Comprehensive and evolutionary analysis of Spodoptera litura-inducible Cytochrome P450 monooxygenase gene family in Glycine max elucidate their role in defense.

Plants being sessile organisms and lacking both circulating phagocytic cells and somatic adaptive immune response, have thrived on various defense mechanisms to fend off insect pests and invasion of pathogens. CYP450s are the versatile enzymes, which thwart plants against insect pests by ubiquitous biosynthesis of phytohormones, antioxidants, and secondary metabolites, utilizing them as feeding deterrents and direct toxins. Therefore, a comprehensive analysis of biotic stress-responsive CYPs from Glycine max was performed to ascertain their function against S. litura-infestation. Phylogenetic analysis and evolutionary studies on conserved domains and motifs disclosed the evolutionary correspondence of these GmCYPs with already characterized members of the CYP450 superfamily and close relatedness to Medicago truncatula. These GmCYPs were mapped on 13 chromosomes; they possess 1-8 exons; they have evolved due to duplication and are localized in endoplasmic reticulumn. Further, identification of methyl-jasmonate, salicylic acid, defense responsive and flavonoid biosynthesis regulating cis-acting elements, their interaction with biotic stress regulating proteins and their differential expression in diverse types of tissues, and during herbivory, depicted their responsiveness to biotic stress. Three-dimensional homology modelling of GmCYPs, docking with heme cofactor required for their catalytic activity and enzyme-substrate interactions were performed to understand the functional mechanism of their action. Moreover, to gain insight into their involvement in plant defense, gene expression analysis was evaluated, which revealed differential expression of 11 GmCYPs upon S. litura-infestation, 12 GmCYPs on wounding while foliar spray of ethylene, methyl-jasmonate and salicylic acid differentially regulated 11 GmCYPs, 6 GmCYPs, and 10 GmCYPs respectively. Our study comprehensively analysed the underlying mechanism of GmCYPs function during S. litura-infestation, which can be further utilized for functional characterization to develop new strategies for enhancing soybean resistance to insect pests.

The calcium connection: exploring the intricacies of calcium signaling in plant-microbe interactions.

The process of plant immune response is orchestrated by intracellular signaling molecules. Since plants are devoid of a humoral system, they develop extensive mechanism of pathogen recognition, signal perception, and intricate cell signaling for their protection from biotic and abiotic stresses. The pathogenic attack induces calcium ion accumulation in the plant cells, resulting in calcium signatures that regulate the synthesis of proteins of defense system. These calcium signatures induct different calcium dependent proteins such as calmodulins (CaMs), calcineurin B-like proteins (CBLs), calcium-dependent protein kinases (CDPKs) and other signaling molecules to orchestrate the complex defense signaling. Using advanced biotechnological tools, the role of Ca2+ signaling during plant-microbe interactions and the role of CaM/CMLs and CDPKs in plant defense mechanism has been revealed to some extent. The Emerging perspectives on calcium signaling in plant-microbe interactions suggest that this complex interplay could be harnessed to improve plant resistance against pathogenic microbes. We present here an overview of current understanding in calcium signatures during plant-microbe interaction so as to imbibe a future direction of research.

Overexpression of flowering locus D (FLD) in Indian mustard (Brassica juncea) enhances tolerance to Alternaria brassicae and Sclerotinia sclerotiorum.

KEY MESSAGE: Overexpression of BjFLD in Brassica juncea imparts resistance against fungal pathogens and increases the yield. These transgenics could lower the use of fungicides, which have detrimental effects on the environment. Productivity of Indian mustard (Brassica juncea) is adversely affected by fungal phytopathogens, Alternaria brassicae and Sclerotinia sclerotiorum. Arabidopsis flowering locus D (FLD) positively regulates jasmonic acid signaling and defense against necrotrophic pathogens. In this study, the endogenous FLD (B. juncea FLD; BjFLD) in Indian mustard was overexpressed in B. juncea to determine its role in biotic stress tolerance. We report the isolation, characterization, and functional validation of BjFLD. The transgene expression was confirmed by qRT-PCR. The constitutive overexpression of BjFLD enhanced the tolerance of B. juncea to A. brassicae and S. sclerotiorum, which was manifested as delayed appearance of symptom, impeded disease progression, and enhanced percentage of disease protection. The transgenic lines maintained a higher photosynthetic capacity and redox potential under biotic stress and could detoxify reactive oxygen species (ROS) by modulating the antioxidant machinery and physiochemical attributes. The BjFLD-overexpressing lines showed enhanced SA level as well higher NPR1 expression. The overexpression of BjFLD induced early flowering and higher seed yield in the transgenic lines. These findings indicate that overexpression of BjFLD enhances the tolerance of B. juncea to A. brassicae and S. sclerotiorum by induction of systemic acquired resistance and mitigating the damage caused by stress-induced ROS.

Harnessing phytomicrobiome signals for phytopathogenic stress management.

Harnessing the phytomicrobiome offers a great opportunity to improve plant productivity and quality of food. In the recent past, several phytomicrobiome microbes have been explored for their potential involvement in increasing crop yield. This review strategically targets to harness the various dimensions of phytomicrobiome for biotic stress management of crop plants. The tripartite interaction involving plantmicrobiome-pathogen has been discussed. Positive interventions in this system so as to achieve disease tolerant plants has been forayed upon. The different signalling molecules sent out by interacting partners of phytomicrobiome have also been analysed. The novel concept of artificial microbial consortium in mitigation of pathogenic stress has also been touched upon. The aim of this review is to explore the hidden potential of phytomicrobiome diversity as a potent tool against phytopathogens, thereby improving crop health and productivity in a sustainable way.

Exploring the new dimensions of selenium research to understand the underlying mechanism of its uptake, translocation, and accumulation.

Selenium (Se) is a vital mineral for both plants and animals. It is widely distributed on the earth's crust and is taken up by the plants as selenite or selenate. Plants substantially vary in their physiological response to Se. The amount of Se in edible plants is genetically controlled. Its availability can be determined by measuring its phytoavailability in soil. The low concentration of Se in plants can help them in combating stress, whereas higher concentrations can be detrimental to plant health and in most cases it is toxic. Thus, solving the double-edged sword problem of nutritional Se deficiency and its elevated concentrations in environment requires a better understanding of Se uptake and metabolism in plants. The studies on Se uptake and metabolism can help in genetic biofortification of Se in plants and also assist in phytoremediation. Moreover, Se uptake and transport, especially biochemical pathways of assimilation and incorporation into proteins, offers striking mechanisms of toxicity and tolerance. These developments have led to a revival of Se research in higher plants with significant break throughs being made in the previous years. This review explores the new dimensions of Se research with major emphasis on key research events related to Se undertaken in last few years. Further, we also discussed future possibilities in Se research for crop improvement.

Groundnut AhcAPX conferred abiotic stress tolerance in transgenic banana through modulation of the ascorbate-glutathione pathway.

A stress inducible cytosolic ascorbate peroxidase gene (AhcAPX) was ectopically expressed in banana (cv. Grand naine) plants to strengthen their antioxidant capacity. High level of AhcAPX gene transcripts and enzyme suggested constitutive and functional expression of candidate gene in transgenic (TR) plants. The tolerance level of in vitro and in vivo grown TR banana plantlets were assessed against salt and drought stress. The TR banana plants conferred tolerance against the abiotic stresses by maintaining a high redox state of ascorbate and glutathione, which correlated with lower accumulation of H2O2, O2 ⋅- and higher level of antioxidant enzyme (SOD, APX, CAT, GR, DHAR and MDHAR) activities. The efficacy of AhcAPX over-expression was also investigated in terms of different physiochemical attributes of TR and untransformed control plants, such as, proline content, membrane stability, electrolyte leakage and chlorophyll retention. The TR plants showed higher photochemical efficiency of PSII (Fv/Fm), and stomatal attributes under photosynthesis generated reactive oxygen species (ROS) stress. The outcome of present investigation suggest that ectopic expression of AhcAPX gene in banana enhances the tolerance to drought and salt stress by annulling the damage caused by ROS.

Meeting the challenge of developing food crops with improved nutritional quality and food safety: leveraging proteomics and related omics techniques.

Eliminating malnutrition remains an imminent priority in our efforts to achieve food security and providing adequate calories, proteins, and micronutrients to the growing world population. Malnutrition may be attributed to socio-economic factors (poverty and limited accessibility to nutritional food), dietary preferences, inherent nutrient profiles of traditional food crops, and to a combination of all such factors. Modern advancements in "omics" technology have made it possible to reliably predict, diagnose, and suggest ways to remedy the low protein content and bioavailability of key micronutrients in food crops. In this review, we briefly describe how proteomics techniques can potentially be used for improving the nutrient profile of major crops, through high throughput multiplexed assays. Food safety is another important issue where proteomics and related platforms can offer solution for absolute quantitation of food allergens and mycotoxins present in the plant-based food. The purpose of the present review is to discuss the proteomic-based strategies in food crops to meet the challenges of overcoming malnutrition throughout the world.

High efficiency transformation of banana [Musa acuminata L. cv. Matti (AA)] for enhanced tolerance to salt and drought stress through overexpression of a peanut salinity-induced pathogenesis-related class 10 protein.

Bananas and plantains (Musa spp. L.) are important subsistence crops and premium export commodity in several countries, and susceptible to a wide range of environmental and biotic stress conditions. Here, we report efficient, rapid, and reproducible Agrobacterium-mediated transformation and regeneration of an Indian niche cultivar of banana [M. acuminata cv. Matti (AA)]. Apical meristem-derived highly proliferative multiple shoot clump (MSC) explants were transformed with the Agrobacterium strain EHA105 harboring a binary vector pCAMBIA-1301 carrying hptII and uidA. Sequential agro-infiltration (10 min, 400 mmHg), infection (additional 35 min, Agrobacterium density A 600 = 0.8) and co-cultivation (18 h) regimen in 100 µM acetosyringone containing liquid medium were critical factors yielding high transformation efficiency (~81 %) corroborated by transient GUS expression assay. Stable transgenic events were recovered following two cycles of meristem initiation and selection on hygromycin containing medium. Histochemical GUS assay in several tissues of transgenic plants and molecular analyses confirmed stable integration and expression of transgene. The protocol described here allowed recovery of well-established putative transgenic plantlets in as little as 5 months. The transgenic banana plants could be readily acclimatized under greenhouse conditions, and were phenotypically similar to the wild-type untransformed control plants (WT). Transgenic plants overexpressing Salinity-Induced Pathogenesis-Related class 10 protein gene from Arachis hypogaea (AhSIPR10) in banana cv. Matti (AA) showed better photosynthetic efficiency and less membrane damage (P < 0.05) in the presence of NaCl and mannitol in comparison to WT plants suggesting the role of AhSIPR10 in better tolerance of salt stress and drought conditions.

Transgenic Brassica juncea plants expressing MsrA1, a synthetic cationic antimicrobial peptide, exhibit resistance to fungal phytopathogens.

Cationic antimicrobial peptides (CAPs) have shown potential against broad spectrum of phytopathogens. Synthetic versions with desirable properties have been modeled on these natural peptides. MsrA1 is a synthetic chimera of cecropin A and melittin CAPs with antimicrobial properties. We generated transgenic Brassica juncea plants expressing the msrA1 gene aimed at conferring fungal resistance. Five independent transgenic lines were evaluated for resistance to Alternaria brassicae and Sclerotinia sclerotiorum, two of the most devastating pathogens of B. juncea crops. In vitro assays showed inhibition by MsrA1 of Alternaria hyphae growth by 44-62 %. As assessed by the number and size of lesions and time taken for complete leaf necrosis, the Alternaria infection was delayed and restricted in the transgenic plants with the protection varying from 69 to 85 % in different transgenic lines. In case of S. sclerotiorum infection, the lesions were more severe and spread profusely in untransformed control compared with transgenic plants. The sclerotia formed in the stem of untransformed control plants were significantly more in number and larger in size than those present in the transgenic plants where disease protection of 56-71.5 % was obtained. We discuss the potential of engineering broad spectrum biotic stress tolerance by transgenic expression of CAPs in crop plants.