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Wheat Information Service
December 79: 24 -27 (1994)

Intermeiocyte connections and cytomixis in intergeneric hybrids III: Roegneria tsukushiensis x Psathyrostachys huashanica

Genlou Sun, Chi Yen and Junliang Yang

Triticeae Research Institute, Sichuan Agricultural University, Dujiangyan City, Sichuan, China

Summary

The F1 intergeneric hybrid of Roegneria tsukushiensi (Honda) B.R.Lu et J.L. Yang with Psathyrostachys huashanica Keng was made and studied cytologically. Conjugation openings were observed. Intercellular migration of chromatin material led to the formation of coenocytism and variation in cell size. These events could lead to spontaneous variation in chromosome numbers. As a possible consequence of migration of chromatin materials, polyploid and aneuploid PMCs appeared. It may combine two different gene pools. There is possibility for transferring drought resistance character from P. huashanica into R. tsukushiensis by chromatin migration among cells. The observed result in this hybrid supports further that Nh genome of P. huashanica has a genetic system for controlling this process.

Key words: Cytomixis; Conjugation opening; Aneuploid; PolypIoid; Variation in chromosome number, Roegneria tsukushiensis, Psathyrostachys huashanica

Introduction

Roegneria tsukushiensis is one of a few good forage grass in Triticeae in South Subtropic region of Far East, but it lacks resistance to drought. Psathyrostachys huashanica Keng is a diploid perennial species. It is restricted to a narrow region in the Huashan Mountain of central China where it occurs on mountain slopes, but is a hardened and drought resistant plant. The intergeneric cross of the R. tsukushiensis with P. huashanica, was made. The intergeneric F1 hybrid was studied cytologically.

We had previously studied the intermeiocyte connections and cytomixis in intergeneric hybrids of Roegneria ciliaris (Trin.) Nevski, Aegilops tauschii Cosson and Triticum aestivum L. with P. huashanica (Sun et al. 1992, 1993b; Yen et al. 1993). It was found that chromatin was transferred through conjugation opening or tube before, during and after meiosis in these hybrids. Consequently, unusual nuclear behavior frequently occurred, such as coenocytism, high level chromosome multiplication, multipolar division, variation in size of pollen grain, aneuploid formation, non- synchronous, and delayed chromatin condensation.

According to our observation, chromatin material migration among cells had been found in all the intergeneric hybrids derived from P. huashanica. We suggested that the Nh genome has a gene system for controlling this process. In order to prove this suggestion, we studied the microsporogensis of R. tsukushiensis x P. huashanica F1 hybrid. The transfer of nucleate materials through conjugation opening, was also found. The results of observation are described and discussed in the present paper.

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