BIOCHEMICAL AND HISTOPATHOLOGICAL STUDIES IN BARLEY FOR COVERED SMUT (Ustilago hordei) RESISTANCE
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Covered smut caused by Ustilago hordei is an important disease of barley in India. In present study, biochemical basis of resistance, histopathological & ultrastructural changes and identification of sources of resistance to U. hordei were undertaken. The biochemical basis of resistance was studied on a set of three barley cultivars viz. PL 426 (resistant), PL 891 (moderately susceptible) and VJM 201 (susceptible). Maximum level of total phenols (0.64 units min-1 g-1 fresh weight) and activity of peroxidase (POD) (86.70 units min-1 g-1 fresh weight) was recorded in PL 426 whereas maximum activity of polyphenoloxidase (PPO) (89.30 units min-1 g-1 fresh weight) and phenylalanine ammonia lyase (PAL) (1.39 units min-1 g-1 fresh weight) was recorded in PL 426 and PL 891, respectively. The aqueous extract of seedlings of PL 426 (resistant variety) inhibited 98% of teliospores at 100% concentration. Ultrastructural comparison of compatible and incompatible Hordeum vulgare-Ustilago hordei, host-pathogen interaction done with scanning electron microscope showed germinated teliospores and trailing hyphae all over the host surface in the compatible interaction. Whereas, in incompatible interaction the teliospores were intact and extracellular polysaccharides were present completely adjacent to teliospores which might be involved in hindering the germination of teliospores. Eighty three germplasm accessions comprising of 74 germplasm lines and 9 varieties were evaluated against covered smut disease. Among the 9 varieties, 5 varieties namely HBL 113, HBL 391, HBL 316, DWRUB 92 and DWRUB 123 were found to be completely free from covered smut disease under field conditions at two locations viz. Ludhiana and Faridkot. PL 172 and PL 891 were categorized as moderately resistant and moderately susceptible, respectively. Among 74 germplasm lines tested at both locations, 41 showed high level of resistance and were found free from disease. BL 1562, BL 1656, BL 1627 and BL 1562, BL 1652 lines were found to be resistant at PAU, Ludhiana and RRS, Faridkot, respectively. 17 germplasm lines showed moderate resistance against covered smut.
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