiO2 NPs for enhancing the drought tolerance of plants.

LncRNA cis- and trans-regulation provides new insight into drought stress responses in wild barley.

Drought is one of the most common abiotic stresses that affect barley productivity. Long noncoding RNA (lncRNA) has been reported to be widely involved in abiotic stress, however, its function in the drought stress response in wild barley remains unclear. In this study, RNA sequencing was performed to identify differentially expressed lncRNAs (DElncRNA) among two wild barley and two cultivated barley genotypes. Then, the cis-regulatory networks were according to the chromosome position and the expression level correction. The GO annotation indicates that these cis-target genes are mainly involved in "ion transport transporter activity" and "metal ion transport transporter activity". Through weighted gene co-expression network analysis (WGCNA), 10 drought-related modules were identified to contract trans-regulatory networks. The KEGG annotation demonstrated that these trans-target genes were enriched for photosynthetic physiology, brassinosteroid biosynthesis, and flavonoid metabolism. In addition, we constructed the lncRNA-mediated ceRNA regulatory network by predicting the microRNA response elements (MREs). Furthermore, the expressions of lncRNAs were verified by RT-qPCR. Functional verification of a candidate lncRNA, MSTRG.32128, demonstrated its positive role in drought response and root growth and development regulation. Hormone content analysis provided insights into the regulatory mechanisms of MSTRG.32128 in root development, revealing its involvement in auxin and ethylene signal transduction pathways. These findings advance our understanding of lncRNA-mediated regulatory mechanisms in barley under drought stress. Our results will provide new insights into the functions of lncRNAs in barley responding to drought stress.

Transcriptome analysis of axillary buds in low phosphorus stress and functional analysis of TaWRKY74s in wheat

BackgroundWheat is one of the main grain crops in the world, and the tiller number is a key factor affecting the yield of wheat. Phosphorus is an essential element for tiller development in wheat. However, due to decreasing phosphorus content in soil, there has been increasing use of phosphorus fertilizer, while imposing risk of soil and water pollution. Hence, it is important to identify low phosphorus tolerance genes and utilize them for stress resistance breeding in wheat.ResultsWe subjected the wheat variety Kenong 199 (KN199) to low phosphorus stress and observed a reduced tiller number. Using transcriptome analysis, we identified 1651 upregulated genes and 827 downregulated of genes after low phosphorus stress. The differentially expressed genes were found to be enriched in the enzyme activity regulation related to phosphorus, hormone signal transduction, and ion transmembrane transport. Furthermore, the transcription factor analysis revealed that TaWRKY74s were important for low phosphorus tolerance. TaWRKY74s have three alleles: TaWRKY74-A, TaWRKY74-B, and TaWRKY74-D, and they all belong to the WRKY family with conserved WRKYGQK motifs. These proteins were found to be located in the nucleus, and they were expressed in axillary meristem, shoot apical meristem(SAM), young leaves, leaf primordium, and spikelet primordium. The evolutionary tree showed that TaWRKY74s were closely related to OsWRKY74s in rice. Moreover, TaWRKY74s-RNAi transgenic plants displayed significantly fewer tillers compared to wild-type plants under normal conditions. Additionally, the tiller numebr of the RNAi transgenic plants was also significantly lower than that of the wild-type plants under low-phosphorus stress, and increased the decrease amplitude. This suggestd that TaWRKY74s are related to phosphorus response and can affect the tiller number of wheat.ConclusionsThe results of this research showed that TaWRKY74s were key genes in wheat response to low phosphorus stress, which might regulate wheat tiller number through abscisic acid (ABA) and auxin signal transduction pathways. This research lays the foundation for further investigating the mechanism of TaWRKY74s in the low phosphorus environments and is significant for wheat stress resistance breeding.

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

Adventitious root (AR) development, affected by various biotic and abiotic factors, is the most important procedure in tea plant (Camellia sinensis L.) cutting propagation. Establishing symbiotic relationships with most terrestrial plants, AMF (Arbuscular mycorrhizal fungus) can mediate the AR formation of several herbaceous and woody plants in previous studies. In this paper, effects of combined application of AMF and exogenous auxin on AR formation of cuttings from different tea plant varieties ('Pingyangtezao', 'Longjing 43' and 'Longjingchangye') were studied. Then we also performed RNA-Seq analysis with 'Pingyangtezao' cuttings aiming to find the possible auxin-related pathway of AM fungal regulation on AR formation. To accurately uncover the regulatory mechanism of AMF on AR formation of tea cuttings, rooting process were separated into four stages (S0, non-rooting; S1, AR protrusion; S2, AR formation and S3, AR elongation) at the same sampling time. Results showed that IBA treatment increased the mycorrhizal colonization rate, especially in 'Pingyangtezao' variety (from 37.58% to 46.29%). Both inoculating AMF and addition of IBA promoted the AR formation, and rooting of different tea plant varieties showed different dependence on auxin. AMF could alleviate the effect of auxin-related inhibitors (2,3,5-triiodobenzoic acid, L-α-(Aminooxy)-β-phenylpropionic acid and α-(phenylethyl-2-oxo)-IAA) on rooting of tea cuttings, even though the colonization of AMF was hindered at various degrees. Transcriptomic analysis showed that different numbers of differentially expressed genes (DEGs) at various rooting stages of tea cuttings with the most at S2 stage (1360 DEGs), indicating the increasing regulation by AMF with the development of AR. Similar trend was found in auxin-related DEGs, and family genes of YUC, GH, PIN, LAX, SAUR, AUX, and ABP involved in the AM fungal regulation on AR formation of tea cuttings. Additionally, AMF strongly mediated auxin transport and signal transduction pathways in tea cuttings as showed by the results of correlation analysis. Overall, interaction of AMF and exogenous auxin in promoting rooting and the preliminary mechanism of AMF regulating AR formation of tea cuttings was deciphered in this paper, which may provide a basis for further deep mechanistic research and cutting propagation of tea production.

Comparative Transcriptome Analysis Identified Genes Associated with Fruit Size in Pepper (Capsicum annuum L.)

Pepper (Capsicum annuum L.) is one of the most widely grown vegetable crops in China, with widespread cultivation worldwide. Fruit weight (size) is a complex trait controlled by multiple factors and is an essential determinant of pepper yield. In this study, we analyzed the transcriptome of two pepper recombinant lines with different fruit weights, ‘B302’ and ‘B400’, at five developmental stages to reveal some of the differentially expressed genes and mechanisms controlling fruit weight. The results showed that 21,878 differential genes were identified between the two specimens. Further analysis of the differentially expressed genes revealed that Boron transporter 4 was significantly highly expressed in the large-fruited pepper and almost not expressed at all in the small-fruited pepper. CaAUX1, CaAUX/IAA, CaGH3, CaSAUR, and other related genes in the Auxin signal transduction pathway were highly expressed in the large-fruited pepper but significantly reduced in the small-fruited pepper. In addition, a comparison of differentially expressed transcription factors at different times revealed that transcription factors such as CaMADS3, CaAGL8, CaATHB13, and CaATHB-40 were highly differentially expressed in the large-fruited pepper, and these transcription factors may be related to pepper fruit expansion. Through weighted gene co-expression network analysis (WGCNA), the MEorangered4 module was shown to have a highly significant correlation with fruit weight, and the key modules were analyzed by constructing the hub core gene network interactions map and core genes regulating fruit weight such as APETALA 2 were found. In conclusion, we find that the expression of relevant genes at different developmental stages was different in ‘B302’ and ‘B400’, and it was hypothesized that these genes play essential roles in the development of fruit size and that the interactions occurring between transcription factors and phytohormones may regulate the development of fruit size.

Analysis of the effect of exogenous auxin on the regulatory relationship between miRNAs and their target genes in rose using high-throughput sequencing

ABSTRACT Rose (Rosa hybrida L.) is one of the major cut flowers in the world. Studying the molecular mechanism of auxin regulation in growth is of great significance for enhancing the understanding of the growth and development processes in rose and informing accurate exogenous auxin application in rose production. However, the response mechanism of rose to miRNA-mediated auxin signal transduction is unclear. In this study, rose plants were treated with IAA, and 75 known miRNAs and 168 novel miRNAs were identified by small RNA sequencing. Among them, 19 known miRNAs and 42 miRNAs were differentially expressed. Many differential miRNAs demonstrated staged responses to auxin treatment. The targeted relationship between miRNA and key transcription factors regulated by auxin in rose was analysed, and the target genes in the ARF family and AUX/IAA family were screened. By using quantitative real-time PCR(qRT-PCR) to verify the expression patterns of the miRNA regulating the auxin signal transduction pathway and its target gene, we found that miR156a, miR160a, miR164a, miR167d, miR396b-3p, novel_miR_189, novel_miR_74, novel_miR_8, and novel_miR_207 were anti-correlated with the ARF family, and miR390a-3p and novel_miR_101 were anti-correlated with the AUX/IAA family. These results provide a theoretical basis for further studies on the auxin regulatory mechanisms in rose.

Auxin participates in regulating the leaf curl development of Wucai (Brassica campestris L.).

Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) belongs to the Brassica genus of the Cruciferae family, and its leaf curl is a typical feature that distinguishes Wucai from other nonheading cabbage subspecies. Our previous research found that plant hormones were involved in the development of the leaf curl in Wucai. However, the molecular mechanisms and the hormones regulating the formation of leaf curl in Wucai have not yet been reported. This study aimed to understand the molecular functions related to hormone metabolism during the formation of leaf curl in Wucai. A total of 386 differentially expressed genes (DEGs) were identified by transcriptome sequencing of two different morphological parts of the same leaf of Wucai germplasm W7-2, and 50 DEGs were found to be related to plant hormones, which were mainly involved in the auxin signal transduction pathway. Then, we measured the content of endogenous hormones in two different forms of the same leaf of Wucai germplasm W7-2. A total of 17 hormones with differential content were identified, including auxin, cytokinins, jasmonic acids, salicylic acids, and abscisic acid. And we found that treatment with auxin transport inhibitor N-1-naphthylphthalamic acid can affect the leaf curl phenotype of Wucai and pak choi (Brassica rapa L. subsp. Chinensis). These results indicated that plant hormones, especially auxin, are involved in developing the leaf curl of Wucai. Our findings provide a potentially valuable reference for future research on the development of leaf curls.

Genome-wide analysis of the SAUR gene family and function exploration of DlSAUR32 during early longan somatic embryogenesis

The early auxin responsive small auxin up-regulated RNA (SAUR) family is an important gene family in the auxin signal transduction pathway. This study focused on the regulatory mechanism of DlSAUR genes during early somatic embryogenesis (SE) and its response to hormone treatment and abiotic stress. Mining of the available Dimocarpus longan Lour. (D. longan) genome sequence yielded 68 putative SAUR genes. Transcript profiles based on RNA-seq data showed that most of the 24 detected DlSAUR genes were highly expressed in the globular embryos (GE) (10) and most of them responded to heat stress and 2,4-D treatment. The results of qRT-PCR showed that most of DlSAUR genes were up-regulated under auxin inhibitor N-1-naphthylphthalamic acid (NPA) and auxin indole-3-acetic acid (IAA) treatments. Moreover, NPA could promote longan SE. The assay for ATAC-seq data analysis showed that chromatin accessibility of 19 of the 24 DlSAUR genes were open during early SE, and most DlSAUR genes differentially expressed during early SE were not associated with H3K4me1 signal enrichment. The DlSAUR32 was selected for subcellular localization and RNA-seq analysis, which encode a cell nuclear-localized protein. Dual-luciferase assays and transient transformation showed that the transcription factors (TFs) DlWRKY75-1 and DlWRKY75-2 might bind to the DlSAUR32 promoters to inhibition gene transcription. Transient overexpression of DlWRKY75-1 and DlWRKY75-2 decreased IAA content in N. benthamiana leaves. Thus, the regulatory network composed of DlSAUR32 and its related TFs may regulate the early longan SE and be involved in the auxin response regulatory pathway of longan.

Transcriptome sequencing reveals potential key genes of cellular changes during the first rapid growth stage of jujube fruit size

ABSTRACT Cell number and size are essential factors in determining the final size of the fruit. However, studies on the cellular changes and molecular mechanisms of jujube fruit size development are still unclear. In this study, changes in fruit length, width, weight, and corresponding mesocarp cells were measured during jujube fruit development. The results showed that cell division and cell expansion jointly participated in the first rapid growth stage of fruit size, and cell expansion was the main factor in the second rapid growth stage of fruit size. In a further study, transcriptome sequencing was used to analyse the expression profile of fruit size's first rapid growth stage. Most of these DEGs were assigned to seven significant trends. Three genes related to the auxin signal transduction pathway and three genes related to the brassinosteroid biosynthesis signal transduction pathway were detected to be directly related to cell enlargement and cell division, respectively, which may regulate the first rapid growth of fruit size. In conclusion, candidate genes were provided for regulating fruit size in this study, which is beneficial for analysing the molecular mechanism of fruit size and lays a foundation for breeding large-fruit jujube cultivars.

Leaf transcriptome analysis of Medicago ruthenica revealed its response and adaptive strategy to drought and drought recovery

BackgroundDrought is one of the main causes of losses in forage crop yield and animal production. Medicago ruthenica (L.) cv. Zhilixing is a high-yielding alfalfa cultivar also known for its high tolerance to drought. We analyzed the transcriptome profile of this cultivar throughout drought stress and recovery and we were able to describe its phased response through the expression profiles of overlapping gene networks and drought-specific genes.ResultsThe ABA and auxin signal transduction pathways are overlapping pathways in response to drought and drought recovery in forage crops. Medicago ruthenica (L.) cv. Zhilixing adopts different strategies at different degrees of drought stress. On the 9th day of drought, transcriptional regulations related to osmoregulation are enhanced mainly through increased activities of carbohydrate and amino acid metabolism, while photosynthetic activities were reduced to slow down growth. With drought prolonging, on the 12th day of drought, the synthesis of proline and other stored organic substances was suppressed in general. After recovery, Medicago ruthenica synthesizes flavonoids through the flavonoid biosynthesis pathway to remove accumulated ROS and repair the oxidative damage from water stress. In addition, the regulation of circadian rhythm seems to accelerate the drought recovery process.ConclusionsMedicago ruthenica adapts to drought by regulating the osmoregulatory system and photosynthesis, which appears to involve the ABA and auxin signaling pathways as key regulators. Furthermore, the synthesis of flavonoids and the regulation of the circadian rhythm can accelerate the recovery process. These results enriched our knowledge of molecular responses to drought and drought recovery in Medicago ruthenica and provide useful information for the development of new legume forage grass varieties with improved adaptability to drought stress.

Early defoliation induces auxin redistribution, promoting paradormancy release in pear buds.

Paradormancy of fruit trees occurs in summer and autumn when signals from adjacent organs stimulate buds to develop slowly. This stage has received less attention that the other stages of dormancy, and the underlying mechanism remains uncharacterized. Early defoliation in late summer and early autumn is usually followed by out-of-season blooming in pear (Pyrus spp.), which substantially decreases the number of buds the following spring and negatively affects fruit production. This early bud flush is an example of paradormancy release. Here, we determined that flower bud auxin content is stable after defoliation; however, polar distribution of the pear (Pyrus pyrifolia) PIN-FORMED auxin efflux carrier 1b (PpyPIN1b) implied that auxin tends to be exported from buds. Transcriptome analysis of floral buds after artificial defoliation revealed changes in auxin metabolism, transport, and signal transduction pathways. Exogenous application of a high concentration of the auxin analog 1-naphthaleneacetic acid (300 mg/L) suppressed PpyPIN1b expression and its protein accumulation in the cell membrane, likely leading to decreased auxin efflux from buds, which hindered flower bud sprouting. Furthermore, carbohydrates and additional hormones also influenced out-of-season flowering. Our results indicate that defoliation-induced auxin efflux from buds accelerates bud paradormancy release. This differs from release of apical-dominance-related lateral bud paradormancy after the apex is removed. Our findings and proposed model further elucidate the mechanism underlying paradormancy and will help researchers to develop methods for inhibiting early defoliation-induced out-of-season bud sprouting.

The molecular characteristics of DOMs derived from bio-stabilized wastewater activated sludge and its effect on alleviating Cd-stress in rice seedlings (Oryza sativa L.)

To recycle fertilizing contents in wastewater activated sludge (WAS) is attracting increasing interest. Dissolved organic matters (DOMs) in WAS with high content are biologically active. In this work, the molecular composition of DOMs derived from two typical bio-stabilized WAS (DOMBWS), aerobic composting (DOMACS) and anaerobic digestion (DOMADS), were analyzed. The mitigative effect and molecular mechanisms of DOMBWS on rice seedlings (Oryza sativa L.) under Cd-stress were investigated. Our study indicated that DOMBWS significantly alleviated Cd-stress and facilitated growth recovery of rice seedlings with distinct absorption mechanisms. DOMACS, primarily composed of CHO class with low molecular weight rich in carboxyl groups, forming labile Cd-DOM complexes, which promoted Cd-absorption of rice seedlings. While DOMADS comprised large molecular weight of CHON class interacted with Cd to produce stable macromolecular complexes in the form of microaggregates, consequently reducing Cd-absorption. At transcriptional level, DOMBWS restored auxin signal transduction and phenylpropanoid biosynthesis pathways in root cells, and got the expression of glutathione S-transferase well. Besides, DOMACS significantly promoted the metabolism of amino acids to alleviate phytotoxicity, while DOMADS improved the DNA repair function of rice seedlings. These findings provided novel insights into land-use of bio-stabilized WAS for remediation of heavy metals contaminated soils and food security.

BSISTER transcription factors directly binds to the promoter of IAA19 and IAA29 genes to up-regulate gene expression and promote the root development

Roots play an important role in the growth and development of plants and auxin participates in regulating plant root development. Some studies have shown that BS (BSISTER) gene (the closest gene of class B gene) is involved in plant root development, but whether BS regulates root development via auxin signaling still not clear. To explore VviBS1 and VviBS2 roles in root development, VviBS1 and VviBS2 were overexpressedin Arabidopsis tt16 mutant and we found that they could restore the phenotype of shorter PR (primary roots) and high density of LR (lateral root) of tt16 compared with the wild type Ws Arabidopsis seedlings. However, the addition of exogenous NAA (naphthalene acetic acid) could not significantly promote the PR length of tt16 Arabidopsis, and the auxin signal transduction of tt16 may be blocked. The expression levels of auxin signal transduction pathway genes in Ws, tt16, p35s:VviBS1 in tt16 and p35s:VviBS2 in tt16 seedlings were detected. It was found that the expression of AtARF2, AtARF12, AtARF14, AtARF15, AtARF20, AtGH3, AtGH3-2 and AtSAUR51 genes in tt16 seedlings was higher than that in Ws, while the expression of AtIAA19 and AtIAA29 in Ws seedlings was higher than that of tt16. More importantly, BS may up regulate AtIAA19 and AtIAA29 expression directly by binding to their promoter. In addition, VviBS1 and VviBS2 also affect seed germination and may regulate leaf yellowing by regulating ethylene synthase. Therefore, our findings reveal a molecular mechanism that BS may modulate root system development via Aux/IAA-based auxin signaling, and provide insight into the BS function in regulation of leaf yellowing.

MiR390 family of Cymbidium goeringii is involved in the development of reproductive organs in transgenic Arabidopsis

BackgroundmiR390s is an ancient family with a high level of conservation among plant miRNAs. Through the auxin signal transduction pathway, miR390 participates in diverse biological processes of plant growth and development. As an important Chinese traditional orchid, Cymbidium goeringii has unique flower shape and elegant fragrance. But its development has been greatly restricted because of the low flower bud differentiation and the difficult reproduction. This study aims to provide guidance for the role of cgo-miR390 in reproductive organ development to enhance the ornamental and economic value of Cymbidium.ResultsMIR390a, MIR390b and MIR390c of C. goeringii were cloned, and their length ranged from 130 to 150 nt. Each precursor sequence of cgo-miR390 contains 2 to 3 mature miRNAs. Three kinds of cgo-miR390s displayed distinct temporal and spatial expression patterns during floral development in C. goeringii. The overexpression of MIR390s alters morphology and function of stamens and pistils in Arabidopsis, such as enlargement of anther aspect ratio and separation of stylar and stigmas, which affects the development of fruits and seeds. In particular, the pollen amount decreased and the seed abortion rate increased in cgo-MIR390c-overexpressed plants.Conclusionscgo-miR390 family affected the development of reproductive organs in transgenic Arabidopsis. The study provides references for the genetic improvement for orchid with potentially great economic benefit.

Identification of Peanut Aux/IAA Genes and Functional Prediction during Seed Development and Maturation.

Auxin-responsive genes AUX/IAA are important during plant growth and development, but there are few relevant reports in peanut. In this study, 44 AhIAA genes were identified from cultivated peanut, of which 31 genes were expressed in seed at varying degrees. AhIAA-3A, AhIAA-16A and AhIAA-15B were up-regulated, while AhIAA-11A, AhIAA-5B and AhIAA-14B were down-regulated with seed development and maturation. The expression patterns of seven genes, AhIAA-1A, AhIAA-4A, AhIAA-10A, AhIAA-20A, AhIAA-1B, AhIAA-4B and AhIAA-19B, were consistent with the change trend of auxin, and expression in late-maturing variety LM was significantly higher than that in early-maturing EM. Furthermore, allelic polymorphism analysis of AhIAA-1A and AhIAA-1B, which were specifically expressed in seeds, showed that three SNP loci in 3′UTR of AhIAA-1A could effectively distinguish the EM- and LM- type germplasm, providing a basis for breeding markers development. Our results offered a comprehensive understanding of Aux/IAA genes in peanut and provided valuable clues for further investigation of the auxin signal transduction pathway and auxin regulation mechanism in peanut.

Molecular evidence to the day length in regulating the short shoot phenomenon during summer in roses (Rosa sp.)

ABSTRACT The short shoot phenomenon is an important phenotype underlying the economic value of roses – node number can directly affect shoot length. To elucidate the molecular mechanism of how day length affects shoot length, the effect of 8, 10, and 12 h day lengths on node number were studied. The number of nodes between the 8 and 12 h treatment groups significantly differed. Node development in the 12 h treatment group occurred significantly earlier than that in the 8 and 10 h treatment groups and the number of nodes reached a maximum on the third day. Using RNA-seq analysis, we identified candidate genes that regulated shoot length; these were involved in the abscisic acid synthesis pathway and auxin signal transduction and synthesis pathways. Furthermore, the abscisic acid content in the shoot tip decreased with an increasing day length, while the auxin content increased with day length.

Over-Expression of Rose RrLAZY1 Negatively Regulates the Branch Angle of Transgenic Arabidopsis Inflorescence.

Branch angle is a key shoot architecture trait that strongly influences the ornamental and economic value of garden plants. However, the mechanism underlying the control of branch angle, an important aspect of tree architecture, is far from clear in roses. In the present study, we isolated the RrLAZY1 gene from the stems of Rosa rugosa ‘Zilong wochi’. Sequence analysis showed that the encoded RrLAZY1 protein contained a conserved GΦL (A/T) IGT domain, which belongs to the IGT family. Quantitative real-time PCR (qRT-PCR) analyses revealed that RrLAZY1 was expressed in all tissues and that expression was highest in the stem. The RrLAZY1 protein was localized in the plasma membrane. Based on a yeast two-hybrid assay and bimolecular fluorescence complementation experiments, the RrLAZY1 protein was found to interact with auxin-related proteins RrIAA16. The over-expression of the RrLAZY1 gene displayed a smaller branch angle in transgenic Arabidopsis inflorescence and resulted in changes in the expression level of genes related to auxin polar transport and signal transduction pathways. This study represents the first systematic analysis of the LAZY1 gene family in R. rugosa. The results of this study will provide a theoretical basis for the improvement of rose plant types and molecular breeding and provide valuable information for studying the regulation mechanism of branch angle in other woody plants.

Transcriptome analysis of genes in response to magnesium nitrate stress on cucumber leaf

Cucumber (Cucumis sativus L.) is a vital vegetable crop worldwide. Mg2+ and NO3− in the surface soil are the major limiting factors to continuous cropping in the main cucumber-producing areas of Shandong province in China. This study aimed to understand the magnesium nitrate- adaption in cucumber. Using a relatively salt tolerant cultivar ‘MC2065’ as experiment material, we analyzed the rate of water loss and changes in transcriptome profiles of cucumber leaves treated with 80 mM Mg(NO3)2 at different wilting stages for 0, 3, 12, and 24 h (T0-CK, T3, T12, T24 groups, respectively). The results showed that magnesium nitrate stress increased the rate of water loss in leaves. A total of 7465 differentially expressed genes (DEGs) were identified from a pool of 15923 genes. The maximum number of DEGs (4373) were observed at T12 vs. T0. For T3 vs. T0 and T24 vs. T0, there were 3763 and 3889 DEGs, respectively. Statistical analysis of gene expression showed 1075 DEGs significant expressed at T3, T12 and T24, compared to CK. Gene Ontology (GO) gene functional analysis of the DEGs identified 52 functionally enriched groups, within the categories of metabolic process, cell part and catalytic activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found DEGs related to plant hormone signal transduction (ko04075) and DNA replication of secondary metabolites were significantly in 86 pathways. Notably, the SAUR family in auxin signal transduction pathway had the highest number of DEGs, followed by PYL and ARR family in abscisic acid and cytokinin pathway. The unique DEGs identified in this study provide crucial information for further study on salt response mechanisms and genetic enhancement of salt resistance in cucumber.

Illumina Sequencing Reveals Conserved and Novel MicroRNAs of Dendrobium nobile Protocorm Involved in Synthesizing Dendrobine, a Potential Nanodrug.

Emergency of nanoparticulate drug delivery systems has improved the target, bioavailability, and curative effect of traditional Chinese medicine (TCM). However, the application of nano-preparation has been limited owing to the low content of active ingredients in part TCM. MicroRNAs (miRNAs) regulate plant growth, development, and response to environmental stresses at post-transcriptional regulation level by cleavage or translational inhibition. The molecular functions of miRNAs playing a role in synthesizing active comportments at medicinal plants have been widely researched. Dendrobium nobile is a perennial herb in the orchidaceae family. D. nobile protocorm can produce plant-specific metabolites at a short period. Therefore, it is a good substitute for producing metabolites. To understand the functions of miRNAs in D. nobile protocorm, Illumina sequencing of D. nobile protocorm (Dnp), D. officinale protocorm (Dcp), and D. nobile leaf (Dnl) were carried out. A total of 439, 412, and 432 miRNAs were identified from Dnp, Dcp, and Dnl, respectively. Some specific miRNAs were identified among them. Through combing GO and KEGG function annotation, miRNAs mainly involved metabolic pathways, plant hormone signal transduction, biological regulation, and protein binding. Acetyl-CoA acetyltransferase (AACT), mevalonate kinase (MK), 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), and 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase (HDS), synthesizing basic precursor isoprene pyrophosphate (IPP) in terpenoid backbone biosynthesis pathway, were predicted as potential targets of 6 different miRNAs. Twenty-six miRNAs participated in auxin, cytokinin, abscisic acid, jasmonic acid, and salicylic acid signal transduction pathway. This report provided valuable candidate genes in Dnp involved in terpenoid biosynthesis and plant hormone signal transduction pathway. At the same time, it can help accelerate the use of dendrobine into nano preparation.