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Genetic Dissection of Epistatic Interactions Contributing Grain Yield Variability in Rice under Drought

Author(s):

Ratna Rani Majumder, Nitika Sandhu, Shailesh Yadav, Margaret Catolos, Ma. Teresa Sta. Cruz, Paul Cornelio Maturan, Lutful Hassan, Mohammad Amir Hossain and Arvind Kumar*  

Abstract:


Aims: The aim of the present study was to evaluate the performance of ‘high’-‘low’ yielding pyramided lines (PLs) with the same combinations of qDTYs in Samba Mahsuri, MR219 and IR64-Sub1 genetic backgrounds and understand the genetic interactions of QTL and with genetic background affecting grain yield.

Background: Epistasis regulates the expression of traits governed by several major/minor genes/QTL. Multiple pyramided lines (PLs) with the same grain yield QTL (qDTYs) combinations but possessing grain yield variability under different levels of reproductive stage drought stress were identified in different rice genetic backgrounds at International Rice Research Institute (IRRI).

Objectives: The objectives of the present study were to evaluate the performance pyramided lines (PLs) with drought QTL in the backgrounds of Samba Mahsuri, MR219 and IR64-Sub1 under reproductive stage drought stress (RS) and NS (non-stress) conditions ii) to understand the effect of epistatic interactions of qDTYs and with genetic background on GY under the differential level of stress iii) to identify the promising drought-tolerant lines with high yield under drought and higher background recovery in different genetic backgrounds.

Methods: The experiments were conducted in 2015DS (dry season), 2015WS (wet season) and 2017 DS at IRRI, Los Baños, Philippines, in a transplanted lowland ecosystem under lowland severe stress (LSS), moderate lowland stress (LMS) and lowland non-stress (LNS). The experiments were laid out in alpha lattice design with two replications.

Results: Several digenic interactions were found in different genetic backgrounds, 13 interactions in Samba Mahsuri, 11 in MR219 and 20 in IR64-Sub1 backgrounds. Among all digenic interactions, one QTL × QTL interaction, 17 QTL × background and 26 background × background interactions resulted in GY reduction in low yielding PLs in different genetic backgrounds under LSS or LMS. Negative interaction of qDTY3.1, qDTY4.1 and qDTY9.1 with background markers and background × background interactions caused up to 15% GY reduction compared to the high yielding PLs under LMS in the Samba Mahsuri PLs. In MR219 PLs, the negative interaction of qDTY2.2, qDTY3.2, qDTY4.1 and qDTY12.1 with the background marker interval RM314-RM539, RM273-RM349 and RM445-RM346, RM473D-RM16, respectively resulted in 52% GY reduction compared to the high yielding PLs under LSS. In IR64-Sub1 PLs, qDTY6.1 interacted with background loci at RM16-RM135, RM228-RM333, RM202-RM287 and RM415-RM558A marker interval under LSS; and at RM475-RM525 marker interval under LMS, causing GY reduction to 58% compared to the high yielding PLs.

Conclusion: High yielding PLs in Samba Mahsuri (IR 99734:1-33-69-1-22-6), MR219 (IR 99784-156-87-2-4-1) and IR64-Sub1 (IR 102784:2-89-632-2-1-2) backgrounds without any negative interactions were identified. The identified selected promising PLs may be used as potential drought-tolerant donors or may be released as varieties for drought-prone ecosystems in different countries.

Keywords:

drought tolerance, epistatic interaction, pyramided lines (PLs), QTL, rice

Affiliation:

Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila, Bangladesh Agricultural University, Mymensingh 2202, Dhaka, Bangladesh Agricultural University, Mymensingh 2202, Dhaka, Rice Breeding Platform, International Rice Research Institute, DAPO Box 7777, Metro Manila



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