Expressed sequence tag （EST） analysis of the pulp of the red-fleshed mutant ＇Cara Cara＇ navel orange provided a starting point for gene discovery and transcriptome survey during citrus fruit maturation. interpretation of the EST datasets revealed that the mutant pulp transcriptome held a high section of stress responses related genes, such as the type III metallothionein-like gene （6.0%）, heat shock protein （2.8%）, Cu/Zn superoxide dismutase （0.8%）, late embryogenesis abundant protein 5 （0.8%）, etc. 133 transcripts were detected to be differentially expressed between the red mutant and its orange-color wild genotype ＇Washington＇ via digital expression analysis. Among them, genes involved in metabolism, defense/stress and signal transduction were statistical overrepresented. Fifteen transcription factors, composed of NAM, ATAF, and CUC transcription factor （NAC）; myeloblastosis （MYB）; myelocytomatosis （MYC）; basic helix-loop-helix （bHLH）; basic leucine zipper （bZIP） domain members, were also included. The data reflected the distinct expression profile and the unique regulatory module associated with these two genotypes. Eight differently expressed genes analyzed in digital were validated by quantitative real- time polymerase chain reaction. For structural polymorphism, both simple sequence repeats and single nucleotide polymorphisms （SNP） loci were surveyed; dinucleotide presentation revealed a bias toward AG/GA/TC/CT repeats （52.5%）, against GC/CG repeats （0%）. SNPs analysis found that transitions （73%） outnumbered transversions （27%）. Seventeen potential cultivar-specific and 387 heterozygous SNP loci were detected from ＇Cara Cara＇ and ＇Washington＇ EST pool.
Jun-Li Ye An-Dan Zhu Neng-Guo Tao Qiang Xu Juan Xu Xiu-Xin Deng
The red-flesh mutant Hong Anliu sweet orange is of high nutritional value due to its lycopene accumulation.Our previous studies on this mutant fruits suggested that photosynthesis and oxidative stress could promote the formation of mutation trait.However,leaf rather than fruit is the major part for some important biological processes such as photosynthesis.In this study,we analyzed the proteomic alteration in leaves of the red-flesh mutant Hong Anliu vs.its wild type （WT）.Ten differentially expressed proteins were identified,of which two were involved in photosynthesis,three in oxidative stress,two in defense,and three in metabolism.The high up-regulation of photosynthetic proteins proved the hypothesis that enhanced photosynthesis could provide and transport more substrates into mutant fruits for carotenoid biosynthesis.Similar to the previous results in fruits,anti-oxidative proteins were highly up-regulated in leaves,suggesting the whole plant of Hong Anliu suffered from enhanced oxidative stress.Proteins involved in defense and metabolism were also identified,and their possible roles in the mutation were discussed.
