Meiotic nondisjunction in resynthesized <Emphasis Type="Italic">Brassica napus</Emphasis> and generation of aneuploids through microspore culture and their characterization |
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Authors: | Jing Wen Xin-hua Zeng Yuan-yuan Pu Li-ping Qi Zai-yun Li Jin-xing Tu Chao-zhi Ma Jin-xiong Shen Ting-dong Fu |
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Institution: | (1) National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement, Huazhong Agricultural University, Wuhan, 430070, People’s Republic of China; |
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Abstract: | Meiotic nondisjunction during microsporegenesis can lead to aneuploid gametes formation and reduced pollen fertility in plants.
This paper reports the prevalence of meiosis I nondisjunction in a resynthesized Brassica napus (AACC, 2n = 38) and its use for aneuploid production. Meiosis in the amphidiploids was characterized by high frequencies of univalents
and multivalents per PMC at diakinesis/metaphase I and notably unbalanced chromosome segregations at anaphase I (AI). In all
the plants observed, 18.95–44.3% of PMCs exhibited a segregation of 18:20 (n − 1:n + 1) at AI which was caused by nondisjunction of one bivalent or the distribution of two homologous univalents to the same
pole. Meiosis proceeded normally after AI then, thus led to the formation of viable n − 1 and n + 1 gametes and high pollen fertility of these plants. Microspore culture was subsequently carried out using these plants
in an attempt to isolate Brassica nullisomics. Four nullisomics (2n = 36), two nullihaploids (2n = 18) and one tetrasomic haploid (2n = 20) were identified cytologically and characterized morphologicaly and physiologically. Amplified fragment length polymorphism
(AFLP) survey suggested that of the six nullisomics/nullihaploids, one nullihaploids lost one A-genome chromosome and the
other five lost C genome chromosome(s). Altogether, different C-genome chromosomes were thought to have been lost in the nullisomics/nullihaploids.
The mechanisms underlying the meiotic abnormalities and the implications of these B. napus nullisomics are discussed. |
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