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Title:	Pyramiding of quantitative trait loci for grain yield under drought into elite Malaysia rice cultivars using marker assisted breeding
Authors:	Noraziyah Abd Aziz Shamsudin (P52192)
Supervisor:	Wickneswari Ratnam, Prof. Dr.
Keywords:	Pyramiding of quantitative trait Quantitative trait loci Grain yield under drought Elite Malaysia rice cultivars Marker assisted breeding Malaysia Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	21-Jul-2014
Description:	Identification of major quantitative trait loci (QTLs), qDTY1.1, qDTY2.2, qDTY3.1, qDTY6.1 and qDTY12.1 with consistent effect on grain yield (GY) under reproductive stage drought stress (RS) has been recently reported at International Rice Research Institute (IRRI). With the objective to improve GY of elite Malaysia rice cultivars under RS for lowland ecosystem, three drought yield QTLs (qDTYs), qDTY2.2, qDTY3.1 and qDTY12.1 were pyramided into MR219 and MRQ74 by marker assisted breeding (MAB). In every generation, foreground selection was performed using RM236, RM12460, RM520 and RM511, the specific marker for qDTY2.2, qDTY3.1 and qDTY12.1, followed by recombinant selection using tightly-linked flanking markers in each target region to minimize the linkage drag. Background selection was conducted for selected plants in BC1F1 generation for fast recover of recipient parent genome. A total of 429 BC1F3 pyramided lines (PLs) with different combinations of qDTY2.2, qDTY3.1 and qDTY12.1 in the backgrounds of MR219 and MRQ74 were developed and evaluated under RS and non-stress (NS) in dry season (DS) of 2013 at IRRI. The GY reductions in RS trials compared to NS trials ranged from 79 to 93%. Plant height (PH) and GY were reduced, and days to flowering (DTF) were delayed under RS as compared to NS. The study also indicated that under RS and NS, the GY was positively correlated to PH but negatively correlated DTF. The recorded mean of GY under RS for MRQ74 was 55 kg ha-1 and 579 kg ha-1, while MR219 did not produce GY. Under NS condition, the mean of GY of MR219 was 5917 kg ha-1 and 6639 kg ha-1 while MRQ74 was 4044 kg ha-1 and 4302 kg ha-1. 37 selected MR219 PLs and 24 selected MRQ74 PLs shows a yield advantage of 1026 to 2805 kg ha-1 and 1203 to 2930 kg ha-1over their recipient parent under RS condition. GY under NS ranging from 5017 to 9364 kg ha-1 for selected MR219 PLs and ranging from 3504 to 6023 kg ha-1 for selected MRQ74 PLs. IR99784-255-78, IR99784-255-49, IR99784-156-95, IR99784-255-91 IR99784-255-55, are the best five PLs under MR219 background with GY ranging from 2073 to 2805 kg ha-1 under RS and 5017 to 8525 kg ha-1 under NS, respectively. IR98008-103-445, IR99616-44-103, IR99616-44-145, IR98010- 202-68 and IR98010-260-56 with the GY ranging from 2271 to 2930 kg ha-1 under RS and 3504 to 5824 kg ha-1 under NS, are the top five PLs under MRQ74 background. MR219 PLs with two qDTYs (qDTY2.2 and qDTY3.1) and MRQ74 PLs with also two qDTYs (qDTY3.1 and qDTY12.1) performed better than PLs with other qDTY combinations indicating the present of positive interaction between qDTY3.1 with qDTY2.2 and qDTY12.1. However, results also proves the non-linear interaction among qDTYs combinations and the efficiency of introgressed qDTY was depends on ecotype of the donor and recipient parents as well as the environment conditions (RS or NS). Overall, reduction in GY under RS condition in PLs was lower than their recipient parent indicating that PLs with qDTYs were more tolerance to drought. Differential yield advantages of different combinations of the qDTYs reported in this study indicate a differential synergistic relationship among qDTY combinations. The study proved marker assisted QTL pyramiding to be an effective strategy to transfer and pyramid several qDTYs from donor parents to mega-varieties.,PhD
Pages:	196
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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