Exploring Gene Indicators to Describe Susceptibility of Chickpea to Ascochyta Blight

Abstract

Chickpea is an important legume crop of dryland in many countries of Africa, America and Asia. It is an important grain crop in Pakistan and represent 70% of total pulses. It is an inexpensive source of protein. The Chickpea crop is affected by many abiotic and biotic stresses. Among these, Ascochyta blight is measured to be one of the most destructive disease of chickpea. In this study, ten different desi and kabuli varities are used for the virulence assay of Ascochytarabiei. These varities showed different levels of resistance against A. rabiei. Prior to inoculation, different biochemicals, physiological and genetic indicators were observed in chickpea lines. Few of them helped us to understand defense mechanism of this crop. The study revealed that the protein content was low in susceptible cultivars as compared to resistant varieties. It was also observed that the susceptible cultivars were having higher concentration of sugar as well as flavonoid contents. It was also observed that the resistant and moderate resistant varieties were having higher level of POD and PAL activity as compared to susceptible. The susceptible plants were also having low weight of shoot as compared to resistant ones. Before the inoculation, it was observed that the biochemicals and physiological indicators such as proline, chlorophyll pigments, phenol, amino nitrogen, catalase, root/ shoot length varied in all treatments and they did not give any clue to describe the resistance and susceptibility of plants. Expression profiling of chitinase gene in chickpea plants showed that it is highly expressed in the resistant cultivars as compared to susceptible. RT-PCR results also show that the resistant cultivars were having higher expression of SOD gene. Expression of SOD gene was very low is highly infected line. Expression of ~-glucosidase could not be observed in any plant which is might be due to reason that ~-glucosidase is typically involved in hypersensitive response (HR) and systemic acquired response (SAR) and it is expressed after infection. The prresent results helped us to understand defense mechanism of chickpea against A. rablei.