MARKER-ASSISTED IMPROVEMENT OF BACTERIAL BLIGHT RESISTANCE OF THE ELITE RICE cv. NLR 34449 (Nellore Mahsuri)
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Date
2021-09-03
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Abstract
Nellore Mahsuri (NLR 34449), is a high yielding, blast resistant, popular variety developed from the cross IR 72/BPT 5204 in the year 2009 by Agricultural Research Station (ARS), Nellore, Andhra Pradesh, possessing, medium-slender grain type which is a desirable trait but susceptible to bacterial blight disease. The present study was designed and executed to improve NLR 34449 for durable resistance against a major biotic stress bacterial blight by incorporating three bacterial blight resistant genes viz., Xa21, xa13 and xa5 into NLR 34449 using Improved Samba Mahsuri as the donor which is a high-yielding fine-grain type bacterial blight resistant variety. Foreground selection of the target resistance genes was done using PCR-based molecular markers, specific for the genes, while 127 SSR markers equally distributed all over the 12 chromosomes of rice were used for target recurrent parent genome recovery (i.e., background selection) through marker-assisted backcross breeding and marker-assisted pedigree breeding. At BC2F2, generation, a total of five plants (NLR-87-35-102, NLR-87-21-103, NLR-87-53-104, NLR-87-13-105 and NLR-87-10-106) were found to be homozygous resistant for all the three target genes
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Improved versions of NLR 34449 viz., F4, BC1F3, BC2F2 plants were developed and evaluated for their resistance against bacterial blight, blast and for key agro-morphological traits. All the selected backcross and pedigree derived lines were observed to show better performance under target biotic stresses, BB and blast as compared to NLR 34449 and were equivalent to the parent variety in terms of grain type. Based on the stringent phenotypic screening along with evaluation for key agro-morphological traits, a solitary BC2F2 plant, viz., NLR-87-10-106 was identified to be better than the recurrent parent, NLR 34449 in terms of yield and other key agro-morphological traits. The significant achievement of the study is the improvement of BB and blast stress resistance in the genetic background of NLR 34449, without any loss of the premium grain quality attributes with marginal improvement in yield attributes.
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MARKER-ASSISTED IMPROVEMENT OF BACTERIAL BLIGHT RESISTANCE OF THE ELITE RICE cv. NLR 34449 (Nellore Mahsuri)