Association of leaf micro-morphological characters with powdery mildew resistance in field-grown mulberry (Morus spp.) germplasm

Abstract

Background and aimsMicro-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.MethodologyOver 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.Principal resultsDifferences 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 = −0.28; 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.ConclusionsResistance to powdery mildew in mulberry is associated with trichome and stomatal features rather than leaf and epidermal thicknesses. Trichome density, stomatal density and stomatal index are shown to be promising markers for screening powdery mildew resistance in breeding programmes.

Association of morphological and biochemical features of mulberry lines with resistance to bacterial leaf spot

“…The significant correlation of DSI with SF, TD, TSS and PP support the report of Chattopadhyay et al (2011) who reported strong negative association of powdery mildew resistance with SF and TD in mulberry. Similarly, a significant negative correlation of soluble sugar with black pod infection with cocoa (Nyadanu et al 2013) and phenol content with with soft rot infection of potato were also supported our findings.…”

“…The SF was determined as the number of stomata per unit leaf area (mm 2 ) (Xu & Zhou 2008). Trichome number was counted from five microscopic observations per entry along the mid-vein side using a Diaplan stereo-dissecting microscope and TD was estimated as the number of trichome per square millimetre (Chattopadhyay et al 2011).…”

Morphological Characteristics and Susceptibility of Basil Species and Cultivars to Peronospora belbahrii

“…The increased amount of BDM in O. basilicum as we reported is consistent with other reports of BDM incidence (Damicone, 2010;McGrath, 2011;Mersha et al, 2012;R€ omer et al, 2010;Wyenandt et al, 2010). Previous studies have demonstrated a correlation between high stomatal density and increased disease incidence with other pathogens on other crops (Alonso-Villaverde et al, 2011;Bala et al, 1992;Chattopadhyay et al, 2011;Furst, 1976;Gill and Nandpuri, 1978;Hern andez et al, 2006;Inder et al, 1999;Jhooty et al, 1978;Kramer and Boyer, 1995;Kumar et al, 2011;Mahajan and Gill, 1998;Mayee and Suryawanshi, 1995;Philip et al, 1991;Shaik, 1985;Sharma et al, 2001;Stenglein et al, 2005). This is the first report to show this same correlation with high stomatal density and increased BDM incidence and severity with Ocimum sp.…”

Correlation of Stomata Density to Rust Severity on Some Accessions of Maize Germplasm

“…The correlation of stomata density to percentage of rust disease on soybean leaves at the 77 th DAP was highly strong with r value 0.9727. Additionally, Chattopadhyay et al (2011) found that the stomata and trichoma density of mulberry leaves had strong correlation to development of powdery mildew disease with r values 0.624 and -0.809, respectively. Pradana et al (2017) specified that the intensity of scab disease on sweet potato leaves at generative phase was extended to 85.10% due to the length of stomata on the upper leaves on susceptible cultivars, and 62.97% of intensity of the disease incidence was influenced by stomata density.…”