The basic helix-loop-helix (bHLH) transcription factors play important roles in many processes such as plant growth, metabolism and response to biotic/abiotic stresses. Sunflower (Helianthus annuus) is a major oil crop, cultivated throughout the world. However, no systematic characterization of bHLH gene members in sunflower (HabHLH) and their functions involved in drought, cadmium tolerance and Orobanche cumana resistance has been reported yet. In this study, 183 HabHLH genes were identified and named according to their chromosomal locations. We classified these proteins into 21 subfamilies by phylogenetic tree analysis. Subsequently, DNA-binding patterns, sequence analysis, duplication analysis and gene structures were analyzed. All of the HabHLH genes were randomly distributed on 17 chromosomes, and 10 pairs of tandem duplicated genes and one pair of segmental duplicated genes were detected in the HabHLH family. Among the duplicated gene pairs, eight pairs of HabHLH genes suffer from positive selection. Moreover, qRT-PCR results revealed significant up-regulated expression of HabHLH024 gene in response to both abiotic (cadmium, drought) and biotic (Orobanche cumana) stresses, suggesting its important functions in response to different stresses. Therefore, HabHLH024 would be the potential candidate gene for the sunflower tolerance breeding.

基本螺旋-环-螺旋 (bHLH) 转录因子在许多过程中发挥重要作用，例如植物生长、代谢和对生物/非生物胁迫的响应。向日葵（Helianthus annuus）是一种主要的油料作物，在世界各地都有种植。然而，尚未报道向日葵 ( HabHLH )中bHLH基因成员的系统表征及其在干旱、镉耐受性和Orobanche cumana抗性中的功能。在本研究中，183 HabHLH基因根据其染色体位置被鉴定和命名。我们通过系统发育树分析将这些蛋白质分为 21 个亚家族。随后，分析了 DNA 结合模式、序列分析、重复分析和基因结构。所有的HabHLH基因被随机分布在17条染色体，并在检测到10对串联重复基因，和一对的节段重复基因HabHLH家族。在重复的基因对中，有八对HabHLH基因受到正选择的影响。此外，qRT-PCR 结果显示HabHLH024基因的表达显着上调，以响应非生物（镉、干旱）和生物（Orobanche cumana) 应力，表明其在应对不同应力时的重要功能。因此，HabHLH024将成为向日葵耐性育种的潜在候选基因。