|LI, XIAOBAI - Zhejiang University|
|YAN, WENGUI - Former ARS Employee|
|AGRAMA, HESHAM - Sultan Qaboos University|
|JIA, LIMENG - Zhejiang University|
|MOLDENHAUER, KAREN - University Of Arkansas|
|CORREA, FERNANDO - Rice Tec, Inc|
|WU, DIANXING - Zhejiang University|
Submitted to: Genes and Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2016
Publication Date: 3/7/2016
Citation: Li, X., Yan, W., Agrama, H., Jackson, A.K., Jia, M.H., Jia, L., Moldenhauer, K., Correa, F., Wu, D. 2016. Genetic analysis of genetic basis of a physiological disorder "straighthead’’ in rice (Oryza sativa L.). Genes and Genomics. doi: 10.1007/s13258-016-0394-6.
Interpretive Summary: Straighthead is a physiological disorder of rice in which the grain does not fill, leaving behind empty panicles with irregular shaped hulls void of any usable rice. In extreme cases the plant may fail to head and yield losses can be as high as 100 %. A variety of factors including high night time temperature, high temperature during seed set, and excess arsenic in the soil may contribute to straighthead. The most widely used strategy to prevent straighthead involves alternate flooding and drying of the rice field during a limited window of time while the rice is growing. However, the alternate flooding and drying cycles is costly for the farmer and can reduce the overall yield. A more cost efficient and environmentally friendly approach relies on growing varieties that are genetically less susceptible to straighthead. Our study used a mapping population to identify two genetic regions that contribute to straighthead resistance. Marker assisted selection can be used to incorporate these genetic regions into future breeding material to generate new rice varieties that confer straighthead resistance.
Technical Abstract: Straighthead is a physiological disorder in rice that causes yield losses and is a serious threat to rice production worldwide. Identification of QTL conferring resistance will help develop resistant cultivars for straighthead control. We conducted linkage mapping to identify QTL involved with straighthead. The study was based on a F2 population developed from a cross between ‘Zhe733(resistant)/R312(susceptible)’. Using phenotypic data of F2 plants and their F2:3 families, two major QTL, qSTH-2 and qSTH-8, were identified using bulked segregant analysis, explaining 11.1 and 28.1 % of the phenotypic variation on chromosome 2 and 8, respectively. The qSTH-2 for straighthead resistance was identified by linkage mapping. qSTH-2 was situated near a QTL responsible for arsenic accumulation. Straighthead is associated with plants that have high amounts of organic arsenic (DMA) in the grain. Additionally, the QTL qSTH-8 was located close to HD5 related with heading date. The close location may be associated with the observation of early heading among straighthead resistant varieties. These findings should be useful for further genetic study of straighthead.