Development of BC4F1 Rice Line of Rathu Heenati/KDML105 and Chai Nat 1 Carrying Bph3 Resistant Gene Against Brown Planthopper by Marker Assisted Selection

Abstract

Currently, the researches on improvement of rice varieties to resist the infestation of brown plant hopper have been in many steps of progress such as resistant gene discovery, gene transformation to the rice target variety, screening process, certified process and the Bph3 resistant gene transferred from Rathu Heenati/KDML105 to Chai Nat 1 was also in developing stage. F₁ lines from those parents carrying Bph3 gene were already produced and the backcross process needed to be carried out to increase the original traits of Chai  Nat  1 but Bph3  resistant  gene  was  still  retained  in  the improved line. Therefore,  the development of BC₄F₁ line of Rathu Heenati/KDML105 and Chai Nat 1 carrying Bph3 resistant gene against brown planthopper by marker assisted selection was carried out. The F₁ and backcross lines were backcrossed with Chai Nat 1 for 4 times to produce the series of backcross lines from BC₁F₁, BC₂F₁, BC₃F₁ and BC₄F₁. The genotype of the backcross lines produced in each time of backcrossing was screened by molecular markers RM170 and RM190 and also their phenotypes of those were evaluated by visualization. The BC₄F₁ improved lines carried heterozygous genotype of Bph3 with the high amount of original traits of Chai Nat 1 (96.875% theoretically) were collected at 20 plants after the 4^th backcrossing.