Drought is one of the main environmental stressors that can alter the water status of plants; negatively affect growth, assimilation, and photosynthesis; and eventually reduce crop yield. We explored the dependence of drought tolerance traits on chlorophyll-A content. Local sunflower cultivars (FH-01, FH-628, FH-633, FH-572, and FH-653) were grown in pots and subjected to drought by withholding water for 10, 15, or 20 d. One month after germination, the leaves of the treated and non-treated plants were collected and subjected to biochemical analyses. Under different water stress levels, the levels of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and proline increased, whereas those of chlorophyll-A decreased. Regression analysis clearly found that proline (−0.442), POD (−0.528), SOD (−0.532), and CAT (−0.814) have negative beta coefficient values. Phylogenetic analysis revealed that the LHC gene family is divided into six clades. Subcellular locations indicated that most LHC genes were located in the chloroplast; however, only few genes were present in the peroxisomes and endoplasmic reticulum. Our research found that Arabidopsis thaliana LHC genes were highly homologous to the LHC genes of Helianthus annuus. Furthermore, the LHC genes of both species are located in the chloroplasts; therefore, they play a role in photosynthesis and renewable energy production. This study opens a new horizon for discussing the role of chlorophyll-A in the drought-related traits of sunflowers.

干旱是可以改变植物水分状况的主要环境压力因素之一；对生长、同化和光合作用产生负面影响；并最终降低作物产量。我们探讨了耐旱性状对叶绿素 A 含量的依赖性。将当地向日葵品种（FH-01、FH-628、FH-633、FH-572 和 FH-653）种植在盆中，并通过停水 10、15 或 20 天来承受干旱。发芽后一个月，收集经过处理和未经处理的植物的叶子并进行生化分析。不同水分胁迫水平下，过氧化物酶（POD）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和脯氨酸水平升高，而叶绿素-A水平降低。回归分析清楚地发现脯氨酸（-0.442）、POD（-0.528）、SOD（-0.532）和CAT（-0.814）具有负β系数值。系统发育分析表明LHC基因家族分为6个进化枝。亚细胞定位表明大多数LHC基因位于叶绿体中；然而，过氧化物酶体和内质网中只存在很少的基因。我们的研究发现拟南芥LHC向日葵LHC基因高度同源此外，LHC基因都位于叶绿体中。因此，它们在光合作用和可再生能源生产中发挥作用。这项研究为讨论叶绿素 A 在向日葵干旱相关性状中的作用开辟了新的视野。