ZEMUN POLJE, YUGOSLAVIA
Maize Research Institute Belgrade
The maize variety accession No. 366 from the Yugoslav MRI collection caries a T cytoplasmic male sterility (cmsT) --Vidakovic, M, Vidakovic, M, Vancetovic, J, Roculj, M In the first part of the search for the restorer cytoplasm in maize (Vidakovic et al., XVIIth Conference on Maize and Sorghum EUCARPIA, Thessaloniki, Greece, Pp. 138, 1996), 50 randomly chosen late varieties from the Collection of Yugoslav varieties of the Maize Research Institute (MRI), Zemun Polje, Belgrade, Yugoslavia, were crossed with a series of ms/+ stocks: ms1/+, ms2/+, ms3/+, ms6/+, ms7/+, ms8/+, ms9/+, ms11/+, ms12/+, ms13/+, ms17/+, ms22/+, ms23/+ and ms24/+. Crosses were made in 1993, with varieties used as females, and the ms/+ stocks as males. Two ears of each cross were taken for further research, and handled separately.

In 1994, F1 ears were sown for further selfing, in order to search for the restorer cytoplasm in 1995 in selfed progenies (100% fertility in such progeny would be an indicator of the restorer cytoplasm for the appropriate ms gene). But in a few F1s (with 6 varieties), sterile plants unexpectedly occurred in 1994, indicating some other source of sterility besides the ms gene with which it was crossed, i.e., crossing with a ms/+ stock to a plant not carrying the appropriate ms gene would result in a 100% fertile F1.

In Table 1 there is a list of F1s (variety x stock) where sterile plants were noticed.

Table 1. List of F1s where sterile plants occurred in 1994.
 
Variety1 366 1172 1465 1485 1570 1853
ms stock
ms1/+ Segr.2 both progenies          
ms2/+ Segr. both progenies   Segr. 1 progeny     Segr. 1 progeny
ms6/+ Segr. 1 progeny         Segr. 1 progeny
ms8/+ Segr. 1 progeny          
ms9/+ 1 progeny 100% sterile 1 progeny 100% sterile Segr. 1 progeny      
ms11/+ Segr. 1 progeny 1 progeny 100% sterile        
ms13/+ 1 progeny 100% sterile Segr. 1 progeny 1 progeny 100% sterile 1 progeny 100% sterile   1 progeny 100% sterile
ms17/+         Segr. 1 progeny  
ms22/+ Segr. 1 progeny          
ms23/+ Segr. 1 progeny          
ms24/+ Segr. 1 progeny          
1Variety is given by an accession number in our gene bank
2Segregates on fertile and sterile plants

In the variety accession No. 366, the occurrence of sterile plants was the most obvious. We supposed that this variety contained some kind of cytoplasmic male sterility, and did additional tests: F1 sterile plants of the ms1/+ stock were pollinated with the line F-7(R), which is a partial restorer for the S cytoplasm, and F1 sterile plants with the ms2/+ stock were pollinated with F-7(R), as well as the line ZPL-217, known as the RfC line.

In 1995, all of the crosses with F-7R and ZPL-217 were sterile, indicating the absence of cms-S, as well as cms-C from population 366. These sterile plants were pollinated with another partial restorer for the cms-S (ZPLB-368/73), as well as with two lines known as restorers for cmsT: R-348 and R455. In 1996, only tests with RfT lines showed full fertility, while others were absolutely sterile. So, variety Zuti zuban from the region of Novi Sad (accession No. 366) carries the T-type of cytoplasmic male sterility.

In this way we checked just the most obvious carrier of cytoplasmic male sterility in this study. Other varieties that showed sterile plants in this experiment are included in a broader checking of the male sterility sources in our gene bank.
 
 


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