Investigation of Drought Induced Biochemical and Gene Expression Changes in Carrot Indicate Cultivar Specific Resilience

Abstract

Background: Carrot is the most important vegetable in Apiaceae family, and it is consumed globally due to its high nutritional quality. Drought stress is major environmental constraint for vegetables especially carrot. Limited data is available regarding the mechanisms conferring drought tolerance in carrot. Methods and Results: Eight commercial carrot cultivars were used in this study and subjected to drought stress under semi-controlled greenhouse conditions. Biochemical, antioxidant enzymatic activity and changes in transcript level of drought related genes was estimated in comparison to their control plants. Gene expression analysis was done by using qRT-PCR. Results revealed that cultivars Coral Orange, Tendersweet and Solar Yellow were resilient to drought stress, which was supported by their higher transcript levels of catalase gene (CAT), superoxide dismutase genes (Cu/ZN-SOD, Cu/Zn-SDC) in these cultivars. The downregulation of PDH1 gene (Proline dehydrogenase 1) was also observed that was associated with upregulation of proline accumulation in carrot plants. Moreover, results also suggested that PRT genes (Proline transporter genes) played a key role in drought tolerance in carrot cultivars.Conclusions: Among the cultivars studied, Coral Orange showed overall resilience under drought stress conditions, whereas cultivars Cosmic Purple and Eregli Black were sensitive. According to our knowledge, this is the first comparative study on drought resilience in several carrot cultivars. It will provide a background for carrot breeding to understand biochemical and molecular responses of carrot plant to drought stress and mechanisms behind it.