Heat stress tolerance in wheat seedling: Clustering genotypes and identifying key traits using multivariate analysis

Area of Science:

• Plant Breeding and Genetics
• Agronomy and Crop Science
• Stress Physiology

Background:

• Global wheat production faces significant challenges due to rising atmospheric temperatures.
• Identifying wheat genotypes with enhanced thermotolerance is critical for food security.
• Developing reliable indicators for heat stress tolerance is essential for efficient breeding programs.

Purpose of the Study:

• To screen bread wheat genotypes for heat stress tolerance under controlled conditions.
• To identify morpho-physiological traits that discriminate heat-tolerant wheat varieties.
• To select superior heat-tolerant wheat genotypes for future breeding efforts.

Main Methods:

• Evaluation of 80 bread wheat genotypes under controlled heat stress (35/25°C D/N) at the seedling stage.
• Application of multivariate statistical techniques, including Principal Component Analysis (PCA), Hierarchical Cluster Analysis, and Linear Discriminant Analysis (LDA).
• Utilizing the Multi-trait Genotype-Ideotype Distance Index (MGIDI) for genotype selection and identification of key discriminating traits.

Main Results:

• Significant variations in morpho-physiological traits were observed under heat stress.
• PCA identified 11 seedling traits contributing to genotypic variability, with substantial correlations among them.
• Cluster analysis grouped genotypes into tolerant (Cluster 1), moderately tolerant (Cluster 2), and susceptible (Cluster 3) categories, with LDA confirming high classification accuracy (93%).
• Twelve superior heat-tolerant genotypes were identified from Cluster 1 using MGIDI.
• Shoot and root dry/fresh weights, chlorophyll content, shoot tissue water content, root-shoot dry weight ratio, and photosystem II efficiency were identified as crucial discriminatory factors for heat stress tolerance.

Conclusions:

• The study successfully identified wheat genotypes with superior thermotolerance, providing valuable genetic resources for breeders.
• Key morpho-physiological traits were validated as reliable indicators for assessing heat stress tolerance in wheat seedlings.
• These findings will guide future research and breeding strategies aimed at improving wheat cultivation in heat-prone regions.