TITLE

2 n megagametophyte formed via SDR contributes to tetraploidization in polyembryonic 'Nadorcott' tangor crossed by citrus allotetraploids

AUTHOR(S)
Xie, Kai-Dong; Wang, Xiao-Pei; Biswas, Manosh; Liang, Wu-Jun; Xu, Qiang; Grosser, Jude; Guo, Wen-Wu
PUB. DATE
October 2014
SOURCE
Plant Cell Reports;Oct2014, Vol. 33 Issue 10, p1641
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Key Message: 2 n megagametophyte formation plays an important role in polyploidization in polyembryonic citrus and is valuable for plant improvement. Abstract: Tetraploid plants are frequently observed in the seedlings of diploid polyembryonic citrus genotypes. However, the mechanisms underlying the formation of tetraploids are still indistinct when apomictic citrus genotypes are used as female parent to cross with tetraploids. Herein, 54 tetraploid progenies, which were unexpectedly obtained previously from four 2 x × 4 x crosses using polyembryonic 'Nadorcott' tangor as seed parent, were analyzed by 22 simple sequence repeat (SSR) markers, aiming to reveal their genetic origin and the mechanism underlying 2 n megagametophyte formation. The results showed that 13 tetraploids from all these four crosses were doubled diploids as indicated by their identical SSR allelic profile with their female parent; while the remaining 41 tetraploids apparently exhibited paternally derived alleles, which confirmed their zygotic origin. Furthermore, the genotyping of all hybrids indicated that all of them arose from 2 n megagametophytes. Based on the genotypes of 2 n megagametophytes, the analysis of maternal heterozygosity restitution (HR) for each marker showed that it varied from 0.00 to 87.80 % with a mean value of 40.89 %. In addition, it was observed that 13 markers displayed a lower rate than 50 %. On the basis of the above results, it can be speculated that the second division restitution (SDR) is the mechanism underlying the 2 n megagametophyte formation in 'Nadorcott' tangor. The elucidation of the mechanism of 2 n megagametophyte formation will be of great help to optimize further sexual hybridization for polyploids in citrus.
ACCESSION #
98256390

 

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