Endang M. Septiningsih, Nurul Hidayatun, Darlene L. Sanchez, Yudhistira Nugraha, Jerome Carandang, Alvaro M. Pamplona, Bertrand C. Y. Collar, Abdelbagi M. Ismail, David J. Mackill

Euphytica (2015) 202:259–268

Abstract

Submergence is an escalating problem in many rice producing areas. A submergence tolerance gene, SUB1, derived from FR13A was previously introduced into six mega varieties through marker assisted backcrossing (MABC) with the final product selected at the BC2 or BC3 generation. Their pheno-type was similar to the original varieties, but they could withstand complete inundation for up to 2 or 3 weeks. Several of these varieties have been released in South and Southeast Asia; nonetheless the devel-opment of additional submergence tolerant varieties is indispensable to provide farmers with diverse choices of varieties that are preferable for the local needs and to avoid ecological vulnerability due to planting only one variety across vast areas. To accelerate this effort, the SUB1gene has now been introgressed into two new popular varieties from Indonesia and the Philip-pines, i.e. Ciherang and PSB Rc18, respectively, through MABC using only one backcross (BC1) with the previously developed IR64-Sub1 as the donor. Since this new donor is closely related to both recurrent parents, a more rapid MABC approach can

be pursued due to the similarity of genetic back-grounds. Using this strategy, new submergence toler-ant varieties Ciherang-Sub1 and PSB Rc18-Sub1 were

developed in less than 2 years, presenting a promising approach to convert additional popular varieties in the future.

See: http://link.springer.com/journal/volumesAndIssues/10681

Fig. 1 Performance of six pairs of non-Sub1 and Sub1 lines in the IRRI submergence demo plot in 2014 dry season. The field plot was completely submerged for 25 days in early 2014 and then drained to allow the plants to recover. The pairs of varieties are as follows: Ciherang (C), Ciherang-Sub1 (C?), PSB Rc18 (P), PSB Rc18-Sub1 (P?), Swarna (S), Swarna-Sub1 (S?), IR64 (I), IR64-Sub1(I?), Samba Mahsuri (M), Samba Mahsuri-Sub1 (M?), BR11 (B), and BR11-Sub1 (B?)