Association of leaf micro-morphological characters with powdery mildew resistance in field-grown mulberry (Morus spp.) germplasm
by Chattopadhyay S., Ali K. A., Doss S. G., Das N. K., Aggarwal R. K., Bandopadhyay T. K. , Sarkar A., Bajpai A. K. (2011)
Soumen Chattopadhyay1,4*, Kabiul Akhter Ali1, S. Gandhi Doss1, Nirvan K. Das1, Ramesh K. Aggarwal2, Tapas K. Bandopadhyay3, A. Sarkar1 and A. K. Bajpai1
1 Central Sericultural Research and Training Institute, Central Silk board, Berhampore 742 101, India
2 Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
3 Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, Nadia, India
in AoB PLANTS 2011 plr002 – doi:10.1093/aobpla/plr002 –
Background and aims
Micro-morphological characteristics can influence fungal infectivity. We sought links between micro-morphology and resistance to powdery mildew in mulberry with the intention of assisting selection of disease-resistant lines.
Over 3 years and under field conditions, we evaluated 30 lines of mulberry with contrasting susceptibilities to powdery mildew (15 resistant and 15 susceptible). Disease severity was related statistically to stomatal area, stomatal density, stomatal index, upper and lower cuticular thicknesses, leaf thickness and trichome density.
Differences between lines were significant (P , 0.05) for all characters studied. Variation between the resistant and susceptible groups was statistically highly significant (P , 0.01) for stomatal index, stomatal area and trichome density.
The powdery mildew-resistant group was distinguished by 17.4 % lower stomatal density, 12.5 % smaller stomatal index per unit leaf area, 20.0 % greater trichome density and 18.0 % higher stomatal area compared with the susceptible group.
Trichome density was negatively correlated with disease severity index and with the accumulative area under disease progression curves.
Stomatal density was positively correlated with both measures of disease severity. Although stomatal area was negatively related to disease severity index (r ¼ 20.28; P , 0.05), the correlation was weak.
There was no statistically significant relationship between stomatal area and the accumulative area under disease progression curves.
The germplasm was partitioned into seven sub-groups based on hierarchical cluster analysis derived from pooled disease severity index scores and three highly significant micro-morphological characters. Eighty per cent of the resistant germplasm accumulated in three cluster components (A1, A2 and B2) characterized by high trichome densities and a high stomatal density and stomatal index.