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Microalgae are a natural source of lipids, carotenoids, and other value-added compounds. The combination of nutrients and their precise ratio have a significant impact on the productivity of microalgae-mediated compounds. The biomass, lipid, chlorophyll, and carotenoid production of three microalgae species, namely, Monoraphidium sp., Chlorella sorokiniana, and Scenedesmus obliquus, were investigated by employing standard photoautotrophic media, namely, BG-11, BBM, and HS CHU-10. BBM was found as the most effective medium since it obtained higher biomass, lipids, and carotenoids from microalgae. The lipids and carotenoids were identified using chromatographic and microscopy techniques. The findings showed that although the Monoraphidium sp. biomass productivity was the lowest, it emerged as a substantial producer of astaxanthin, whereas the Chlorella sorokiniana culture could grow in a variety of media and produced β-carotene as a major carotenoid. On the other hand, Scenedesmus obliquus was found to be a considerable source of lipids and β-carotene. This study provided a comprehensive understanding of the appropriate medium selection in order to extract an assortment of value-added compounds from freshwater microalgae species.

Salt stress is one of the most severe environmental stresses limiting the productivity of crops, including rice. However, there is a lack of information on how salt-stress sensitivity varies across different developmental stages in rice. In view of this, a comparative evaluation of contrasting rice varieties CSR36 (salt tolerant) and Jaya (salt sensitive) was conducted, wherein NaCl stress (50 mM) was independently given either at seedling (S-stage), tillering (T-stage), flowering (F-stage), seed-setting (SS-stage) or throughout plant growth, from seedling till maturity. Except for S-stage, CSR36 exhibited improved NaCl stress tolerance than Jaya, at all other tested stages. Principal component analysis (PCA) revealed that the improved NaCl stress tolerance in CSR36 coincided with enhanced activities/levels of enzymatic/non-enzymatic antioxidants (root ascorbate peroxidase for T- (2.74-fold) and S+T- (2.12-fold) stages and root catalase for F- (5.22-fold), S+T- (2.10-fold) and S+T+F- (2.61-fold) stages) and higher accumulation of osmolytes (shoot proline for F-stage (5.82-fold) and S+T+F- (2.31-fold) stage), indicating better antioxidant capacitance and osmotic adjustment, respectively. In contrast, higher shoot accumulation of Na+ (14.25-fold) and consequent increase in Na+/K+ (14.56-fold), Na+/Mg+2 (13.09-fold) and Na+/Ca+2 (8.38-fold) ratio in shoot, were identified as major variables associated with S-stage salinity in Jaya. Higher root Na+ and their associated ratio were major deriving force for other stage specific and combined stage salinity in Jaya. In addition, CSR36 exhibited higher levels of Fe3+, Mn2+ and Co3+ and lower Cl− and SO42−, suggesting its potential to discriminate essential and non-essential nutrients, which might contribute to NaCl stress tolerance. Taken together, the findings provided the framework for stage-specific salinity responses in rice, which will facilitate crop-improvement programs for specific ecological niches, including coastal regions.

Abstract Banana is an important fruit crop in the tropics and subtropics; however, limited information on biomarkers and signature volatiles is available for selecting commercial cultivars. Clonal fidelity is a major contributor to banana yield and aroma; however, there are no useful biomarkers available to validate clonal fidelity. In this study, we performed the molecular profiling of 20 banana cultivars consisting of diploid (AA or AB) and triploid (AAA or AAB or ABB) genomic groups. We screened 200 molecular markers, of which 34 markers (11 RAPD, 11 ISSR, and 12 SSR) yielded unequivocally scorable biomarker profiles. About 75, 69, and 24 allelic loci per marker were detected for RAPD, ISSR, and SSR markers, respectively. The statistical analysis of molecular variance (AMOVA) exhibited a high genetic difference of 77% with a significant FST value of 0.23 (p

Drought restricts plant growth and productivity. Silicon has beneficial effects on imparting drought tolerance in plants. Present work was intended to evaluate the effect of Si on polyethylene glycol-6000 (PEG) induced osmotic stress in local landraces of finger millet. The seeds of stress-tolerant and stress-sensitive landraces of finger millet were treated with distilled water, 15% PEG, and PEG+Si (5-25 ppm). The ameliorative effect of Si was evaluated in terms of percentage seed germination, seedling growth, accumulation of osmolyte and activity of antioxidative enzymes. PEG-induced osmotic stress reduced seed germination, seedling growth, and augmented osmolyte accumulation. It also elevated the levels of antioxidant enzymes. The exogenous supplementation of silicon significantly improved seed germination as well as early seeding growth. Positive effects of Si were reflected in decline in malondialdehyde (MDA) content and improved glycine betaine content and antioxidant enzymes in PEG-induced stress tolerant as well as susceptible landraces. The Si-induced ameliorated effects on all the parameters studied were more pronounced in the stress-tolerant landrace (FM/ST/01) than the stress-sensitive landrace (FM/RT/01). These results clearly indicate advantageous effects of Si in relieving PEG-induced stress during seed germination and early seeding growth and suggest a possibility of better stand establishment by application of silicon containing fertilizer during seed sowing.

The Dendrobium hybrid cultivar ‘Emma White’ is an ornamental, successfully commercialised orchid. We used a gamma ray-induced early flowering mutant and the Illumina HiSeqX10 sequencing platform to generate the first draft de novo whole genome sequence and assembly. The draft sequence was 678,650,699 bp in length, comprising 447,500 contigs with an N50 of 1423 and 33.48% GC content. Comparing 95,529 predicted genes against the Uniprot database revealed 60,741 potential genes governing molecular functions, biological processes and cellular components. We identified 216,232 simple sequence repeats and 138,856 microsatellite markers. Chromosome-level genome assembly of Dendrobium huoshanense was used to RagTag-scaffold available contigs of the mutant, revealing a total length of 687,254,899 bp with an N50 of 2096. The longest final contiguous length was 18,000,059 bp from 30,571 bp. BUSCO genome completeness was 93.6%. This study is valuable for investigating the mechanisms of mutation, and developing Dendrobium hybrid cultivars using mutation breeding.

Abstract Blackgram [Vigna mungo (L.) Hepper] (2n = 2x = 22), an important Asiatic legume crop, is a major source of dietary protein for the predominantly vegetarian population. Here we construct a draft genome sequence of blackgram, for the first time, by employing hybrid genome assembly with Illumina reads and third generation Oxford Nanopore sequencing technology. The final de novo whole genome of blackgram is ~ 475 Mb (82% of the genome) and has maximum scaffold length of 6.3 Mb with scaffold N50 of 1.42 Mb. Genome analysis identified 42,115 genes with mean coding sequence length of 1131 bp. Around 80.6% of predicted genes were annotated. Nearly half of the assembled sequence is composed of repetitive elements with retrotransposons as major (47.3% of genome) transposable elements, whereas, DNA transposons made up only 2.29% of the genome. A total of 166,014 SSRs, including 65,180 compound SSRs, were identified and primer pairs for 34,816 SSRs were designed. Out of the 33,959 proteins, 1659 proteins showed presence of R-gene related domains. KIN class was found in majority of the proteins (905) followed by RLK (239) and RLP (188). The genome sequence of blackgram will facilitate identification of agronomically important genes and accelerate the genetic improvement of blackgram.

Drought is one of the major yield‐limiting factors under climatic adversaries. The positive role of silicon (Si) in drought tolerance of plants has unfolded a new avenue for enhancing crop productivity through better Si use efficiency. It is hence interesting to understand the mechanistic insights pertaining to its beneficial roles under drought stress conditions. Higher plants sense drought stress via roots which, regulate aboveground plant growth under stress. Cellular and molecular modulations occurring at the root and soil interphases influence the survival and growth of plants under drought stress; therefore, it is intriguing to know how Si influences the soil–root interphase and how this interaction augments overall plant growth under drought. In this review, we summarised the roles of Si in the root systems, rhizosphere and their interactions that could improve plant's growth and development under drought conditions. We have discussed the direct and indirect effects of Si‐induced belowground changes on plant roots, soil physical, chemical and biological properties, and their mutual interactions in eliciting defence signalling, including hormone signalling pathways. A mechanistic model of Si‐induced beneficial effects in water‐limited environments is suggested, which could help improve the management of rainfed croplands through Si fertilisation. [ABSTRACT FROM AUTHOR]

Abstract Plant bioregulators (PBRs) represent low-cost chemicals for boosting plant defense, especially under stress conditions. In the present study, redox based PBRs such as thiourea (TU; a non-physiological thiol-based ROS scavenger) and hydrogen peroxide (H2O2; a prevalent biological ROS) were assessed for their ability to mitigate NaCl stress in rice variety IR 64. Despite their contrasting redox chemistry, TU or H2O2 supplementation under NaCl [NaCl + TU (NT) or NaCl + H2O2 (NH)] generated a reducing redox environment in planta, which improved the plant growth compared with those of NaCl alone treatment. This was concomitant with better K+ retention and upregulated expression of NaCl defense related genes including HAK21, LEA1, TSPO and EN20 in both NT and NH treated seedlings. Under field conditions, foliar applications of TU and H2O2, at vegetative growth, pre-flowering and grain filling stages, increased growth and yield attributes under both control and NaCl stress conditions. Principal component analysis revealed glutathione reductase dependent reduced ROS accumulation in source (flag leaves) and sucrose synthase mediated sucrose catabolism in sink (developing inflorescence), as the key variables associated with NT and NH mediated effects, respectively. In addition, photosystem-II efficiency, K+ retention and source-sink relationship were also improved in TU and H2O2 treated plants. Taken together, our study highlights that reducing redox environment acts as a central regulator of plant’s tolerance responses to salt stress. In addition, TU and H2O2 are proposed as potential redox-based PBRs for boosting rice productivity under the realistic field conditions.

Cesium (Cs) is a soil contaminant and toxic to the ecosystem, especially the plant species. In this study, we have assessed the potential of a halophyte Sesuvium portulacastrum for its Cs tolerance and accumulation. Thirty days old S. portulacastrum plants were subjected to different concentrations of Cs (0, 5, 10, 25, 50, and 150 mg·L−1 Cs) using cesium chloride. The biomass and photosynthetic pigments were not affected up to 25 mg·L−1 Cs treatment while a significant decline in pigment levels was observed at higher concentrations. The Cs treatments increased protein content at low concentrations while higher concentrations were inhibitory. Under Cs exposure, significant induction of antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) was observed. The antioxidant enzyme activities were upregulated up to 50 mg·L−1 Cs but decreased significantly at 150 mg·L−1. The accumulation of Cs was dose and tissue-dependent as evidenced by a higher accumulation of Cs in leaves (536.10 μg·g−1) as compared to stem (413.74 μg·g−1) and roots (284.69 μg·g−1). The results suggest that S. portulacastrum is a hyper-accumulator of Cs and could be useful for the phytoremediation of Cs-contaminated soils.