Spontaneous triploids of rye collected in Turkey.

Abstract

Cultivated rye (Secale cereale L.) is known as a diploid plant species having 14 chromo somes. As exceptional examples, its triploids have been reported: spontaneous triploids from twin plants (Muntzing 1937, Lamm 1944, a triploid naturally occurring from a diploid population with four B chromosomes (Kishikawa 1966) and artificially induced triploids (Kostoff 1939, Breslavetz 1940, Pilch 1978, Benavente and Orellana 1984.In 1982, the spike samples of rye were collected in Greece and Turkey by the members of the Kyoto University Ethnobotany Team (Sakamoto 1986). Using these samples, the geographical distribution and frequency of rye plants with B chromosomes were examined. During this examination, three triploids with 21 chromosomes were found. This paper deals with their cytology and morphology and discusses their origin. Materials and methodsForty-one accessions of rye (S4351 to S4391) were originally collected as spike samples at wheat fields in Greece and Turkey (only two accessions, S4352 and S4353, were collected at a rye field) (Sakamoto 1986). Six (S4351 to S4356) of them were collected at five sites in Greece and 35 (S4357 to S4391) at 19 sites in Turkey (Fig. 1). Each accession was comprised by all grains obtained from one spike. From 190 grains of the Greek samples sown 180 plants were obtained, and from 1,118 grains of the Turkish samples 892 plants were obtained.The chromosome number of these 1,072 plants was checked at the first metaphase of meiosis (MI) in pollen mother cells (PMCs) using the acetocarmine smear method. Chro mosome pairing at MI was also observed using the acetocarmine squash method. Pollen fertility was assessed from the percentage of pollen grains not only that were round but also with a cytoplasm well stainable with glycerine carmine. Results and discussionOf 1,072 rye plants observed, three plants were triploids but the remaining were all di -ploids. One (S4364-51) of the triploids was found in the accession collected from site A at 47.3 km from Sungurlu to the northwest, on the way to cankiri in Turkey, and the others (S4374-8 and S4374-21) from site B at 34.4 km from Erzurum to the west, on the way to Erzincan in Turkey (Fig. 1). The frequency of occurrence of spontaneous rye triploids under cultivation in Turkey was 0.34% (3/892) in all, and they were of independent origin at two different sites. All of them were derivatives from not twin plants but single plants, whereas spontaneous triploids were occasionally detected as a pair to twin plants in many grasses (Muntzing 1937). Whether or not the frequency of occurrence of spontaneous triploids from single plants is high is not certain. Further cytological data on rye cultivated at many regions in the world are needed.

Meiotic associations at metaphase I in diploid, triploid, and tetraploid Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski.

“…These expected triva lent frequencies were close to those observed (Table 1) genome chromosomes. The trivalent frequencies observed in these autotriploid plants of Psathyrostachys juncea (Table 1) are much higher than that reported for autotriploid Secale cereale (Niwa et al 1989), in which 2.37 to 3.01 trivalents were observed. It appeared that chromosome length was not responsible for the variations in trivalent frequency.…”