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Heat-shock proteins (HSP) are molecular chaperones for protein molecules. These proteins play an important role in protein-protein interactions such as, folding and assisting in the establishment of proper protein conformation and prevention of unwanted protein aggregation. A small HSP gene GHSP26 present in Gossypium arboreum responds to dehydration. In the present study, an attempt was made to overcome the problem of drought stress in cotton. A cDNA of GHSP26 was isolated from G. arboreum, cloned in plant expression vector, pCAMBIA-1301 driven by the cauliflower mosaic virus 35S promoter and introduced into Gossypium hirsutum. The integration and expression studies of putative transgenic plants were performed through GUS assay; PCR from genomic DNA, and quantitative real-time PCR analysis. Transgenic cotton plants showed an enhanced drought tolerance, suggesting that GHSP26 may play a role in plant responsiveness to drought.

Two closely related genes GUSP1 and GUSP2, within the universal stress protein (USP) family, were identified and cloned from water-stressed leaves of Gossypium arboreum. GUSP1 and GUSP2 genes code for proteins with predicted molecular weights of 18.2 and 19.1 kDa, respectively. Sequence analysis showed that GUSP1 and GUSP2 are highly similar to the bacterial MJ0577-type of adenosine-triphosphate-binding Usp proteins, which have been proposed to function as a molecular switch. Nucleotide sequences of these two genes showed 81% sequence similarity while their encoded proteins share 75% amino acid homology. Both proteins have high percentages of similarity (17% to 61%) to the USPs from a variety of bacteria and plants. Real-time polymerase chain reaction expression analysis revealed a high level of GUSP gene expression in leaves, roots, and stems exclusively in plants following water stress. The highest levels of droughtinducible expression were found in the leaves. A progressive decrease in expression was observed in the stem and roots compared to very low expression in control tissues.

Global food security concerns impact greatly on the United Nation's Sustainable Development Goals, which are heavily focused on eradicating hunger by 2030. The Global Food Security Index of 2019 has reported that 88% of countries claim their is enough food supply in their countries, but it is a dreadful reality that every one in three countries is facing insufficient availability of food supply as per the index, meaning more than 10% of the population is malnourished. Since nutrition is one of the main factors in maintaining a healthy lifestyle and meeting the requirements of food security, several national nutrition surveys conducted in various countries have provided an avenue for governments to assess malnutrition problems across the population. For example, the National Nutrition Survey carried out in 2011 in Pakistan indicated that more than 50% of the population was food insecure based on the nutritional status of available food. This survey also highlighted the acute deficiency of micronutrients in the diet resulting in several disorders, especially among the female population. In view of these facts, efforts are being made globally to enhance the nutritional value of our agricultural products, especially staple crops, by using several biotechnological approaches.

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Phytate is a major constituent of wheat seeds and chelates metal ions, thus reducing their bioavailability and so the nutritional value of grains. Transgenic plants expressing heterologous phytase are expected to enhance degradation of phytic acid stored in seeds and are proposed to increase the in vitro bioavailability of mineral nutrients. Wheat transgenic plants expressing Aspergillus japonicus phytase gene (phyA) in wheat endosperm were developed till T generation. The transgenic lines exhibited 18-99 % increase in phytase activity and 12-76 % reduction of phytic acid content in seeds. The minimum phytic acid content was observed in chapatti (Asian bread) as compared to flour and dough. The transcript profiling of phyA mRNA indicated twofold to ninefold higher expression as compared to non transgenic controls. There was no significant difference in grain nutrient composition of transgenic and non-transgenic seeds. In vitro bioavailability assay for iron and zinc in dough and chapatti of transgenic lines revealed a significant increase in iron and zinc contents. The development of nutritionally enhanced cereals is a step forward to combat nutrition deficiency for iron and zinc in malnourished human population, especially women and children.

In response to water deficit stress, plants show quantitative and qualitative differences in gene expression. By using differential display and RACE (rapid amplification of cDNA ends) polymerase chain reaction (PCR) techniques an alpha crystalline‐type small heat shock protein gene (GHSP26) was isolated and characterized from Gossypium arboreum L. Alignments of 1108 bp genomic and 1026 bp cDNA sequences revealed that the GHSP26 gene comprises a single open reading frame of 230 amino acids and it contains a single intron. The gene product contains the highly conserved alpha crystalline region, spanning amino acid residues 133 to 217 and a Met‐rich region from 94 to 117aa at the N terminus. Predicted amino acid sequence shares 65%, 63%, 59%, 58%, 56%, 55%, 53%, and 22% identities with Petunia hybrida, Nicotiana tabacum, Arabidopsis thaliana, Zea mays, Agrostis stolonifera, Triticum aestivum, Oryza sative, and Nitrosococcus oceani, respectively. Expression profile of the gene was studied from leaf, stem, and root tissues, through reverse transcriptase polymerase chain reaction (RT‐PCR) and quantitative real‐time RT‐PCR analysis. The results indicated that the gene was expressed in all tissues tested in both fully hydrated and dehydrated plants. However, the gene was 100‐fold more abundant in dehydrated leaves, while only two‐fold abundant in stressed root and stem as compared to control tissues.

The cotton (Gossypium arboreum) stress-related gene GHSP26 responds to dehydration. To elucidate its stress tolerant mechanism at the transcriptional level, we isolated and characterized the promoter region (PGHSP26, -2,831 bp) flanking the 5' GHSP26 coding region from the genomic DNA. A series of PGHSP26 deletion derivatives was created for the identification of the upstream region of the gene required for the promoter activity. Each deletion construct was analyzed by agrobacterium mediated transient transformation in tobacco leaves after treatment with abscissic acid (ABA), heavy metals and dehydration. Promoter fragments of 716 bp or longer showed two-fold or greater induction after each treatment. These findings further our understanding of the regulation of GHSP26 expression and provide a new drought-inducible promoter system in transgenic plants.