Ijaz Aqsa, Khan Muhammad Kashif Riaz, Haidar Sajjad
Nuclear Institute for Agriculture and Biology College (NIAB-C), Faisalabad, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, 45650, Pakistan.
Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, 38000, Pakistan.
BMC Plant Biol. 2025 Sep 2;25(1):1194. doi: 10.1186/s12870-025-06939-3.
Escalating global temperatures pose an ongoing threat to cotton production by disrupting essential morphological, physiological, and metabolic processes during early plant development. These early stages are critical for crop establishment, yet the genetic basis of heat tolerance at this phase remains insufficiently characterized. Therefore, advancing our understanding of early-stage responses is essential for the development of heat-tolerant genotypes.
A total of 79 cotton genotypes were assessed under controlled conditions and two elevated temperature treatments, HST-1 (45 °C) and HST-2 (48 °C), with emphasis on their morphological and physiological responses to heat stress under glasshouse conditions. Box plot was used to visualise trait distributions. Correlation analysis elucidated interrelationships among various traits. Principal component analysis (PCA) was conducted to reduce dimensionality and identify major axes of variation. The multi-trait genotype-ideotype distance index (MGIDI) was employed to rank genotypes based on overall performance.
Heat stress significantly reduced shoot and root elongation, biomass accumulation, and relative water content, while increasing excised leaf water loss. Photosynthetic rate, stomatal conductance, and instantaneous water use efficiency declined markedly, although transpiration rate remained relatively stable. PCA effectively distinguished tolerant from susceptible genotypes and revealed key traits associated with tolerance, while MGIDI identified eight top performing lines: G1 (NIAB-377), G4 (NIAB-868), G8 (NIBGE-IR-15), G9 (NIAB-512 33/4), G39 (NIA-Noori), G67 (Cyto-535), G69 (NIAB-512), and G78 (SLH-01).
Our results show substantial genotypic variability in early-stage heat stress responses in cotton and establish a rigorous multivariate framework for trait-based selection. This integrative multivariate approach facilitates the targeted selection of thermo-tolerant genotypes with enhanced morphological and physiological traits, advancing the breeding of climate-resilient cotton.
全球气温不断上升，通过扰乱棉花早期发育过程中的基本形态、生理和代谢过程，对棉花生产构成持续威胁。这些早期阶段对作物的生长至关重要，但该阶段耐热性的遗传基础仍未得到充分表征。因此，深入了解早期反应对于培育耐热基因型至关重要。
在可控条件下，对79个棉花基因型进行了评估，并设置了两种高温处理，即HST-1（45°C）和HST-2（48°C），重点研究了它们在温室条件下对热胁迫的形态和生理反应。使用箱线图来直观呈现性状分布。相关性分析阐明了各种性状之间的相互关系。进行主成分分析（PCA）以降低维度并确定主要变异轴。采用多性状基因型-理想型距离指数（MGIDI）根据总体表现对基因型进行排名。
热胁迫显著降低了地上部和根部的伸长、生物量积累以及相对含水量，同时增加了离体叶片的水分损失。光合速率、气孔导度和瞬时水分利用效率显著下降，尽管蒸腾速率保持相对稳定。主成分分析有效地将耐热基因型与敏感基因型区分开来，并揭示了与耐热性相关的关键性状，而MGIDI确定了八个表现最佳的品系：G1（NIAB-377）、G4（NIAB-868）、G8（NIBGE-IR-15）、G9（NIAB-512 33/4）、G39（NIA-Noori）、G67（Cyto-535）、G69（NIAB-512）和G78（SLH-01）。
我们的结果表明，棉花在早期热胁迫反应中存在显著的基因型变异，并建立了一个基于性状选择的严格多变量框架。这种综合多变量方法有助于有针对性地选择具有增强形态和生理性状的耐热基因型，推动适应气候变化的棉花育种。
