MOLECULAR TAGGING OF SORGHUM DOWNY MILDEW (Peronosclerospora sorghi) DISEASE RESISTANCE LOCI IN MAIZE (Zea mays L.)

K.P. JADHAV¹*, P.M. TAMILARASI², G.R. SAYKHEDKAR³, N. SENTHIL⁴, M. RAVEENDRAN⁵, J. RAMALINGAM^6
1Centre for Plant Molecular Biology and Biotechnology, TNAU, Coimbatore, Tamil Nadu, India
²Centre for Plant Breeding and Genetics, TNAU, Coimbatore, Tamil Nadu, India
³Centre for Plant Molecular Biology and Biotechnology, TNAU, Coimbatore, Tamil Nadu, India
⁴Department of Biotechnology, AC & RI, TNAU, Madurai.625 104, Tamil Nadu, India
⁵Centre for Plant Molecular Biology and Biotechnology, TNAU, Coimbatore, Tamil Nadu, India
⁶Centre for Plant Molecular Biology and Biotechnology, TNAU, Coimbatore, Tamil Nadu, India
* Corresponding Author : kashjadhav2007@gmail.com

Received : 08-09-2015     Accepted : 29-10-2015     Published : 14-11-2015
Volume : 7     Issue : 9       Pages : 652 - 657
Int J Agr Sci 7.9 (2015):652-657

Keywords : Peronosclerospora sorghi, Recombinant Inbred Line, Spreader row technique, co-segregation, Marker assisted selection
Academic Editor : Rachana Chandragupta Acharya, Deivasigamani Manivelu, U. K. S. Kushwaha, Pallav Kaushik Deshpande
Conflict of Interest : None declared
Acknowledgements/Funding : Financial support from DBT for the project BT/PR/108910/GBD/27/111/2008 and UGC for providing junior research fellowship to first author is greatly acknowledged.

Sorghum downy mildew (SDM) caused by Peronosclerospora sorghi is a major constraint, which drastically affects maize production and productivity. Conventional breeding approaches to resolve the problem through evolving resistant varieties has resulted in limited success due to the longer breeding cycle. In order to exploit marker assisted selection (MAS) approach for developing resistant varieties, there is a paucity of information on markers linked with the trait. We report here the strategy for identification of markers linked to SDM resistance by selective genotyping, a first crucial step towards selection of resistant lines through MAS. The mapping population of maize Recombinant Inbred lines (158) of UMI 79 and UMI 936 (w) was developed and screened for their resistance levels, both in the field and glasshouse conditions, by spreader row technique and seedling spray inoculation technique, respectively. A total of 35 SSRs, 6 reported to be linked to SDM disease resistance QTL earlier with 29 other SSRs located on chromosome 3 was surveyed for parental polymorphism. Interestingly, of the six markers reported earlier, four were found polymorphic for the parents used in the present study also along with nine other markers. Through phenotypic screening, extreme phenotypes comprising of seven each of resistant and susceptible RILs, were selected and used for selective genotyping employing the polymorphic markers. Among the 13 markers surveyed, an SSR marker bnlg420 showed co-segregation with SDM resistant lines which proves to be a potential tag for introgression of the SDM resistant trait in UMI79 background.