Assessment of wheat variety distinctness using SSR markers

摘要

Assessment of variety distinctness is important for both the registration and the protection of particular variety. However, the current testing system, which assesses a range of morphological characters of each pair of varieties grown side-by-side, is time-consuming and is not suitable for the assessment of hundreds of samples. The objective of this study was to develop a procedure for the assessment of wheat variety distinctness using simple sequence repeat (SSR) markers. A comparison between the molecular and morphological proifle of 797 varieties was made. On the basis of the comparison, pairs of va-rieties with a genetic similarity value (GSV) ≤90% were deemed to be distinct, accounting for ~85% of varieties assessed in wheat regional trials. For the remaining ~15% of varieties, GSVs between different varieties were >90%, among which ~35% were not distinct and the other ~65% were distinct. Therefore, if given a GSV>90%, the pairs of varieties should be morphologicaly assessed in the ifeld. To avoid any errors in the assessments, we proposed the elimination of contaminant plants from the sample before comparing the varietal genotypes, scoring of the genotype at each locus with a pair of alele numbers when constructing a molecular proifle, and faithfuly recording two aleles at a non-homozygous locus. To reduce the workload and cost, a three-grade markers comparison among varieties is suggested. In addition, 80 SSR markers and a technical procedure for assessment of wheat variety distinctness have been proposed. Based on the procedure, the distinctness assessment of ~85% of al wheat varieties is completed in our laboratory annualy. Consequently, total ifeld assessment has been reduced considerably.