Inheritance Of Adult Plant Resistance Research Articles

Adult plant resistance to leaf rust and stem rust of wheat in a newly developed recombinant inbred line population

Leaf rust caused by Puccinia triticina and stem rust by P. graminis f. sp. tritici are the most destructive diseases of wheat (Triticum aestivum L.), resulting in substantial yield losses globally. A continuous search for new sources of effective rust resistance genes is necessary to develop improved cultivars with durable resistance. This study aimed to investigate inheritance of adult-plant resistance in a recombinant inbred line (RIL) population of a cross between wheat cultivars ‘Popo’ and ‘Kariega’, and to identify breeding lines possessing both leaf rust and stem rust resistance. A panel of 179 RILs, two parental cultivars and three checks were evaluated in South Africa at two localities, Cedara and Tygerhoek, in 2014 and 2015. Disease response ranged from highly resistant to highly susceptible. Analysis of variance indicated highly significant (p < 0.001) differences among the RILs for both diseases across the testing environments. Broad-sense heritability estimates were 0.53 and 0.77 for leaf rust and stem rust, respectively. Twenty-six RILs were selected showing significantly higher levels of resistance to both pathogens. The moderate to high heritability estimates for leaf rust and stem rust resistance favours the use of the newly developed RILs for resistance breeding against the two diseases.

Genetic diversity for adult plant resistance to leaf rust in bread wheat (Triticum aestivumL.)

There is an increasing worldwide interest in adult plant resistance (APR) since most examples of durable resistance to leaf rust in wheat are this kind. Twelve bread wheat genotypes were studied for inheritance of APR to leaf rust using pathotype 77-5 (121R63-1), the most prevalent and widely virulent one on bread wheat germplasm in India. Resistance was controlled by a pair of dominant and recessive genes each in CPAN 1676 and CSP 44 and by two independent dominant genes each in CPAN 1796, Frontana, HD 2009, HD 2135, HUW 37, HW 517, Nainari 60, Pavon 76,VL 404 and WG 138. Segregation patterns observed in their intercrosses showed the presence of at least four genes, including a recessive one, among these genotypes in addition to known APR genes Lr34, Lr46, Lr48, Lr49 and Lr68. The present findings are expected to contribute toward enriching diversity for leaf rust resistance in bread wheat improvement programmes.

Relationship between Partial Resistance and Inheritance of Adult Plant Resistance Gene Lr 46 of Leaf Rust in Six Bread Wheat Varieties

Leaf rust caused by Puccinia triticina Eriks. is an important disease of wheat (Triticum aestivum L.) in Egypt and worldwide. Six Egyptian wheat were evaluated and tested for their levels of adult plant resistance to leaf rust at Sadat City location during three successive growing seasons i.e. 2011/12, 2012/13 and 2013/14. Wheat varieties Gemmeiza 9, Giza 168 and Gemmeiza 7 showed the highest levels of partial resistance and lower values of percentage final rust severity (FRS) did not exceeded up to 30% as well as area under disease progress curve (AUDPC) not more than 250. On the other hand, Gemmeiza 1, Sakha 93 and Sids 1 were the highly susceptible or fast rusting varieties. These varieties showed the highest levels of percentage FRS and AUDPC compared with the partially resistant varieties under the same field conditions. To determine the inheritance of adult plant resistance to leaf rust tested wheat varieties were crossed with the seven adult plant resistance monogenic lines i.e. Lr 38, Lr 42, Lr 43, Lr 44, Lr 45, Lr 46, and Lr 47. The resulted F1 plants were selfed to produce F2 seeds. F2 plants were tested at adult plant stage under field conditions at Sadat City location during 2012/13 growing season. Segregations of F2 plants at adult plant stage revealed that the wheat varieties Giza 168 and Gemmeiza 9 have the same three genes i.e. Lr 45, Lr 46 and Lr 47. While the other tested varieties Sakha 93, Gemmeiza 1, Gemmeiza 7 and Sids 1 do not carry any of the tested leaf rust resistance genes.

Genetic basis for and inheritance of resistance to Race 1 and Race 2 of Kabatiella caulivora in Trifolium subterraneum ssp. subterraneum and ssp. yanninicum

A study of a partial diallel involving crosses of seven cultivars of subterranean clover (Trifoliumsubterraneum ssp. subterraneum and ssp. yanninicum) was undertaken to determine the genetic basis of resistance to both Race 1 and Race 2 of Kabatiella caulivora at seedling and adult plant stages. Relationships between variance (Vr) and covariance (Wr) revealed that adult plant resistance to Race 1 and both seedling and adult plant resistance to Race 2 were controlled by simple additive and dominant gene effects, whilst seedling resistance to Race 1 was controlled by epistatic gene effects. Three of the four most resistant parents (cultivars Daliak, Denmark and Meteora) showed a dominant gene effect for adult plant resistance to Race 1. However, the other resistant parent, cv. Goulburn, and the most susceptible parent, cv. Woogenellup, both were controlled by recessive gene effects (i.e, gene effects conferred by recessive genes). Cultivar Denmark again showed dominant gene effects in relation to resistance to Race 2 at both seedling and adult plant stages, whilst recessive gene effects were evident in susceptible adult plants of cv. Daliak in response to Race 2. Estimates of genetic variance components confirmed that dominance variance (H1 and H2) was much greater than additive variance (D) and there were more dominant alleles (i.e., more alleles that had dominant effects) than recessive alleles (i.e., more alleles that had recessive effects) present across all the cultivars. An examination of segregation ratios in three F2 populations revealed that inheritance of adult plant resistance to Race 1 was controlled by a dominant gene in cv. Daliak and cv. Meteora, and by two dominant genes in cv. Denmark. The additional resistance gene present in cv. Denmark may well explain its apparent stable resistance to both races in the field. This study provides an insight into the genetic basis for and inheritance of resistance to this disease that will assist breeding programs aimed at improving resistance.

Inheritance of High Levels of Adult‐Plant Resistance to Stripe Rust in Five Spring Wheat Genotypes

Inheritance of adult‐plant resistance to stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici) in five spring wheats (Triticum aestivum L. em. Thell) following inoculation with the Mexican race Mex96‐11 was studied. All possible crosses among these resistant genotypes and a susceptible genotype, ‘Avocet‐YrA’, were made in a one‐way diallel mating design. F1 crosses, F2 populations, and F2:F3 and F5 single seed‐descent lines were evaluated under artificial field epidemics initiated with race Mex96‐11. The adult‐plant resistance in crosses of resistant parent with Avocet‐YrA tended to be incompletely dominant and was based on the interaction of gene Yr18 and at least three additional additive genes in each parent. Transgressive segregation was detected in all F2 populations and F5 single seed‐descent lines of the resistant parent inter‐crosses, indicating that some additive genes were nonallelic. Combining ability analyses indicated that additive gene effects were more important than nonadditive gene effects in the inheritance of adult plant resistance to stripe rust in the evaluated material. Estimates of narrow‐sense heritability ranged from 0.88 to 0.96. Stripe rust resistance in these wheats is expected to be durable.

Inheritance of seedling and adult plant resistance to leaf rust of selected Australian spring and English winter wheat varieties

AbstractGenetic studies were conducted to gain an understanding of the inheritance of adult plant resistance (APR) to leaf rust in six common wheat varieties. The Australian varieties ‘Cranbrook’ and ‘Harrier’ each carry two genes for APR to leaf rust. These genes are genetically independent of the seedling resistance genes Lr23 and Lrl7b, carried by the respective varieties. Adult plant resistance in ‘Suneca’ was conferred by at least two genes, in addition to the seedling genes Lr1 and Lrli. It is likely that the APRs in ‘Cranbrook’, ‘Harrier’ and ‘Suneca’ are conferred by uncharacterized gene(s). Tests of allelism confirmed that seedling resistances in the varieties ‘Avocet R’, ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are conferred by Lrli. Adult plant resistance in the variety ‘Hereward’ was inherited monogenically, whereas varieties ‘Moulin’ and ‘Pastiche’ each carried two dominant genes. On the basis of rust specificity and pedigree analysis, it would seem likely that the APR genes in ‘Hereward’, ‘Moulin’ and ‘Pastiche’ are also currently uncharacterized.

The inheritance of adult plant resistance to stem rust derived from wheat cultivars Bonza and Chris

The wheat (Triticum aestivum L.) cultivars Bonza and Chris have adult plant resistance to stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. &amp; Henn.) in addition to genes for specific resistance. Both cultivars were crossed to a susceptible wheat, LMPG. Lines carrying the adult plant resistances of the two parents were produced by selecting for seedling susceptibility in the greenhouse and adult plant resistance in the field to race 15B-1 (TMH). Three homozygous lines derived from Bonza and two from Chris were crossed and backcrossed to LMPG. Backcross F2 families were grown in a field nursery inoculated with a multi-race mixture of eight stem rust isolates including 15B-1. Stem rust severities in percent were recorded. An analysis of the data indicated that adult plant resistance of Bonza was controlled by a single recessive gene and that of Chris by two complementary recessive genes. Since the resistance was effective against a complex mixture of virulent stem rust races, it should be of interest to wheat breeders. Key words: Stem rust, Puccinia graminis, common wheat, Triticum aestivum, adult plant resistance

Inheritance of Adult‐Plant Resistance to Powdery Mildew in Knox 62 and Massey Winter Wheats

Adult‐plant resistance (APR) to powdery mildew [Blumeria graminis (D.C.) E. O. Speer f. sp. tritici Em. Marchal; syn Erysiphe graminis f. sp. tritici] is more durable than hypersensitive major gene resistance, but little is kown about the inheritance of this type of resistance. Inheritance of APR was studied in four winter wheat (Triticum aestivum L.) crosses. Parents, F1, F2, F3, and backcross populations were evaluated in the field under natural epidemics of powdery mildew. The number of genes governing APR in ‘Massey’ and ‘Knox 62’ wheats was estimated by both qualitative and quantitative methods. Mildew severity was used in the qualitative methods, while are under the disease progress curve was used in quantitative estimates. Results indicate that two to three genes confer APR in these cultivars. Heritability estimates or APR ranged from 0.40 to 0.56 wen standard units and F3/F2 regression methods were used. The variance components method estimated higher heritabilities which ranged from 0.79 to 0.95 Since APR in these cultivars is governed by few genes and heritability estimates are moderate to high, selection for this resistance in early segregating generations should be effective. Powdery mildew resistance in Knox 62 has been effective during its commercial cltivation over 20 yr. Massey has maintained its APR to powdery mildew since its relase in 1981; therefore, APR derived rom these cultivars is expected to be durable.

Inheritance of Adult Plant Resistance to Leaf Rust in Six Durum Wheat Cultivars

Leaf rust [Puccinia recondita Rob. ex Desm. f. Sp. tritici D.M. Henderson] was widespread in Canada and the USA in 1986 and some Canadian cultivars were less resistant than expected. Studies on the inheritance of leaf rust resistance were begun to provide information of use to durum wheat breeders. The inheritance of adult plant resistance to race 15 of leaf rust was investigated in six durum wheat (Triticum turgidum L. var. durum) cultivars, Lloyd, Medora, Pelissier, Quilafen, Stewart 63, and Wakooma, which had been previously shown to carry genes for seedling resistance. Each cultivar had been crossed and backcrossed to a susceptible line, RL6089. Four of the F2 populations and 29 or 30 F2 families from each of the six backcrosses were tested with race 15 in a field nursery. The results were compared with those for the same material tested at the seedling stage in a greenhouse. The combined data showed that each of the genes for seedling resistance was effective at the adult plant stage in the field. The segregation of the BC1F2 progenies indicated that Lloyd carries a dominant gene and Pelissier a recessive gene, that are effective only in adult plants. Thus, all of the seedling resistance genes are of potential value to durum wheat breeders and Lloyd and Pelissier carry additional genes for adult plant resistance that should also be useful.

Inheritance of adult plant resistance to powdery mildew in swedes

SummaryA complete diallel set of crosses, including selfs, was produced from 11 inbred lines of swedes and assessed for adult plant resistance to powdery mildew in a replicated field trial. The plants were inoculated with powdery mildew spores on 23 July 1987. Traces of mildew were visible on 3 August. By 14 September the most susceptible inbred line had 95% of its leaf area infected, whereas the three most resistant lines derived from cvs Bangholm Dima (two lines) and Bangholm Magres (one line) had only 5%. Resistance was controlled by partially recessive genes. There was no evidence of maternal effects. The implications for breeding inbred and F1 hybrid swede cultivars are discussed.

Inheritance and Expression of Adult Plant Resistance to Leaf Rust in Era Wheat

The inheritance of adult plant resistance to leaf rust (Puccinia recondita f. sp. tritici) was studied in the bread wheat (Triticum aestivum) cultivar Era in Morocco and the United States. Adult plant resistance was shown to be conferred by two complementary genes, Lr13 and Lr34. The magnitude of the effect resulting from the gene interaction was influenced by environment. Lr10 and an unknown gene for seedling resistance were also present in Era

Inheritance of adult plant resistance to mildew in oats

SUMMARYAdult plant resistance of a durable nature in oat cv. Maldwyn was studied in a cross with the very susceptible cv. Selma, using a replicated F3 population grown under field conditions. Segregation was found to be continuous, with no discrete classes, and a preponderance of segregants showing intermediate values between the two parents indicating additive genetic control. The number of effective genetic factors segregating in this cross was estimated to be four when material was at the ‘boot stage’ (G.S. 45) and eight or nine at the stage when flowering was complete (G.S. 69). At this latter stage Maldwyn was estimated to be contributing about seven factors for resistance, and the susceptible Selma one or possibly two.Further improvement, through accumulation of factors from both parents, could be expected and this has subsequently been achieved.The possible effects, on the durability of resistance in highly resistant transgressive segregants, from increased selection pressure on the pathogen are discussed.

The field reaction to stem rust of 'Chinese Spring' substitution lines carrying chromosomes from 'Hope' and 'Thatcher' wheats

Studies were done in an attempt to determine the inheritance of adult plant resistance to stem rust (Puccinia graminis f. sp. tritici Eriks. and E. Henn.) in the wheat (Triticum aestivum L.) cultivars 'Hope' and 'Thatcher'. 'Chinese Spring' substitution lines carrying individual chromosomes from 'Hope' and 'Thatcher' were tested in field rust nurseries, three times each with races 15B-1 and 56, and twice with multirace mixtures. In 1976 it was found that the date of heading often had a significant effect on rust severity, with early lines showing less rust. In 1977 and 1984 the lines were divided into three groups based on maturity and were planted on three dates about 10 days apart to make heading dates more uniform. The data indicate that 'Hope' has genes for resistance to race 56 on chromosomes 3B (Sr2) and 4D, and to a multirace mixture on 1B, 3B, and 7B. 'Thatcher' possibly has genes for resistance to race 56 on chromosomes 6A and 3B (Sr12). The results show that the resistance of both cultivars is complex and most genes have only small effects.Key words: Triticum, Puccinia, rust resistance, substitution lines.