Marker-Assisted Introgression of Saltol QTL Enhances Seedling Stage Salt Tolerance in the Rice Variety "Pusa Basmati 1".

Vivek Kumar Singh,Ranjith Kumar Ellur,Amit Kumar,Kunnummal Kurungara Vinod,Sadhna Maurya,Brahma Deo Singh,Prolay Kumar Bhowmick,Ashok Kumar Singh,Madan Pal Singh,Subbaiyan Gopala Krishnan

doi:10.1155/2018/8319879

Vivek Kumar Singh, Ranjith Kumar Ellur + Show 8 more

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https://doi.org/10.1155/2018/8319879

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Abstract

Marker-assisted selection is an unequivocal translational research tool for crop improvement in the genomics era. Pusa Basmati 1 (PB1) is an elite Indian Basmati rice cultivar sensitive to salinity. Here, we report enhanced seedling stage salt tolerance in improved PB1 genotypes developed through marker-assisted transfer of a major QTL, Saltol. A highly salt tolerant line, FL478, was used as the Saltol donor. Parental polymorphism survey using 456 microsatellite (SSR)/QTL-linked markers revealed 14.3% polymorphism between PB1 and FL478. Foreground selection was carried out using three Saltol-linked polymorphic SSR markers RM8094, RM493, and RM10793 and background selection by 62 genome-wide polymorphic SSR markers. In every backcross generation, foreground selection was restricted to the triple heterozygotes of foreground markers, which was followed by phenotypic and background selections. Twenty-four near isogenic lines (NILs), with recurrent parent genome recovery of 96.0–98.4%, were selected after two backcrosses followed by three selfing generations. NILs exhibited agronomic traits similar to those of PB1 and additional improvement in the seedling stage salt tolerance. They are being tested for per se performance under salt-affected locations for release as commercial varieties. These NILs appear promising for enhancing rice production in salinity-affected pockets of Basmati Geographical Indication (GI) areas of India.

Highlights

Rice plants suffer severe salt injury in both seedling and reproductive stages; the most common damages are attributed to osmotic imbalance, membrane destabilisation, and failure of photosynthetic machinery [1]
We report marker-aided introgression of the QTL Saltol from FL478 into Pusa Basmati 1 (PB1) and the resulting improvement in seedling stage salt tolerance of the PB1 near isogenic lines (NILs)
Genome-wide polymorphism survey using 435 survey using microsatellite (SSR) markers identified a total of 62 polymorphic markers between PB1 and FL478, ranging from 4–7 markers spanned on each chromosome, resulting in an overall polymorphism of 14.7% between the parents (Table 1)

Summary

Introduction

Rice plants suffer severe salt injury in both seedling and reproductive stages; the most common damages are attributed to osmotic imbalance, membrane destabilisation, and failure of photosynthetic machinery [1]. The damage due to salt stress is often cumulative as the seedling stage sensitivity leads to poor crop establishment, and reproductive stage sensitivity results in reduced yields [2]; the combined effect of damages at both the stages may lead to total crop loss. Seedling stage tolerance can sustain crop production in salinity prone areas by promoting good initial establishment leading to healthy vegetative growth that can augment crop yield [3]. Apart from the understanding of physiological and metabolic responses to salt stress, quantitative trait loci (QTLs) and genes governing salt tolerance have been reported in rice.

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