miRNAs associated to fruit antioxidants under drought stress in tomato lines

Antioxidants in humans act as ROS-scavenging, help in the maintenance of an healthy immune system and have a preventative function against many degenerative and proliferative diseases. Humans are unable to synthesise most of antioxidants provided by plants through food and their levels can be dramatically affected by environmental constraints such as drought. Thus, identifying genetic reservoirs of drought tolerance and elucidating genetic mechanisms controlling the interaction between drought stress and fruit content of antioxidants can help in breeding drought tolerant plants with high fruit quality. This study aimes to investigate microRNA (miRNA) species controlling fruit antioxidant accumulation upon drought challenge in tomato lines. In particular, tomato cv M82 and IL9ADM, differing in their tolerance to drought stress, were used to carry out a comparative analysis at two different watering conditions: restitution of 100% (Full Restitution of Water, FRW) and 50% (Half Restitution of Water, HRW) of plant water lost. IL9ADM is an introgression line selected at the University of Naples, harboring, in the genomic context of the cv M82, from 28 to 36 cM of the chromosome 9, a homozygous S. pennellii DNA introgression.Under FRW regime, AsA content was 27.26 ± 0.70 and 25.02 ± 1.81 mg 100 g-1 FW in IL9ADM and M82, respectively, whereas at HRW it was 32.82 ± 2.20 and 34.79 ± 1.83 mg 100 g-1 FW in IL9ADM and M82. The total phenolic content significantly decreased in HRW condition in M82 whereas a significant increase in the total carotenoids was observed only in M82 fruit under drought. In addition, HPLC analysis are in progress in order to quantify specific carotenoids and target phenolic compounds. Also, miRNA species mediating regulative mechanisms in fruit metabolic pathways upon drought stress are being identified by a comparative study combining RNA-seq and miRNA-seq approaches.