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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

cause mutations in an abiotic stress-responsive gene named as OST2/AHA1

(Osakabe & Osakabe, 2017). This leads to improved stomatal response in

Arabidopsis thaliana. OsRR22, OsSIT1, and OsNAC041 genes increased

salinity tolerance in Rice (Li et al., 2014; Zhang et al., 2019; Bo et al., 2019).

CRISPR/Cas9 facilitated editing of cold tolerance MYB30 gene and panicle

length OsPIN5b gene and grain size GS3 gene (Zeng et al., 2020), OsCOLD1

(Ma et al., 2015), and TIFY1a, TIFY1b (Huang et al., 2017) genes improved

cold tolerance in Oryza sativa L. Similarly, CRISPR/Cas9 mediated editing

of NPRI (Erpen-Dalla et al., 2019), SINPR1 (knock-out) (Li et al., 2019)

and SIMAPK3 (knock-out) (Wang et al., 2017a) improved tolerance to water

deficiency in tomato plants. CRISPR/Cas9 mediated editing of Heat Shock

Protein 90 (HSP90) increased tolerance to high temperature in Tetraselmis

suecica (Xu et al., 2020). CRISPR/Cas9 based editing of Drb2a and Drb2b

increased salinity and drought tolerance whereas SAPK1 and SAPK2

enhanced salt tolerance in Glycine max L. (Curtin et al., 2018; Lou et al.,

2017). Cpf1 has been used in Arabidopsis thaliana L. and Oryza sativa L.

(Tang et al., 2017, 2018). Other examples of CRISPR/Cas based genome

editing approaches with promise in fighting devastating abiotic plant stress

conditions are summarized in Table 11.1.

11.4.2 POTENTIALITY OF CRISPR/Cas-MEDIATED EFFECTIVE TOOL

IN UNDERSTANDING BIOTIC STRESS RESPONSE

CRISPR/Cas mediated genome editing produced tolerance in plants towards

viruses, bacteria, nematodes, insects, and fungal pathogens. Editing of

recessive eIF4E gene increased resistance to Papaya ring-spot mosaic

virus-W, Zucchini yellow mosaic virus and cucumber vein yellowing

virus in Cucumis sativus L. (Chandrasekaran et al., 2016). CRISPR/Cas9

based targeting of Initiation factors like eIF4E and eIF(iso) 4E eIF4E/

exon involved in infection of Turnip mosaic virus (TuMV) in Arabidopsis

thaliana L., and eIF4G involved in infection of Rice Tungro Disease Resis­

tance developed resistance in these plants (Pyott et al., 2016; Macovei et al.,

2018). CRISPR/Cas9-mediated targeting of Ocimum basilicum candidate

susceptibility gene ObDMR6 which is a homolog of DMR6 generated

transgene-free downy mildew-resistant sweet basil varieties (Hasley et al.,

2021). CRISPR/Cas9 generated transgene-free mutants in sweet basil by

Agrobacterium-mediated transformation (Navet & Tian, 2020). CRISPR/

Cas inactivated endogenous banana streak provirus in banana (Tripathi et al.,