Genetic engineering strategies for biotic and abiotic stress tolerance and quality enhancement in horticultural crops: a comprehensive review

Abstract

Genetic engineering technique offers myriads of applications in improvement of horticultural crops for biotic and abiotic stress tolerance, and produce quality enhancement. During last two decades, a large number of transgenic horticultural crops has been developed and more are underway. A number of genes including natural and synthetic Cry genes, protease inhibitors, trypsin inhibitors and cystatin genes have been used to incorporate insect and nematode resistance. For providing protection against fungal and bacterial diseases, various genes like chitinase, glucanase, osmotin, defensin and pathogenesis-related genes are being transferred to many horticultural crops world over. RNAi technique has been found quite successful in inducing virus resistance in horticultural crops in addition to coat protein genes. Abiotic stresses such as drought, heat and salinity adversely affect production and productivity of horticultural crops and a number of genes encoding for biosynthesis of stress protecting compounds including mannitol, glycine betaine and heat shock proteins have been employed for abiotic stress tolerance besides various transcription factors like DREB1, MAPK, WRKY, etc. Antisense gene and RNAi technologies have revolutionized the pace of improvement of horticultural crops, particularly ornamentals for color modification, increasing shelf-life and reducing post-harvest losses. Precise genome editing tools, particularly CRISPR/Cas9, have been efficiently applied in tomato, petunia, citrus, grape, potato and apple for gene mutation, repression, activation and epigenome editing. This review provides comprehensive overview to draw the attention of researchers for better understanding of genetic engineering advancements in imparting biotic and abiotic stress tolerance as well as on improving various traits related to quality, texture, plant architecture modification, increasing shelf-life, etc. in different horticultural crops.

Targeting Glycinebetaine for Abiotic Stress Tolerance in Crop Plants: Physiological Mechanism, Molecular Interaction and Signaling

“…Sushu-2 increased GB production within the chloroplast [192]. This resulted in improved tolerance to salinity and oxidative stress in the transgenic sweet potato plants due to better photosynthetic efficiency, membrane integrity, and ROS scavenging compared to the stressed plants [193].…”

Salinity and crop yield

“…Such attempts across the scale levels are rare, and even impossible to apply at the field level in Europe if genetically modified crops are involved. It is surprising that, in spite of the complexity of salt tolerance, there are commonly claims in the literature that the transfer of a single or a few genes can increase the tolerance of plants to saline conditions (for review see: Parmar et al 2017). In a review of the former decade, examples of genetically improved crops were evaluated with information available for only 19 reports including quantitative estimates of plant growth.…”

Molecular mechanisms underlying stress response and adaptation

“…Responses include changes in gene expression, as well as morphological and physiological changes . A wide variety of adaptations have evolved, as they impact the survival and distribution of species . For example, in response to diverse genotoxic stresses, such as ionizing and ultraviolet (UV) radiation, oxidative stress, and chemotherapeutic agents, the genotoxic stress response system is activated to repair DNA damage; in the case of irreparable damage, apoptosis is induced in favor of organismal survival .…”

“…[4][5][6] A wide variety of adaptations have evolved, as they impact the survival and distribution of species. 7,8 For example, in response to diverse genotoxic stresses, such as ionizing and ultraviolet (UV) radiation, oxidative stress, and chemotherapeutic agents, the genotoxic stress response system is activated to repair DNA damage; in the case of irreparable damage, apoptosis is induced in favor of organismal survival. [9][10][11] Dysregulation of the genotoxic stress response system has been implicated in the development of human cancer, and stress-induced responses have been utilized for the development of new anti-cancer therapies.…”