Screening of resistant Indonesian black rice cultivars against bacterial leaf blight

Abstract

Black rice production in Indonesia constrained by the bacterial blight disease (BLB) caused by Xanthomonas oryzae pv. oryzae pathotype IV (Xoo). Breeding of BLB resistant cultivars is considered the most sustainable method for BLB disease control, both from an environmental and agricultural perspective. Indonesia has many local black rice varieties that can be used as genes resource to support breeding program producing resistant cultivars. The present research focuses on screening local Indonesian black rice cultivars for resistance against BLB and analyzing the expression of these resistance genes in black rice after inoculation with Xoo. The black rice cultivars Cempo Ireng, Pari Ireng, Melik, Pendek, and Indmira, were inoculated with Xoo while white rice cv. Conde, IRBB21, IR64, and Java14 were used as controls. We assayed the phenotypic performance of the cultivars samples after Xoo inoculation and analyzed their resistance gene expression at 24 and 96 h after Xoo inoculation semiquantitatively. The cultivar showed the best performance was selected for further analysis of the resistance genes using Real-time quantitative PCR. Cempo Ireng was indicated the most resistant cultivar against BLB disease based on the lowest disease intensity and Area Under Disease Progress Curve (AUDPC) value. Cempo Ireng expressed resistant genes xa5, Xa10, Xa21 and RPP13-like after inoculation of Xoo. The expression of xa5, Xa10, and Xa21 was up-regulated while that of RPP13-like was down-regulated in Cempo Ireng.