Abstract
BackgroundAs an important biofuel plant, the demand for higher yield Jatropha curcas L. is rapidly increasing. However, genetic analysis of Jatropha and molecular breeding for higher yield have been hampered by the limited number of molecular markers available.ResultsAn ultrahigh-density linkage map for a Jatropha mapping population of 153 individuals was constructed and covered 1380.58 cM of the Jatropha genome, with average marker density of 0.403 cM. The genetic linkage map consisted of 3422 SNP and indel markers, which clustered into 11 linkage groups. With this map, 13 repeatable QTLs (reQTLs) for fruit yield traits were identified. Ten reQTLs, qNF-1, qNF-2a, qNF-2b, qNF-2c, qNF-3, qNF-4, qNF-6, qNF-7a, qNF-7b and qNF-8, that control the number of fruits (NF) mapped to LGs 1, 2, 3, 4, 6, 7 and 8, whereas three reQTLs, qTWF-1, qTWF-2 and qTWF-3, that control the total weight of fruits (TWF) mapped to LGs 1, 2 and 3, respectively. It is interesting that there are two candidate critical genes, which may regulate Jatropha fruit yield. We also identified three pleiotropic reQTL pairs associated with both the NF and TWF traits.ConclusionThis study is the first to report an ultrahigh-density Jatropha genetic linkage map construction, and the markers used in this study showed great potential for QTL mapping. Thirteen fruit-yield reQTLs and two important candidate genes were identified based on this linkage map. This genetic linkage map will be a useful tool for the localization of other economically important QTLs and candidate genes for Jatropha.
Highlights
As an important biofuel plant, the demand for higher yield Jatropha curcas L. is rapidly increasing
In this study, we only found repeatable QTLs (reQTLs) associated with the number and the total weight of fruits, but no reQTL was associated with average fruit weight per fruit, which may indicate that these reQTLs affect the fruit yield by the number of fruits, and the total fruit weight, rather than the average fruit weight per fruit
Our understanding of the genetic architecture of traits in J. curcas is increasing with the development of new analytical methods
Summary
As an important biofuel plant, the demand for higher yield Jatropha curcas L. is rapidly increasing. Jatropha curcas L., characterized by drought resistance, low cost of planting, fast growth rate and high oil content, is one of the highest potential energy plants among oil-bearing tree species [3, 4]. Increasing yield or oil content is the most important breeding objective for J. curcas researchers. Jatropha curcas is a native plant, originated in Mexico and Central America. A previously reported genome sequence of J. curcas was 285.9 Mb, with the mean and N50 scaffold lengths of 1.9 and 3.8 kb, respectively [8]. An upgraded J. curcas genome sequence was 397 Mb, and the mean and N50 scaffold lengths were 7.6 and 16.0 kb, respectively [9].
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