The low nutritive value of maize endosperm protein is genetically corrected in quality protein maize (QPM), which contains the opaque 2 gene along with numerous modifiers for kernel hardness. We report here a two generation marker-based backcross breeding program for incorporation of the opaque 2 gene along with phenotypic selection for kernel modification in the background of an early maturing normal maize inbred line, V25. Using the flanking marker distances from opaque 2 gene in the cross V 25 xCML 176, optimum population size for the BC(2) generation was computed in such a way that at least one double recombinant could be obtained. Whole genome background selection in the BC(2) generation identified three plants with 93 to 96% recurrent parent genome content. The three BC(2)F(2) families derived from marker identified BC(2) individuals were subjected to foreground selection and phenotypic selection for kernel modification. The tryptophan concentration in endosperm protein was significantly enhanced in all the three classes of kernel modification viz., less than 25%, 25--50% and more than 50% opaqueness. BC(2)F(3) lines developed from the hard endosperm kernels were evaluated for desirable agronomic and biochemical traits in replicated trials and the best line was chosen to represent the QPM version of V25, with tryptophan concentration of 0.85% in protein. The integrated breeding strategy reported here can be applied to reduce genetic drag as well as the time involved in a conventional line conversion program, and would prove valuable in rapid development of specialty corn germ plasm.

Proteins are essential components of the human diet. Dietary proteins could be derived from animals and plants. Animal protein, although higher in demand, is generally considered less environmentally sustainable. Therefore, a gradual transition from animal- to plant-based protein food may be desirable to maintain environmental stability, ethical reasons, food affordability, greater food safety, fulfilling higher consumer demand, and combating of protein-energy malnutrition. Due to these reasons, plant-based proteins are steadily gaining popularity, and this upward trend is expected to continue for the next few decades. Plant proteins are a good source of many essential amino acids, vital macronutrients, and are sufficient to achieve complete protein nutrition. The main goal of this review is to provide an overview of plant-based protein that helps sustain a better life for humans and the nutritional quality of plant proteins. Therefore, the present review comprehensively explores the nutritional quality of the plant proteins, their cost-effective extraction and processing technologies, impacts on nutrition, different food wastes as an alternative source of plant protein, and their environmental impact. Furthermore, it focuses on the emerging technologies for improving plant proteins' bioavailability, digestibility, and organoleptic properties, and highlights the aforementioned technological challenges for future research work.

Suppression of nonsense codons in Schizosaccharomyces pombe by sup3-e tRNAUGA or sup3-i tRNAUAA is reduced or abolished by mutations within the suppressor locus. Twenty-five suppressor-inactive sup3-e genes and thirteen mutant sup3-i genes were isolated from S. pombe genomic clone banks by colony hybridization. Sequence analysis of these revertant alleles corroborates genetic evidence for mutational hotspots within the sup3 tRNA gene. Fifteen types of point mutations or insertions were found. Many of these replace bases which are highly or completely conserved in eucaryotic tRNA genes. Transcription of the altered sup3 genes in a Saccharomyces cerevisiae extract enabled the identification of mutations which affect the rate of 5'-end maturation or splicing of the tRNA precursors or both. A total of seven mutations were found which alter transcriptional efficiencies. Of these, five are located outside the internal transcription control regions.The genetic analysis of tRNA-mediated nonsense suppression is well advanced in procaryotes and in the lower eucaryotes Saccharomyces cerevisiae and Schizosaccharomyces pombe (11,44,45). Fine-structure maps have been constructed for a number of suppressor loci in these organisms by examining the recombination frequencies between mutations within a given tRNA gene (14,20,27,37). We are pursuing the biochemical characterization of defined mutations at the sup3-e and sup9-e loci of S. pombe (20).These loci encode tRNAUGA genes, both of which have recently been cloned and sequenced (21, 49). Although located on different chromosomes, these genes share an almost identical dimeric tRNA gene arrangement; the serine tRNA gene is separated by seven base pairs from an initiator tRNAMet gene. These dimeric genes are transcribed into approximately 190-nucleotide-long precursors that differ by only a single base at the tip of the extra arm of the serine tRNA and several bases outside the tRNA coding regions. Mature tRNAs are produced via a complex processing pathway which includes the excision of an intervening sequence from the serine tRNA half of the precursor.In this paper, we report the characterization of 38 in vivo-derived sup3 revertant alleles by cloning and sequence analysis. They contain 15 types of point mutations or singlebase insertions within the sup3 tRNAser gene. Cloned alleles were transcribed in an Saccharomyces cerevisiae extract, allowing the identification of mutations affecting tRNA gene transcription and 5'-end maturation and splicing of the resulting transcripts. MATERIALS AND METHODSIsolation and sequence analysis of sup3 alleles. The Schizosaccharomyces pombe strains used in this work have been described by Hofer et al. (20) Gergen et al. (17). The hybridization probe consisted of the 1.0-kilobase HindIII-BamHI fragment containing the sup3-e gene (21) and was labeled to a specific activity of 106 to 108 cpm/,ug with T4 DNA polymerase and [a-32P]dATP (3,000 Ci/mmol). Plasmid DNA was prepared from strongly hybridizing colonies and digested with HindIII and EcoRI. ...

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