Abstract
BackgroundAvailability of irrigation water is becoming a major limiting factor in rice cultivation. Production in rainfed areas is affected in particular by drought events, as these areas are commonly planted to high-yielding drought-susceptible rice (Oryza sativa L.) varieties. The use of bulk segregant analysis (BSA), taking grain yield (GY) as a selection criterion, has resulted in the identification of several large-effect QTL. A QTL mapping study was undertaken on a BC1F3:4 population developed from the cross IR55419-04/2*TDK1 with the aim of identifying large-effect QTL in the background of TDK1, a popular variety from Lao PDR.ResultsThe study identified three QTL—qDTY 3.1 (RM168-RM468), qDTY 6.1 (RM586-RM217), and qDTY 6.2 (RM121-RM541)—for grain yield under drought. qDTY 3.1 and qDTY 6.1 , showed consistent effect across seasons under lowland drought-stress conditions while qDTY 6.1 and qDTY 6.2 showed effect under both upland and lowland drought conditions. The test of QTL effect, conducted through a QTL class analysis, showed the complimentary nature of qDTY 3.1 and qDTY 6.1 . Both QTL showed specific patterns of effect across different maturity groups within the mapping population and higher stability for grain yield was seen across stress levels for lines with both QTLs as compared to those with single or no QTL.ConclusionsThe study offers a clear understanding of large-effect QTL for grain yield under drought and their effect as individual QTL and in various combinations. The study also opens up an opportunity to develop a drought-tolerant version of TDK1 through marker-assisted backcross breeding and has led to a large-scale QTL pyramiding program aiming to combine these QTL with Sub1 in the background of TDK1 as recipient variety.
Highlights
Availability of irrigation water is becoming a major limiting factor in rice cultivation
A QTL mapping study conducted on a BC1F3:4 population, developed from the cross IR55419-04/2*TDK1, showed the presence of three QTL—qDTY3.1 (RM168 to RM468), qDTY6.1 (RM586 to RM217), and qDTY6.2 (RM121 to RM541). qDTY3.1 and qDTY6.1 showed a consistent effect across seasons under lowland droughtstress conditions while qDTY6.1 and qDTY6.2 showed effect under both upland and lowland conditions
The test of QTL effect and stability analysis of the lines showed the combination of these QTL to be the most advantageous across a wide range of stress levels and across upland and lowland ecosystems. qDTY3.1 and qDTY6.1, in particular, showed highly complementary effects on grain yield (GY) across stress and non-stress ecosystems
Summary
Availability of irrigation water is becoming a major limiting factor in rice cultivation. Recent research has shown that varieties developed through direct selection for grain yield (GY) under drought-stress and non-stress conditions from progenies derived from crosses of drought-tolerant donors and high-yielding drought-susceptible varieties provide a yield advantage under drought [6,7,8], in addition to maintaining a high yield potential under non-stress conditions These findings led to a series of QTL-identification studies on a wide range of donor and recipient parents, resulting in the identification of several large-effect QTL for grain yield under varying severities of reproductive-stage drought-stress for both direct-seeded upland and transplanted lowland ecosystems [5,9,10,11,12,13,14]. The studies indicate the importance of the QTL regions in improving current varieties for yield under drought following MAB and in developing new drought-tolerant varieties following marker-assisted selection (MAS), and in deciphering the physiological and molecular mechanisms behind the yield advantage conferred by these QTL
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
