Development of Rice Lines for Bacterial Leaf Blight Resistance using Backcross Method and Marker-assisted Selection

Abstract

Bacterial leaf blight (BLB) disease is caused by bacteria Xanthomonas oryzae pv. oryzae (Xoo). Infection of this disease can occur at all stages of rice plants from seedling to heading. It can make yield loss up to 80%. The utilization of resistant varieties has been considered to be one of the most effective ways to control the disease. At present, there are few BLB resistant rice varieties and it cannot broad spectrum resistant to BLB strains.The resistant varieties having different BLB resistant genes are associated with the different strains of the pathogen.It is necessary to improve rice varieties for widely resistance to BLB stains. Rice improvement for BLB disease resistance was conducted by crossing between a line (RGDU07097-1-MAS-8-9-B-1) with BLB disease resistance used as donor parent and a variety (CH1) with good plant type used as recurrent parent to produce F₁ hybrids. The F₁ plants were backcrossed to recurrent parent for production of BC₁F₁ and BC₂F₁ progenies. Selection was done using DNA markers specific to xa5 and Xa21 genes controlling BLB disease resistance in each backcross generations. The highest percentage of recurrent parent, CH1, from BC₂F₁ progeny of the cross was selected with genetic background was 98%, 96.5% and 92.5%, respectively. The selected BC₂F₁ plants were self-pollinated to produce BC₂F₂ progenies. The BC₂F₂ progenies obtained were tested for disease resistance.The result showed 9of 408 BC₂F₂ plants resistant to BLB disease.These lines can provide yield same as CH1 and BLB disease resisitance.