Cytological observation of chromosome breakage in wheat male gametophytes caused by gametocidal action of Aegilops triuncialis-derived chromosome 3C^t

Abstract

In this study, we investigated the chromosome breakage caused by gametocidal (Gc) chromosome 3C^t and its interaction with the suppressor gene Igc1 (inhibitor of gametocidal gene 1) on wheat chromosome 3B. We demonstrated cytologically that patterns of 3C^t-induced chromosomal fragmentation in microspores differed from patterns observed for other Gc genes. Uninuclear microspores of the monosomic 3C^t addition line had high frequencies of micronuclei, possibly explaining its low fertility. Chromosome fragmentation was observed in prometaphase and metaphase of the first pollen mitosis in the monosomic 3C^t addition line. Patterns of chromosome fragmentation were different from those previously reported for Gc chromosomes 2S of Aegilops speltoides, 4S^sh of Ae. sharonensis and 2C^cy of Ae. cylindrica; many chromosome fragments were observed in prometaphase of the first pollen mitosis in the monosomic 3C^t addition plants. In anthers at the binuclear stage, many microspores at the uninuclear stage coexisted with normally developed microspores.