Genetic analysis and QTL detection for resistance to white tip disease in rice.

Tong Zhou,Yongjian Fan,Hui Feng,Ying Lan,Cunyi Gao,Feng Sun,Lihui Wei,Lijiao Wang,Yijun Zhou,Linlin Du,Wenbiao Shen,Tai Wang

doi:10.1371/journal.pone.0106099

Abstract

The inheritance of resistance to white tip disease (WTDR) in rice (Oryza sativa L.) was analyzed with an artificial inoculation test in a segregating population derived from the cross between Tetep, a highly resistant variety that was identified in a previous study, and a susceptible cultivar. Three resistance-associated traits, including the number of Aphelenchoides besseyi (A. besseyi) individuals in 100 grains (NA), the loss rate of panicle weight (LRPW) and the loss rate of the total grains per panicle (LRGPP) were analyzed for the detection of the quantitative trait locus (QTL) in the population after construction of a genetic map. Six QTLs distributed on chromosomes 3, 5 and 9 were mapped. qNA3 and qNA9, conferring reproduction number of A. besseyi in the panicle, accounted for 16.91% and 12.54% of the total phenotypic variance, respectively. qDRPW5a and qDRPW5b, associated with yield loss, were located at two adjacent marker intervals on chromosome 5 and explained 14.15% and 14.59% of the total phenotypic variation and possessed LOD values of 3.40 and 3.39, respectively. qDRPW9 was considered as a minor QTL and only explained 1.02% of the phenotypic variation. qLRGPP5 contributed to the loss in the number of grains and explained 10.91% of the phenotypic variation. This study provides useful information for the breeding of resistant cultivars against white tip disease in rice.

Highlights

White tip disease of rice (WTDR), which is caused by the rice white tip nematode (Aphelenchoides besseyi, A. besseyi), is one of the most serious nematode diseases affecting rice worldwide [1,2,3,4,5]
Phenotypic variation A dramatic difference in NA, loss rate of panicle weight (LRPW) and LRGPP was observed between Huaidao No.5 and Tetep (Table 1)
The relative yield loss was preferentially used in this study to evaluate the resistance level of plants against WTDR, which was described by the LRPW

Summary

Introduction

White tip disease of rice (WTDR), which is caused by the rice white tip nematode (Aphelenchoides besseyi, A. besseyi), is one of the most serious nematode diseases affecting rice worldwide [1,2,3,4,5]. The development of resistant rice cultivars has been considered as the primary strategy for controlling white tip disease [6,7]. Many nematode resistance loci, such as H1, GroV1, Cre and Mi3, have been identified in tomato, potato, soybean and other crops [11,12,13,14], and some have even been cloned and functionally analyzed [15,16,17,18]. A gene (Has-1Og) resistant to the cyst nematode (Heterodera sacchari) has been identified in rice [19]. These results suggested that host plants, including rice, harbored defense mechanisms to fight against nematodes, and these mechanisms have developed over long-term co-evolution. Elucidating the resistance mechanisms involved will contribute to a better understanding of nematodeplant interactions and assist with the breeding of nematoderesistant cultivars [20]

Methods

Results

Conclusion