Leaf Growth Rate Research Articles

Assessing the growth, yield, and biochemical composition of greenhouse cherry tomatoes with special emphasis on the progressive growth report

The growth of plants hinges on a complex interplay of biochemical and physiological activities across various growth stages. These intricate processes dynamically adapt to different environmental conditions, shaping both plant development and productivity. This study explores the impact of greenhouse climate on the growth, yield, and biochemistry of winter-grown cherry tomatoes ‘Cheramy F1’. A randomized complete block design (RCBD) under split plot arrangements (3 Rows) with three replications (3 plants from each row) was adopted. The data were collected on various dates during the period extending from December to March of two consecutive growing seasons in 2022 and 2023, and presented as averages. An analysis of variance was applied to statistically analyze the collected data at a confidence level of p < 0.05. The climatic conditions in the greenhouse were calculated as temperature ranging from a minimum of 10.5 °C to the maximum of 41.3 °C by an average of 21.2 °C during the vegetative stage and from 8.2 °C to 32.3 °C by an average of 20.9 °C during the fruit-bearing stage, with an average CO2 concentration fluctuated within the range of 385.61 ppm to 510.30 ppm and an average light intensity of 94.62 to 240.45 W/m². This study assessed various growth parameters such as plant height, leaf growth, stem diameter, leaf spacing, leaf count, leaf area, and inflorescence count per plant, and suggested the optimum range of greenhouse conditions for each stage. The key results of this study revealed the Progressive Growth Report (PGR), predicting daily potential growth rates of plants: plant height, 2.86 to 3.81 cm/day; growth rate of mature older leaf: 0.003988 m2/day; middle younger leaf: 0.008733 m2/day; top nascent leaf: 0.010722 m2/day; three to five leaves per week; and one inflorescence per week. In our accidental observation, we noticed unusual plant growth and yield responses because of the various growing postures and positions that the plants adopted in the greenhouse. An exceedingly significant difference among the inflorescences was found in view of their growth, productivity and biochemical composition. A non-significant interaction was found between the fruit keeping quality (shelf days), fruit height, fruit diameter, and inflorescence number. The present study results highlight the possible responses of greenhouse-grown cherry tomatoes to different ranges of temperature, light intensity, and CO2 concentrations, offering valuable insights for optimizing greenhouse cherry tomatoes cultivation.

Dynamics of Mulatto Grass Regrowth Depending on Rotational Cattle Grazing Management

This study was carried out to characterize the dynamics of forage accumulation during the regrowth of Mulatto grass submitted to rotational grazing strategies. The treatments corresponded to combinations between two pre-grazing conditions (95% and a maximum light interception during regrowth—LI95% and LIMax) and two post-grazing conditions (post-grazing heights of 15 and 20 cm), according to a 2 × 2 factorial arrangement and randomized complete block design, with four replications. Rates of leaf growth (LGR), stems growth (SGR), total growth (TGR), leaf senescence (LSR), grass accumulation (GAR) (kg·ha−1·day−1), and the senescence/canopy growth ratio during different stages of regrowth. There was no difference between the management strategies for TGR. However, a higher GAR was reported for pastures managed with LI95% relative to LIMax, of 161.7 and 120.2 kg DM ha−1·day−1, respectively. Pastures managed with LI95% have a lower SGR in the intermediate and final regrowth period, reflecting the efficient control in the stalks production. On the other hand, in pastures managed, the LIMax showed higher SGR and LSR in the final regrowth phase. Thus, the LAI was higher in pastures managed at LI95% compared to those managed at LIMax, of 163.9 and 112.7 kg DM ha−1·day−1, respectively. Mulatto grass pastures, which were managed at LI95% pre-grazing, corresponded to approximately 30 cm in height, showed higher LAI, and ensured a low SGR throughout the regrowth period, constituting a more efficient management strategy.

Comparative Analysis of Vegetative Development and Leaf Morpho-Anatomy in Three Taxa of Ornamental Alocasia (Araceae)

This study examines the growth patterns, leaf morpho-anatomical traits and physiological characteristics of three ornamental taxa of Alocasia: A. melo, A reginae and Alocasia × morfontanensis ‘Bambino’. Using optical and scanning electron microscopy, the research obtained anatomical details of the leaves. Alocasia × morfontanensis ‘Bambino’ exhibited the highest leaf growth rate among the taxa studied, showing significant leaf number increases from the 8th to the 12th week after planting. Alocasia melo produced 2–3 new basal shoots after 20 weeks, whereas the other two taxa did not produce any. Alocasia melo displayed the greatest relative water content and leaf thickness, while A. reginae showed the highest chlorophyll stability. This study also revealed variations in the adaxial and abaxial leaf color, stomatal width, epidermal thickness, and elemental composition among the taxa involved, with A. melo containing rhodium and high levels of calcium on their leaf surface. These findings contribute to the understanding of the Alocasia leaf morpho-anatomy and growth, which is useful for optimizing Alocasia cultivation and production across diverse ecosystems.

Supplemental nitrogen alleviates the negative effects of higher temperature on the vegetative growth of canola regardless of carbon dioxide concentration

Climate change components, including carbon dioxide (CO2) and temperature, can influence crop productivity and nutritional value, posing a threat to food security. Many studies have investigated the mitigation of climate change factors by nitrate and/or ammonium application, but there has been little focus on the role of urea in the interactive effects of these factors. We examined the effects of temperature, CO2, and supplemental nitrogen (N in the urea form) on growth and physiological traits of canola (Brassica napus). Plants were grown under two temperature regimes (22/18 °C and 28/24 °C, 16 h light/8 h dark), two CO2 concentrations (400 and 700 µmol mol−1), and three levels of N (zero, no supplement; low, based on 50 kg ha−1; high, based on 100 kg ha−1) for 21 days after one week of initial growth under 22/18 °C. In this study, gas exchange, chlorophyll fluorescence, chlorophyll, flavonoids, nitrogen balance index (NBI), plant growth and biomass, and tocopherols, were measured. Higher temperatures decreased net CO2 assimilation (AN), water use efficiency, effective quantum yield of photosystem II, nonphotochemical quenching (qNP), chlorophyll, flavonoids, stem height and diameter, leaf area and number, dry mass, and β-, γ-, and δ-tocopherols, but increased stomatal conductance. Elevated CO2 increased AN, qNP and leaf area ratio, but decreased stomatal conductance (gs). Supplemental nitrogen alleviated the effects of temperature stress by increasing gs, chlorophyll, NBI, stem height and diameter, leaf area, growth rate, and dry mass. Overall, these findings suggest that under climate change, N supplementation may be used to alleviate environmental stress on plants.

Modeling cassava root system architecture and the underlying dynamics in shoot–root carbon allocation during the early storage root bulking stage

Abstract Background and aims Plants store carbohydrates for later use during, e.g., night, drought, and recovery after stress. Carbon allocation presents the plant with tradeoffs, notably between growth and storage. We asked how this tradeoff works for cassava (Manihot esculenta) pre- and post-storage root (SR) formation and if manipulation of the number of storage organs and leaf growth rate might increase yield. Methods We developed a functional-structural plant model, called MeOSR, to simulate carbon partitioning underlying cassava growth and SR formation in conjunction with the root system's three-dimensional (3D) architecture (RSA). We compared the model results to experimental data and simulated phenotypes varying in the number of SR and leaf growth rate. Results The simulated 3D RSA and the root mass closely represented those of field-grown plants. The model simulated root growth and associated carbon allocation across developmental stages. Substantial accumulation of non-structural carbohydrates (NSC) preceded SR formation, suggesting sink-limited growth. SR mass and canopy photosynthesis might be increased by both increasing the number of SR and the leaf growth rate. Conclusion MeOSR offers a valuable tool for simulating plant growth, its associated carbon economy, and 3D RSA over time. In the first month, the specific root length increased due to root branching, but in the third month, it decreased due to secondary root growth. The accumulation of NSC might initiate SR development in cassava. Cassava growth is relatively slow during the first 3 months, and a faster crop establishment combined with a greater SR growth might increase yield.

Optimized Nitrogen Application Rate Significantly Increases Total Economic Value and Quality of Flue-Cured Tobacco due to the Improvement of Superior Tobacco Yield

Summary With the improvement of irrigation and transportation infrastructures, single tobacco cultivation has been converted into tobacco–vegetable double cultivation in Yunnan Province. High residual nitrogen (N) levels in soil before tobacco transplanting induced by the excessive N input during the vegetable cultivation season resulted in a reduction of economic income and the quality of flue-cured tobacco. Therefore, the objective of this paper is to describe the optimization of N management and to provide a better understanding of the mechanism of optimal N application rate on the economic benefit and quality of tobacco. A field experiment with six N application rates (0, 45, 60, 75, 90, and 105 kg N ha−1) was carried out with a randomized block design in 2021 and 2022 in Yunnan Province. The economic value and yield, intrinsic chemical and processing quality, leaf growth rate and agronomic characters were determined. Compared with the currently recommended 105 kg N ha−1 rate, 75 kg N ha−1 significantly increased the total economic value and superior tobacco yields, improved the integrated grade of chemical compounds and resulted in leaf midrib proportions in an appropriate range. The total economic value positively correlated with the superior tobacco leaf yields (R2 = 0.91, p &lt; 0.001), while not with medium and inferior leaf yield. The daily leaf growth rate in prosperous growth stage significantly correlated with the yield of superior tobacco and reached its maximum at a N rate of 75 kg N ha−1. The sum of N application rate and soil residual N before transplanting correlated with the total economic value (R2 = 0.66, p &lt; 0.05) and superior leaf yield (R2 = 0.64, p &lt; 0.05), respectively. Based on the amount of soil residual N before transplanting, the optimal N application rate was 66 kg N ha−1 which was 39 kg N ha−1 lower than the currently recommended N rate (105 kg N ha−1). Our results highlighted that the technical consultants and farmers should adjust the N application rate appropriately according to the residual N amount before transplanting and optimize the water and fertilizer management especially in the prosperous growth stage. An optimized N rate is not only of economic benefit and the improvement of quality of tobacco cultivation, but also environment friendly.

The resilience of transplanted seagrass traits encourages detection of restoration success

Restoration of coastal ecosystems, particularly those dominated by seagrasses, has become a priority to recover the important ecosystem services they provide. However, assessing restoration outcomes as a success or failure remains still difficult, probably due to the unique features of seagrass species and the wide portfolio of practices used on transplanting actions. Here, several traits (maximum leaf length, number of leaves, leaf growth rate per shoot, and leaf elemental carbon and nitrogen contents) of transplanted seagrass Posidonia oceanica were compared to reference meadows in five sites of Western Mediterranean Sea in which restoration were completed in different times. Results have evidenced the resilience of transplanted P. oceanica shoots within a few years since restoration, as traits between treatments changed depending on the elapsed time since settlement. The highlighted stability of the restoration time effect suggests that the recovery of the plants is expected in four years after transplanting.

Patch age alters seagrass response mechanisms to herbivory damage

Natural disturbances can produce a mosaic of seagrass patches of different ages, which may affect the response to herbivory. These pressures can have consequences for plant performance. To assess how seagrass patch age affects the response to herbivory, we simulated the effect of herbivory by clipping leaves of Halodule wrightii in patches of 2, 4 and 6 years. All clipped plants showed ability to compensate herbivory by increasing leaf growth rate (on average 4.5-fold). The oldest patches showed resistance response by increasing phenolic compounds (1.2-fold). Contrastingly, the concentration of phenolics decreased in the youngest patches (0.26-fold), although they had a similar leaf carbon content to controls. These results suggest that younger plants facing herbivory pressure reallocate their phenolic compounds towards primary metabolism. Results confirm the H. wrightii tolerance to herbivory damage and provides evidence of age-dependent compensatory responses, which may have consequences for seagrass colonization and growth in perturbed habitats.

Effects of summer pruning on the growth and photosynthetic characteristics of pepper (Capsicum annuum L.)

The objective of the study is to investigate the mechanism by which summer pruning enhances the growth of pepper plants, as indicated by growth and fruit appearance indicators, photosynthetic rate and gas exchange parameters, rapid light response and induction kinetics curves and the related chlorophyll fluorescence parameters. The results indicated that the leaf growth rate, the individual pepper fruit weight, and the fruit longitudinal and cross diameters of the pruned group were significantly higher than those of the control. The stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr) of the pruned group were significantly higher than those of the control. The initial slope of the rapid light response curve, which represents light energy utilisation efficiency (α), the maximum electron transfer rate (Jmax) and saturated light intensity (PARsat) were all higher in the summer pruning group than in the control group. The F0 of the pruned group decreased by 16.83%, Fv/F0 increased by 23.69%, PIabs increased by 58.33%, and DIo/RC decreased by 22.09% compared to the control group. In summary, summer pruning significantly improves the leaf growth rate and fruit appearance quality of pepper, effectively promotes the photosynthesis of functional leaves, and reduces the degree of stress under adverse environmental conditions.

Integrated Metabolome and Transcriptome Analysis of Gibberellins Mediated the Circadian Rhythm of Leaf Elongation by Regulating Lignin Synthesis in Maize.

Plant growth exhibits rhythmic characteristics, and gibberellins (GAs) are involved in regulating cell growth, but it is still unclear how GAs crosstalk with circadian rhythm to regulate cell elongation. The study analyzed growth characteristics of wild-type (WT), zmga3ox and zmga3ox with GA3 seedlings. We integrated metabolomes and transcriptomes to study the interaction between GAs and circadian rhythm in mediating leaf elongation. The rates of leaf growth were higher in WT than zmga3ox, and zmga3ox cell length was shorter when proliferated in darkness than light, and GA3 restored zmga3ox leaf growth. The differentially expressed genes (DEGs) between WT and zmga3ox were mainly enriched in hormone signaling and cell wall synthesis, while DEGs in zmga3ox were restored to WT by GA3. Moreover, the number of circadian DEGs that reached the peak expression in darkness was more than light, and the upregulated circadian DEGs were mainly enriched in cell wall synthesis. The differentially accumulated metabolites (DAMs) were mainly attributed to flavonoids and phenolic acid. Twenty-two DAMs showed rhythmic accumulation, especially enriched in lignin synthesis. The circadian DEGs ZmMYBr41/87 and ZmHB34/70 were identified as regulators of ZmHCT8 and ZmBM1, which were enzymes in lignin synthesis. Furthermore, GAs regulated ZmMYBr41/87 and ZmHB34/70 to modulate lignin biosynthesis for mediating leaf rhythmic growth.

Mechanism underlying the rapid growth of Phalaenopsis equestris induced by 60Co-γ-ray irradiation.

Gamma (γ)-ray irradiation is one of the important modern breeding methods. Gamma-ray irradiation can affect the growth rate and other characteristics of plants. Plant growth rate is crucial for plants. In horticultural crops, the growth rate of plants is closely related to the growth of leaves and flowering time, both of which have important ornamental value. In this study, 60Co-γ-ray was used to treat P. equestris plants. After irradiation, the plant's leaf growth rate increased, and sugar content and antioxidant enzyme activity increased. Therefore, we used RNA-seq technology to analyze the differential gene expression and pathways of control leaves and irradiated leaves. Through transcriptome analysis, we investigated the reasons for the rapid growth of P. equestris leaves after irradiation. In the analysis, genes related to cell wall relaxation and glucose metabolism showed differential expression. In addition, the expression level of genes encoding ROS scavenging enzyme synthesis regulatory genes increased after irradiation. We identified two genes related to P. equestris leaf growth using VIGS technology: PeNGA and PeEXPA10. The expression of PeEXPA10, a gene related to cell wall expansion, was down-regulated, cell wall expansion ability decreased, cell size decreased, and leaf growth rate slowed down. The TCP-NGATHA (NGA) molecular regulatory module plays a crucial role in cell proliferation. When the expression of the PeNGA gene decreases, the leaf growth rate increases, and the number of cells increases. After irradiation, PeNGA and PeEXPA10 affect the growth of P. equestris leaves by influencing cell proliferation and cell expansion, respectively. In addition, many genes in the plant hormone signaling pathway show differential expression after irradiation, indicating the crucial role of plant hormones in plant leaf growth. This provides a theoretical basis for future research on leaf development and biological breeding.

Plant growth regulators improve the growth and physiology of transplanted Thalassia Hemprichii fragments

IntroductionThe transplantation of seagrass fragments with shoots and rhizomes is the most common method for the ecological restoration of damaged seagrass meadows.MethodsThe aim of this study was to explore the effects of exogenous addition (10 mg per month for 3 months) of three commonly used plant growth regulators (PGRs), including indoleacetic acid (IAA), gibberellin (GA3), and paclobutrazol (PP333) on the growth and physiology of transplanted Thalassia hemprichii fragments (TTFs), with and without the rhizome apex (RA), using a simulation test. [Results] IAA and GA3 elevated the photosynthetic capacity and growth rate of TTF leaves but did not significantly alter leaf length and width. In contrast, PP333 reduced the leaf photosynthetic capacity and growth rate, while greatly increasing the leaf width and root viability. Additionally, PP333 treatment led to an increase in antioxidant enzyme activities (peroxidase [POD], superoxide dismutase [SOD], and catalase [CAT]), as well as malondialdehyde (MDA) and total phenol contents in TTFs, indicating some stress effects on the seagrass. Furthermore, IAA and GA3 decreased soluble sugar and protein contents and increased starch content in TTF tissues, whereas PP333 treatment elevated both nonstructural carbohydrate and soluble protein contents. The presence of RA positively affected the growth and physiology of T. hemprichii compared with TTFs without RA. There was a significant interaction between the PGRs and RA on leaf growth rate, chlorophyll fluorescence variables, and photosynthetic pigment content of the TTFs (p &amp;lt; 0.05).DiscussionThis study provides guidelines for the application of PGRs during the transplantation of T. hemprichii fragments for the restoration of seagrass meadows.

Application of humic acid increases the economic value and yield of superior tobacco as well as improves the chemical and processing quality

AbstractThe overuse of nitrogen (N) fertilizer in the vegetable growing season leads to a high amount of soil residual N and a decrease of resistance to tobacco disease in the vegetable–tobacco continuous cultivation system, which will seriously threaten the sustainable development of tobacco production. Humic acid (HA) rich in bioactive substances and microelements may enhance leaf growth rate and improve the quality of tobacco. A two‐factor randomized block experiment was carried out over 2 years to evaluate the effects of additional applying HA (0 and 150 L ha−1) combined with three N rates (0, 60, and 90 kg N ha−1) on tobacco growth, economic value, chemical, and processing quality. Applying HA significantly increased the tobacco economic value by 5%–28%. The superior tobacco yields positively correlated with the economic value (R2 = 0.88), which was the key factor determining the increase of the economic value. The application of HA decreased the disease severity and increased the microelement uptake and the daily leaf growth rate in the prosperous growing stage which was positively correlated with the superior tobacco yield. Applying HA significantly improved the chemical quality and reduced the leaf midrib proportion. At the N rate of 60 kg N ha−1, HA showed the best effect of improving quality and increasing income. Our results demonstrated that the addition of HA can significantly improve the economic value and the chemical and processing quality of tobacco. The best effect can be achieved by adjusting the N rate appropriately according to the amount of soil residual N before transplanting tobacco seedlings.

Determination of the Optimal and Lethal Dose for Mutagenicity of Rice Cultivars by Ethel Methane Sulphate

The experiment was carried out in the laboratories of the Department of Field Crops - College of Agriculture - Al-Qasim Green University to study optimal and lethal doses for mutagenicity of rice (Oryza sativa L.) cultivars by Ethel Methane Sulphate. The experiment design included two factors, the first factor being three cultivars : (V1= Amber 33, V2= Jasmine, and V3= Tigris) and the second factor nine concentrations (E0 = 0, E1 = 0.5, E2 = 1, E3=1.5, E4 = 2, E5 = 2.5, E6 =3, E7 =3.5 and E4 =4, respectively). The treatments were distributed in a factorial experiment according to the design of a complete randomized design (CRD) with three replications. The results obtained showed that the control treatment recorded the highest germination percentage but did not differ significantly from the E1 and E2 treatments, the E2 treatment gave the highest seedling vigor, dry matter production rate, and leaf growth rate, and there were no differences in the rice cultivars in the study in all the studied traits, the interactions were not significant in all the studied traits except the leaf growth rate, the treatment E3×V3, and E2×V2 excelled in the leaf growth rate and gave the highest value, while the E4×V2 treatment had the lowest leaf growth rate.

Malate production, sugar metabolism, and redox homeostasis in the leaf growth zone of Rye (Secale cereale) increase stress tolerance to aluminum stress: A biochemical and genome‐wide transcriptional study

Global soil acidification is increasing, enlarging aluminum (Al) availability in soils, leading to reductions in plant growth. This study investigates the effect of Al stress on the leaf growth zones of Rye (Secale cereale, cv Beira). Kinematic analysis showed that the effect of Al on leaf growth rates was mainly due to a reduced cell production rate in the meristem. Transcriptomic analysis identified 2272 significantly (log2fold > |0.5| FDR < 0.05) differentially expressed genes (DEGs) for Al stress. There was a downregulation in several DEGs associated with photosynthetic processes and an upregulation in genes for heat/light response, and H2O2 production in all leaf zones. DEGs associated with heavy metals and malate transport were increased, particularly, in the meristem. To determine the putative function of these processes in Al tolerance, we performed biochemical analyses comparing the tolerant Beira with an Al sensitive variant RioDeva. Beira showed improved sugar metabolism and redox homeostasis, specifically in the meristem compared to RioDeva. Similarly, a significant increase in malate and citrate production, which are known to aid in Al detoxification in plants, was found in Beira. This suggests that Al tolerance in Rye is linked to its ability for Al exclusion from the leaf meristem.

Evaluation of Intercropped Aloe vera with Plantain on Growth and Yield Status in a Real Culture Situation in Daloa, Côte d'Ivoire

Rains decrease and irregularity represent a threat to farmers and call for crops of interest’s promotion like Aloe vera, requiring little water. Therefore, lands rarity compels the valorization inter-row crops’ spacing occupying wide spaces. Thus, the research has been led in the Central - West of Côte d'Ivoire in order to evaluate the effect of plantain banana tree (Musa sp) and Aloe vera association on these crops growth and yield. For this, an implement with a complete randomization design including two treatments with eight repetitions was achieved. The processings were consisted in planting either one Aloe vera plant (treatment 1) or two Aloe vera plants (treatment 2) between four plantain tree plants. The interval used for the planting of banana shoots in the 40-cm deep seed holes was 3 m x 2 m. The results showed that treatment 2 has speeded up the appearance of Aloe vera’s leave and encouraged the generation of a high number of leaves (39 leaves) longer (20.06 cm) and wider (2.78 cm) bringing about large fresh and dry biomasses, compared to treatment 1 and the control, with 125.42 g and 64.27 g, respectively. As for plantain banana tree, the intercropping favored a higher leaf emergence rate with a high number of leaves (23 leaves) longer and wider, 113.53 cm and 58.70 cm long, respectively. The intercropping also favored in plantain banana a large number of hands (7) and fingers (32) with a finger length of 35.25 cm weighing on average 0.46 kg and causing a mass of 9.23 kg / bunch. Bananas bunch yield higher in the associated plantain banana trees (15.39 t. ha-1) compared to controls (7.83 t. ha-1).

Booting heat stress alters leaf photosynthesis, growth rate, phenology and yield in rice

BackgroundThe phenomenon of global warming results in a significant rise in temperature which adversely affects the growth, physiology, and yield of rice. In order to gain insight into the impacts of booting heat stress (at 42 °C, 3 h for 7 days), we investigated its effect in three rice genotypes, namely, N22, KDML105 and IR64. ResultsBooting heat stress caused an extended phenology and a lower photosynthesis and plant growth rate but an increase in chalkiness. Although, the prolonged phenology from dough to physiological maturity resulted in a longer duration of grain filling, the adverse effects of this were a significantly lower yield component, yield and harvest index across all varieties of rice. Among cultivars, N22 demonstrated an adapted ability to maintain leaf gas exchange and compensated for the vegetative part by an increase in tiller numbers resulting in a less affected growth rate. It caused extended grain filling by prolonging the phenology. Consequence, N22 had the lowest reduction in number of seed panicle−1, number of filled seeds hill−1, yield, harvest index, and percentage chalkiness. KDML105 was adapted to booting heat stress by maintaining leaf gas exchange, increasing specific leaf area and prolonging phenology. The longest extended phenology and high photosynthesis during dough grain were associated with moderate yield reduction and chalkiness. Nonetheless, IR64 demonstrated significant reductions in photosynthesis, growth rate, and yield but the highest percentage of grain chalkiness. ConclusionTherefore, the response of N22, KDML105 and IR64 to booting heat stress could be indicated as being heat tolerant, moderately heat sensitive, and heat sensitive, respectively. This approach can be applied to crop modeling and rice heat tolerance in breeding programs.

Cytokinin Promotes Jasmonic Acid Accumulation in the Control of Maize Leaf Growth.

Plant organ growth results from the combined activity of cell division and cell expansion. The co-ordination of these two processes depends on the interplay between multiple hormones that determine the final organ size. Using the semidominant Hairy Sheath Frayed1 (Hsf1) maize mutant that hypersignals the perception of cytokinin (CK), we show that CK can reduce leaf size and growth rate by decreasing cell division. Linked to CK hypersignaling, the Hsf1 mutant has an increased jasmonic acid (JA) content, a hormone that can inhibit cell division. The treatment of wild-type seedlings with exogenous JA reduces maize leaf size and growth rate, while JA-deficient maize mutants have increased leaf size and growth rate. Expression analysis revealed the increased transcript accumulation of several JA pathway genes in the Hsf1 leaf growth zone. A transient treatment of growing wild-type maize shoots with exogenous CK also induced the expression of JA biosynthetic genes, although this effect was blocked by the co-treatment with cycloheximide. Together, our results suggest that CK can promote JA accumulation, possibly through the increased expression of specific JA pathway genes.

Transcriptome Sequencing of Agave amaniensis Reveals Shoot-Related Expression Patterns of Expansin A Genes in Agave.

Agave species are widely planted for fiber production. However, the molecular basis of agave fiber development has not been well understood. In this study, we performed a transcriptomic analysis in A. amaniensi, a well-known variety with high-quality fiber production. Approximately 43.87 million clean reads were obtained using Illumina sequencing. The de novo assembly produced 66,746 unigrams, 54% of which were annotated in a public database. In the Nr database, 21,490 unigenes of A. amaniensis were shown to be most closely related to Asparagus officinalis. Nine expansin A orthologs with full coding regions were obtained, which were named EXP1a, EXP1b, EXP2, EXP3, EXP4a, EXP4b, EXP11, EXP12, and EXP13. The maximum likelihood phylogenetic tree revealed the species-specific expansion of expansin genes in Arabidopsis, rice and agave. The expression analysis suggested the negative correlation between the expression of expansin genes and the leaf growth rate, except AhEXP11. Moreover, expansin genes were differentially affected by abiotic and biotic stresses. Notably, AhEXP2 expression level was highly upgraded after the infection of Phytophthora nicotiana. Nutrient deficiency also influent expansin genes expression. Together, our research will benefit future studies related to fiber development, disease resistance and nutrient usage in agave.

Variation in Symptom Development and Infectivity of Banana Bunchy Top Disease among Four Cultivars of Musa sp.

Banana bunchy top disease (BBTD) is an invasive viral disease spreading in Africa. It is transmitted by banana aphids and infected planting material, causing production losses. Clean seeds and timely eradication of diseased plants are effective tools in BBTD management. These depend on timely disease detection. We assessed the relationship between symptom expression and infectivity of the virus in four cultivars of banana. Plantlets from four cultivars, ‘FHIA 25’; ‘Aloga’; ‘Ebenga’ and ‘Sotoumon’, were exposed to viruliferous aphids and monitored for symptom expression. They were also tested as sources for virus transmission fortnightly by allowing non-viruliferous aphids acquisition access prior to transfer to healthy test plants. The time required to show symptoms and the symptom expression were compared, and infection tested by PCR. Disease expression varied from four weeks in ‘FHIA 25’ to fifteen in ‘Sotoumon’. Only the symptomatic leaves tested positive and could act as infection sources. Overall, ‘FHIA 25’ was the most susceptible cultivar, while ‘Sotoumon’ was the least susceptible and most rapidly expressive of BBTD, yet there was no difference in the leaf emergence rate between the cultivars. These results present important aspects of BBTD control and the safety of planting materials that should be tested in the field.