Marker assisted improvement of low soil phosphorus tolerance in the bacterial blight resistant, fine-grain type rice variety, Improved Samba Mahsuri

H K Mahadeva Swamy,K Surekha,L V Subba Rao,B Laxmi Prasanna,M S Madhav,M S Prasad,S M Balachandran,R M Sundaram,G S Laha,M B V N Kousik,M S Anantha,P Brajendra,G Harika,T Dilip,C Cheralu,S K Hajira,C H Balachiranjeevi,V P Bhadana,V Gouri Shankar,G Rekha,Rohitashw Kumar ,Ravindra Ramrao Kale ,K Pranathi,M Anila

doi:10.1038/s41598-020-78186-5

Abstract

Improved-Samba-Mahsuri (ISM), a high-yielding, popular bacterial blight resistant (possessing Xa21, xa13, and xa5), fine-grain type, low glycemic index rice variety is highly sensitive to low soil phosphorus (P). We have deployed marker-assisted backcross breeding (MABB) approach for targeted transfer of Pup1, a major QTL associated with low soil P tolerance, using Swarna as a donor. A new co-dominant marker, K20-1-1, which is specific for Pup1 was designed and used for foreground selection along with functional markers specific for the bacterial blight resistance genes, Xa21, xa13, and xa5. A set of 66 polymorphic SSR marker were used for the background selection along with a pair of flanking markers for the recombination selection in backcross derived progenies and in BC2F2 generation, 12 plants, which are homozygous for Pup1, all the three bacterial blight resistance genes and possessing agro-morphological traits equivalent to or better than ISM were selected and selfed to produce BC2F3s. They were evaluated in plots with low soil P and normal soil P at ICAR-IIRR, Hyderabad for their low soil P tolerance, and bacterial blight resistance and superior lines were advanced to BC2F6. One of the lines, when tested at multiple locations in India was found promising under both normal as well as low soil P conditions.

Highlights

Rice, one of the most important staple food crops of the globe, which is being grown in more than 117 countries, provides more than one-fifth of the calories and is consumed by more than 3 billion people
The newly developed marker, produced an amplicon of size 89-bp in the low P tolerant varieties, viz., Kasalath and Vandana, while an amplicon of size 92-bp was amplified in the sensitive rice variety, viz., Improved Samba Mahsuri (ISM), when resolved in 8% native PAGE (Supplementary Fig. 1)
The newly developed marker, K20-1-1 was tested in a F2 population consisting of 135 individuals derived from the cross Improved Samba Mahsuri/ Swarna

Summary

Introduction

One of the most important staple food crops of the globe, which is being grown in more than 117 countries, provides more than one-fifth of the calories and is consumed by more than 3 billion people. Identification of Pup[1] QTL, which confers tolerance to low soil P2 and the better performance of Pup[1] containing rice lines in different genetic backgrounds in both upland and irrigated conditions[14] opens the way to improve the rice cultivars for low soil P conditions. As Pup[1] is known to improve tolerance to low soil P in both irrigated and upland rice varieties and, availability of closely linked and functional markers for Pup[1], motivated us to genetically improve the tolerance level of the elite, low P sensitive, high-yielding, bacterial blight resistant, fine-grain type Indian rice variety with low glycemic index, Improved Samba Mahsuri (ISM) through the strategy of MABB

Methods

Results

Discussion

Conclusion