Identification and Expression Analysis of Genes Involved in Endodormancy Break and Sprouting in Potato (Solanum Tuberosum L.)

Abstract

The potato (Solanum tuberosum) is one of the important staple food crop of the world. It is the fourth most important crop in total production and the fourth largest contributor to human caloric consumption, after the three cereals rice, wheat and maize. Potato tuber dormancy plays key role in agriculture as it is seen in various tuber crops as this phenomenon affects sprouting vigour as well as the shelf life of crops such as potatoes. The aim of the present study is to have a better understanding at phytohormonal application, morpho-physiological, gene expression and transcriptome level studies. Publically available RNA-seq data of Dormant tuber (DT), Dormancy release tuber (DRT) and Sprouting tuber (ST) from European Nucleotide Archive (ENA) has been downloaded and analysed in-silico. A total of 4,052, 3,654, 2075 differentially expressed genes are found for DT&DRT, DT&ST, DRT&ST conditions respectively. Field experiments have been conducted to study the effects of the phytohormones (Gibberellic acid and Auxin) and ethanol in the two promising potato varieties i.e. Kufri Bahar and Kufri Surya. Kufri surya shows delayed plant emergence in comparison to Kufri Bahar for a period of 7-10 days. Pant emergence data shows that Treatment 3 (1.0 GA3 mg/ml) has highest potential to address the problem of slow emergence (low sprout vigour). Kufri Surya responded to the exogenous application of gibberellic acid in terms of early plant emergence and enhanced shoot height. To investigate the delayed plant emergence, Sucrose synthase (SUSY), Auxin response factor 1 (ARF1), Catalase (CAT1), Inositol Polyphosphate Kinase (IPKa), Tubulin, Copalyl diphosphate synthase (CDS), GA20ox-2, Glucose-6-phosphate gene, Malate dehydrogenase were selected for gene expression study. Out of these genes, CPS (ent-Copalyl diphosphate synthase) gene and GA20ox2 have been observed at 8-fold low level of expression in Kufri Surya compared to Kufri Bahar. It shows that the de-novo Gibberellic acid biosynthesis is rate limiting factor in Kufri Surya leading to delayed sprouting and poor plant emergence during early days after planting.