Fusarium wilt pandemic: current understanding and molecular perspectives.

Plant diseases pose a severe threat to the food security of the global human population. One such disease is Fusarium wilt, which affects many plant species and causes up to 100% yield losses. Fusarium pathogen has high variability in its genetic constitution; therefore, it has evolved into different physiological races to infect different plant species spread across the different geographical regions of the world. The pathogen mainly affects plant roots, leading to colonizing and blocking vascular bundle cells, specifically xylem vessels. This blocking results in chlorosis, vascular discoloration, leaf wilting, shortening of plant, and, in severe cases, premature plant death. Due to the soil-borne nature of the wilt pathogen, neither agronomic nor plant protection measures effectively reduce the incidence of the disease. Therefore, the most cost-effective management strategy for Fusarium wilt is developing varieties resistant to a particular race of the fungus wilt prevalent in a given region. This strategy requires understanding the pathogen, its disease cycle, and epidemiology with climate-changing scenarios. Hence, in the review, we will discuss the pathogenic aspect and genetics of the Fusarium wilt, including molecular interventions for developing climate-smart wilt tolerant/resistant varieties of crops. Overall, this review will add to our knowledge for advancing the breeding of resistance against the wilt pandemic.

Drought stress in maize: stress perception to molecular response and strategies for its improvement.

Given the future demand for food crops, increasing crop productivity in drought-prone rainfed areas has become essential. Drought-tolerant varieties are warranted to solve this problem in major crops, with drought tolerance as a high-priority trait for future research. Maize is one such crop affected by drought stress, which limits production, resulting in substantial economic losses. It became a more serious issue due to global climate change. The most drought sensitive among all stages of maize is the reproductive stages and the most important for overall maize production. The exact molecular basis of reproductive drought sensitivity remains unclear due to genes' complex regulation of drought stress. Understanding the molecular biology and signaling of the unexplored area of reproductive drought tolerance will provide an opportunity to develop climate-smart drought-tolerant next-generation maize cultivars. In recent decades, significant progress has been made in maize to understand the drought tolerance mechanism. However, improving maize drought tolerance through breeding is ineffective due to the complex nature and multigenic control of drought traits. With the help of advanced breeding techniques, molecular genetics, and a precision genome editing approach like CRISPR-Cas, candidate genes for drought-tolerant maize can be identified and targeted. This review summarizes the effects of drought stress on each growth stage of maize, potential genes, and transcription factors that determine drought tolerance. In addition, we discussed drought stress sensing, its molecular mechanisms, different approaches to developing drought-resistant maize varieties, and how molecular breeding and genome editing will help with the current unpredictable climate change.