NAA Treatment Research Articles

VvARF19 represses VvLBD13-mediated cell wall degradation to delay softening of grape berries

Abstract The fruit softening directly impacts its storage life, transportability, and customer acceptance. Auxin plays a key role during fruit ripening, but the underlying mechanisms of how auxin regulates fruit softening remain unclear. In this study, we investigated the regulatory roles of auxin on berry cell wall degradation during grape (Vitis vinifera L.) softening. During grape berry development, berry firmness and auxin content are both firstly increasing and then decreasing, and peaks occur at 4-6 WAFB (weeks after full blooming). Exogenous NAA (α-naphthalene acetic acid, a synthetic auxin) treatment inhibits berry softening by delaying propectin, cellulose and hemicellulose degradation, which maintains cell wall integrity in the grape flesh. Weighted gene co-expression network analysis (WGCNA) shows that VvLBD13 correlated with VvARF19 could be a key gene in this delaying of berry softening, which involved in auxin signal transduction and cell wall degradation metabolism. Over-expression and transient over-expression of VvLBD13 in tomato or in grape berry indicate that VvLBD13 accelerates hemicellulose degradation by binding the promoters of VvXTH10 (the xyloglucan endotransglucosylase/hydrolase 10) and VvEXPLA1 (expansion-like A1), which results in rapid softening after veraison. Collectively, this research furnishes an exhaustive understanding of the auxin- driven regulatory mechanisms of grape berry softening.

Response of GA3, NAA, and KNO3 treatments on in vitro seedgermination and shoot performance of highland bamboo(Oldeania alpina L.)

Oldeania alpina (K. Schum) Stapleton is an African alpine bamboo, native of Ethiopia to Zambia. The untreated seeds of O. alpina do not give good germination. Therefore, the effects of different seed pretreatments on germination and shoot quality were evaluated. The pre-sowing treatments were highly significant (P ≤ 0.001) for all studied parameters. The seeds subjected to 8% Gibberellic acid (GA3) treatment produced the highest germination percent (30%) while 6% NAA naphthalene acetic acid produced 23% germination. The values of MGT (mean germination time), PV (peak value) and VI (vigorous index) were also analyzed and interpreted to evaluate the germination of seed and shoot quality of the emerging plants. Moreover, the highest values for morphological parameters were recorded for 8% GA3 and 6 % NAA. Hence, the use of 8% GA3 or 6% NAA pretreatment is recommended to enhance the germination and shoot quality of O. alpina.

Application of combined GA3 and NAA treatments to improve yield and quality of Okra (Abelmoschus esculentus L.)

In Bangladesh, okra is an important popular summer vegetable. However, traditional farming practices often lead to suboptimal yields. Thus, the study was designed to determine the ideal GA3 and NAA doses for accelerating okra growth, yield, and quality characteristics. A three-replication, randomized complete block design was adopted. Foliar sprays with three concentrations of GA3 (0 ppm, 150 ppm, and 250 ppm) and NAA (0 ppm, 150 ppm, and 250 ppm) were applied in 2022 and 2023. In comparison to the control, the combined application of GA3 @ 150 ppm and NAA @ 150 ppm improved plant height, leaf number, leaf area, branch number, internode length, bud number, pod number, pod length, pod diameter, and 1000 seed weight average over the two years. Furthermore, GA3 @ 150 ppm with NAA 150 ppm increased yield by 35.08% and 27.01% in 2022 and 2023 respectively, above the control. Combining NAA @ 150 ppm with GA3 resulted in higher levels of vitamin C, TSS, magnesium, and zinc by 19.31%, 81.2%, 22.73% and 21.43% in 2022 and 22.83%, 50.57%, 18.07%, 33.33% in 2023 respectively, compared to the control. In contrast, GA3 and NAA decreased potassium and calcium in both year when compared to the control. Overall, the results of this experiment indicated that using GA3 @ 150 ppm with NAA @ 150 ppm could enhance okra growth, yield, and quality. These findings provide insightful information for improving okra cultivation techniques and improving Bangladesh’s productivity in agriculture and food security.

Restorer of fertility like 30, encoding a mitochondrion-localized pentatricopeptide repeat protein, regulates wood formation in poplar.

Nuclear-mitochondrial communication is crucial for plant growth, particularly in the context of cytoplasmic male sterility (CMS) repair mechanisms linked to mitochondrial genome mutations. The restorer of fertility-like (RFL) genes, known for their role in CMS restoration, remain largely unexplored in plant development. In this study, we focused on the evolutionary relationship of RFL family genes in poplar specifically within the dioecious Salicaceae plants. PtoRFL30 was identified to be preferentially expressed in stem vasculature, suggesting a distinct correlation with vascular cambium development. Transgenic poplar plants overexpressing PtoRFL30 exhibited a profound inhibition of vascular cambial activity and xylem development. Conversely, RNA interference-mediated knockdown of PtoRFL30 led to increased wood formation. Importantly, we revealed that PtoRFL30 plays a crucial role in maintaining mitochondrial functional homeostasis. Treatment with mitochondrial activity inhibitors delayed wood development in PtoRFL30-RNAi transgenic plants. Further investigations unveiled significant variations in auxin accumulation levels within vascular tissues of PtoRFL30-transgenic plants. Wood development anomalies resulting from PtoRFL30 overexpression and knockdown were rectified by NAA and NPA treatments, respectively. Our findings underscore the essential role of the PtoRFL30-mediated mitochondrion-auxin signaling module in wood formation, shedding light on the intricate nucleus-organelle communication during secondary vascular development.

Genome-wide characterization, functional analysis, and expression profiling of the Aux/IAA gene family in spinach

BackgroundThe auxin/indole-3-acetic acid (Aux/IAA) gene family is a crucial element of the auxin signaling pathway, significantly influencing plant growth and development. Hence, we conducted a comprehensive investigation of Aux/IAAs gene family using the Sp75 and Monoe-Viroflay genomes in spinach.ResultsA total of 24 definitive Aux/IAA genes were identified, exhibiting diverse attributes in terms of amino acid length, molecular weight, and isoelectric points. This diversity underscores potential specific roles within the family, such as growth regulation and stress response. Structural analysis revealed significant variations in gene length and molecular weight. These variations indicate distinct roles within the Aux/IAA gene family. Chromosomal distribution analysis exhibited a dispersed pattern, with chromosomes 4 and 1 hosting the highest and lowest numbers of Aux/IAA genes, respectively. Phylogenetic analysis grouped the identified genes into distinct clades, revealing potential evolutionary relationships. Notably, the phylogenetic tree highlighted specific gene clusters suggesting shared genetic ancestry and potential functional synergies within spinach. Expression analysis under NAA treatment unveiled gene-specific and time-dependent responses, with certain genes exhibiting distinct temporal expression patterns. Specifically, SpoIAA5 displayed a substantial increase at 2 h post-NAA treatment, while SpoIAA7 and SpoIAA9 demonstrated continuous rises, peaking at the 4-hour time point.ConclusionsThese observations indicate a complex interplay of gene-specific and temporal regulation in response to auxin. Moreover, the comparison with other plant species emphasized both shared characteristics and unique features in Aux/IAA gene numbers, providing insights into the evolutionary dynamics of this gene family. This comprehensive characterization of Aux/IAA genes in spinach not only establishes the foundation for understanding their specific functions in spinach development but also provides a valuable resource for experimental validation and further exploration of their roles in the intricate network of auxin signaling pathways.

The Effect of Benzyl Amino Purin and NaphtalenaAcetic Acid Applications on Direct Shoot Organogenesis in Porang (Amorphophallus muelleri B)

Porang (Amorphophallus muelleri B.) is a tuberous plant with the potential to be the main source of carbohydrates and is rich in benefits. Porang proliferation is limited by a 6-month dormancy period per year, and generative propagation is unlikely due to the seeds being apomictic triploid. The aimed of my research to analyze the application of BAP and NAA in culture media for direct propagation of porang shoots. The explant used in this research was young leaves. The research was arranged in a completely randomized design with a combination of BAP and NAA hormones added to the MS medium. There were three BAP treatments, namely 1.0 mg/L, 2.0 mg/L, and 3.0 mg/L, while NAA treatments consisted of 2 levels, namely 2.0 mg/L and 4.0 mg/L. The addition of 1.0 mg/L BAP combined with 4.0 mg/L NAA was the best treatment that produced seven shoots with an average shoot length of 2.14 cm and root length of 3.6 cm, with the earliest bud emergence (9.7 weeks after planting).

Influence of Naphthalene Acetic Acid, Gibberellic Acid and Calcium Chloride on Quality Parameters of Kagzi Lime (Citrus aurantifolia Swingle)

An experiment was carried out to investigate the influence of Naphthalene acetic acid, Gibberellic acid and Calcium chloride on quality parameters of Kagzi lime (Citrus aurantifolia Swingle) in the Garden, Dept. of Fruit Science, C. S. Azad University of Agriculture and Technology, Kanpur (U.P.) during two cropping seasons i.e., 2021-2022, 2022-2023. The experiment was laid out in Randomized Block Design with three replications and Ten treatments viz, T1-NAA (20 ppm), T2-NAA (40 ppm), T3-NAA (60 ppm), T4-GA3 (10 ppm), T5-GA3 (20 ppm), T6-GA3 (30 ppm),T7-CaCl2 (0.10%),T8-CaCl2 (0.15%),T9-CaCl2 (0.2%) and T10-Control (water spray only). During both years of investigation, it was recorded that GA3 at 20 ppm exhibited significantly higher amount of total soluble solids (9.300Brix) andtitratable acidity (8.70%) as compared to all other treatments. Similarly, NAA treatments also contributed to an increase in the TSS and titratable acidity content with the rise in their concentrations. In terms of TSS: acid ratio, there were no significant differences were recorded within the treatments, indicating its stability. Ascorbic acid content was significantly higher in GA3 treated fruits and with the GA3 at 20 ppm maximum amount of ascorbic acid was recorded (56.47 mg/100ml juice) while the control fruits had the lowest ascorbic acid content. The juice content in fruits were increased in NAA and GA3 treatments, while in CaCl2 treatments it remained relatively stable. Higher amount of juice content (56.49%) was also recorded in fruits treated with GA3 at 20 ppm. In the context of sugar content, GA3 at 20 ppm also exhibited the highest reducing (0.86%), non-reducing (0.70%) and total sugar (1.56%) content in the plains of north India.

Auxin synthesis promotes N metabolism and optimizes root structure enhancing N acquirement in maize (Zea mays L.).

Foliar NAA increases photosynthate supplied by enhancing photosynthesis, to strengthen root activity and provide a large sink for root carbohydrate accumulation, which is beneficial to acquire more nitrogen. The improvement of grain yield is an effective component in the food security. Auxin acts as a well-known plant hormone, plays an important role in maize growth and nutrient uptake. In this study, with maize variety Zhengdan 958 (ZD958) as material, the effects of auxin on nitrogen (N) uptake and assimilation of seedling maize were studied by hydroponic experiments. With water as the control, naphthalene acetic acid (NAA, 0.1mmol/L) and aminoethoxyvinylglycine (AVG, 0.1mmol/L, an auxin synthesis inhibitor) were used for foliar spraying. The results showed that NAA significantly improved photosynthetic rate and plant biomass by 58.6% and 91.7%, respectively, while the effect of AVG was opposite to that of NAA. At the same time, key enzymes activities related N assimilation in NAA leaves were significantly increased, and the activities of nitrate reductase (NR), glutamine synthetase (GS) and glutamate synthase (GOGAT) were increased by 32.3%, 22.9%, and 16.2% in new leaves. Furthermore, NAA treatment promoted underground growth. When compared with control, total root length, root surface area, root tip number, branch number and root activity were significantly increased by 37.8%, 22.2%, 35.1%, 28.8% and 21.2%. Root growth is beneficial to N capture in maize. Ultimately, the total N accumulation of NAA treatment was significantly increased by 74.5%, as compared to the control. In conclusion, NAA foliar spraying increased endogenous IAA content, and enhanced the activity of N assimilation-related enzymes and photosynthesis rate, in order to build a large sink for carbohydrate accumulation. In addition, NAA strengthened root activity and regulated root morphology and architecture, which facilitated further N uptake and plant growth.

1-Naphthaleneacetic Acid Improved the In Vitro Cell Culturing by Inhibiting Apoptosis.

In vitro cell culturing witnessed its applications in scientific research and industrial activities. Attempts to shorten the doubling time of cultured cells have never ceased. In plants, auxin is applied to promote plant growth, the synthetic derivative 1-Naphthaleneacetic acid (NAA) is a good example. Despite the auxin's naturally occurring receptors are not present in mammalian cells, studies suggested they may affect cell culturing. Yet the effects and mechanisms are still unclear. Here, an up to 2-fold increase in the yield of in vitro cultured human cells is observed. Different types of human cell lines and primary cells are tested and found that NAA is effective in all the cells tested. The PI staining followed by FACS suggested that NAA do not affect the cell cycling. Apoptosis-specific dye staining analysis implicated that NAA rescued cell death. Further bulk RNA sequencing is done and it is identified that the lipid metabolism-engaging and anti-apoptosis gene, ANGPTL4, is enhanced in expression upon NAA treatment. Studies on ANGPTL4 knockout cells indicated that ANGPTL4 is required for NAA-mediated response. Thus, the data identified a beneficial role of NAA in human cell culturing and highlighted its potency in in vitro cell culturing.

Exogenous Application of Calcium, α-Naphthaleneacetic Acid and 1Methylcyclopropene Improved Fruit Growth and Oil Yield of Oil Palm (Elaeis guineensis Jacq.) Grown on Ultisol

<span>Soil acidity is one of the main factors limiting the growth and sustainable production of oil palm in Indonesia. The aim of this study was to evaluate the effect of various exogenous compounds on improving fruit growth and oil yield of palm oil grown on Ultisol. The experiment employed three treatments which were arranged in a Randomized Complete Block Design (RCBD) with three replications. The treatments were: 1-MCP (0, 100, 200, and 300 ppm), CaCl</span><span>2 </span><span>(0 and 50 ppm) and NAA (0 and 200 ppm). Application of Ca</span><span>2+</span><span>, NAA and 1-MCP either single or in combination improved fruit growth and oil yield by increasing almost all variables, except the number of bunches, bunch weight and fruit set. The 100 ppm 1-MCP + 50 ppm Ca</span><span>2+ </span><span>+ 200 ppm NAA treatments showed the highest oil-to-dry mesocarp content. To get the highest oil to bunch (OB), the combination of 100 ppm 1-MCP + 200 ppm NAA; 50 ppm Ca</span><span>2+ </span><span>+ 200 ppm NAA, and a single treatment of 50 ppm Ca</span><span>2+ </span><span>were very promising to be utilized.</span>

Shoot Formation and Growth by NAA and Cytokinin Treatments in Node Culture of Rose ‘Natal Briar’ and ‘Deep Purple’

Shoot Formation and Growth by NAA and Cytokinin Treatments in Node Culture of Rose ‘Natal Briar’ and ‘Deep Purple’

Genome-Wide Identification and Expression Analysis of Auxin Response Factor (ARF) Gene Family in Betula pendula

As the key transcription factors regulating auxin responsive genes expression, auxin response factors (ARFs) play critical roles in diverse aspects of plant growth and development. Betula pendula is a valuable ornamental tree, and the information on ARF gene family of B. pendula is needed for better understanding. The publication of the genome sequence of B. pendula enable to analyze the bioinformatics information and expression pattern of BpeARF gene family on the genome-wide basis. In this study, physical and chemical properties, chromosome location, phylogenetic relationship, gene structure, conserved domain, motif composition, and cis-acting element of BpeARF gene family were analyzed, and expression patterns of BpeARF genes were investigated using completely random design in different tissues and under exogenous NAA and drought treatments. A total of 17 BpeARF genes was identified from B. pendula genome, which were unevenly distributed on 13 chromosomes and encoded adequate proteins ranging from 613 to 1135 amino acids in length. Three BpeARF gene pairs were formed by segmental duplication, and the Ka/Ks values of these BpeARF gene pairs were less than 1. According to the phylogenetic relationship among B. pendula, Betula platyphylla, Populus trichocarpa, and Arabidopsis thaliana, the BpeARF genes were divided into four classes, and the intron/exon structure, conserved domain, and motif composition showed high similarity among the BpeARF genes within the same class. The cis-acting elements in the promoter regions of BpeARF genes were related to tissue development, hormone response, and stress resistance. Quantitative real-time PCR exhibited diverse expression patterns of BpeARF genes in different tissues and in response to exogenous auxin treatment and drought stress. The expressions of one, ten, seven, and three BpeARF genes were the high levels in buds, young leaves, stems, and roots, respectively. Under exogenous NAA treatment, six BpeARF genes in stems and roots were upregulated expression at all timepoints. Under drought stress, BpeARF7 and BpeARF15 were upregulated in stems and roots, and BpeARF5 and BpeARF6 were downregulated in leaves, stems, and roots. Our results provided valuable information for the classification and putative functions of BpeARF gene family, which may be helpful for selecting candidate genes and verifying gene function in the genetic engineering of birch trees in further research.

Auxin mediated elevated CO2-induced stolon growth and soluble sugar accumulation in creeping bentgrass

Stolon is crucial for competitive ability, stresses tolerance, as well as carbohydrate and nutrition storage in plants. In our previous study, stolon growth as well as the content of both indole-3-acetic acid (IAA) and carbohydrates (glucose, sucrose, and fructose) in stolon nodes and internodes were found to be increased due to elevated CO2 in stoloniferous creeping bentgrass. The objectives of this study were to determine the roles of auxin and the underlying mechanism of auxin in regulating elevated CO2-induced improvement on stolon growth and carbohydrate accumulation in stolon nodes and internodes of creeping bentgrass. Plants were treated with foliar applications of auxin (1-naphthalene acetic acid, NAA) and auxin transport inhibitor (2,3,5-triiodobenzoic acid, TIBA) at different concentrations to observe their effects on stolon growth. Hence, 10 mg⋅L−1 NAA and 100 mg⋅L−1 TIBA were selected as optimal concentrations to foliarly spray plants grown under either ambient CO2 (400 µmol⋅mol−1) or elevated CO2 (800 µmol⋅mol−1). Under water control and NAA treatments, stolon growth (stolon internode number, total stolon length, and stolon biomass) and contents of carbohydrate (glucose, sucrose, and fructose) were significantly increased by elevated CO2, but no positive effects were found in TIBA treatments in stolon nodes and internodes of creeping bentgrass. The results confirmed that IAA mediated elevated CO2-enhancement in stolon growth and carbohydrates accumulation in stolon nodes and internodes. The increase in IAA level was mainly associated with genes involved in auxin synthesis and transport in stolon nodes and internodes of creeping bentgrass. Our results would provide new insights for the rapid growth of stoloniferous plants under the scenario of continuous rise of the atmosphere CO2 concentration.

The Effect of BAP and NAA Combination on Callus Induction of Aglaonema Siam Aurora Leaf Explants in Vitro

This research aims to determine the effect of the Naphthalene Acetic Acid and Benzyl Amino Purine combination on callus growth of Aglaonema Siam Aurora leaf explants and to determine the combination level at the most optimal concentration on the callus growth of Aglaonema Siam Aurora leaf explants. Observation variables included callus emergence time, explants percentage of formed callus, callus length, and explant life percentage. The explants that where used were the first young leaves explants from shoots that were opened, with 2x2 cut size. Results show that the addition of a NAA and BAP combination had an effect on . Combination of 1.2 ppm BAP + 1 ppm NAA treatment is the most optimum treatment for callus growth with a callus percentage of 87.5%, the callus start time at week 3, the average callus length is 0.77 mm and the percentage number of survived explants is 100%

Exogenous auxin regulates the growth and development of peach fruit at the expansion stage by mediating multiple-hormone signaling

BackgroundFruit expansion stage is crucial to fruit yield and quality formation, and auxin plays a significant role by mediating multi-hormone signals during fruit expansion. However, till now, it is still unclear of the molecular regulatory network during auxin-mediated peach fruit expansion.ResultsHere, exogenous NAA application markedly increased IAA content and drastically decreased ABA content at the fruit expansion stage. Correspondingly, NAA mainly induced the auxin biosynthesis gene (1 PpYUCCA) and early auxin-responsive genes (7PpIAA, 3 PpGH3, and 14 PpSAUR); while NAA down-regulated ABA biosynthesis genes (2 PpNCED, 1 PpABA3, and 1 PpAAO3). In addition, many DEGs involved in other plant hormone biosynthesis and signal transduction were significantly enriched after NAA treatment, including 7 JA, 7 CTK, 6 ETH, and 3 GA. Furthermore, we also found that NAA treatment down-regulated most of genes involved in the growth and development of peach fruit, including the cell wall metabolism-related genes (PpEG), sucrose metabolism-related genes (PpSPS), phenylalanine metabolism-related genes (PpPAL, Pp4CL, and PpHCT), and transcription factors (PpNAC, PpMADS-box, PpDof, PpSBP, and PpHB).ConclusionOverall, NAA treatment at the fruit expansion stage could inhibit some metabolism processes involved in the related genes in the growth and development of peach fruit by regulating multiple-hormone signaling networks. These results help reveal the short-term regulatory mechanism of auxin at the fruit expansion stage and provide new insights into the multi-hormone cascade regulatory network of fruit growth and development.

In vitro multiplication of “Kepok” banana (Musa acuminata x Musa balbisiana) using different concentration of BAP and NAA in MS media

This study aims to determine the effect of different composition of BAP and NAA concentration added to Murashige and Skoog (MS) basic media on the in vitro multiplication of Indonesian “Kepok” banana variety. The research was conducted at the Tissue Culture Laboratory of Bonto-Bonto Horticultural Plant Seed Center. A completely randomized design (CRD) was employed with two factors tested. Four concentrations of each BAP and NAA used were 0 ppm, 4.5 ppm, 5 ppm, and 5.5 ppm for BAP, and 0 ppm, 2 ppm, 2.5 ppm, and 3 ppm for NAA resulted in 15 composition of BAP:NAA in addition to control (without the hormones). The results show no interaction between the BAP and NAA treatments, BAP concentration of 5 ppm gave the best result on parameter time to shoots emergence (7.50 DAP). NAA concentration of 2.5 ppm gave the best results on root emergence time (8.61 DAP), time to plantlet formation (11.72 DAP), number of roots (4.81 roots) and root length (5.93 cm).

Effect of BAP (6-Benzylaminopurine) and NAA (α-Napthalene Acetic Acid) treatment on Micropropagation of Adansonia digitata L.

The African Baobab, also known as Kalpvriksha (Adansonia digitata L.), is a significant multi-purpose tree that has gained popularity among people, primarily in African countries, for its use as food, fodder, clothing, and ropes. There is one of the obstacle arises in growing this plant by farmers in India is the lack of planting materials. The young plants of A. digitata L. have to be imported form selected nurseries. Therefore, micropropagation can be used as a substitute method to create offspring that are genetically similar to the parent plant. In order to micropropagate Kalpvriksh (A. digitata L.), this experiment is being conducted utilizing shoot tip explants. For shoot proliferation, these explants are grown in MS medium containing various concentrations of BAP (6- Benzylamino purine): 0.5, 1.0, 1.5, 2.5, 5.0 mg/L. Shoots are rooted in a medium containing at the same concentration of NAA (α-Napthalene Acetic Acid) 0.5 mg/L alone or with combination. Complete Randomized Design (CRD) is used to conduct each experiment. ANOVA and the Duncan New Multiple Range test are used to examine the data. According to the technique for micropropagation of A. digitata L. The concentration of BAP and NAA was found to be 1.5 mg/L and 0.5 mg/L respectively which showed better enhancement for shoot regeneration and rooting for micropropagation of Kalpvriksha (Adansonia digitata L.) tree.

Study on the Rooting Physiological Mechanism of Schisandra chinensis (Turcz.) Baill. Green-Branched Cuttings

Schisandra chinensis (Turcz.) Baill. is an important medicinal plant in northeast China. Cutting propagation is an effective method for the rapid propagation of many tree species. This research aimed to determine a suitable growing medium and appropriate root hormone type, concentration and treatment time through the utilization of different substrates and hormones to treat one-year-old branches of S. chinensis. The optimal treatment achieved a rooting rate of 60% with 225 ppm ABT and 75 ppm NAA for 2.5 h. The substrate of vermiculite/perlite = 1:1 (urea+potassium) was beneficial to the adventitious root formation, which reached 79%. The adventitious root primordium of S. chinensis originated from the junction of the xylem and cambium. ABT and NAA treatments altered the peak timing of POD, PPO and IAAO in S. chinensis cuttings. During the adventitious root formation of S. chinensis cuttings, the high endogenous IAA concentration promoted the occurrence of adventitious roots in the early stage and the lower endogenous IAA and GA3 concentrations promoted the elongation and growth of adventitious roots in the later period. Low ABA and ZR concentrations enabled adventitious root formation and elongation. An efficient cutting propagation system would enable the mass propagation of S. chinensis seedlings.

A Combinatorial TIR1-Aux/IAA Co-Receptor System for Peach Fruit Softening

Fruit softening is an important characteristic of peach fruit ripening. The auxin receptor TIR1 (Transport Inhibitor Response 1) plays an important role in plant growth and fruit maturation. Still, little research has been conducted on the relation of TIR1 to the softening of peach fruits. In this study, the hardness of isolated peach fruits was reduced under exogenous NAA treatment at low concentrations. At the same time, the low concentration of NAA treatment reduced the transcription level of PpPG and Ppβ-GAL genes related to cell wall softening and PpACS1 genes related to ethylene synthesis. The transient overexpression of the PpTIR1 gene in peach fruit blocks caused significant down-regulation of the expression of early auxin-responsive genes, ethylene synthesis, and cell wall metabolic genes related to fruit firmness. Through yeast two-hybrid technology, bimolecular fluorescence complementary technology, and a firefly luciferase complementation imaging assay, we were able to unveil an interaction between PpTIR1 and PpIAA1/3/5/9/27 proteins. Furthermore, it was determined that the interaction depended on auxin and its type and concentration. These results show that the PpTIR1-Aux/IAA module has a possible regulatory effect on fruit ripening and softening.

Overexpression of peanut (Arachis hypogaea L.) AhGRFi gene enhanced root growth inhibition under exogenous NAA treatment in Arabidopsis thaliana.

The 14-3-3 protein is a kind of evolutionary ubiquitous protein family highly conserved in eukaryotes. Initially, 14-3-3 proteins were reported in mammalian nervous tissues, but in the last decade, their role in various metabolic pathways in plants established the importance of 14-3-3 proteins. In the present study, a total of 22 14-3-3 genes, also called general regulatory factors (GRF), were identified in the peanut (Arachis hypogaea) genome, out of which 12 belonged to the ε group, whereas 10 of them belonged to the non- ε-group. Tissue-specific expression of identified 14-3-3 genes were studied using transcriptome analysis. The peanut AhGRFi gene was cloned and transformed into Arabidopsis thaliana. The investigation of subcellular localization indicated that AhGRFi is localized in the cytoplasm. Overexpression of the AhGRFi gene in transgenic Arabidopsis showed that under exogenous 1-naphthaleneacetic acid (NAA) treatment, root growth inhibition in transgenic plants was enhanced. Further analysis indicated that the expression of auxin-responsive genes IAA3, IAA7, IAA17, and SAUR-AC1 was upregulated and GH3.2 and GH3.3 were downregulated in transgenic plants, but the expression of GH3.2, GH3.3, and SAUR-AC1 showed opposite trends of change under NAA treatment. These results suggest that AhGRFi may be involved in auxin signaling during seedling root development. An in-depth study of the molecular mechanism of this process remains to be further explored.