Abstract
Rice is highly sensitive to salinity stress during the seedling establishment phase. Salt stress is widely occurring in cultivated areas and severely affects seed germination ability and seedling establishment, which may result in a complete crop failure. The objective of the present study is to identify quantitative trait loci (QTLs) related to salt tolerance of the germination and seedling stages in a rice backcross inbred line (BIL) population that was derived from a backcross of an Africa rice ACC9 as donor and indica cultivar Zhenshan97 (ZS97) as the recurrent parent. Under salt stress, ACC9 exhibited a higher germination percentage, but more repressed seedling growth than ZS97. Using the BIL population, 23 loci for germination parameters were detected at the germination stage and 46 loci were identified for several morphological and physiological parameters at the seedling stage. Among them, nine and 33 loci with the ACC9 alleles increased salt tolerance at the germination and seedling stages, respectively. Moreover, several major QTLs were found to be co-localized in the same or overlapping regions of previously reported genes for salt stress. These major loci will facilitate improving salt-tolerance rice in genome-breeding programs.
Highlights
The world population is estimated to increase by more than two billion in the 30 years while agricultural areas are facing a real decrease [1]
The seed germination parameters (GR-3d, Germination rate (GR)-7d) of Africa rice IRGC96717 (ACC9) and Zhenshan 97 (ZS97) were similar under control conditions (CK) (Figure 1A); under salt stress (18 dS m−1 NaCl), ACC9 displayed better performance in terms of germination percentage than ZS97 (Figure 1B,C)
ACC9 showed a significantly lower germination index (GI) than ZS97 under CK, but an opposite pattern was observed under salt stress (Figure 1D)
Summary
The world population is estimated to increase by more than two billion in the 30 years while agricultural areas are facing a real decrease [1]. Drought and salinity are the most serious factors that affect rice production worldwide [2]. It is estimated that more than 7% of arable land areas for crop cultivation are affected by salinity due to improper irrigation and fertilizer abuse [3]. Rice is one of the staple foods for two-thirds of the world population [4]. The increase in food production, rice production, is urgent to meet the demand of the growing population. To increase rice production of saline-affected areas, identification of quantitative trait loci (QTLs) associated with salt tolerance is an essential step for the improvement in varieties of salt-tolerant rice
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