Lignification based screening of pea (Pisum sativum L.) germplasm for resistance to rust (Uromyces viciae–fabae)

Abstract

Pea, Pisum sativum L. (2n = 14), is the third most important legume crop worldwide after common bean and chickpea. Pea production is severely affected by rust caused by Uromyces viciae-fabae. Lignification is one of the most important mechanisms playing a very significant role in plant disease resistance. In the present study, a total of 115 pea entries of the Australian germplasm together with four standard controls were observed for the presence of total lignin content (72 h) and its accumulation in relation to the different components of resistance. Out of all the test entries, one resistant entry ‘EC865975’ showed the maximum increase in total lignin content even more than the resistant check. It also exhibited a low AUDPC (the Area under the Disease Progress Curve) value of 292 and showed formation of smaller pustules measuring 0.7 mm in size with reduction in their number. Further, it was found that the total lignin content was highly negatively correlated (r = -0.796) with AUDPC. The higher accumulation of lignin content was found in resistant test entries over susceptible ones. The principal component analysis of the different parameters revealed that the total lignin content and AUDPC were only the parameters mostly contributing to the total phenotypic variation to the extent of 81.92% as they exhibited their Eigenvalue > 1. Further, the regression analysis considering the total lignin content as the independent variable and AUDPC, size and number of pustules, 100 seed weight and seed area as predictor variables revealed that the total lignin content caused 75.2% alteration in other predictor variables. Hence, the present study confirmed that the lignification can be used as a key biochemical parameter for screening of resistant sources from the various pea germplasms.