LeMYC2 acts as a negative regulator of blue light mediated photomorphogenic growth and promotes the growth of adult tomato plants

Background: Arabidopsis ZBF1/MYC2bHLH transcription factor is a repressor of photomorphogenesis, and acts as a point of cross talk in light, abscisic acid (ABA) and jasmonic acid (JA) signaling pathways. MYC2 also functions as a positive regulator of lateral root development and flowering time under long day conditions. However, the function of MYC2 in growth and development remains unknown in crop plants. Results: Here, we report the functional analyses of LeMYC2 in tomato (Lycopersicon esculentum). The amino acid sequence of LeMYC2 showed extensive homology with Arabidopsis MYC2, containing the conserved bHLH domain. To study the function of LeMYC2 in tomato, overexpression and RNA interference (RNAi) LeMYC2tomato transgenic plants were generated. Examination of seedling morphology, physiological responses and light regulated gene expression has revealed that LeMYC2 works as a negative regulator of blue light mediated photomorphogenesis. Furthermore, LeMYC2 specifically binds to the G-box of LeRBCS-3A promoter. Overexpression of LeMYC2 has led to increased root length with more number of lateral roots. The tomato plants overexpressing LeMYC2 have reduced internode distance with more branches, and display the opposite morphology to RNAi transgenic lines. Furthermore, this study shows that LeMYC2 promotes ABA and JA responsiveness. Conclusions: Collectively, this study highlights that working in light, ABA and JA signaling pathways LeMYC2 works as an important regulator for growth and development in tomato plants

Functional interconnections of HY1 with MYC2 and HY5 in Arabidopsis seedling development

Arabidopsis seedling development is controlled by many regulatory genes involved in multiple signaling pathways. The functional relationships of these genes working in multiple signaling cascades have started to be unraveled. Arabidopsis HY1/HO1 is a rate-limiting enzyme involved in biosynthesis of phytochrome chromophore. HY5 (a bZIP protein) promotes photomorphogenesis, however ZBF1/MYC2 (a bHLH protein) works as a negative regulator of photomorphogenic growth and light regulated gene expression. Further, MYC2 and HY1 have been shown to play important roles in jasmonic acid (JA) signaling pathways. Here, we show the genetic interactions of HY1 with two key transcription factor genes of light signaling, HY5 and MYC2, in Arabidopsis seedling development. Our studies reveal that although HY1 acts in an additive manner with HY5, it is epistatic to MYC2 in light-mediated seedling growth and gene expression. This study further demonstrates that HY1 additively or synergistically functions with HY5, however it works upstream to MYC2 in JA signaling pathways. Taken together, this study demonstrates the functional interrelations of HY1, MYC2 and HY5 in light and JA signaling pathways

Effect of Temperature induction response on Cell viability, Cell Survivability, Malondialdehyde content and total soluble protein content of cotton (Gossypium hirsutum L.) genotypes

“Temperature Induction Response” (TIR) technique was employed to investigate the effect of temperature on popular 20 cotton (Gossypium hirsutum L.) genotypes in a laboratory experiment conducted at the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore during 2020-2021. Identical sized ten days old cotton seedlings were selected and subjected to inductive temperature (gradual temperature raised from 28 to 40℃) for 4 h and non-inductive temperature (46℃ for 3 h, 47℃ for 3 h, 48℃ for 3 h and 48℃ for 4 h) for specific time duration. KC3 and SVPR6 recorded highest thermotolerance among the genotypes and TSH325 and TSH357 showed moderate thermotolerance while TSH375 and TSH383 were sensitive, in terms of seedling survival, cell viability, total soluble protein and malondialdehyde compared to remaining genotypes under non-inductive temperature

Impact of elevated temperature on root traits and microbial interaction in cotton (Gossypium hirsutum L.) genotypes

Climate change mainly alters the plant phyllosphere and rhizosphere resource allocations. Compared with shoot parameters, there is less information about how roots, especially root system architecture (RSA) and their interactions with others, may respond to elevated temperature changes. These responses could greatly influence different species acquisition of resources and their competition with their neighbours. The main aim of this experiment was to evaluate the effects of ambient temperature (T1) and elevated temperature (+4oC) (T2) in Open-top chamber (OTC) on root traits and microbial interaction changes in cotton (Gossypium hirsutum L.). A pot experiment was conducted at the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, during 2020-2021 to investigate the root traits and microbial interactions. Cotton varieties, namely KC3, SVPR6, TSH325, TSH357 and TSH375 were screened at the seedling level for cellular thermo tolerance and further, at the root level, these selected varieties were studied against the elevated temperature condition for 10 days in OTC during the stage of flowering to boll development period along with control temperature condition. Root interactions' intensity and direction may fluctuate as a result of variations in RSA responses between species. Negative root interactions could become more intense under high temperature circumstances and species with bigger roots and greater early root growth had stronger competitive advantages. The present findings showed that elevated temperatures promote various microbial growths in the geothermal regions, enhancing the root angle and root length of cotton species. Among the genotypes, KC3 and SVPR6 performed better under elevated temperatures.

Effect of drought on gas exchange and chlorophyll fluorescence of groundnut genotypes

Drought is one of the major threats to groundnut productivity, causing a greater loss than any other abiotic factor. Water stress conditions alter plant photosynthetic activity, impacting future growth and assimilating mobilization towards sink tissues. The purpose of this study was to investigate how drought impacts the photosynthesis of plants and its links to drought tolerance. The influence of reproductive stage drought on photosynthetic activity and chlorophyll fluorescence of groundnut is well studied. The experiment was conducted in Kharif 2019 (Jul-Sep), where recent series in groundnut genotypes (60 nos) sown under rainfed conditions and water stress was created by withholding irrigation for 20 days between 35-55 days after sowing in the field to simulate drought conditions. Imposition of water deficit stress reduced PS II efficiency, which significantly altered the photosynthetic rate in the leaf. Observation of gas exchange parameters viz., photosynthetic rate, stomatal conductance and transpiration rate after 20 days of stress imposition revealed that of all 60 genotypes, 20 genotypes (VG 17008, VG 17046VG 18005, VG 18102, VG 18077, VG 19572, VG 19709, VG 18111, VG19561, VG19576, VG 19620, VG 19681, VG 19688, etc.,) had better Photosynthetic rate, Stomatal conductance. Similarly, PS II efficiency analyzed through fluorescence meter revealed that among the 60 and all the genotypes given above recorded higher value in Fv/Fm. Results obtained from Cluster analysis and PCA confirmed that photosynthetic rate and Fv/Fm is useful parameter in screening adapted cultivars under drought stress. These findings lay the groundwork for a future study to decipher the molecular pathways underpinning groundnut drought resistance

Functional interconnection of MYC2 and SPA1 in the photomorphogenic seedling development of Arabidopsis

MYC2 is a basic helix-loop-helix transcription factor that cross talks with light, abscisic acid (ABA), and jasmonic acid (JA) signaling pathways. Here, we have shown that Arabidopsis (Arabidopsis thaliana) MYC2 directly binds to the G-box present in the SUPPRESSOR OF PHYTOCHROME A1 (SPA1) promoter and that it controls the expression of SPA1 in a COP1-dependent manner. Analyses of atmyc2 spa1 double mutants suggest that whereas MYC2 and SPA1 act redundantly to suppress photomorphogenic growth in the dark, they function synergistically for the suppression of photomorphogenic growth in the light. Our studies have also revealed that MYC2-mediated ABA and JA responses are further modulated by SPA1. Taken together, this study demonstrates the molecular and physiological interrelations of MYC2 and SPA1 in light, ABA, and JA signaling pathways

Maximizing the Productivity and Profitability of Summer Irrigated Greengram (Vigna radiata L.) by Combining Basal Nitrogen Dose and Foliar Nutrition of Nano and Normal Urea

Field experiment was conducted at wetland farm of Tamil Nadu Agricultural University, Coimbatore, during summer season, 2022 with an objective of maximizing the productivity and profitability of greengram by adopting varied dose of basal nitrogen and foliar application of nano and normal urea at Flower Initiation (FI) stage and 15 days thereafter. The experiment was laid out in factorial randomized block design and replicated thrice with the following treatments viz., N1 - 100% RDN (25kg N ha-1), N2 - 80% RDN (20kg N ha-1), N3 - 60% RDN (15kg N ha-1) and N4 - Control as factor I, and F1 - Nano urea @ 2ml litre-1 of water, F2 - Nano urea @ 3ml litre-1 of water, F3 - Nano urea @ 4ml litre-1 of water and F4 - 1% urea as factor II. The experiment results revealed that, 100% RDN and nano urea foliar spray @ 4ml litre-1 of water significantly registered higher fertility co-efficient (71.2%), pods plant-1 (38.5 Nos.), seeds pod-1 (12.7 Nos.) and maximum grain yield (1291 kg ha-1). Nevertheless, it was on par with the application of 80% RDN and nano urea foliar spray @ 4ml    litre-1 of water, which recorded fertility co-efficient of 70.6%, 38.0 pods plant-1, 12.6 seeds pod-1 and grain yield of 1289 kg ha-1. In economics perspective also, application of 100% RDN and foliar supplement of nano urea @ 4ml litre-1 accounted maximum gross return (₹100114 ha-1), net return (₹53549 ha-1) and benefit-cost ratio (2.15), which was comparable with application of 80% RDN and foliar application of nano urea @ 4ml litre-1 of water at FI stage and 15 days thereafter. Based on the experimental results, it is concluded that reduced application of basal nitrogen i.e., 80% RDN with nano urea foliar spray @ 4ml litre-1 of water at FI stage and 15 days thereafter found to be the optimal nitrogen dose and nano urea foliar nutrition for maximizing the productivity and profitability of summer irrigated greengram

Enhancing Morpho-Physiological and Yield Potential of Rice using Nutrients and Plant Growth Regulators

Rice (Oryza sativa L.) is one of the major cereals and the staple food crops which is cultivated all over the   world. In order to meet the growing demand of population, it is important to increase the productivity of crop. The productivity of crop is influenced by nutrients and growth hormones. With this background, a field experiment was conducted during the month of January-May 2023 at wetland farms, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India to evaluate the effect of different foliar nutrients and growth regulators on growth, physiology, biochemical and yield attributes in rice. The experimental layout was Factorial Randomized Block Design (FRBD) with two varieties (CO55 and ADT 57). The treatments consisted of foliar spray of T1- Control (water spray), T2- Nutrio-hormonal consortia 1, T3- Nutrio-hormonal consortia 2, T4- Rice booster 1 and T5- Rice booster 2 given at the booting stage and 15 days after the first spray. Among the treatments, T5- Rice booster 2 significantly improved leaf area (1813.99 cm2, 2059.78 cm2), leaf area index (4.53, 5.15), crop growth rate (32.07 g/m2/day, 37.89 g/m2/day), chlorophyll index (37.60, 41.73), photosynthetic rate (27.15 µmol CO2 m-2 s-1, 30.04 µmol CO2 m-2 s-1), Transpiration rate (11.83 mmol H2O m-1 s-1, 14.20 mmol H2O m-1 s-1 ), soluble protein content (16.23 mg/g, 17.30 mg/g), nitrate reductase activity (98.15 µg of NO2/g/h, 112.47 µg of NO2/g/h) in ADT- 57 variety at both sprays, respectively. Foliar application of rice booster 2 (T5) resulted in higher number of productive tillers (23), number of spikelets per panicle (165.5), spikelet fertility (95.48%), 1000 grain weight (17.35g), grain yield/ plant (31.40g), grain yield/hectare (6694.32 Kg/ha), harvest index (45.44%) in ADT 57 and resulted in 15% yield increment over the control. Thus the present study concluded that the foliar application of rice booster 2 (T5) significantly improved the growth, physiology, biochemical and yield attributes in rice variety ADT 57

Screening Blackgram (Vigna mungo (L.) Hepper) Genotypes for Salt Tolerance at Germination and Seedling Stages

Aim: Salt stress negatively affects the growth and development of plants. An effective and important strategy to develop salinity tolerant crops is to harness the genetic diversity within the crop germplasm by identification of salinity tolerant genotype. The present study was carried out with an objective to screen blackgram genotypes (A31, DPU 968, KU 7720, LBG 787, PLU 621, TMV 1, Tutiminimum, VBG 18028, VBG 18032, and VBN 2) for salt tolerance at germination and seedlings stage and identification of saline tolerant blackgram genotype based on salt stress tolerance indices. Study Design: Factorial and arranged in a completely randomized design. Place and Duration of Study: Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore; May-June 2022. Methodology: Using petriplate and roll towel techniques, blackgram seed germination indices and seedling growth indices such as germination percentage, germination index, mean germination time, seedling vigour index, shoot and root length, fresh and dry seedling weight, and stress tolerance indices were recorded. Two-way ANOVA, Principle Component Analysis (PCA) and Cluster Heat-map Analysis were used to analyze the data. Results: PCA indicates that salinity stress accounted for 86.2 percent of the variation, whereas the individual genotype contributes only 5.4 percent of the variation observed in germination and growth parameters that were studied in blackgram under control and 130mM NaCl salt stress conditions. Among the ten blackgram genotypes, stress tolerance index was highest for LBG 787 (0.831) followed by KU7720 (0.722). On the other side, the stress susceptible index was found to be lower for the blackgram genotype KU7720 (0.335) followed by LBG 787 (0.592), as compared to other genotypes screened. Cluster heat-map analysis for all the measured parameters revealed that blackgram genotype LBG 787 was clustered with PLU 621 and VBG 18028 and found to tolerate the salt stress level (130mM NaCl stress) compared to other blackgram genotypes. Conclusion: Observations indicate that the blackgram genotypes KU 7720, LBG 787, PLU 621 and VBG 18028 exhibit greater tolerance towards salinity during the germination and seedling growth stages