Phytases (myo-inositol hexakisphosphate phosphohydrolases) hydrolyze the phosphate ester bonds of phytate-releasing phosphate and lower myo-inositol phosphates and/or myo-inositol. Phytases, in general, are known to enhance phosphate and mineral uptake in monogastric animals such as poultry, swine, and fish, which cannot metabolize phytate besides reducing environmental pollution significantly. In this study, the molecular, biophysical, and biochemical properties of phytases are reviewed in detail. Alterations in the molecular and catalytic properties of phytases, upon expression in heterologous hosts, are discussed. Diverse applications of phytases as feed additives, as soil amendment, in aquaculture, development of transgenic organisms, and as nutraceuticals in the human diet also are dealt with. Furthermore, phytases are envisaged to serve as potential enzymes that can produce versatile lower myo-inositol phosphates of pharmaceutical importance. Development of phytases with improved attributes is an important area being explored through genetic and protein engineering approaches, as no known phytase can fulfill all the properties of an ideal feed additive.

SummaryAgrobacterium-mediated genetic transformation has been optimized in indica rice susceptible to sap-sucking insects, viz., brown planthopper (BPH) and green leafhopper (GLH). Snowdrop lectin gene ( gna) from Galanthus nivalis, driven by phloem-specific rice-sucrose-synthase promoter, along with herbicide resistance gene (bar) driven by CaMV 35S promoter, was employed for genetic transformation. Embryogenic calli -after cocultivation with Agrobacterium strain LBA4404 harbouring Ti plasmid pSB111-bar-gnawere selected on the medium containing phosphinothricin. PCR and Southern blot analyses confirmed the stable integration of both the genes into genomes of transgenic (T 0 ) rice plants. Northern and Western blot analyses revealed the expression of gna in the transgenic plants. In the T 1 and T 2 generations, the gna and bar transgenes showed co-segregation at a ratio of 3 : 1. Plant progenies expressing gna, in T 1 and T 2 , exhibited substantial resistance against BPH and GLH pests. This is the first report dealing with transgenic indica rice exhibiting high resistance to both insects.

SummaryA hybrid-proline-rich protein encoding gene (CcHyPRP) has been isolated and characterized, for the first time, from the subtracted cDNA library of pigeonpea (Cajanus cajan L.) plants subjected to drought stress. Functionality of CcHyPRP has been validated for abiotic stress tolerance using the heterologous yeast and Arabidopsis sys- CcHyPRP-transgenics driven by stress-inducible rd29A exhibited similar stress-tolerance as that of CaMV35S-lines without any negative effects on plant morphology, implying that stress-inducible promoters are preferable for production of stress tolerant transgenics. The overall results amply demonstrate the profound effect of CcHyPRP in bestowing multiple abiotic stress tolerance at cellular and whole plant levels. Accordingly, the multipotent CcHyPRP seems promising as a prime candidate gene to fortify crop plants with abiotic stress tolerance.

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Transgenic rice plants, expressing snowdrop lectin [Galanthus nivalis agglutinin (GNA)], obtained by Agrobacterium-mediated genetic transformation, were evaluated for resistance against the insect, the whitebacked planthopper (WBPH). The transgene gna was driven by the phloem-specific, rice-sucrose synthase promoter RSs1, and the bar was driven by the CaMV 35S promoter. In our previous study, the transgenic status of these lines was confirmed by Southern, Northern and Western blot analyses. Both the transgenes, gna and bar, were stably inherited and co-segregated into progenies in T1 to T5 generations. Insect bioassays on transgenic plants revealed the potent entomotoxic effects of GNA on the WBPH. Also, significant decreases were observed in the survival, development and fecundity of the insects fed on transgenic plants. Furthermore, intact GNA was detected in the total proteins of WBPHs fed on these plants. Western blot analysis revealed stable and consistent expression of GNA throughout the growth and development of transgenic plants. Transgenic lines expressing GNA exhibited high-level resistance against the WBPH. As reported earlier, these transgenics also showed substantial resistance against the brown planthopper and green leafhopper.