Insight of PBZ mediated drought amelioration in crop plants.

Water scarcity is a significant environmental limitation to plant productivity as drought-induced crop output losses are likely to outnumber losses from all other factors. In this context, triazole compounds have recently been discovered to act as plant growth regulators and multi-stress protectants such as heat, chilling, drought, waterlogging, heavy metals, etc. Paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)- 4, 4-dimethyl-2-(1H-1, 2, 4-trizol-1-yl)-pentan-3-ol)] disrupts the isoprenoid pathway by blocking ent-kaurene synthesis, affecting gibberellic acid (GA) and abscisic acid (ABA) hormone levels. PBZ affects the level of ethylene and cytokinin by interfering with their biosynthesis pathways. Through a variety of physiological responses, PBZ improves plant survival under drought. Some of the documented responses include a decrease in transpiration rate (due to reduced leaf area), higher diffusive resistance, relieving reduction in water potential, greater relative water content, less water use, and increased antioxidant activity. We examined and discussed current findings as well as the prospective application of PBZ in regulating crop growth and ameliorating abiotic stresses in this review. Furthermore, the influence of PBZ on numerous biochemical, physiological, and molecular processes is thoroughly investigated, resulting in increased crop yield.

Correlation between expression and activity of ADP glucose pyrophosphorylase and starch synthase and their role in starch accumulation during grain filling under drought stress in rice.

ADP glucose pyrophosphorylase (AGPase, EC 2.7.7.27) and starch synthase (SS, EC 2.4.1.21) are key regulatory enzymes involved in the starch biosynthesis. Comprehensive analysis of transcription levels of ADP-glucose pyrophosphorylase and starch synthase genes was performed in leaves, roots, and developing grains of drought susceptible (IR64) and drought-tolerant (N22) cultivars under applied water deficit stress (WDS). AGPase and SS genes are differentially regulated in leaves, roots, and grains under the drought stress. The expression pattern of SS and AGPase genes was correlated with the activity of both AGPase, SS, and starch content of developing grains under the drought. Drought stress reduced transitory starch in leaves and enhanced storage starch in developing grains. An increase in the activity of AGPase in developing grains was due to induced expression of ADP glucose pyrophosphorylase large subunit 3 (AGPL3) in N22 and both ADP glucose pyrophosphorylase small subunit 2 (AGPS2) & ADP glucose pyrophosphorylase large subunit 3 (AGPL3) in IR64 and a positive correlation was established with starch content. Similarly, an increase in the SS activity in developing grains was due to induced expression of soluble starch synthase (SSIIB, SSIVA, and SSIVB) in N22 and SSIVB in IR64.

Starch accumulation in rice grains subjected to drought during grain filling stage.

Drought stress during the grain filling stage severely affects the quality and quantity of starch in rice grains. The enzymes such as ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) and starch synthase (SS, EC 2.4.1.21) are the key regulatory enzymes involved in the starch biosynthesis. In this study, the activity of the AGPase and starch synthase (SS) was correlated with the qualitative and quantitative parameters such as sucrose, starch, amylose, amylopectin, and resistant starch in leaves, roots, and grains of drought tolerant (N22) and drought susceptible (IR64) cultivars under applied water deficit stress (WDS). Drought stress enhanced the remobilization of stored starch from leaves to developing rice grains which was positively correlated with a decrease in the starch and starch synthase activity in leaves. Starch accumulation in developing grains was positively correlated with an increase in the AGPase and SS activity under drought. It was found that starch, amylopectin, and sucrose content in developing grains increased under water deficit stress (WDS), while amylose content decreased in both the varieties. However, in leaves, the SS activity decreased while AGPase activity was found to be increased under WDS in both varieties. Decreased starch content in matured grains was due to shortening of grain filling stage as drought stress caused early plant senescence. Yield reduction under drought was more in susceptible variety IR64 as compared to tolerant genotype N22.

Cloning, characterization, and expression of a new cry1Ab gene from DOR Bt-1, an indigenous isolate of Bacillus thuringiensis.

A new cry1Ab gene was cloned from the promising local isolate, DOR Bt-1, a Bacillus thuringiensis strain isolated from castor semilooper (Achaea janata L.) cadavers from castor bean (Ricinus communis L.) field. The nucleotide sequence of the cloned cry1Ab gene indicated that the open reading frame consisted of 3,465 bases encoding a protein of 1,155 amino acid residues with an estimated molecular weight of 130 kDa. Homology comparisons revealed that the deduced amino acid sequence of cry1Ab had a variation of seven amino acid residues compared to those of the known Cry1Ab proteins in the NCBI database and this gene has been designated as cry1Ab26 by the B. thuringiensis δ-endotoxin Nomenclature Committee. cry1Ab26 was cloned into pET 29a(+) vector and expressed in E. coli strain BL21 (DE3) under the control of T7 promoter with IPTG induction. ELISA, SDS-PAGE, and Western blot analysis confirmed the expression of 130-kDa protein. Insect bioassays with neonate larvae of Helicoverpa armigera showed that the partially purified Cry1Ab26 caused 97 % mortality within 5 days of feeding.

Development and characterization of microsatellite markers (SSR) in Sesamum (Sesamum indicum L.) species.

Microsatellites, also known as simple sequence repeats (SSRs), are the class of repetitive DNA sequences present throughout the genome of many plant and animal species. Recent advances in molecular genetics had been the introduction of microsatellite markers to investigate the genetic structuring of natural plant populations. We have employed an enrichment strategy for microsatellite isolation by using multi-enzymes digestion, microsatellite oligoprobes, and streptavidin magnetic beads in Sesamum (Sesamum indicum L.). More than 200 SSR motifs were detected (SSR motifs ≥2 repeat units or 6 bp); 80 % of the clones contained SSR motifs. When regarding SSRs with four or more repeat units and a minimum length of 10 bp, 132 of them showed repeats. Eighteen SSR markers were initially characterized for optimum annealing temperature using a gradient PCR technique. Among the 18 SSR markers characterized, five were found to be polymorphic and used to analyze 60 Sesamum germplasm accessions. The maximum number of alleles detected was four with a single primer and the least number of two alleles with three primers with an average PIC value of 0.77. SSRs are a valuable tool for estimating genetic diversity and analyzing the evolutionary and historical development of cultivars at the genomic level in sesame breeding programs.

Cephalometric evaluation of oropharyngeal airway dimension changes in pre- and postadenoidectomy cases.

AIM: The aim is to compare and evaluate the airway dimension changes, adenoidal nasopharyngeal ratio (ANR), airway area and airway percentage in patients in pre- and postadenoidectomy with normal individuals. MATERIALS AND METHODS: After obtaining informed consent, a sample of 15 patients (eight males and seven females) of 7 to 12 years were selected for adenoidectomy by an otolaryngologist, lateral cephalograms were taken in natural head position before adenoidectomy and after 1 month postadenoidectomy. Statastical analysis was done to evaluate the results using Statastical Package for Social Sciences. Results showed airway (P1, P2, P3, P4), airway percentage, airway area showed significant increase (p < 0.0001), whereas ANR showed significant reduction after 1 month postadenoidectomy. CONCLUSION: One month postadenoidectomy showed increased airway area, airway percentage and reduced ANR. CLINICAL SIGNIFICANCE: Obstructive mouth breathing due to adenoids in growing children can cause alteration in craniofacial morphology leading to adenoid facies, adenoidectomy procedure helps in alleviating the obstruction and facilitates the normal growth of craniofacial complex.