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Wheat Information Service
Number 77: 13 - 18 (1993)


Intermeiocyte connections and cytomixis in intergeneric hybrids. II.
Triticum aestivum x Psathyrostachys huashanica Keng


Genlou Sun, Chi Yen and Junliang Yang

Triticeae Research institute, Sichuan Agricultural University, Dujiangyan city, Sichuan, China


Summary

The intergeneric F1 hybrid of Psathyrostachys huashanica Keng with Triticum aestivum L. cv. J-11 was produced and studied cytologically. Chromatin transfer through conjugation openings among microsporocytes was observed. The chromatin migration occurred at the chromonema stage of the prophase of meiotic PMCs and stage of resting nuclei of young pollen grain. The consequential, unusual nuclear behavior frequently occurred, such as coenocytism, high level chromosome multiplication, multipolar division, variation in size of pollen grain and appearance of aneuploid. These events could lead to the doubling of spontaneous chromosome number. The possible origin of autoallopolyploid and aneuploid plants by these processes is discussed in the paper.


Introduction

We had previously studied the intermeiocyte connections and cytomixis in intergeneric hybrids of Roegneria ciliaris (Trin.) Nevski with Psathyrostachys huashanica Keng. It was found that chromatin transferred through conjugation tube or conjugation opening before, during and after meiosis in the hybrid. Consequently, unusual nuclear behavior frequently observed included coenocytism, cell size variation and abnormal chromosome or nucleus number, non- synchronous or multipolar division, and delayed chromatin condensation (Yen et al. 1993).

In order to study biosystematic relationships between Triticum aestivum and Psathyrostachys huashanica Keng, we studied the microsporogenesis of their F1 hybrid. The variations in cell size and chromosome number per cell, the chromatin material migration among microsporocytes, and the formation of conjugation tube and opening were observed in Roegneria ciliaris x Psathyrostachys huashanica. In Triticum aestivum x P. huashanica F1 hybrid, all these phenomenona were also observed except the conjugation tube.

This paper reports descriptions of nuclear material transferring, coenocytism, chromosome number diminution and multiplication, and multipolar division in the F1 hybrids of Psathyrosachys huashanica with T. aestivum.


Materials and methods

Psathyrostachys huashanica Keng (2n=14, N
h Nh) used in this study was collected from the Huashan Mt., Shaanxi province, China. Triticum aestivum L. cv. J-11 (2n=42, AABBDD) is a selected strain of a landrace native to Sichuan province.

Hybridization was made by pollinating hand-emasculated spikes of T. aestivum cv. J-11 with pollen of P. huashanica. Immature hybrid embryos were cultured on N6 and C
17 media 16-17 days after pollination. The hybrid seedlings obtained were transplanted into soil pots when the seedlings reached the three leave stage.

For cytological observations, young spikes of the F1 hybrid were fixed in Carnoy's fluid. Chromosome numbers were counted at metaphase I of the PMCs. Microsporogenesis was studied on slides prepared by standard acetocarmine squashing.

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