Multiparent-Derived, Marker-Assisted Introgression Lines of the Elite Indian Rice Cultivar, 'Krishna Hamsa' Show Resistance against Bacterial Blight and Blast and Tolerance to Drought.

Jyothi Badri,Revadi Padmashree,Gandhudi Lakshmidevi,Vattikutti Jhansi Lakshmi,Divya Balakrishnan,Vikas Kumar Singh,Madamsetty Srinivasa Prasad,Raman Meenakshi Sundaram,Subhakara Rao Isetty,Uma Maheshwar Singh,Gouri Shankar Laha,Arvind Kumar,Aravind Kumar Jukanti,L R K Jaividhya,Yasaswini Vishnu Priya Varanasi,Lella Venkata Subba Rao,T Ram

doi:10.3390/plants11050622

Abstract

Major biotic stresses viz., bacterial blight (BB) and blast and brown plant hopper (BPH) coupled with abiotic stresses like drought stress, significantly affect rice yields. To address this, marker-assisted intercross (IC) breeding involving multiple donors was used to combine three BB resistance genes—xa5, xa13 and Xa21, two blast resistance genes—Pi9 and Pi54, two BPH resistance genes—Bph20 and Bph21, and four drought tolerant quantitative trait loci (QTL)—qDTY1.1, qDTY2.1, qDTY3.1 and qDTY12.1—in the genetic background of the elite Indian rice cultivar ‘Krishna Hamsa’. Three cycles of selective intercrossing followed by selfing coupled with foreground selection and phenotyping for the target traits resulted in the development of 196 introgression lines (ILs) with a myriad of gene/QTL combinations. Based on the phenotypic reaction, the ILs were classified into seven phenotypic classes of resistance/tolerance to the following: (1) BB, blast and drought—5 ILs; (2) BB and blast—10 ILs; (3) BB and drought—9 ILs; (4) blast and drought—42 ILs; (5) BB—3 ILs; (6) blast—84 ILs; and (7) drought—43 ILs; none of the ILs were resistant to BPH. Positive phenotypic response (resistance) was observed to both BB and blast in 2 ILs, BB in 9 ILs and blast in 64 ILs despite the absence of corresponding R genes. Inheritance of resistance to BB and/or blast in such ILs could be due to the unknown genes from other parents used in the breeding scheme. Negative phenotypic response (susceptibility) was observed in 67 ILs possessing BB-R genes, 9 ILs with blast-R genes and 9 ILs harboring QTLs for drought tolerance. Complex genic interactions and recombination events due to the involvement of multiple donors explain susceptibility in some of the marker positive ILs. The present investigation successfully demonstrates the possibility of rapid development of multiple stress-tolerant/resistant ILs in the elite cultivar background involving multiple donors through selective intercrossing and stringent phenotyping. The 196 ILs in seven phenotypic classes with myriad of gene/QTL combinations will serve as a useful genetic resource in combining multiple biotic and abiotic stress resistance in future breeding programs.

Highlights

Rice, an important crop for human sustenance, occupies a prominent place in the Indian agriculture
Several high yielding crop varieties have been developed in the past using conventional breeding approaches but combining high yield with multiple stress-resistant/tolerance using this approach is tedious
Selective intercrossing of multiparent-derived F1 ’s was adopted in stacking multiple genes/quantitative trait loci (QTL) into a single background assisted by foreground selection (FGS) up to IC3 F1 followed by stringent phenotypic selection for the desirable agronomic traits in the later segregating generations

Summary

Introduction

An important crop for human sustenance, occupies a prominent place in the Indian agriculture It is the cheapest source of calories for the developing countries and is a staple food crop for more than half of the global population, despite the changing climatic, social and economic scenario. Development of climate resilient varieties with multiple stress tolerance is needed for preventing yield losses and increasing the income of rice farmers in an environmentally sustainable manner. Conventional and marker-assisted backcross breeding has traditionally been used to introduce useful agronomic traits into elite cultivars; combining high yield with multiple stress tolerance using these approaches is tedious. The simultaneous occurrences of multiple abiotic and biotic stresses have demanded the development of climate-smart rice by combining quantitative trait loci (QTL) and genes for tolerance or resistance to various stresses in the genetic background of high yielding cultivars to confer a wider range of tolerance or resistance [1]. With days to 50% flowering in the range of 88 to 100 days, plant height of 81 to 87 cm (+87.71%)

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