Construction of an anchoring SSR marker genetic linkage map and detection of a sex-linked region in two dioecious populations of red bayberry

Red bayberry(Morella rubra)is an evergreen fruit tree found in southern China whose whole-genome sequence has recently been published.We updated the linkage map of the species by adding 118 SSR markers and the femalespecific marker MrFT2_BD-SEX.The integrated map included eight linkage groups and spanned 491 cM.Eleven sexassociated markers were identified,six of which were located in linkage group 8,in agreement with the previously reported location of the sex-determining region.The MrFT2_BD-SEX marker was genotyped in 203 cultivated accessions.Among the females of the accessions,we found two female-specific alleles,designated W-b(151 bp)and W-d(129 bp).We previously found that‘Dongkui’,a female cultivar,could produce viable pollen(we refer to such plants‘Dongkui-male’)and serve as the paternal parent in crosses.The genotypes of the MrFT2_BD-SEX marker were W-b/Z in‘Biqi’and W-d/Z in‘Dongkui-male’.The progeny of a cross between these parents produced a 3:1 female(W-)to male(ZZ)ratio and the expected 1:1:1:1 ratio of W-b/W-d:W-b/Z:W-d/Z:Z/Z.In addition,the flowering and fruiting phenotypes of all the F1 progeny fit their genotypes.Our results confirm the existence of ZW sex determination and show that the female phenotype is controlled by a single dominant locus(W)in a small genomic region(59 kb and less than 3.3 cM).Furthermore,we have produced a homozygous“super female”(WW)that should produce all-female offspring in the F2 generation,providing a foundation for commercial use and presenting great potential for use in modern breeding programs.

Development of 107 SSR markers from whole genome shotgun sequences of Chinese bayberry(Myrica rubra) and their application in seedling identification

Chinese bayberry （Myrica rubra Sieb. et Zucc.） is one of the important subtropical fruit crops native to the South of China and Asian countries. In this study, 107 novel simple sequence repeat （SSR） molecular markers, a powerful tool for genetic diversity studies, cultivar identification, and linkage map construction, were developed and characterized from whole genome shotgun sequences. M13 tailing for forward primers was applied as a simple method in different situations. In total, 828 alleles across 45 accessions were detected, with an average of 8 alleles per locus. The number of effective alleles ranged from 1.22 to 10.41 with an average of 4.08. The polymorphic information content （PIC） varied from 0.13 to 0.89, with an average of 0.63. Moreover, these markers could also be amplified in their related species Myrica cerifera （syn. More/la cerifera） and Myrica adenophora. Seventy-eight SSR markers can be used to produce a genetic map of a cross between ＇Biqi＇ and ＇Dongkui＇. A neighbor-joining （N J） tree was con- structed to assess the genetic relationships among accessions, and the elite accessions ＇Y2010-70＇, ＇Y2012-140＇, and ＇Y2012-145＇, were characterized as potential new genotypes for cultivation.

Anaphylaxis and generalized urticaria from eating Chinese bayberry fruit

Chinese bayberry Myrica rubra is a very popular fruit in southeastern China.In spite of its wide consumption,no allergies to this fruit have been reported previously.Here we report on a 40-year-old woman suffering from anaphylaxis to Chinese bayberry fruit.Prick-prick skin tests revealed strong reactions to fresh Chinese bayberry fruits as well as to peach,and weaker reactions to some other fruits including apple,melon,and banana.ImmunoCAP analysis revealed identical titers of specific IgE(4.3 kU A /L) to peach extract and its lipid transfer protein(LTP,rPru p 3),which was confirmed by detection of a 9 kD band following immunoblotting.Immunoblot analysis with Chinese bayberry extract gave bands of 22,45,and 90 kD,but no 9 kD band was recognized.There was also no evidence of LTP recognition for loquat(36 kD) or melon(24 kD).This first report of a severe allergic reaction to Chinese bayberry fruit in a patient with LTP-mediated peach allergy indicates that other as yet unidentified non-pollen related fruit allergens are involved in this new severe fruit allergy.