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Plasma membrane proteolipid 3 (Pmp3) is a gene family involved in abiotic stress response and cellular protection. Here we report cloning of two genes PgPmp3-1 and PgPmp3-2 from Pennisetum glaucum, and characterization with respect to their functions and responsiveness to various abiotic stresses. Both PgPmp3-1 and PgPmp3-2 genes are 171 bp long and encode for 56 amino acid long peptides. PgPmp3 sequences share 70–99% sequence identity with their homologs. Protein secondary structure prediction revealed membrane-spanning regions containing a membrane potential modulator domain in both PgPmp3 proteins. In silico network analyses revealed Pmp3 co-expression and association with proteins conferring abiotic stress tolerance in plants. Expression profiles of PgPmp3-1 and PgPmp3-2 revealed their up-regulation in P. glaucum under cold and salt stresses, but showed reduced expression in response to heat stress. These findings provide insight into the role of P. glaucum Pmp3 in abiotic stress amelioration.

Crop productivity strongly depends on several biotic and abiotic factors. Salinity is one of the most important abiotic factors, besides drought, extreme temperatures, light and metal stress. The enhanced burden of secondary salinization induced through anthropogenic activities increases pressure on glycophytic crop plants. The recent isolation and characterization of salt tolerance genes encoding signaling components from halophytes, which naturally grow in high salinity, has provided tools for the development of transgenic crop plants with improved salt tolerance and economically beneficial traits. In addition understanding of the differences between glycophytes and halophytes with respect to levels of salinity tolerance is also one of the prerequisite to achieve this goal. Based on the recent developments in mechanisms of salt tolerance in halophytes, we will explore the potential of introducing salt tolerance by choosing the available genes from both dicotyledonous and monocotyledonous halophytes, including the salt overly sensitive system (SOS)-related cation/proton antiporters of plasma (NHX/SOS1) and vacuolar membranes (NHX), energy-related pumps, such as plasma membrane and vacuolar H+ adenosine triphosphatase (PM& V-H+ATPase), vacuolar H+ pyrophosphatases (V-H+PPase) and potassium transporter genes. Various halophyte genes responsible for other processes, such as crosstalk signaling, osmotic solutes production and reactive oxygen species (ROS) suppression, which also enhance salt tolerance will be described. In addition, the transgenic overexpression of halophytic genes in crops (rice, peanut, finger millet, soybean, tomato, alfalfa, jatropha, etc.) will be discussed as a successful mechanism for the induction of salt tolerance. Moreover, the advances in genetic engineering technology for the production of genetically modified crops to achieve the improved salinity tolerance under field conditions will also be discussed.

Crop productivity is largely dependent on environmental stress factors such as water scarcity, salinity, extreme temperature, etc. Plant cell membranes perceive the environmental cues by membrane bound kinase molecules such as RLKs (receptor-like kinases) and HKs (histidine kinases) and transduce them to the target genes through signaling molecules like MAPK (mitogen activated protein kinase) cascade, CDPKs (calcium-dependent protein kinases), and CIPKs (CBL-interacting protein kinases) and elicit appropriate responses. Protein phosphorylation is one of the key mechanisms underlying this signal transduction pathway. Understanding the chemistry of protein kinases will help in development of crop varieties with improved traits and yield under stress conditions through transgenic or breeding approaches. The present topic describes the various protein kinases involved in plant signal transduction and also describes functional validation of a few signaling genes. Genomic technologies have become an integrated part of breeding programs recently and efforts in this direction are also discussed.

Peanut is an important oilseed and food legume cultivated as a rain-fed crop in semi-arid tropics. Drought and high salinity are the major abiotic stresses limiting the peanut productivity in this region. Development of drought and salt tolerant peanut varieties with improved yield potential using biotechnological approach is highly desirable to improve the peanut productivity in marginal geographies. As abiotic stress tolerance and yield represent complex traits, engineering of regulatory genes to produce abiotic stress-resilient transgenic crops appears to be a viable approach. In the present study, we developed transgenic peanut plants expressing an Arabidopsis homeodomain-leucine zipper transcription factor (AtHDG11) under stress inducible rd29A promoter. A stress-inducible expression of AtHDG11 in three independent homozygous transgenic peanut lines resulted in improved drought and salt tolerance through up-regulation of known stress responsive genes (LEA, HSP70, Cu/Zn SOD, APX, P5CS, NCED1, RRS5, ERF1, NAC4, MIPS, Aquaporin, TIP, ELIP) in the stress gene network, antioxidative enzymes, free proline along with improved water use efficiency traits such as longer root system, reduced stomatal density, higher chlorophyll content, increased specific leaf area, improved photosynthetic rates, and increased intrinsic instantaneous WUE. Transgenic peanut plants displayed high yield compared to non-transgenic plants under both drought and salt stress conditions. Holistically, our study demonstrates the potentiality of stress-induced expression of AtHDG11 to improve the drought, salt tolerance in peanut.

Peanut is an important oilseed and food legume cultivated as a rain-fed crop in semi-arid tropics. Drought and high salinity are the major abiotic stresses limiting the peanut productivity in this region. Development of drought and salt tolerant peanut varieties with improved yield potential using biotechnological approach is highly desirable to improve the peanut productivity in marginal geographies. As abiotic stress tolerance and yield represent complex traits, engineering of regulatory genes to produce abiotic stress-resilient transgenic crops appears to be a viable approach. In the present study, we developed transgenic peanut plants expressing an Arabidopsis homeodomain-leucine zipper transcription factor (AtHDG11) under stress inducible rd29A promoter. A stress-inducible expression of AtHDG11 in three independent homozygous transgenic peanut lines resulted in improved drought and salt tolerance through up-regulation of known stress responsive genes (LEA, HSP70, Cu/Zn SOD, APX, P5CS, NCED1, RRS5, ERF1, NAC4, MIPS, Aquaporin, TIP, ELIP) in the stress gene network, antioxidative enzymes, free proline along with improved water use efficiency traits such as longer root system, reduced stomatal density, higher chlorophyll content, increased specific leaf area, improved photosynthetic rates, and increased intrinsic instantaneous WUE. Transgenic peanut plants displayed high yield compared to non-transgenic plants under both drought and salt stress conditions. Holistically, our study demonstrates the potentiality of stress-induced expression of AtHDG11 to improve the drought, salt tolerance in peanut.

Maize has traditionally been the main staple diet in the Southern Asia and Sub-Saharan Africa and widely grown by millions of resource poor small scale farmers. Approximately, 35.4 million hectares are sown to tropical maize, constituting around 59% of the developing worlds. Tropical maize encounters tremendous challenges besides poor agro-climatic situations with average yields recorded

All environmental cues lead to develop secondary stress conditions like osmotic and oxidative stress conditions that reduces average crop yields by more than 50% every year. The univalent reduction of molecular oxygen (O2) in metabolic reactions consequently produces superoxide anions (O2 •−) and other reactive oxygen species (ROS) ubiquitously in all compartments of the cell that disturbs redox potential and causes threat to cellular organelles. The production of ROS further increases under stress conditions and especially in combination with high light intensity. Plants have evolved different strategies to minimize the accumulation of excess ROS like avoidance mechanisms such as physiological adaptation, efficient photosystems such as C4 or CAM metabolism and scavenging mechanisms through production of antioxidants and antioxidative enzymes. Ascorbate-glutathione pathway plays an important role in detoxifying excess ROS in plant cells, which includes superoxide dismutase (SOD) and ascorbate peroxidase (APX) in detoxifying O2 •−radical and hydrogen peroxide (H2O2) respectively, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in recycling of reduced substrates such as ascorbate and glutathione. Efficient ROS management is one of the strategies used by tolerant plants to survive and perform cellular activities under stress conditions. The present chapter describes different sites of ROS generation and and their consequences under abiotic stress conditions and also described the approaches to overcome oxidative stress through genomics and genetic engineering.

Molecular chaperones (Hsps) have been shown to facilitate protein folding or assembly under various developmental and adverse environmental conditions. The aim of this study was to unravel a possible role of heat-shock proteins in conferring abiotic stress tolerance to plants. We isolated a cDNA encoding a cytoplasmic Hsp70 (PgHsc70) from Pennisetum glaucum by screening heat-stress cDNA library. PgHsc70 cDNA encoding 649 amino acids represents all conserved signature motifs characteristic of Hsp70s. The predicted molecular model of PgHsc70 protein suggests that the N-terminus ATP-binding region is evolutionarily conserved, in comparison to C-terminus peptide-binding domains. A single intron in ATPase domain coding region of PgHsc70 exhibited a high degree of conservation with respect to its position and phasing among other plant Hsp70 genes. Recombinant PgHsc70 protein purified from E. coli possessed in vitro chaperone activity and protected PgHsc70 expressing bacteria from damage caused by heat and salinity stress. Nucleotide sequence analysis of 5' flanking promoter region of PgHsc70 gene revealed a potential heat-shock element (HSE) and other putative stress-responsive transcription factor binding sites. Positive correlation existed between differentially up-regulated PgHsc70 transcript levels and the duration and intensity of different environmental stresses. Molecular and biochemical analyses revealed that PgHsc70 gene was a member of the Hsp70 family and suggested that its origin was from duplication of a common ancestral gene. Transcript induction data, presence of several putative stress-responsive transcription factor-binding sites in the promoter region of PgHsc70 and the presence of a protective in vitro chaperone activity of this protein against damage caused by heat and salinity, when expressed in E. coli, suggest its probable role in conferring abiotic stress tolerance to this plant.

High temperature response (HTR) or heat stress response (HSR) is a highly conserved phenomenon, which involves complex networks among different crop species. Heat stress usually results in protein dysfunction by improper folding of its linear amino acid chains to non-native proteins. This leads to unfavourable interactions and subsequent protein aggregation. To tackle this, plants have developed molecular chaperone machinery to maintain high quality proteins in the cell. This is governed by increasing the level of pre-existing molecular chaperones and by expressing additional chaperones through signalling mechanism. Dissecting the molecular mechanism by which plants counter heat stress and identification of important molecules involved are of high priority. This could help in the development of plants with improved heat stress tolerance through advanced genomics and genetic engineering approaches. Owing to this reason molecular chaperones/Heat shock proteins (Hsps) are considered as potential candidates to address the issue of heat stress. In this chapter, recent progress on systematic analyses of heat shock proteins, their classification and role in plant response to heat stress along with an overview of genomic and transgenic approaches to overcome the issue, are summarized.