QTL analysis of Na+ and Cl- accumulation related traits in an intergeneric BC1 progeny of Citrus and Poncirus under saline and nonsaline environments

Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 692-705 ◽  
Author(s):  
Ilhami Tozlu ◽  
Charles L Guy ◽  
Gloria A Moore

The effects of salinization with 40 mM NaCl on Poncirus trifoliata (L.) Raf., Citrus grandis (L.) Osb., their F1, and a BC1 progeny population (C. grandis × (F1)) were investigated by means of Na+ and Cl- analyses and QTL (quantitative trait loci) mapping. A total of 38 traits related to different tissue or whole-plant Na+ and (or) Cl- accumulation was analyzed in salinized and nonsalinized BC1 progeny clones. The comparison of the three parental types with the BC1 progeny under control and saline conditions showed that the BC1 progeny plants segregated transgressively for many traits. First mapping analyses resulted in a total of 73 potential quantitative trait loci (PQTL) with LOD scores [Formula: see text]3.0 located on a previously generated linkage map. Fifty-three percent of the mapped PQTLs were for traits associated with salinity. The small progeny population size used made further analyses of these PQTLs necessary. By considering LOD scores, map locations, and correlation analyses of the traits, it was possible to identify 17 regions of the citrus genome of interest: 8 of them may contain genuine QTLs of large effect and 9 regions are worthy of further study. Correlation analyses and locations of PQTLs indicated that many traits were controlled by fewer genes than the actual number of QTLs mapped for them. For example, 21 PQTLs mapped for Na+ accumulation and Cl-/Na+ ratios were located in a cluster at the beginning of one linkage group (LG), while 10 PQTLs mapped for Cl- accumulation and Cl-/Na+ ratios were located in a cluster at the beginning of another LG. This is the first step in identifying QTLs that have a major impact on salt tolerance and (or) mineral accumulation in citrus.Key words: Citrus grandis, Poncirus trifoliata, salinity stress, QTL mapping, transgressive segregation, mineral analysis, sodium, chloride, salt tolerance, citrus genetics.

Genome ◽  
1999 ◽  
Vol 42 (5) ◽  
pp. 1020-1029 ◽  
Author(s):  
Ilhami Tozlu ◽  
Charles L Guy ◽  
Gloria A Moore

The effects of salinization with 40 mM sodium chloride on Poncirus trifoliata (L.) Raf., Citrus grandis (L.) Osb., their F1, and a BC1 progeny population [C. grandis × (F1)] were investigated by measuring growth and dry mass production of different tissues and by QTL (quantitative trait locus) mapping. A total of 36 traits related to growth (six traits) and tissue or whole plant dry mass production (30 traits) in salinized and non-salinized BC1 progeny clones were evaluated. The comparison of the three parental types to the BC1 progeny under control and saline conditions showed that the BC1 progeny plants segregated transgressively for many of these traits. Mapping analyses of these quantitative traits resulted in a total of 70 potential quantitative trait loci (PQTL) with LOD scores greater than or equal to 3.0 located on a previously generated linkage map. Sixty-nine percent of the mapped PQTLs were for traits associated with salinity. The small progeny population size used made further analyses of these PQTLs necessary. By considering LOD scores, map locations, and correlation analyses of the traits, it was possible to identify 16 regions of the citrus genome of interest, six of which were involved in both growth and dry mass production. Correlation analyses and locations of PQTLs indicated that many of these regions may contain one or a few genuine QTLs of large effect. This is a first step in identifying QTLs that have a major impact on growth and dry mass production in Citrus under both optimum and stressful environments.Key words: Citrus grandis, Poncirus trifoliata, salinity stress, QTL mapping, morphological traits, transgressive segregation, NaCl, sodium, chloride, salt tolerance, citrus genetics, breeding.


Plants ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 33 ◽  
Author(s):  
Md. Islam ◽  
John Ontoy ◽  
Prasanta Subudhi

Soil and water salinity is one of the major abiotic stresses that reduce growth and productivity in major food crops including rice. The lack of congruence of salt tolerance quantitative trait loci (QTLs) in multiple genetic backgrounds and multiple environments is a major hindrance for undertaking marker-assisted selection (MAS). A genome-wide meta-analysis of QTLs controlling seedling-stage salt tolerance was conducted in rice using QTL information from 12 studies. Using a consensus map, 11 meta-QTLs for three traits with smaller confidence intervals were localized on chromosomes 1 and 2. The phenotypic variance of 3 meta-QTLs was ≥20%. Based on phenotyping of 56 diverse genotypes and breeding lines, six salt-tolerant genotypes (Bharathy, I Kung Ban 4-2 Mutant, Langmanbi, Fatehpur 3, CT-329, and IARI 5823) were identified. The perusal of the meta-QTL regions revealed several candidate genes associated with salt-tolerance attributes. The lack of association between meta-QTL linked markers and the level of salt tolerance could be due to the low resolution of meta-QTL regions and the genetic complexity of salt tolerance. The meta-QTLs identified in this study will be useful not only for MAS and pyramiding, but will also accelerate the fine mapping and cloning of candidate genes associated with salt-tolerance mechanisms in rice.


Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 620
Author(s):  
Noppawan Nounjan ◽  
Wuttipong Mahakham ◽  
Jonaliza L. Siangliw ◽  
Theerayut Toojinda ◽  
Piyada Theerakulpisut

Jasmine rice (Oryza sativa L.), or Khao Dawk Mali 105 (KDML105), is sensitive to drought and salt stresses. In this study, two improved drought-tolerant chromosome segment substitution lines (CSSLs) of KDML105 (CSSL8-103 and CSSL8-106), which carry drought tolerance quantitative trait loci (QTLs) on chromosome 8, were evaluated for salt tolerance and were compared with KDML105 and the QTL donor DH103, their parents and the salt-tolerant genotype Pokkali. After being subjected to salt stress for 6 days, 3-week-old seedlings of Pokkali showed the highest salt tolerance. Parameters related to photosynthesis were less inhibited in both CSSLs and the donor DH103, while these parameters were more severely damaged in the recurrent parent KDML105. Albeit a high ratio of Na+/K+, CSSLs and DH103 showed similar or higher contents of soluble sugar and activity of superoxide dismutase (SOD; EC1.15.1.1) compared with Pokkali, indicating possible mechanisms of either tissue or osmotic tolerance in these plants. The expression of a putative gene Os08g41990 (aminotransferase), which is located in DT-QTL and is involved in chlorophyll biosynthesis, significantly decreased under salt stress in KDML105 and CSSL8-103, while no obvious change in the expression of this gene was observed in Pokkali, DH103 and CSSL8-106. This gene might play a role in maintaining chlorophyll content under stress conditions. Taken together, the results of this study indicate that DT-QTL could contribute to the enhancement of photosynthetic performance in CSSL lines, leading to changes in their physiological ability to tolerate salinity stress.


2001 ◽  
Vol 125 (1) ◽  
pp. 406-422 ◽  
Author(s):  
Mikiko L. Koyama ◽  
Aurora Levesley ◽  
Robert M.D. Koebner ◽  
Timothy J. Flowers ◽  
Anthony R. Yeo

2003 ◽  
Vol 128 (4) ◽  
pp. 508-514 ◽  
Author(s):  
Courtney A. Weber ◽  
Gloria A. Moore ◽  
Zhanao Deng ◽  
Fred G. Gmitter

Mapping quantitative trait loci (QTL) associated with freeze tolerance was accomplished using a Citrus grandis (L.) Osb. × Poncirus trifoliata (L.) Raf. F1 pseudo-testcross population. A progeny population of 442 plants was acclimated and exposed to temperatures of -9 °C and -15 °C in two separate freeze tests. A subpopulation of 99 progeny was genotyped for random amplified polymorphic DNA (RAPD), cleaved amplified polymorphic sequence (CAPS), sequence characterized amplified region (SCAR), and sequence tagged site (STS) markers to produce a linkage map for each parent. Potential QTL were identified by interval mapping, and their validity was corroborated with results from means comparison (t test), one-way analysis of variance (F test), and bulked segregant analysis (BSA). Multiple analytical methods provided evidence supporting putative QTL and decreased the probability of missing significant QTL associated with freeze tolerance. QTL with a large effect on freeze tolerance were located on both the Citrus and Poncirus linkage maps. In addition, clusters of markers with significantly different means between marker present and absent classes indicating minor QTL that contribute smaller effects on the level of tolerance were found on the linkage maps of both species.


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