Softening is a developmentally programmed ripening process, associated with biochemical changes in cell wall fractions involving hydrolytic processes resulting in breakdown of cell-wall polymers such as cellulose, hemicelluloses and pectin etc. Various hydrolytic reactions are brought about by polygalacturonase, pectin methyl esterase, pectate lyase, rhamnogalacturonase, cellulase and β-galactosidase etc. Besides these enzymes, expansin protein also plays an important role in softening. Textural changes during ripening help in determining the shelf life of a fruit. An understanding of these changes would help in formulating procedures for controlling fruit softening vis-à-vis enhancing shelf life of fruits. In the present review an attempt has been made to coalesce recent findings on biochemistry of fruit softening.

Wheat is one of the main sources of calories and protein of the world's population and therefore the pathogens that cause rust diseases of the crop are a real threat to food security. Besides the continuous evolution of rust pathogens which repeatedly results in overcoming the resistance of commercial varieties throughout the world, plant breeders are also now challenged by the impacts of global climatic changes. Agricultural practices will need to keep pace with the intensification of sustainable food production in order to face the challenge of feeding a world population estimated to reach about nine billion by 2050. Contemporary wheat breeding has increasingly focused on the future, culminating in the emergence of a global partnership for breeding new wheat varieties with resistance to rust pathogens. Plant breeding now employs a wide range of both long-established and frontier technologies aimed at achieving the United Nations Millennium Development Goals of ending hunger and extreme poverty (MDG1), while concurrently promoting environmental sustainability (MDG7) through global partnerships for development (MDG8).

The effects of ethylene on plants have been recognized since the Nineteenth Century and it is widely known as the phytohormone responsible for fruit ripening and for its involvement in a number of plant growth and development processes. Elucidating the mechanisms involved in the ripening of climacteric fruit and the role that ethylene plays in this process have been central to fruit production and the improvement of fruit quality. The biochemistry, genetics and physiology of ripening has been extensively studied in economically important fruit crops and a considerable amount of information is available which ranges from the ethylene biosynthesis pathway to the mechanisms of perception, signaling and control of gene expression. However, there is still much to be discovered about these processes and the objective of this review is to present a brief historic account of how ethylene became the focus of fruit ripening research as well as the development and the state-of-art of these studies at both biochemical and genetic levels.

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Ethylene-induced ripening in tomato (Lycopersicon esculentum) resulted in the accumulation of a transcript designated LeEF-Ts(mt) that encodes a protein with significant homology to bacterial Ts translational elongation factor (EF-Ts). Transient expression in tobacco and sunflower protoplasts of full-length and truncated LeEF-Ts(mt)-GFP fusion constructs and confocal microscopy observations clearly demonstrated the targeting of LeEF-Ts(mt) to mitochondria and not to chloroplasts and the requirement for a signal peptide for the proper sorting of the protein. Escherichia coli recombinant LeEF-Ts(mt) co-eluted from Ni-NTA resins with a protein corresponding to the molecular weight of the elongation factor EF-Tu of E. coli, indicating an interaction with bacterial EF-Tu. Increasing the GDP concentration in the extraction buffer reduced the amount of EF-Tu in the purified LeEF-Ts(mt) fraction. The purified LeEF-Ts(mt) stimulated the poly(U)-directed polymerization of phenylalanine 10-fold in the presence of EF-Tu. Furthermore, LeEF-Ts(mt) was capable of catalysing the nucleotide exchange reaction with E. coli EF-Tu. Altogether, these data demonstrate that LeEF-Ts(mt) encodes a functional mitochondrial EF-Ts. LeEF-Ts(mt) represents the first mitochondrial elongation factor to be isolated and functionally characterized in higher plants.