Absisic Acid Research Articles

Cytokinin and MAX2 signaling pathways act antagonistically in drought adaptation of Arabidopsis thaliana

Understanding the mechanisms, especially those associated with phytohormones, of plant drought adaptation is crucial for sustaining agricultural production in the era of climate change. Arabidopsis histidine kinases (AHKs), an integral part of the cytokinin signaling pathway, and more axillary growth 2 (MAX2), a key component of the strigolactone and karrikin signaling pathways are reported to act as negative and positive regulators, respectively, in plant adaption to drought. However, the potential interaction between these singaling pathways in plant drought adaptation is not fully understood. To address this query, we assessed drought tolerance levels and associated phenotypic and physiological traits of the max2 single mutant, ahk2 ahk3 double mutant, ahk2 ahk3 max2 triple mutant, and wild-type (WT) Arabidopsis thaliana plants. Our findings revealed a distinct hierarchy in drought tolerance among these genotypes, as indicated by the differences in plant growth and stress survival rates. Specifically, the max2 mutant displayed the lowest drought tolerance level, followed by WT, ahk2 ahk3 max2, and ahk2 ahk3 plants. Additionally, the observed changes in leaf relative water content, leaf surface temperature, and cuticle formation were coherently aligned with the observed hierarchy of drought tolerance levels. Under drought conditions, the max2 mutant exhibited higher oxidative stress and membrane damage, as evidenced by increased levels of reactive oxygen species (ROS), malondialdehyde, and electrolyte leakage. In contrast, the ahk2 ahk3 and ahk2 ahk3 max2 mutants showed low and intermediate levels, respectively, for these parameters. The max2 mutant displayed reduced sensitivity, whereas ahk2 ahk3 and ahk2 ahk3 max2 mutants demonstrated high and intermediate sensitivities, respectively, to exogenous abscisic acid (ABA) treatments. Additionally, the expression analysis of several genes associated with the investigated drought tolerance-related traits showed a positive correlation between the transcript levels and corresponding trait(s) in both mutant and WT plants under drought conditions. Our results collectively indicate the presence of an antagonistic interaction between AHK and MAX2 signaling pathways in plant drought adaptation, impacting ABA responsiveness, leaf water retention, cuticle development, and ROS homestasis. The findings of this study provide a valuable foundation for developing agricultural methods to improve plant drought resilience.

Determination of Allelopathic and Antimicrobial Effects of Four Different Plant Species

The investigation of allelopathic and antimicrobial effects of four different plant extracts is the aim of this study. The aqueous extract of plants (Lepidium draba L., Acroptilon repens (L.) DC., Thymus kotchyanus Boiss&Hohen. var. kotchyanus, Inula peacockiana (Aitch.&Hemsl.) Koravin,) were applied to seedlings of cultivated (Pisum sativum L. and Hordeum vulgare L.) and weed (Amaranthus retroflexus L. and Portulaca oleraceae L.). Seedlings were irrigated with aqueous extract (1 %) for 15 days to observe the physiological responses. The morphological changes, chlorophyll levels and phytohormone concentrations were determined. The Lepidium draba and Inula peacockiana extracts affected development of all of the target seedlings and caused lesion on the leaves. Acroptilon repens and Thymus kotschyanus extracts caused a decrease in gibberellic acid (GA) whereas increase in absisic acid (ABA) levels. For investigation of antimicrobial activities, hexane, methanol and water extracts were prepared. Extracts were applied on Bacillus cereus, Staphylococ aureus, Pseudomonas syringae and Escherichia coli for antibacterial and Rhizoctonia solani, Fusarium oxysporum and Aspergillus niger for antifungal effects. Inula peacockiana and Acroptilon repens extracts had a great antimicrobial activity. While all plant extracts inhibited Rhizoctonia solani, Fusarium oxysporum growth and spore development of Aspergillus niger. The antifungal activity of extracts were better than antibacterial activity. As a conclusion, these plants have allelopathic potential for natural weed control and antimicrobial potential for medicinal uses.

Irrigation Levels and Abscisic Acid Effects on the Yield and Fruit Quality of Strawberry

In this study, the effects of four irrigation regimes (IR125, IR100, IR75 and IR50) and Absisic Acid (ABA) application on the cv. Rubygem strawberries, considering yield, and some fruit quality characteristics (Soluble solid content, fruit firmness, pH and color properties) were investigated under Spanish type high tunnels in the Mediterranean region of Turkey. From March to May, 20 mol L-1 of Abscisic Acid was administered three times via foliar application. The treatments IR125, IR100, IR75, and IR50 received 712, 575, 438, and 301 mm of water, respectively, during the trial.. The highest average yield per plant was obtained from ABA IR125 combination as 1124.5 (g/plant). It was determined that the ABA application increased the yield by approximately 8%, although it was not statistically significant compared to the control conditions. In addition to this, abscisic acid applications had no statistically significant influence on pH, fruit color, fruit firmness, or fruit weight parameters, while a SSC parameters statistically significant effected. Based on our findings, it is expected that the IR125 and IR100 irrigation applications will be applied more frequently in future investigations. Furthermore, the findings suggest that combining ABA with the proper amount of irrigation water, as well as ABA applications in water stress or multiple stress circumstances, may be useful in increasing plant adaptation capacity

A training on the manufacture of abscisic acid hormone (ABA) plant growth inhibitors during the COVID-19 pandemic

The motivation of State Senior High School 5 Tuban students in the learning process has declined drastically, due to the COVID-19 pandemic. Similarly, basic competence in Biology, including the use of plant growth materials to solve common problems, appears very minimal. Therefore, the training on the manufacture of "Absicic Acid Hormone (ABA)" plant growth inhibitors was conducted using simple and inexpensive substances. The activity commenced with COVID-19 awareness, followed by the ABA production, evaluation and mentoring. The results showed that the participants were very enthusiastic about the training (92.91%). Furthermore, the study also succeeded in increasing ABA knowledge and skills from 31.11-62.74%.

A basic helix-loop-helix transcription factor CabHLH113 positively regulate pepper immunity against Ralstonia solanacearum

Pepper's (Capsicum annum) response to bacterial pathogen Ralstonia solanacearm inoculation (RSI) and abiotic stresses is known to be synchronized by transcriptional network; however, related molecular mechanisms need extensive experimentation. We identified and characterized functions of CabHLH113 -a basic helix-loop-helix transcription factor-in pepper immunity to R. solanacearum infection. The RSI and foliar spray of phytohormones, including salicylic acid (SA), methyl jasmonate (MeJA), ethylene (ETH), and absicic acid (ABA) induced transcription of CabHLH113 in pepper. Loss of function of CabHLH113 by virus-induced-gene-silencing (VIGS) compromised defense of pepper plants against RSI and suppressed relative expression levels of immunity-associated marker genes, i.e., CaPR1, CaNPR1, CaDEF1, CaHIR1 and CaABR1. Pathogen growth was significantly increased after loss of function of CabHLH113 compared with un-silenced plants with remarkable increase in pepper susceptibility. Besides, transiently over-expression of CabHLH113 induced HR-like cell death, H2O2 accumulation and up-regulation of defense-associated marker genes, e.g. CaPR1, CaNPR1, CaDEF1, CaHIR1 and CaABR1. Additionally, transient over-expression of CabHLH113 enhanced the transcriptional levels of CaWRKY6, CaWRKY27 and CaWRKY40. Conversely, transient over-expression of CaWRKY6, CaWRKY27 and CaWRKY40 enhanced the transcriptional levels of CabHLH113. Collectively, our results indicate that newly characterized CabHLH113 has novel defense functions in pepper immunity against RSI via triggering HR-like cell death and cellular levels of defense linked genes.

Genome-Wide Association Study Dissects the Genetic Architecture of Maize Husk Tightness.

The husk is a leafy outer tissue that encloses a maize ear. Previously, we identified the optimum husk structure by measuring the husk length, husk layer number, husk thickness and husk width. Husk tightness (HTI) is a combined trait based on the above four husk measurements. Unveiling the genetic basis of HTI will aid in guiding the genetic improvement of maize for mechanical harvesting and for protecting the ear from pest damage and pathogen infection. Here, we used a maize associate population of 508 inbred lines with tropical, subtropical and temperate backgrounds to analyze the genetic architecture of HTI. Evaluating the phenotypic diversity in three different environments showed that HTI exhibited broad natural variations and a moderate heritability level of 0.41. A diversity analysis indicated that the inbred lines having a temperate background were more loosely related than those having a tropical or subtropical background. HTI showed significant negative correlations with husk thickness and width, which indicates that thicker and wider husks wrapped the ear tighter than thinner and slimmer husks. Combining husk traits with ∼1.25 million single nucleotide polymorphisms in a genome-wide association study revealed 27 variants that were significantly associated with HTI above the threshold of P < 7.26 × 10–6. We found 27 candidate genes for HTI that may participate in (1) husk senescence involving lipid peroxidation (GRMZM2G017616) and programmed cell death (GRMZM2G168898 and GRMZM2G035045); (2) husk morphogenesis involving cell division (GRMZM5G869246) and cell wall architecture (GRMZM2G319798); and (3) cell signal transduction involving protein phosphorylation (GRMZM2G149277 and GRMZM2G004207) and the ABSISIC ACID INSENSITIVE3/VIVIPAROUS1 transcription factor (GRMZM2G088427). These results provide useful information for understanding the genetic basis of husk development. Further studies of identified candidate genes will help elucidate the molecular pathways that regulate HTI in maize.

GROWTH AND MINRAL STATUS OF COTTON PLANTS AS AFFECTED BY ABSICISIC ACID AND SALT STRESS

Application of antioxidant materials like absicisic acid to alleviate salinity stress and promote cotton growth is high effectiveness target, whereas cotton plant is an attractive industrial crop. Pot experiment was conducted to evaluate the effect of salinity stress and absicisic acid (antioxidant materials to alleviate salinity stress) on cotton growth and macro nutrients status in shoots of cotton plants. Plants subjected to two salinity levels (2500 and 5000 ppm as diluted sea water), and tap water (250ppm) as control, sprayed absicisic acid (ABA) with two concentrations (20 and 40 ppm of ABA) and distilled water as a control. Salinity decreased stem and leaves dry weight compare to the control treatment. The lower concentrations of ABA (20 and 40 ppm as a foliar spray) improve dry weight of stem and leaves. Reversely, leaves/stem ratio decreased with both concentrations of the absicisic acid. The increment in dry weight of leaves and stem or their sum showed its higher values by application 40 ppm from ABA under the 5000 ppm salinity level and also under fresh water treatment but under the 2500 ppm treatment the highest values were by 20 ppm of growth regulator. Nevertheless, L/S ratio decreased by ABA treatment, whereas, the high concentration of ABA (40ppm) was super than lower concentration (20ppm) under both salinity levels. Generally, it can be used diluted seawater in irrigation of cotton plant with spraying abscisic acid to alleviate the harmful effect of salinity.

Karrikin Improves Osmotic and Salt Stress Tolerance via the Regulation of the Redox Homeostasis in the Oil Plant Sapium sebiferum.

Karrikins are reported to stimulate seed germination, regulate seedling growth, and increase the seedling vigor in abiotic stress conditions in plants. Nevertheless, how karrikins alleviate abiotic stress remains largely elusive. In this study, we found that karrikin (KAR1) could significantly alleviate both drought and salt stress in the important oil plant Sapium sebiferum. KAR1 supplementation in growth medium at a nanomolar (nM) concentration was enough to recover seed germination under salt and osmotic stress conditions. One nanomolar of KAR1 improved seedling biomass, increased the taproot length, and increased the number of lateral roots under abiotic stresses, suggesting that KAR1 is a potent alleviator of abiotic stresses in plants. Under abiotic stresses, KAR1-treated seedlings had a higher activity of the key antioxidative enzymes, such as superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, in comparison with the control, which leads to a lower level of hydrogen peroxide, malondialdehyde, and electrolyte leakage. Moreover, the metabolome analysis showed that KAR1 treatment significantly increased the level of organic acids and amino acids, which played important roles in redox homeostasis under stresses, suggesting that karrikins might alleviate abiotic stresses via the regulation of redox homeostasis. Under abiotic stresses, applications of karrikins did not increase the endogenous abscisic acid level but altered the expression of several ABA signaling genes, such as SNF1-RELATED PROTEIN KINASE2.3, SNF1-RELATED PROTEIN KINASE2.6, ABI3, and ABI5, suggesting potential interactions between karrikins and ABA signaling in the stress responses. Conclusively, we not only provided the physiological and molecular evidence to clarify the mechanism of karrikins in the regulation of stress adaptation in S. sebiferum but also showed the potential value of karrikins in agricultural practices, which will lay a foundation for further studies about the role of karrikins in abiotic stress alleviation in plants.

Comparative transcriptomic analysis reveals novel roles of transcription factors and hormones during the flowering induction and floral bud differentiation in sweet cherry trees (Prunus avium L. cv. Bing).

In sweet cherry trees, flowering is commercially important because the flowers, after fertilization, will generate the fruits. In P. avium, the flowering induction and flower organogensis are the first developmental steps towards flower formation and they occur within specialized organs known as floral buds during the summer, nine months before blooming. During this period the number of floral buds per tree and the bud fruitfulness (number of flowers per bud) are stablished affecting the potential yield of orchards and the plant architecture. The floral bud development is sensitive to any type of stress and the hotter and drier summers will interfere with this process and are calling for new adapted cultivars. A better understanding of the underlying molecular and hormonal mechanisms would be of help, but unlike the model plant Arabidopsis, very little is known about floral induction in sweet cherry. To explore the molecular mechanism of floral bud differentiation, high-throughput RNA sequencing was used to detect differences in the gene expression of P. avium floral buds at five differentiation stages. We found 2,982 differentially expressed genes during floral bud development. We identified genes associated with floral initiation or floral organ identity that appear to be useful biomarkers of floral development and several transcription factor families (ERF, MYB, bHLH, MADS-box and NAC gene family) with novel potential roles during floral transition in this species. We analyzed in deep the MADS-box gene family and we shed light about their key role during floral bud and organs development in P. avium. Furthermore, the hormonal-related signatures in the gene regulatory networks and the dynamic changes of absicic acid, zeatin and indolacetic acid contents in buds suggest an important role for these hormones during floral bud differentiation in sweet cherry. These data provide a rich source of novel informacion for functional and evolutionary studies about floral bud development in sweet cherry and new tools for biotechnology and breeding.

Arabidopsis GLR3.5-modulated seed germination involves GA and ROS signaling

ABSTRACTSeed germination, a crucial developmental step, is regulated by multiple plant endogenous signals, among which phytohormones absisic acid (ABA) and gibberellin (GA) act antagonistically. Reactive oxygen species (ROS) interact with the two hormones to coordinate germination. We have previously reported that Arabidopsis glutamate receptor homolog3.5 (AtGLR3.5) modulates calcium signal to attenuate the repression effect of ABA on seed germination and that amino acid L-methionine functions upstream of AtGLR3.5, resulting in calcium influx. Here, we show that AtGLR3.5 modulates GA and ROS signaling during seed germination. Our findings provide a more complete picture as to the molecular mechanisms of AtGLR3.5 in seed germination control.

Identifying drought-resilient flax genotypes and related-candidate genes based on stress indices, root traits and selective sweep

Drought hampers flax yield and oil quality particularly at the reproductive stage. Here, 105 flax accessions were assessed for drought tolerance under irrigated and drought-stressed conditions across three environments using eight stress indices. Total root length (TRL), total root volume (TRV) and diameter class length (DCL) were analyzed in two selected groups of accessions contrasting for drought tolerance. These genotypes were further submitted to selective sweep analysis using 394 genome-wide microsatellite (SSR) loci to identify markers potentially associated with drought tolerance and drought-responsive candidate genes. The results obtained for yield under stress (Ys) and yield under irrigated condition (Yp) indicated significant genotypic response to water treatments (P < 0.001). Hierarchical clustering and heatmap analyses of stress indices identified the oil type flax cultivars O_CAN_C_CN19004 (AC Emerson) and O_CAN_C_CN19003 (AC McDuff) as the most drought tolerant. Some fiber type flax accessions were also clustered in the tolerant group. The drought tolerant group showed 29, 42, and 22% superior TRL, TRV and DCL, respectively, than its sensitive counterpart under drought. The SSR loci under selective sweep, Lu254 and Lu709 were significantly associated with Ys, and accessions carrying the favorable haplotype exhibited 21.7% higher Ys. Various candidate genes involved in absicic acid pathway, auxin signaling, Ca2+ signaling, photosynthesis regulation, and drought-responsive transcription factors were identified at the selective sweep loci. The identified tolerant accessions can be used for conferring drought tolerance to elite cultivars, while the selective sweep SSR loci linked to drought-responsive candidate genes could be useful in MAS.

Response of some vegetative growth, yield and yield components characters of cotton for Absicic acid spraying under effect of water stress

Field experiment was carried out in Babylon / AL-Musseib during (2017) season to study the effect of leaves spraying with Multiple ABA concentrations on some characters of vegetative growth and yield of Lashata cotton cultivar under the effect of water stress.&#x0D; Randomized Complete Block Design was used with three replicates according to split plot arrangement. The study included four irrigation periods ( 10,15, 20, 25 days) between each irrigation time ( Main Plots ) while ABA spray concentrations (0,40,80,120) μM occupy the ( Sub plots ). The results showed presence of significant differences in studied characters with ABA spray, So 80 μM of ABA predominate and gave the highest plant height 93.07 cm and vegetative branches number 4.12 branches.plant-1, total boll number 13.35 bolls. Plant-1 , seed cotton yield 34.02 gm. Plant-1, also there is significant differences among irrigation periods, as irrigation treatment each 10 days gave the highest average plant height 91.54 cm , number of sympodial branches 12.77 branch.plant-1 , number of open bolls 12.74 bolls . plant-1, seed number per bolls 24.95 seed.bolls-1 and seed cotton yield 33.75 gm.plant-1. Interaction between irrigation periods and ABA spray concentration had a significant effect on the studied characters whereas irrigation treatment of every 10 days with ABA sprays of 80 micromole concentration.

Development and Optimization of Immunoenzyme Technique for the Localization of Absicic Acid in Cucumber

Development and Optimization of Immunoenzyme Technique for the Localization of Absicic Acid in Cucumber

Phytohormones

In this study, the effects of plant hormones known as the classical quintet; auxine, cytokinin, giberellin, absisic acid, ethylene hormones as well as the ones discovered by recent studies, i.e. brassinosteroid, salicylic acid, strigolactone and jasmonic acid on plant physiology, their uses in agriculture, and effects on the environment due to misuse of these hormones were compiled and the literature on the phytohormones was updated.

PRODUCTION OF OIL PALM SEX INFLORESCENSE AND ITS RESPONSE ON THE TREATMENT OF PLANT EXOGENOUS HORMONE TREATMENT UNDER DROUGHT CONDITION

To determining effects of drought on the oil palm sex inflorescene and its response on plant hormone treatmet under drought condition. Then it was carried out the serial treatment at indonesian oil palm research institute (IOPRI) field area trial in Pulau Maria, Asahan District, North Sumatra during 4 year (2013 until midle of 2016). These area having flat topography class with sandy loam texture of typic paleudult soil type and suffering frequently of 200- 460 mm water deficit per year. The trial were undertaken on oil palm tenera's type with 8 years old (planted in 2005). The trial including, 4 kind of phytohormone plus the control treatment, which treated on plant with several of dose and frequency. The phytohormone were IAA (auxsin, Indole-3-acetic acid), BAP (citokinin, 6-benzylaminopurine), GA_3 (gibberelline, gibberellic acid), dan ABA (absisic acid). The dose of each of these kind of hormone were 100, 300, dan 500 ppm, with frequenscy application once and twice per year. The trial design following randomized block design with 3 replicated. Individual unit treatment was the indivduplant. The variable that observed were female, male, and aborted inflorescence; number of frond production; and vegetative growth (height of plant and length of rachis frond). Analysis effect the drought on oil palm sex inflorescene were done by correlation analysis between rainfall and water deficit with inflorescene production. The result shown drought period decline of female inflorescense, and increasing male and aborted inflorescense. Auxin (IAA) treatment, induced vegetatif growth, but contrarily, declining female inflorescense production and increasing male and aborted inflorescense. Gibberelline (GA_3) treatment, decreasing commonly female inflorescense production, and increasing male and aborted inflorescense, mainly in the certain peak of drought periods. Citokinin (ABA) and absicic asid (ABA), tend tokeep female inflorescense production in drought condition, in a way reducing number of aborted inflorescense. Citokinin (BAP), was dominantly plant hormone to keep female inflorescense production.

PHYSICOCHEMICAL PROPERTIES OF TOW MANGO CULTIVARS EWAIS AND ZEBDA (Mangifera indica L.) IN EGYPT

This study was conducted at Ismailia Governorate, Egypt. The investigation aimed to evaluate physicochemical characteristics of two mango cultivars i.e., Ewais and Zebda (Mangifera indica L.). Mango trees, 10 years old (planting distance 7 × 7 m) from each cultivar were selected to be nearly size and being in their off bearing. Leaves at different stages of growth and fruits were investigated. Results revealed that, Ewais leaves have phenolic compounds from 80.36 to 92.82 (mg gfw), Cytokinin from 3.60 to 4.41 (ng/gfw), gibberilic acid from 28.58 to 36.61 (µg/gfw), absisic acid from 8.44 to 9.5 (µg/gfw), total protein from 4.38 to 9.13(g 100 gdw), total free amino acids from 23.72 to 36.70 (m mol 100 gdw), total protein from 5.83 to 7.22 (µmol gfw), total carbohydrate from 18.76 to 21.09 (g 100gdw), total chlorophyll from 1.55 to 2.11 (mg/gfw) and total carotenoid from 0.82 to 0.98 (mg/gfw). Enzymes activities (mmol gfw) in Ewais leaves were as follow, catalase between 26.23 and 50.31, peroxidase between 1.23 and 2.80, polyphednol oxidase from 101 .29 to 106.62 and amylase from 7.13 to 8.1. These results dependant on growth stages and were superior for Zebda cultivar. Ewais cultivar has higher yield (yield tree, kg) (92.82) than zebda (89.27). Fruits of Ewais have a higher performance parameters than fruits of Zebda.

An analysis of the development of cauliflower seed as a model to improve the molecular mechanism of abiotic stress tolerance in cauliflower artificial seeds

The development stages of conventional cauliflower seeds were studied and the accumulation of dehydrin proteins through the maturation stages was investigated with the aim of identifying methods to improve the viability of artificial seeds of cauliflower. While carbohydrate, ash and lipids increased throughout the development of cauliflower traditional seeds, proteins increased with the development of seed and reached the maximum level after 75 days of pollination, however, the level of protein started to decrease after that. A significant increase in the accumulation of small size dehydrin proteins (12, 17, 26 KDa) was observed during the development of cauliflower seeds. Several experiments were conducted in order to increase the accumulation of important dehydrin proteins in cauliflower microshoots (artificial seeds). Mannitol and ABA (Absisic acid) increased the accumulation of dehydrins in cauliflower microshoots while cold acclimation did not have a significant impact on the accumulation of these proteins. Molybdenum treatments had a negative impact on dehydrin accumulation. Dehydrins have an important role in the drought tolerance of seeds and, therefore, the current research helps to improve the accumulation of these proteins in cauliflower artificial seeds. This in turns improves the quality of these artificial seeds. The current results suggest that dehydrins do not play an important role in cold tolerance of cauliflower artificial seeds. This study could have an important role in improving the understanding of the molecular mechanism of abiotic stress tolerance in plants.

PRODUCTION OF OIL PALM SEX INFLORESCENSE AND ITS RESPONSE ON THE TREATMENT OF PLANT EXOGENOUS HORMONE TREATMENT UNDER DROUGHT CONDITION

To determining effects of drought on the oil palm sex inflorescene and its response on plant hormone treatmet under drought condition. Then it was carried out the serial treatment at indonesian oil palm research institute (IOPRI) field area trial in Pulau Maria, Asahan District, North Sumatra during 4 year (2013 until midle of 2016). These area having flat topography class with sandy loam texture of typic paleudult soil type and suffering frequently of 200- 460 mm water deficit per year. The trial were undertaken on oil palm tenera's type with 8 years old (planted in 2005). The trial including, 4 kind of phytohormone plus the control treatment, which treated on plant with several of dose and frequency. The phytohormone were IAA (auxsin, Indole-3-acetic acid), BAP (citokinin, 6-benzylaminopurine), GA_3 (gibberelline, gibberellic acid), dan ABA (absisic acid). The dose of each of these kind of hormone were 100, 300, dan 500 ppm, with frequenscy application once and twice per year. The trial design following randomized block design with 3 replicated. Individual unit treatment was the indivduplant. The variable that observed were female, male, and aborted inflorescence; number of frond production; and vegetative growth (height of plant and length of rachis frond). Analysis effect the drought on oil palm sex inflorescene were done by correlation analysis between rainfall and water deficit with inflorescene production. The result shown drought period decline of female inflorescense, and increasing male and aborted inflorescense. Auxin (IAA) treatment, induced vegetatif growth, but contrarily, declining female inflorescense production and increasing male and aborted inflorescense. Gibberelline (GA_3) treatment, decreasing commonly female inflorescense production, and increasing male and aborted inflorescense, mainly in the certain peak of drought periods. Citokinin (ABA) and absicic asid (ABA), tend tokeep female inflorescense production in drought condition, in a way reducing number of aborted inflorescense. Citokinin (BAP), was dominantly plant hormone to keep female inflorescense production.

ABA Sensitivity as a Criterion for Drought Tolerance in Wheat (Triticum aestivum L.) Cultivars

Abstract Criteria used for evaluating drought tolerance of wheat cultivars demanding more time and efforts are usually not efficient and conclusive. Present study was conducted to evaluate ABA sensitivity as a criterion for evaluating drought tolerance of wheat cultivars at an early stage. Ten cultivars of wheat were subjected to drought at 3-leaf stage to select the most sensitive and two tolerant cultivars using mortality rate. Tatara was found the most susceptible whereas GA-2002 and Chakwal-50 were the cultivars with maximum drought tolerance. These cultivars were used to study sensitivity to applied absicic acid (based on germination index and relative growth inhibition rate) and physiological responses (leaf water content, chlorophyll stability index, coefficient of relative inhibition and proline accumulation) under drought stress. Highest ABA-sensitivity was recorded in GA-2002 and Chakwal-50 whereas Tatara manifested minimum sensitivity. ABA-sensitivity corresponded to physiological indices of drought tolerance. Results show that ABA-sensitivity is an efficient criterion that can be used to evaluate drought tolerance of wheat cultivars at early stage.

Mechanisms for tolerance to water-deficit stress in plants inoculated with arbuscular mycorrhizal fungi. A review

The expansion of areas affected by drought worldwide has a negative effect on yield and crops production, making water deficits the most significant abiotic stress that limits the growth and development of plants. The use of arbuscular mycorrhizal fungi (AMF) is a strategy that mitigates the effects of this stress in a sustainable way, given the increase in the tolerance to water deficit stress in plants inoculated with these fungi; however, the exact mechanism is unknown because the response depends on the water-deficit stress type and is specific to the AMF and the plant. This review describes the mechanisms that explain how the AMF colonization of roots can modify the response of plants during a water deficit, as well as its relationship with physiological processes that determine yield, photosynthesis and photoassimilate partitioning. These mechanisms may include modifications in the content of plant hormones, such as strigolactones, jasmonic acid (JA) and absicic acid (ABA). The JA appears to be involved in the stress signal in mycorrhizal plants through an increase of ABA concentrations and, at the same time, ABA has a regulating effect on strigolactone concentrations. Also, there is improvement of plant water status, stomatal conductance, nutritional status and plant responses to cope with a water deficit, such as osmotic adjustment, and antioxidant activity. These modifications cause an increase in CO2 assimilation and photoassimilate production, improving plant growth during a drought.