Identification of QTLs for Salt Tolerance at the Germination and Seedling Stages in Rice

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.

Genetic Mapping to Detect Stringent QTLs Using 1k-RiCA SNP Genotyping Platform from the New Landrace Associated with Salt Tolerance at the Seedling Stage in Rice

“…The QTLs and their position reported in this study are different from other studies [ 8 , 50 , 51 , 74 , 75 , 76 ] except for qSL1 . Only qSL1 QTL shared the same map location.…”

“…In the sensitive parent, the value of Na + concentration was more than 0.10 mmolg −1 dwt, whereas the tolerant parent had 0.07 mmolg −1 dwt and a high Na + /K + ratio for salt-sensitive individuals, which was lower in salt-tolerant individuals. Water absorption is lower when Na + accumulation is higher; as a result, plant growth was extremely hampered since the enzymatic connection was disrupted in the plant cell, which also disrupted the proteins and ultimately caused the early death of the plant, reducing grain yield [ 8 , 47 , 48 , 49 , 50 , 51 ]. The tolerant set had a high survival (95%), but the sensitive set had a lower survival (50%).…”

“…In this study, the tolerant set had a high shoot length of 55.0 cm, ranging from 53.6 cm–56.4 cm, but the sensitive set had a lower shoot length of 28.85 cm. The tolerant individual had a higher shoot biomass (0.22 g), and the sensitive individual had a lower biomass (0.05 g), strongly supporting a larger amount of biomass and longer shoot length, which enhanced faster growth at the seedling stage where the Na + concentration was diluted in the plant tissue/body [ 8 , 50 , 51 , 52 ].…”

“…There was a negative correlation among the SES score with K + concentration, survival root length, and SPAD value; shoot length with SPAD value; and Na + /K + ratio with shoot length, K + concentration, SPAD value, and root length. In saline conditions, a higher amount of Na + concentration accumulates in the plant body, causing the early death of the plant and reducing the grain yield [ 8 , 47 , 48 , 49 , 50 , 51 ]. The relationship between the different variables helps us to select procedures in the plant breeding program.…”

Identification and Validation of QTLs for Yield and Yield Components under Long-Term Salt Stress Using IR64 CSSLs in the Genetic Background of Koshihikari and Their Backcross Progenies

“…Since salt tolerance is governed by quantitative trait loci (QTLs), to gain knowledge on salt tolerance mechanisms and for breeding purposes, intense efforts have been made regarding QTL mapping. Numerous QTLs were detected for salt tolerance at the seedling stage in rice [27][28][29][30][31][32][33][34][35][36]. Among them, a famous QTL, Saltol, with large effects was identified, and it has been used for developing salt-tolerant cultivars across many countries [37][38][39].…”