| I. Research Notes Structural heterozygosity and male sterility in Triticum aestivum L.1) S. S. MAAN and K. A. LUCKEN North Dakota State University, Fargo, North Dakota 58102, U.S.A Abstract Male-sterile and partially male fertile common wheat (Triticum aestivum L.) plants were selected from crosses of Chinese Spring x Nebraska 542437-Lee and x 2 Selkirk2. All F3-F5 plants were male sterile or partially male fertile, and most of these plants had 2n=42 (21II or 19II 1IV or 19II O4). Progeny of male steriles included plants with one or two multivalents ( 16II 1IV 1VI, 17II 1III 1IV), and one plant had 2n= 37 (15II 1III 4I). Apparently, selection for male sterility resulted in plants with heterozygous chromosomal interchanges and aneuploidy. Introduction Several workers ( 1, 2, 3, 4) have reported male sterile plants among progenies from intervarietal crosses of common wheat. These genetic male sterile stocks were developed by selfing the partially male fertile plants or by crossing the male sterile plants with pollen from the fertile plants. In one report (2), transmission of the male sterility effect through the pollen and the F2 segregation ratios indicated that the male sterile plants had one homozygous recessive gene for male sterility. In this paper, we report the development of a male sterile hard red spring wheat with chromosome-structural heterozygosity. Experimental results One male-sterile F1 plant (No.64-952) was obtained from a cross between Chinese Spring mono-iso-6B and R1-Lee (Nebraska No.542437/Lee). This male sterile plant (2n=20II+1I) was crossed with pollen from common wheat varieties Chinese Spring, Chris and Selkirk. One or more male sterile plants were obtained from crosses with each of the three varieties. One male sterile BCF1 (65-1816) plant (2n=21II,19II 1IV) from the second cross with Selkirk (No.64-952 x 2 Selkirk) set five seeds and produced five F2 plants, four male sterile and one partially fertile (Tables 1 and 2). The F3, F4 and F5 plants from crosses with Selkirk were examined for the percentage of seed set on bagged heads and for the chromosome number and chromosome pairing at metaphase I of meiosis in the pollen mother cells (Table 2). Of the five partially fertile F3 plants, two were examined cytologically and both had 2n=21II or 19II O4. Of the 39 F4 and F5 plants, 13 were completely male sterile, 15 set 5% or less seed on the bagged heads. Of the remaining 11 F4-F5 Plants, 7 set 10%, 1 set 20%, and 3 set 50% or more seeds. The classification of the 15 plants with 5% or less seeds in the sterile class would give a segregation ratio of 28 sterile: 11 partially fertile, a single-gene segregation? Of the 39 F4-F5 Plants, 37 were examined cytologically; 35 had 2n=42=21II or 19II1IV (a chain or a ring or both), 1 had 2n=42=21II or 19II1V1I, and 1 had 2n=37= 15II1III4I. Most F5 plants had a chain-of-four or a ring-of-four. Only four F5 plants had 2n= 21II. These four male sterile plants with normal 21 chromosome pairs were from two F4 plants with 2n=42 (21II, 19II O4). A critical examination might have shown the presence of a multivalent in these F5 plants. A cross of one male sterile F2 plant (No. 66-4455) with Selkirk pollen produced plants with different percentages of seed set and with different chromosome pairing configurations (Table 2). Of five plants from the cross of No. 66-4455 x Selkirk, two plants, Nos. 67-1145 and 67-1146, had some of the pollen mother cells with two multivalents, 17II1III1IV and 16II1IV1VI, respectively. The occurrence of more than one multivalent in these plants, and various frequencies of a multivalent among the F5 plants, indicated that all these male sterile plants did not have the same chromosome interchange - also that some of the plants had more than one chromosome interchange. |
| 1) Published with the approval of the Director, North Dakota State Agricultural Experiment Station, as Journal Article No.229. |
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