QTL analysis of Na super(+)- and Cl super(-)-accumulation related traits in an intergeneric BC sub(1) progeny of Citrus and Poncirus under saline and nonsaline environments

• Published in: Genome Vol. 42; no. 4; pp. 692 - 705
• Main Authors: Tozlu, I, Guy, CL, Moore, G A
• Format: Journal Article
• Language: English
• Published: 01.08.1999
• Subjects: Citrus grandis; Poncirus trifoliata
• ISSN: 0831-2796; 1480-3321

The effects of salinization with 40 mM NaCl on Poncirus trifoliata (L.) Raf., Citrus grandis (L.) Osb., their F sub(1), and a BC sub(1) progeny population (C. grandis x (F sub(1))) were investigated by means of Na super(+) and C1 super(-) analyses and QTL (quantitative trait loci) mapping. A total of 38 traits related to different tissue or whole-plant Na super(+) and (or) Cl super(-) accumulation was analyzed in salinized and nonsalinized BC sub(1) progeny clones. The comparison of the three parental types with the BC sub(1) progeny under control and saline conditions showed that the BC sub(1) progeny plants segregated transgressively for many traits. First mapping analyses resulted in a total of 73 potential quantitative trait loci (PQTL) with LOD scores >=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 super(+) accumulation and Cl super(-)/Na super(+) ratios were located in a cluster at the beginning of one linkage group (LG), while 10 PQTLs mapped for Cl super(-) accumulation and Cl super(-)/Na super(+) 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.