Citrus plants, traditionally cultivated in tropical and subtropical climates, are highly vulnerable to cold stress, which can drastically affect both yield and fruit quality.
With climate change triggering more frequent and intense cold spells, the demand for citrus varieties that can withstand these conditions has never been greater. Although previous studies have pointed to the protective role of glycine betaine (GB) in plants under cold stress, the molecular pathways governing GB accumulation have remained unclear—until now. New research offers new genetic insights to enhance citrus cold tolerance.
In a recent study in Horticulture Research, an international team of scientists from Guangxi University of Chinese Medicine and Huazhong Agricultural University identified the PtrPAT1 gene in Poncirus trifoliata, a hardy citrus relative known for its cold resistance. Their findings reveal that PtrPAT1 plays a crucial role in cold tolerance by stimulating the biosynthesis of GB, providing a potential genetic tool to improve cold resistance in commercial citrus crops.
The research focused on the PtrPAT1 gene, which belongs to the GRAS transcription factor family and is highly responsive to cold stress. The team discovered that PtrPAT1 is localized in both the nucleus and plasma membrane, where it activates the PtrBADH-1 gene, a key player in GB production. Through genetic modification, researchers showed that overexpressing PtrPAT1 in transgenic tobacco plants increased GB accumulation, boosted antioxidant enzyme activity, and enhanced cold tolerance. In contrast, silencing PtrPAT1 resulted in lower GB levels and a marked increase in cold sensitivity. Notably, the team pinpointed a specific DNA motif, TTTCATGT, in the PtrBADH-1 promoter, which binds with PtrPAT1 to activate gene expression, confirming its role as a transcriptional activator. These findings position PtrPAT1 as a critical regulator of cold stress, paving the way for potential genetic engineering in citrus crops.
Ji-Hong Liu, co-corresponding author of the study, said: “This research marks a major breakthrough in understanding how citrus plants manage cold stress. Identifying PtrPAT1 and its role in regulating GB biosynthesis opens new avenues for developing cold-resistant citrus varieties, which are vital as climate change continues to impact agricultural productivity.”
The implications of this discovery extend beyond citrus cultivation. The ability to harness PtrPAT1 could lead to the creation of genetically modified citrus varieties with enhanced resilience to cold stress, reducing crop losses and stabilizing yields in vulnerable regions. The research could also inspire similar genetic strategies in other crops, providing a roadmap for improving stress resistance across agriculture.
As climate change continues to challenge global food security, innovations like these will be crucial in ensuring the sustainability and resilience of crop production.
