Improvement of Salt Tolerance Using Wild Rice Genes

Abstract

Salt stress causes significant reductions in rice production worldwide; thus, improving salt tolerance is a promising approach to meet the increasing food demand. Wild rice germplasm is considered a valuable genetic resource for improving rice cultivars. However, information regarding the improvement of salt tolerance in cultivated rice using wild rice genes is limited. In this study, we identified a salt-tolerant line Dongxiang/Ningjing 15 (DJ15) under salt-stress field conditions from the population of a salt tolerant Dongxiang wild rice × a cultivated rice variety Ningjing16 (NJ16). Genomic resequencing analysis of NJ16, DJ15 and Dongxiang wild rice revealed that the introgressed genomic fragments were unevenly distributed over the 12 chromosomes (Chr.) and mainly identified on Chr. 6, 7, 10, and 11. Using quantitative trait locus (QTL) mapping, we found 9 QTL for salt tolerance (qST) at the seedling stage located on Chr. 1, 3, 4, 5, 6, 8, and 10. In addition, sequence variant analysis within the QTL regions demonstrated that SKC1/HKT8/HKT1;5 and HAK6 transporters along with numerous transcriptional factors were the candidate genes for the salt tolerant QTL. The DJ15/Koshihikari recombinant inbred lines that contained both qST1.2 and qST6, two QTL with the highest effect for salt tolerance, were more tolerant than the parental lines under salt-stress field conditions. Furthermore, the qST6 near-isogenic lines with IR29 background were more tolerant than IR29, indicating that qST1.2 and qST6 could improve salt tolerance in rice. Overall, our study indicates that wild rice genes could markedly improve the salt tolerance of cultivated rice.

Back to the Wild: On a Quest for Donors Toward Salinity Tolerant Rice

“…Ganeshan et al (2016) showed that crosses between O. sativa and O. rufipogon or O. nivara could result in salinity tolerance. Hybrids of O. rufipogon × O. sativa were found to contain nine quantitative trait loci (QTL) and candidate genes (e.g., HKT1;5, HAK6 and some transcriptional factors) controlling the salt tolerance at the seedling stage (Quan et al, 2018), and 13 of 15 QTLs for salinity tolerance found were from O. rufipogon (Tian et al, 2011). Wang et al (2017) identified 10 QTLs for salt tolerance from introgression lines derived from O. rufipogon and O. sativa (cv.…”

“…RNA-sequencing found four differentially expressed genes, OsGH3-2, OsGH3-8, CML15, and GEM, located in these QTL regions from O. rufipogon. Recombinant inbred lines (RILs) also derived from a cross of O. rufipogon × O. sativa showed superior performance with respect to salinity stress (Quan et al, 2018). The cultivated varieties, BRRI Dhan 55(AS996), in Bangladesh and DRR Dhan 40, Jaraya and Chinsurah Nona 2 in India have been released after interspecific hybridization with O. rufipogon or O. nivara (Supplementary Table S1).…”

Identification of new QTL for salt tolerance from rice variety Pokkali

“…For instance, qRSKC1.1 , qSNaC1.1 , qSKNa1 , qRNaC1 and qRKNa1 were located within the Saltol segment (11.0 Mb‒12.2 Mb) on chromosome 1 (Thomson et al, ), and the nearest bin marker Bin1_11.35‐11.50 harboured the SKC1 gene (11.46 Mb) (Ren et al, ). Furthermore, qSIS1 , qRSKC1.2 and qSNaC1.2 on chromosome 1 were co‐localized with qSIS1.39 (39.5 Mb) detected in a set of introgression lines of Pokkali as donor (De Leon et al, ) and qST1.1 (40.3 Mb) from a salt‐tolerant Dongxiang wild rice (Quan et al, ). This region is also close to OsHAK5 (40.8 Mb), OsHAK6 (40.9 Mb) and OsHAK2 (41.1 Mb) which encode high‐affinity potassium transporters mediating K + uptake (Banuelos, Garciadeblas, Cubero, & Rodriguez‐Navarro, ; Horie et al, ).…”

Natural variation at OsCERK1 regulates arbuscular mycorrhizal symbiosis in rice

“…However, Dongxiang county in Jiangxi province is the northernmost region of China where a large population of wild rice varieties exist and may have played a critical role in the evolution of indica rice as a source of gene evolution for better survival and growth under stress conditions (Xie et al ., ; Zhang et al ., ). Indeed, wild rice from Dongxiang county maintains agronomically important traits such as infertility and stress tolerance (Shen et al ., ; Zhang et al ., ; Quan et al ., ; Deng et al ., ). Therefore, this area serves as an important genetic resource for rice breeding (Zhang et al ., ).…”