Novel function of a putative TaCOBL ortholog associated with cold response

Area of Science:

• Plant molecular biology
• Agricultural science
• Genetics

Background:

• The COBRA protein family is crucial for plant cell wall biosynthesis and expansion.
• While studied in other species, COBRA genes (COBLs) in wheat (Triticum aestivum) lack systematic investigation.
• Understanding TaCOBLs can reveal insights into wheat stress tolerance.

Purpose of the Study:

• To identify and characterize COBRA-like genes (TaCOBLs) in wheat.
• To investigate the role of TaCOBLs in response to abiotic stresses.
• To explore the association between TaCOBL-5B haplotypes and cold resistance.

Main Methods:

• Homology cloning to obtain full-length TaCOBL sequences.
• Conserved motif analysis to confirm protein family membership.
• Quantitative reverse transcription PCR (qRT-PCR) to analyze transcript induction under stress.
• Development of a co-dominant marker (Ta5BF/Ta5BR) for TaCOBL-5B haplotypes.
• Promoter activity assays under low temperature.

Main Results:

• Full-length TaCOBL sequences were successfully cloned from wheat.
• TaCOBL transcripts showed induction by cold, drought, salinity, and abscisic acid (ABA).
• Two haplotypes (Hap5B-a and Hap5B-b) of TaCOBL-5B were identified, differing by an indel in the 5' flanking region.
• Hap5B-a was significantly correlated with enhanced cold resistance.
• The Hap5B-a promoter, containing a TATA-box, exhibited higher activity than Hap5B-b under low temperatures.

Conclusions:

• TaCOBL genes are involved in wheat's response to abiotic stresses, particularly cold.
• The TaCOBL-5B haplotype Hap5B-a, likely acquired during polyploidization, contributes positively to cold resistance.
• Promoter variations, such as the TATA-box, influence TaCOBL gene expression and cold tolerance in wheat.