The HpGIF1-HpABC44 module facilitates heavy metal detoxification via improved ABA sensitivity and ROS scavenging.

Area of Science:

• Plant molecular biology
• Biochemistry
• Genomics

Background:

• ATP-binding cassette (ABC) transporters are crucial for detoxification in plants.
• While studied in model plants, their roles in commercial crops like pitaya are less understood.
• Understanding pitaya ABC transporters can reveal insights into heavy metal tolerance mechanisms.

Purpose of the Study:

• To identify and characterize ATP-binding cassette (ABC) transporters in the pitaya genome.
• To investigate the role of specific pitaya ABC transporters, particularly HpABC44, in response to heavy metal stress.
• To elucidate the regulatory mechanism of HpABC44 activation by heavy metals.

Main Methods:

• Genome-wide identification and subfamily classification of pitaya ABC transporters (HpABCs).
• Bioinformatic analyses including gene structure, motif analysis, and promoter element identification.
• Gene Ontology analysis for subcellular localization and function prediction.
• RT-qPCR to assess HpABC expression under heavy metal stress.
• Functional analysis of HpABC44 using transgenic Arabidopsis (HpABC44-OE) under heavy metal treatment.
• Yeast one-hybrid and luciferase reporter assays to determine transcription factor interactions.

Main Results:

• 116 pitaya ABC transporters (HpABCs) were identified and classified into eight subfamilies.
• HpABCs exhibit conserved features within subfamilies and have undergone purifying selection.
• HpABC44 expression was significantly upregulated by heavy metals, suggesting a detoxification role.
• Overexpression of HpABC44 in Arabidopsis reduced reactive oxygen species accumulation under heavy metal stress.
• HpABC44 activation by heavy metals is mediated by the heavy metal-induced transcription factor HpGIF1.

Conclusions:

• This study provides a comprehensive analysis of pitaya ABC transporters and their potential roles in detoxification.
• HpABC44 is a key player in pitaya's response to heavy metal stress, contributing to detoxification and oxidative stress management.
• The findings reveal a novel regulatory pathway involving HpGIF1 in the heavy metal-induced activation of HpABC44, offering insights into plant heavy metal tolerance.