Paecilomyces variotii extracts promote growth and alleviate nutrient deficiency symptoms in apple

It is essential to find environment-friendly agrochemicals to cope with the problems of nutrient imbalance, fruit quality decline, and physiological disorders during apple fruit production, which is beneficial for improving the quality and yield of apple. A natural extract from Paecilomyces variotii (ZNC), an endophytic fungus, has been used widely to enhance crop performance. However, an understanding of the mechanism underlying ZNC-triggered growth and alleviation of nutrient deficiency-associated symptoms in apples remains elusive. Here, the photosynthesis, leaf growth, and fruit quality were enhanced by adding ZNC. In addition, ZNC relieved nutrient deficiency-related symptoms promoted the differentiation of root morphology and vitality, and reduced the accumulation of osmoprotectants and reactive oxygen species, thereby promoting growth under normal and nutrient-deficient conditions. Finally, genome-wide RNA sequencing reveals the ZNC-regulated mechanisms involved in hormone and metal ion pathways. Our study reveals the role of ZNC in promoting growth and improving the quality of apple, providing a new direction for reducing the use of chemical fertilizers and pesticides.