Group 1 chromosomes of the Triticeae tribe have been studied extensively because many important genes have been assigned to them. In this paper, chromosome 1 linkage maps of Triticum aestivum, T. tauschii, and T. monococcum are compared with existing barley and rye maps to develop a consensus map for Triticeae species and thus facilitate the mapping of agronomic genes in this tribe. The consensus map that was developed consists of 14 agronomically important genes, 17 DNA markers that were derived from known-function clones, and 76 DNA markers derived from anonymous clones. There are 12 inconsistencies in the order of markers among seven wheat, four barley, and two rye maps. A comparison of the Triticeae group 1 chromosome consensus map with linkage maps of homoeologous chromosomes in rice indicates that the linkage maps for the long arm and the proximal portion of the short arm of group 1 chromosomes are conserved among these species. Similarly, gene order is conserved between Triticeae chromosome 1 and its homoeologous chromosome in oat. The location of the centromere in rice and oat chromosomes is estimated from its position in homoeologous group 1 chromosomes of Triticeae.

This report describes the rationale, approaches, organization, and resource development leading to a large-scale deletion bin map of the hexaploid (2n ϭ 6x ϭ 42) wheat genome (Triticum aestivum L.). Accompanying reports in this issue detail results from chromosome bin-mapping of expressed sequence tags (ESTs) representing genes onto the seven homoeologous chromosome groups and a global analysis of the entire mapped wheat EST data set. Among the resources developed were the first extensive public wheat EST collection (113,220 ESTs). Described are protocols for sequencing, sequence processing, EST nomenclature, and the assembly of ESTs into contigs. These contigs plus singletons (unassembled ESTs) were used for selection of distinct sequence motif unigenes. Selected ESTs were rearrayed, validated by 5Ј and 3Ј sequencing, and amplified for probing a series of wheat aneuploid and deletion stocks. Images and data for all Southern hybridizations were deposited in databases and were used by the coordinators for each of the seven homoeologous chromosome groups to validate the mapping results. Results from this project have established the foundation for future developments in wheat genomics.

Restriction fragment length polymorphism (RFLP) markers were used to map male fertility restoring gene that was transferred from chromosome 6U of Aegilops umbellulata Zhuk. to wheat. Segments of chromosome 6U bearing the gene that restore fertility to T. timopheevi Zhuk. male sterile cytoplasm were identified in all four translocation lines by two probes, BCD21 and BCD342. Lines 040-5, 061-1 and 061-4 are T6BL.6BS-6U translocations, while line 2114 is a T6AL.6AS-6U translocation. Line 2114 has a much larger 6U chromosomal segment and lower frequency of transmission of male gametes with the alien segment than the other three lines. The restoring gene carried by the 6U segment in 2114 showed high expressivity and complete penetrance. This restoring gene is designated Rf6. A homoeologous chromosome recombination mechanism is discussed for the alien gene transfer.