CRISPR/Cas9-mediated homology donor repair base editing system to confer herbicide resistance in maize (Zea mays L.).

Weed infestation is a significant concern to crop yield loss, globally. The potent broad-spectrum glyphosate (N-phosphomethyl-glycine) has a widely utilized herbicide, acting on the shikimic acid pathway within chloroplast by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). This crucial enzyme plays a vital role in aromatic amino acid synthesis. Repurposing of CRISPR/Cas9-mediated gene-editing was the inflection point for generating novel crop germplasm with diverse genetic variations in essential agronomic traits, achieved through the introduction of nucleotide substitutions at target sites within the native genes, and subsequent induction of indels through error-prone non-homologous end-joining DNA repair mechanisms. Here, we describe the development of efficient herbicide-resistant maize lines by using CRISPR/Cas9 mediated site-specific native ZmEPSPS gene fragment replacement via knock-out of conserved region followed by knock-in of desired homologous donor repair (HDR-GATIPS-mZmEPSPS) with triple amino acid substitution. The novel triple substitution conferred high herbicide tolerance in edited maize plants. Transgene-free progeny harbouring the triple amino acid substitutions revealed agronomic performances similar to that of wild-type plants, suggesting that the GATIPS-mZmEPSPS allele substitutions are crucial for developing elite maize varieties with significantly enhanced glyphosate resistance. Furthermore, the aromatic amino acid contents in edited maize lines were significantly higher than in wild-type plants. The present study describing the introduction of site-specific CRISPR/Cas9- GATIPS mutations in the ZmEPSPS gene via genome editing has immense potential for higher tolerance to glyphosate with no yield penalty in maize.

Osteoporosis in Asthma and COPD.

Asthma and Chronic Obstructive Pulmonary Disease (COPD) are principally lifestyle related chronic inflammatory airway disease. They are globally associated with various systemic comorbidities and mortality. Osteoporosis is the common associated metabolic bone disease with respiratory disturbances, which affect the prognosis and increase mortality and morbidity in the patients. Apart from OSTEOPOROSIS, exhaustive attention has been paid towards other associated systemic comorbidities like cardiovascular diseases, cerebrovascular diseases, metabolic syndrome, malnutrition, skeletal muscle dysfunction (sarcopenia), anxiety, depression and so on (Iheanacho et al. in Int J Chronic Obstr Pulm Dis 15:439-460, 2020; Singh et al. in Eur Respir J 53:1900164, 2019). Osteoporosis is a significant extrapulmonary manifestation in asthma and COPD, which are grossly neglected and inadequately treated. The comorbidities have significant impact in terms of morbidity, mortality and economic burden in asthma and COPD patients, hence management of asthma and COPD should comprise thorough management, as this will also have an impact on the outcome of these patients. Various risk factors such as smoking, systemic inflammation, vitamin deficiency, and the use of oral or inhaled corticosteroid are responsible for osteoporosis in patients with asthma and COPD. The presence of osteoporosis in patients with asthma and COPD is invariably asymptomatic unless complicated by fragility fractures, therefore, it is necessary to explore the pathogenesis of osteoporosis in asthma and COPD and special attention is to be paid for early recognition of patients at high risk for osteoporosis in these patients. This chapter is focussed on osteoporosis as an extrapulmonary manifestation of asthma and COPD with an emphasis on the pathogenesis, risk factor, potential mechanism of osteoporosis, diagnosis, and prevention with passing reference to treatment as well in asthma and COPD patients.