Identification and genetic analysis of EMS-mutagenized wheat mutants conferring lesion-mimic premature aging.

BACKGROUND: Lesion-mimic and premature aging (lmpa) mutant lmpa1 was identified from the ethyl methane sulfonate (EMS) mutant library in the bread wheat variety Keda 527 (KD527) background. To reveal the genetic basis of lmpa1 mutant, phenotypic observations and analyses of chlorophyll content and photosynthesis were carried out in lmpa1, KD527 and their F1 and F2 derivatives. Further, bulked segregation analysis (BSA) in combination with a 660 K SNP array were conducted on the F2 segregation population of lmpa1/Chinese spring (CS) to locate the lmpa1 gene. RESULTS: Most agronomic traits of lmpa1 were similar to those of KD527 before lesion-like spots appeared. Genetic analysis indicated that the F1 plants from the crossing of lmpa1 and KD527 exhibited the lmpa phenotype and the F2 progenies showed a segregation of normal (wild type, WT) and lmpa, with the ratios of lmpa: WT = 124:36(χ2 = 1.008 < =3.841), indicating that lmpa is a dominant mutation. The combination of BSA and the SNP array analysis of CS, lmpa1 and lmpa1/CS F2 WT pool (50 plants) and lmpa pool (50 plants) showed that polymorphic SNPs were enriched on chromosome 5A, within a region of 30-40 Mb, indicating that the wheat premature aging gene Lmpa1 was probably located on the short arm of chromosome 5A. CONCLUSIONS: EMS-mutagenized mutant lmpa1 deriving from elite wheat line KD527 conferred lmpa. Lmpa phenotype of lmpa1 mutant is controlled by a single dominant allele designated as Lmpa1, which affected wheat growth and development and reduced the thousand grain weight (tgw) of single plant in wheat. The gene Lmpa1 was tentatively located within the region of 30-40 Mb near to the short arm of chromosome 5A.

Expression of potential resistance genes to the English grain aphid, Sitobion avenae, in wheat, Triticum aestivum.

The English grain aphid, Sitobion avenae (F.) (Homoptera: Aphididae), is a dominant and destructive pest in wheat, Triticum estivum L. (Poales: Poaceae), production regions in China and other grain-growing areas worldwide. Patterns of gene expression of the S. avenae-resistant synthetic wheat line 98-10-35, the S. avenae-susceptible line1376, and their hybrid population, and the differences in segments between 98-10-35/1376 F3 resistant plants and resistant parents of 98-10-35, as well as those between the F3 resistant and susceptible populations, were examined with differential display reverse transcription PCR. The results showed that five patterns of differential expression were detected between the progeny and its resistant parents: 1) The gene was silenced in one of the parents; 2) Special expression showed in the progeny; 3) Expression was consistent with the resistant parents; 4) Up expression showed in the progeny but not in the parents; 5) Down expression showed in the progeny but not in the parents. Paired t-test results were not significant; however, the probability value (0.9158) indicated that gene expression on the RNA level were consistent with resistant bands found in F3 resistant individuals and resistant parents, as well as the F3 resistant and susceptible populations. For both the F3 of 98-10-35/1376 and the parents, the total number of amplified bands was 202, with an average of 25.3 per primer. The number of differential bands was 116, with an average of 14.5 per primer amplified and a polymorphism ratio of 56.3%. In the present study, differential expression genes in the resistant line 98-10-35 were all up-regulated. Among them, gene expression of resistant groups in the F3 population was in agreement with patterns 2, 3, and 4. However, the susceptible line 1376 did not have this gene expression on the RNA level. This pattern is expected to be used to select and analyze target genes from the same F3 population and the resistant parents. The results suggest that it can be employed as a new method for molecular assisted breeding.