Positive interactions of major-effect QTLs with genetic background that enhances rice yield under drought

Nitika Sandhu,Shalabh Dixit,Challa Venkateshwarlu,Arvind Kumar,Prashant Vikram,Margaret Catolos,B P Mallikarjuna Swamy

doi:10.1038/s41598-018-20116-7

Abstract

To improve the grain yield of the lowland-adapted popular rice variety Samba Mahsuri under reproductive-stage drought (RS) and to understand the interactions between drought QTLs, two mapping populations were developed using marker-assisted selection (MAS) and marker-assisted recurrent selection (MARS). The mean grain yield of pyramided lines (PLs) with qDTY2.2 + qDTY4.1 in MAS is significantly higher under RS and irrigated control than lines with single QTLs. Among MARS PLs, lines with four qDTYs (qDTY1.1 + qDTY2.1 + qDTY3.1 + qDTY11.1) and two QTLs (qDTY1.1 + qDTY11.1) yielded higher than PLs with other qDTY combinations. The selected PLs showed a yield advantage of 0.3–2.0 t ha−1 under RS. An allelic profile of MAS PLs having same qDTY combination but with different yields under drought was studied. Hierarchical clustering grouped together the selected lines with high yield under drought. Epistasis test showed the interaction of qDTY4.1 and qDTY9.1 loci with qDTY7.1 significantly increased yield under drought and all the lines with higher yield under drought possessed the conserved region of qDTY7.1 on chromosome 7. The positive interactions among QTLs, effectiveness of QTLs in different backgrounds, introgression of DTY QTLs together with resistance to biotic stresses shall help enhance grain yield under RS.

Highlights

The increasing population, declining water availability with increasing demand, climate change and abiotic stresses are serious threats to world food security
The present study reports an integrated strategy of QTL pyramiding to develop pyramided lines (PLs) with high grain yield under reproductive-stage drought stress together with tolerance of biotic stress
The results reported in the present study indicate the effectiveness of introgressed QTLs, interaction of QTLs with other loci, to further enhance Grain yield (GY) under reproductive-stage drought stress while following marker-assisted selection (MAS) and marker-assisted recurrent selection (MARS) approaches

Summary

Introduction

The increasing population, declining water availability with increasing demand, climate change and abiotic stresses are serious threats to world food security. An effective breeding approach to develop drought-tolerant rice varieties could lead to food security under situations of accelerating food demand, depleting resources, and predicated climatic variability[3]. Various strategies such as conventional hybridization and selection procedures, ideotype breeding, heterosis breeding, wide hybridization, molecular breeding[3], and new genomics tools and technologies can be used to increase yield potential. The objectives of the study were to (1) evaluate the effects of qDTY2.2 and qDTY4.1 in a Samba Mahsuri background using the MAB approach, which had earlier shown effects in an IR64 background; (2) understand the interactions of drought grain yield QTLs qDTY1.1, qDTY2.1, qDTY3.1, and qDTY11.1 in a Samba Mahsuri background using the MARS breeding approach; and (3) develop high-yielding blast-and drought-tolerant Samba Mahsuri PLs for cultivation by farmers

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Conclusion