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Bread is one of the major constituents of the human diet and wheat (Triticum aestivum L.) is the most important cereal for bread making. The gluten proteins (glutenins and gliadins) are recognised as important components affecting the processing quality of wheat flour. In this research, we investigated a particular glutenin subunit allele in an Australian cultivar, H45. Based on protein and DNA assays, the Glu-B1 allele of H45 seems to be Glu-B1al, an allele that includes a functional duplication of a gene encoding an x-type high-molecular-weight glutenin subunit, and is thought to increase dough strength through overexpression of that subunit. Yet H45 does not have the dough properties that would be expected if it carries the Glu-B1al allele. After confirming that H45 overexpresses Bx subunits and that it has relatively low un-extractable polymeric protein (an indicator of weak dough), we cloned and sequenced two Bx genes from H45. The sequences of the two genes differ from each other, and they each differ by four single-nucleotide polymorphisms (SNPs) from the sequence that has been reported for the Glu-B1al x-type glutenin genes of the Canadian wheat cultivar Glenlea. One of the SNPs leads to an extra cysteine residue in one of the subunits. The presence of this additional cysteine may explain the dough properties of H45 through effects on cross-linkage within or between glutenin subunits. We propose that the Glu-B1 allele of H45 be designated Glu-B1br, and we present evidence that Glu-B1br is co-inherited with low un-extractable polymeric protein.

Olive leaf spot is a disease of olive (Olea europaea L.) caused by the fungal pathogen, Spilocea oleaginea Cast. Progeny derived from crosses among susceptible, resistant, and semiresistant parental lines were assessed in the field for 8 years and classified as either resistant or susceptible. DNA from some of the progeny of this segregating population was used to identify molecular markers linked to olive leaf spot disease using the randomly amplified polymorphic DNA (RAPD) technique and bulked segregant analysis (BSA). Two DNA bulks were constructed, each containing 13 progeny showing either resistance or susceptibility for the disease, and screened for polymorphisms using 100 primers. One primer produced two polymorphic bands, one of ≈700 base pairs (bp) from the susceptible bulk and the other of ≈780 bp from the resistant bulk. The 780 bp marker appeared in 70.6% of the segregating progeny and 100% of parents showing resistance to leaf spot disease, while the 700 bp marker appeared in 47.1% of the segregating progeny and 100% of the parents showing susceptibility. These markers can be used as screening tools in olive improvement programs.

A sequence-tagged site (STS) was developed to identify a genetic marker linked to resistance to olive leaf spot caused by the pathogen, Spilocea oleaginea (Cast) (syn. Cycloconium oleaginum Cast.). The STS was based on a randomly amplified polymorphic DNA (RAPD) marker of about 780 base pairs (bp) linked to olive leaf spot resistance. Several primer pairs were developed to flank the sequence, and one pair produced the expected polymorphism between resistant and susceptible individuals tested, and was used as an STS marker. This primer pair was tested against parents and 34 individuals from a population segregating for resistance to olive leaf spot, and 12 commercial olive (Olea europaea L.) cultivars showing various levels of resistance to the disease. The STS marker was present in 71.4% of the parents and progeny that were designated as resistant, and was absent in 87% of the parents and progeny showing susceptibility. These primers were also able to distinguish cultivars such as `Koroneiki' and `Leccino', that are reported to show resistance to olive leaf spot, from `Barouni' and `Mission', that are reported to be susceptible. This is the first report of a STS marker for olive, and its use will assist greatly in screening olive progeny for resistance to leaf spot in breeding programs.

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