Abiotic stresses with a dehydration component (drought, salt, and freezing) involve, as a common feature, increased numbers of inactive proteins – denatured, aggregated or oxidatively damaged. Maintaining proteins in their functional conformation, preventing aggregation of non-native proteins, refolding of denatured proteins to their native conformation and removal of non-functional and potentially harmful polypeptides are all vital for cell survival under dehydration stress. To achieve this, plants respond to drought by synthesis of protective proteins such as dehydrins and chaperones and by degradation of irreversibly damaged proteins by proteases. Here we review the important cellular functions of dehydrins, chaperones, proteases and protease inhibitors, together with their role in the response to drought, that make them potential biochemical markers for assessing drought tolerance.
COBISS.SI-ID: 3815784
Protein breakdown by proteases is basic to the plant response to abiotic stresses such as drought. A large number of genes encoding proteases or putative proteases exist in plants. Only a few of those involved in the response to drought have been characterized, and their regulation is poorly understood. We have identified two new subtilases from leaves of Phaseolus vulgaris L. cultivar Zorin, PvSLP1 and PvSLP2. PvSLP1 was identified at the gene level, using primers based on the gene sequence of the putative drought induced serine protease from Arachis hypogaea L. In P. vulgaris, expression of the PvSLP1 transcript did not change on water withdrawal. PvSLP2 was isolated and characterized at the protein level, together with complete gene and cDNA sequences. The deduced amino acid sequences of both PvSLP1 and PvSLP2 are characteristic of plant subtilases of the S8 family of clan SB. PvSLP2 shows 33% sequence identity to PvSLP1. Expression of the PvSLP2 transcript did not change on withdrawal of water, but its proteolytic activity in leaves increased, depending on the age and position of the leaf. In addition, the level of activity in senescent leaves of well watered plants was higher than in mature or young leaves. These results, together with the fact that PvSLP2 cleaves peptide bonds following an Arg residue, point to regulation of PvSLP2 subtilase activity at translational and/or post-translational levels and suggest a specific role in the response to drought and senescence.
COBISS.SI-ID: 26305831
Mutation breeding is important to enhance disease and pest resistance in order to cope with challenging environment, raised demand for food, and feed due to the increase in human population. With the development of genetic engineering and biotechnology, new possibilities for plant breeding arise for improving cultivars with desired characteristics that derive either by classical breeding, genetic modification by transformation, forward and reverse genetic techniques. Mutagenesis is particularly suitable for altering qualitative traits under the control of major genes, such as disease resistance. It creates novel traits, while classical breeding just recombines already existed traits. Most of the commercial mutants are produced by chemical or irradiation mutagenesis and transformations, while reverse genetics is used in basic research.
COBISS.SI-ID: 3896680