cDNA structure and expression patterns of a low-temperature-specific wheat gene tacr7

Area of Science:

• Plant Molecular Biology
• Wheat Genetics
• Stress Physiology

Background:

• The gene tacr7, encoding a unique hydrophobic protein with a transmembrane domain, was identified in hard red winter wheat (HRWW).
• The tacr7 gene is specifically induced by low temperatures (2°C) and not by abscisic acid (ABA) or other stresses like salt, dehydration, or heat.

Purpose of the Study:

• To characterize the low-temperature-specific wheat gene tacr7 and its transcript accumulation patterns.
• To investigate the differential expression of tacr7 in freeze-resistant versus freeze-susceptible HRWW genotypes under cold stress.

Main Methods:

• Isolation of the wheat cDNA pTACR7 using RT-PCR with mRNA from wheat crown tissue and primers from barley cognate pHVCR8.
• Northern blot hybridization to analyze steady-state levels of tacr7 transcripts under various conditions (low temperature, ABA, salt, dehydration, heat).
• Quantitative analysis of tacr7 transcript accumulation in freeze-resistant and freeze-susceptible HRWW genotypes exposed to low temperature.

Main Results:

• tacr7 transcripts accumulated in wheat seedlings, crown tissue, and callus cultures upon transfer to 2°C.
• No tacr7 transcripts were detected under ABA, salt, dehydration, or heat stress.
• tacr7 transcripts accumulated to a greater extent in freeze-resistant HRWW than in freeze-susceptible HRWW crown tissue at 2°C, with a 30% difference at 3 weeks.

Conclusions:

• The tacr7 gene represents a novel low-temperature-specific gene in wheat, distinct from ABA- and stress-inducible genes.
• Differential accumulation of tacr7 transcripts in contrasting HRWW genotypes suggests its potential role in freeze tolerance mechanisms.