Near-Isogenic Lines of Japonica Rice Revealed New QTLs for Cold Tolerance at Booting Stage

Abstract

Low temperature stress severely hampers rice productivity, and hence elaborating chilling-mediated physiochemical alterations and unravelling cold tolerance pathways will facilitate cold resilient rice breeding. Various cold tolerant Near-isogenic lines (NILs) selected at the booting stage through backcrossing of a japonica landrace Lijing2 (cold tolerant) with cold sensitive Towada (a japonica cultivar). The cold tolerance attributes of NILs was validated over two years by evaluating the spikelet fertility followed by correlation of nineteen morphological traits with the rate of seed setting (RSS). Results revealed BG, FG, 1-2IL, RSLL, and UIL were significantly correlated with RSS and had nearer marker interval distance with cold tolerance in QTL analysis. Two QTLs, qCTB-7-a and qCTB-7-b, were found for RSS based on a mixed linear model. Alleles of two QTLs were contributed by Lijing2 and genetic distances between the peaks were 0.00 and 0.06cM, which explained 5.70% and 8.36% variation, respectively, One QTL for 1-2IL, RSLL, and ILBS, while two QTLs for FG, BG, and UIL were also identified. These findings can be exploited to engineer low temperature stress tolerant rice in times of climate change.

QTL detection and fine mapping of qCTB1 for cold tolerance at the early seedling and booting stages in rice

“…There are various ways to evaluate the cold tolerance at the booting stage, including natural low temperature, short-term deep cold-water irrigation, longterm deep cold-water irrigation and artificial chamber environments. Natural low temperature and long-term deep cold-water irrigation are simple and effortsaving methods, that have been commonly used to evaluate cold tolerance at the booting stage (Xu et al, 2008;Sun et al, 2019). While short-term deep cold-water irrigation and an artificial chamber could better control the influence of factors such as heading date and external environment, and are especially suitable for the cold tolerance evaluation of the genetic populations with segregation at heading date (Ye et al, 2010;Xiao et al, 2018).…”

“…As a thermophilic crop evolving in tropical and subtropical areas, rice is sensitive to cold stress (Kovach et al, 2007). There are about 15 million hectares of fields under threat of cold stress in 24 rice-producing countries, including the major areas of Korea, Japan, and China (Sun et al, 2019). Estimates of 3-5 million tons of rice are lost annually due to cold stress (Zhu et al, 2015).…”

Evaluation of Toraja (Indonesia) local aromatic rice mutant developed using heavy-ion beam irradiation

“…To correctly assess the early heading date and high yield traits, putative mutant lines and wild type should be crossed. Segregating populations could be derived from crosses between near-isogenic lines which exhibited phenotypic characteristics (Sun et al 2019). They are much easier to analyze than those derived from remote crosses.…”

Responses of Flavonoids, Phenolics, and Antioxidant Activity in Rice Seedlings between Japonica and Indica Subtypes to Chilling Stress

“…Therefore, the breeding of rice tolerant to chilling stress is required for sustainable agriculture and food security in rice growing countries [13][14][15][16][17]18]. There were several quantitative trait loci (QTLs) involved in chilling stress have been isolated and cloned [19][20][21], however introduction of these genes into commercial rice has not been yet approached. The search for compounds in rice which involve in the mechanism of chilling mechanism might be more potential, because the application of these constituents on rice plants during either the vegetative or productive stages might be more promising.…”