Three studies backed by the Chinese Academy of Sciences and recently published in Horticultural Research have shed light on the physiology and chemistry behind key characteristics of apples, including colour and sweetness and an improved understanding of calcium availability in apple trees. With China being the largest producer of apples in terms of volume, it is not surprising that many of the country’s plant scientists are studying the crop.
Many apple trees suffer from calcium deficiency, which is exacerbated by excessive nitrogen use. When nitrogen levels rise, calcium becomes increasingly locked in forms that trees cannot use, leading to physiological disorders such as bitter pit and cork spot. Now researchers from Shandong Agricultural University have unveiled the intricate relationship between nitrogen and calcium in apple leaves using advanced techniques such as electron probe micro-analysis and transcriptome sequencing to explore how nitrogen-driven oxalate synthesis influences calcium dynamics.
Dr. Shun-Feng Ge, one of the study’s lead authors, emphasised the significance of these findings. “Unravelling the nitrogen-calcium interaction is essential for enhancing apple quality. Our research provides a blueprint for developing smarter fertilisation strategies that can mitigate calcium deficiency and improve fruit quality,” he said. He added that the implications of this study extend beyond basic plant biology. By fine-tuning nitrogen and calcium application, growers can prevent calcium deficiency disorders, while the research also opens new doors for breeding apple rootstocks with enhanced calcium efficiency.
Meanwhile, his colleagues at Shandong Agricultural University and Shandong Academy Agricultural Sciences investigated the role that fruit aroma plays in influencing consumer preference. Additionally, while the mechanisms behind aroma compound synthesis are well known, much less is understood about how stress conditions, such as salinity, might be managed to boost these essential compounds. This knowledge gap has spurred research aimed at uncovering the genetic factors that govern fruit aroma, particularly in challenging environmental conditions.
Through a series of detailed experiments, the researchers identified the genes that play key roles in the aroma production process, and how levels of aroma production are influenced by saline stress. Dr. Xuesen Chen, the lead researcher behind the study, commented, “Our research provides a novel perspective on how abiotic stress can be harnessed to enhance fruit aroma. Not only does it deepen our understanding of the genetic regulation of aroma biosynthesis, but it also offers actionable strategies for improving fruit quality in saline environments”.
Finally, researchers from Qingdao Agricultural University looked at the role of DNA methylation in the fading of apple skin colour. The team focused on the Daihong apple variety, which shows substantial colour loss during fruit development. By examining methylation patterns and gene expression profiles, they identified critical epigenetic factors involved in the process, providing greater understanding for breeders of new varieties.
