Evaluation of inheritance to leaf rust in wheat using area under disease progress curve

Six varieties, Kundan (K), Galvez-87 (G), Trap (T), Chris (C), Mango (M) and PBW-348 (P) along with fast ruster, Agra Local (AL), were screened for seedling reaction and adult pant response to leaf rust. Seedlings of all six varieties were susceptible while adult plants showed lower susceptability response than Agra Local. The F1s among the varieties, and also with Agra Local, showed the values lesser than the respective mid parental values for AUDPC suggesting a polygenic mode of inheritance. ANOVA for combining ability effects indicated variation due to the GCA and SCA effects, which indicated that both additive as well as non-additive type of genetic variances, govern AUDPC. The higher values for the GCA variance over the SCA variance indicated the predominance of an additive component over the dominance component for AUDPC. Significant values for GCA effects indicated that Kundan, Galvez-87 and Trap can be used as good general combiners for AUDPC. The crosses, KxAL, GxAL and TxAL showed significant sca effects for AUDPC, which indicated the predominance of non-additive gene effects in these crosses. Additive x additive and dominance x dominance components of the 5- parameter model were highly significant and contributed maximum extent compared to the additive and dominance components in the cross KxG, while dominance and dominance x dominance components contributed maximum in the remaining crosses. Under such a situation, improvement in the character may be expected through standard selection procedure, which may first exploit the additive gene effects and simultaneously care should be taken to see that the dominance effects are not dissipated, but rather they should be concentrated.     

Tetraploids,triploids, and 2n pollen from diploid interspecific crosses with cassava

Summary Interspecific crosses of five cultivated cassava varieties (2n=36) were made with two related Manihot species, M. epruinosa (2n=36) and M. glaziovii (2n=36). From these diploid interspecific crosses, four spontaneous tetraploids (2n=4x=72) and two triploids (2n=3x=54) were isolated for the first time in cassava. Occurrence of relatively high frequencies (0.1%–35.6%) of 2n pollen and of apomixis seems to be associated with sexual polyploidization. The tetraploids and triploids were very vigorous and one of the tetraploids performed as well as the best variety in uniform yield trials conducted in Nigeria. These spontaneous polypoloids provide greater genetic variation and offer an opportunity to breed radically new cassava varieties. Approaches for isolating and utilizing the polyploid cassava clones for varietal and population improvement are discussed.     

Rice (<i>Oryza sativa</i> L.) Breeding among Hassawi Landrace and Egyptian Genotypes for Stem Borer (<i>Chilo agamemnon</i> Bles.) Resistance and Related Quantitative Traits

Rice stem borer (Chilo agamemnon Bles.) is a primary insect pest of rice and is a major limiting factor to rice production. Breeding for insect-resistant crop varieties has been an economic way of integrated pest management (IPM) as it offers a viable and ecologically acceptable approach. This study was aimed to evaluate rice genotypes for their resistance against rice stem borer. Seven parental genotypes with twenty one F1 crosses were evaluated for genotypic variation in field experiments. Analysis of variance revealed significant differences for the studied traits in almost all crosses and parents. In addition, the mean squares of parents versus their crosses were signifi- cant for stem borer resistance and other associated traits. Moreover, both general combining ability (GCA) and specific combining ability (SCA) variances were highly significant for all characters studied in the F1 generation. Based on GCA, 4 genotypes (Sakha101, Gz6903-3-4-2-1, Gz9577-4-1-1 and Hassawi) exhibited highly significant negative values for stem borer resistance (–0.53, –1.06, –0.18 and –0.49, respectively) indicating they are the best combiners for stem borer resistance. Based on SCA analysis, nine cross combinations showed highly significant negative effects for stem borer resistance. Similarly, the cross Giza178 Hassawi was the best combination with significantly highest value for early maturity. In addition, seven crosses showed highly significant negative SCA for plant height trait. On the other hand, for panicle length, number of primary branches/panicle, panicle weight and 1000-grain weight, seven, four, eight and six crosses showed highly significant positive SCA, respectively. The result further revealed that the non-additive dominance genetic variance was higher than the additive variance for all evaluated traits indicating that non-additive genetic variances have a role in their inheritance. The broad-sense heritability estimates were high for all the studied traits. The stem borer resistance was significantly correlated with panicle weight and 1000-grain weight, which also showed a highly significant correlation with grain yield/plant. Thus these traits can be effectively employed in a breeding program to confer resistance against stem borer infestation in rice. It was further supported by biplot analysis, which clustered these potentially important traits into two quadrants showing their importance in any future breeding program to control stem borer infestation. This study has contributed valuable information for evaluation of genetic diversity in the local rice germplasm and its utilization in futuristic rice genetic improvement programs.     

Studies on protein content and yield levels in rice

Summary Crosses between low and high protein varieties revealed the dominance of low protein over high protein content. The number of desirable segregants with the double combination of high protein and yield were scored in each generation. The increasing frequency of desirable segregants from the F₂ to the F₃ generation in all the crosses increase the chances of selecting desirable recombinants for propagating improved rice varieties. Hybridisation followed by selection may help in developing varieties with high protein content and superior yield potential.     

Inheritance of seed protein content and other agronomic characters in long bean (Vigna sesquipedalis Fruw.)

Summary Seven varieties of long bean, which included three local and four exotic, were crossed in a complete diallel. This was an attempt to study the inheritance of crude protein content, protein yield, flowering date, pod yield and yield components.Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in crude protein content, number of pods per plant and number of seeds per pod. For seed weight and pod length, additive variance was more important.The crude protein content, protein yield and number of pods per plant appeared to be controlled by overdominance effects. Partial dominance seemed to be the case for flowering date, pod length and seed weight; complete to overdominance for pod yield. High protein appeared to be associated with recessive genes whereas there was a general trend of high yielding parents carrying more dominant genes.     

Diallelic analysis of quantitative traits in hexaploid wheat (Triticum aestivum L.)

Abstract

A complete diallel study of crosses between eight wheat varieties was carried out to determine the relative magnitude of components of genetic variation and heritability for important grain yield, quality and drought‐related traits. The data appeared adequate for the additive‐dominance model. The additive effects predominated for most traits, and consequently the narrow‐sense heritability was high to moderately high for flag leaf area, weight and venation, stomatal frequency and size, epidermal cell size, biomass, protein content, number of tillers, spike length, spike density, 1000‐grain weight and grain yield. These results appear promising for selecting better plants in the segregating populations with some degree of improvement for yield, quality and physiological efficiency.     

Combining ability analysis of beta-Carotene,total carotenoids and other grain characteristics in pearl millet

Summary Combining ability studies with respect to grain quality characteristics viz., beta-Carotene, total carotenoids, protein content, 250-grain weight, grain hardness and grain yield were carried out from a 13x13 diallel cross set in pearl millet [Pennisetum typhoides (Burm S&H)].The parents versus hybrids comparison indicated significant heterosis for all the traits under study. In general the hybrids having higher grain yield had bold hard grains with more carotene but low protein content, although a few hybrids combined high yield with an average protein percentage. The relative proportions of the general and specific combining ability variances indicated predominance of non-additive genetic variance with respect to all the traits. The per se performance of parents provided a fairly good indication of their combining ability in most cases. Parents possessing desirable grain quality characteristics were identified. Breeding implications are discussed.Part of the Ph.D. dissertation submitted to the Punjab Agricultural University by the senior author in partial fulfilment of the requirements for the degree     

Biomass yield and heterosis of crosses within and between European winter cultivars of turnip rape (<Emphasis Type="Italic">Brassica rapa</Emphasis> L.)

Because of its high growth rate at low temperatures in early spring, there is renewed interest in Brassica rapa as a winter crop for biomass production in Europe. The available cultivars are not developed for this purpose however. An approach for breeding bioenergy cultivars of B. rapa could be to establish populations from two or more different cultivars with high combining ability. The objective of this study was to evaluate the heterosis for biomass yield in the European winter B. rapa genepool. The genetic variation and heterosis of the biomass parameters: dry matter content, fresh and dry biomass yields were investigated in three cultivars representing different eras of breeding by comparing full-sibs-within and full-sibs-between the cultivars. Field trials were performed at two locations in Germany in 2005–2006. Mean mid-parent heterosis was low with 2.5% in fresh and 3.0% in dry biomass yield in full-sibs-between cultivars. Mean values of individual crosses revealed a higher variation in mid-parent heterosis ranging from 14.6% to −7.5% in fresh biomass yield and from 19.7% to −12.7% in dry biomass yield. The low heterosis observed in hybrids between European winter cultivars can be explained by the low genetic variation between these cultivars as shown earlier with molecular markers. In conclusion, a B. rapa breeding program for biomass production in Europe should not only use European genetic resources, but should also utilize the much wider worldwide variation in this species.     

Genetic parameters and direct,maternal and heterosis effects on litter size in a diallel cross among three commercial varieties of Iberian pig

The Iberian pig is one of the pig breeds that has the highest meat quality. Traditionally, producers have bred one of the available varieties, exclusively, and have not used crosses between them, which has contrasted sharply with other populations of commercial pigs for which crossbreeding has been a standard procedure. The objective of this study was to perform an experiment under full diallel design among three contemporary commercial varieties of Iberian pig and estimate the additive genetic variation and the crossbreeding effects (direct, maternal and heterosis) for prolificacy. The data set comprised 18 193 records for total number born and number born alive from 3800 sows of three varieties of the Iberian breed (Retinto, Torbiscal and Entrepelado) and their reciprocal crosses (Retinto × Torbiscal, Torbiscal × Retinto, Retinto × Entrepelado, Entrepelado × Retinto, Torbiscal × Entrepelado and Entrepelado × Torbiscal), and a pedigree of 4609 individuals. The analysis was based on a multiple population repeatability model, and we developed a model comparison test that indicated the presence of direct line, maternal and heterosis effects. The results indicated the superiorities of the direct line effect of the Retinto and the maternal effect of the Entrepelado populations. All of the potential crosses produced significant heterosis, and additive genetic variation was higher in the Entrepelado than it was in the other two populations. The recommended cross for the highest yield in prolificacy is a Retinto father and an Entrepelado mother to generate a hybrid commercial sow.     

Assessment of Genetic Diversity in <Emphasis Type="Italic">Trigonella foenum-graecum</Emphasis> Based on Nuclear Ribosomal DNA,Internal Transcribed Spacer and RAPD Analysis

Fenugreek (Trigonella foenum-graecum) is receiving global attention due to rare medicinal properties of significance to human health. Gene banks possess scanty germplasm and very little background information regarding its genetic variability that has hampered its improvement. We investigated the extent of variability among 17 Indian varieties of fenugreek using phenotypic and genetic markers. Multilocus genotyping by ten random amplified polymorphic DNA (RAPD) primers detected an average of intraspecific variations amounting to 64.7% polymorphism in banding patterns. Analysis of molecular variance indicated that a greater proportion of total genetic variation exists within population (91%) rather than among populations. Higher values of Nei’s gene diversity (h) and Shannon Information Index (i) and genetic distance analysis validate higher genetic diversity among Indian fenugreek varieties. SNPs at 14 sites of rDNA region revealed further lineages of distinct varieties with main RAPD clusters. The representative sequences of each subgroup and all distinct varieties have been submitted to NCBI database and assigned Gen Accession numbers HM 176640–176649. The measures of relative genetic distances among varieties of fenugreek did not completely correlate with the geographical distances of places of their development. The homogeneous phenotypic markers proved insufficient in exhibiting genetic divergence among fenugreek varieties studied. Eventually, the knowledge of their genetic relationships, DNA bar coding and phylogenies might contribute for the designing of intraspecific crosses between cultivars of this fenugreek collection with potential interest in seed spices breeding programme.     

Genetic studies of yield contributing traits in Amaranthus

Summary Genetical studies on grain yield and its contributing traits were made in a six parent complete diallel in the F₁ and F₂ generations of one of the most widely grown grain species of grain amaranths (Amaranthus hypochondriacus L.). Graphical analysis indicated that epistasis exists for 1,000-grain weight in the F₁. Grain weight/panicle, yield/plant and harvest index indicated absence of non-allelic gene interaction. The harvest index in the F₁ and F₂ and grain weight/ panicle, 1,000-grain weight, yield/plant in the F₂ appeared to be controlled by overdominance effects. Higher grain yield appeared to be associated with dominant genes. Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in grain yield/ plant and harvest index in the F₁ and F₂. For 1,000-grain weight additive genetic variance was more important in the F₁ and non-additive in F₂. There was overdominance of a consistent nature in the two analyses for harvest index in the F₁ and F₂, grain weight/ panicle, 1,000-grain weight and yield/plant in the F₂ and partial dominance for 1,000-grain weight in the F₁.     

Analysis of diallel cross in Phaseolus aureus roxb

Summary In a diallel cross of Phaseolus aureus involving five varieties, combining ability and gene action for grain yield, grains per pod and pods per plant were estimated. The study indicated that both general combining ability and specific combining ability effects were significant and important for all three traits. Partial dominance for grain yield and partial to over-dominance for grains per pod and pods per plant were observed. Dominant genes seem to govern the inheritance of all three characters. Combining ability, and graphical and component variance analyses indicated that the grain yield and two of its components are influenced by both additive and non-additive gene action.     

湿地松×洪都拉斯加勒比松遗传多样性的ISSR分析

杂交育种是产生遗传变异、表型变异及选择新变异的重要方法。然而系统发育不清晰,选择较近的亲缘关系亲本用于杂交子代往往表现出较低的遗传多样性。为探究湿地松、洪都拉斯加勒比松种间杂交后代遗传多样性水平,对8个湿地松×洪都拉斯加勒比松家系进行ISSR分析。利用10条引物共产生60个表达清晰可用于分析的标记,其中48个标记表现为多态性,占总标记数的80%; 湿加松各个家系多态位点百分率在5%～23.33%之间; 各个家系基因多样性指数在 0.015 2～0.087 2之间,Shannon指数的范围在 0.021 6～0.129 4之间(家系水平为 0.293 4)。8个家系间的基因分化系数G_st为0.743 5,即总的遗传变异中有74.35%的变异存在于家系间,家系内的遗传变异占总遗传变异的25.65%。采用UPGMA法对湿加松的8个家系进行了聚类分析,确定了各个家系之间的遗传亲缘关系。8个家系间的基因流N_m为 0.172 5,表明基因流处于较低水平。     

Genetics of transgressive segregation for yield and yield components in wheat

Three crosses of spring wheat (Triticum aestivum L. em Thell) involving six cultivars (WC29, WH291, SGP 14, RAJ. 1972, WH377 and HD 2329) were selected on the basis of combining ability analysis to study genetics of transgressive segregation for tillers/plant, grains/spike, 1000 grain weight and grain yield/plant using various mating designs. Diallel analysis indicated that both additive and non- additive components were significant for all the characters. On the basis of general combining ability and specific combining ability effects, the parents WH 291 and WH 377 were found to be good general combiners for tillers/ plant, 1000 grain weight and grain yield/plant. For grains/spike SGP 14 was found to be a good general combiner. The cross WH 377 × HD 2329 for tillers/plant, SGP 14 × Raj. 1972 for grains/spike and grain yield/plant and WC 29 × WH 291 for 1000 grain weight were found to be good cross combinations. Generation mean analysis indicated that the additive-dominance model was inadequate for all the characters in all the crosses except for 1000 grain weight in WC29 × WH291. Additive component was more pronounced than non-additive components for all the characters in all the crosses except for tillers/ plant in WH 377 × HD 2329. Predictions for transgressive segregants from F₃ was more accurate than that from generation mean analysis. However, prediction from both the sources were equally efficient if additive-dominance model was adequate. In general, observed frequencies of transgressive segregants were more in F₂ and BIPi than F₄ but the majority of them were discarded on progeny testing. Biparental mating had an impact in increasing the frequencies of transgressive segregants for different characters in all the crosses. The crosses, WH 377 × HD 2329 for grain yield/ plant, SGP 14 × Raj. 1972 for tillers/plant and WC 29 × WH 291 for grains/spike and 1000 grain weight were found to be potential crosses for transgressive segregants. A comparison of combining ability of parents and crosses, and observed and predicted frequencies of transgressive segregants indicated that the potential crosses for transgressive segregants were those that had high sea effects and involved high and low general combiners. The crosses involving low general combiners irrespective of their sea effects showed poor performance with respect to transgressive segregation.     

Comparison of bread wheat lines selected by doubled haploid, single-seed descent and pedigree selection methods

 Yield performance of each group of ten spring bread wheat lines selected by doubled haploid (DH), single-seed descent (SSD) and pedigree selection (PS) methods from three F₁ crosses was compared with the aim of evaluating the DH method in breeding programs. Populations of 65–97 DH lines and 110 SSD lines per cross were used for selection. PS lines were developed by repeated selections from 1500 F₂ plants. Yield evaluation was performed at the F₆ generation of SSD and PS lines along with DH lines in a 2-year field experiment. It took only 2 years from the planting of wheat materials for DH production to the planting of selected DH lines for yield evaluation. There was no significant difference in grain yield between DH lines and PS lines selected from an F₁ cross whose parental varieties were closely related in their pedigrees. In two crosses with low coefficients of parentage and a large variation in their progenies, grain yield of selected DH lines was significantly lower than those of selected SSD and PS lines. These results confirm that the DH method can save time in obtaining recombinant inbred lines ready for yield evaluation. However, a larger DH population is required to achieve the same level of genetic advance with the PS method in crosses containing greater genetic variation. Received: 23 December 1997 / Accepted: 12 March 1998     

EXPERIMENTAL STUDIES OF PONDEROSA PINE. II. QUANTITATIVE GENETICS OF MORPHOLOGICAL TRAITS

We studied fourteen morphological attributes of 511 seedling stage progeny involving crosses between Pinus ponderosa ponderosa parents as well as intervarietal crosses of P. p. ponderosa × P. p. scopulorum. Intravarietal progeny were distinctly differentiated genetically from intervarietal sibships in seven of the fourteen characters examined. The patterns of differentiation observed strongly suggest a syndrome of selective responses to increased water stress in the progeny with a scopulorum parent and for comparatively more rapid, columnar growth in the progeny of the intravariety crosses which involved only P. p. ponderosa parents. These differences are consistent with known ecological distinctions between the habitats of the two varieties. Narrow-sense heritability estimates, obtained from half-sib progeny analysis, indicated that considerable levels of additive genetic variance remain present in several traits. We could detect no relationship between the amount of additive genetic variance present for a particular character and its presumed relevance to fitness.     

Genetically based differences in photochemical activities of isolated maize (Zea mays L.) mesophyll chloroplasts

Photochemical activity of isolated mesophyll chloroplasts was measured as Hill reaction activity (HRA) and photosystem 1 (PS1) activity in three diallel crosses of maize (Zea mays L.) inbred lines and F₁ hybrids. Statistically significant differences between genotypes together with positive heterotic effect in F₁ generation were found for both traits studied. These differences were more pronounced when HRA or PS1 activity was expressed per leaf area unit or dry matter unit compared to the expression per chlorophyll content unit. Analysis of variance showed that both the genetic and non-genetic components of variation in the photochemical activity of isolated mesophyll chloroplasts are present in all three diallel crosses examined. The positive heterosis in F₁ hybrids probably arises from non-additive genetic effects of a positive dominance type. Additive genetic effects were also statistically highly significant. We found no differences between reciprocal crosses. This revised version was published online in September 2006 with corrections to the Cover Date.     

A quantitative evaluation of inter-varietal hybrids of Brassica campestris L.

Summary A quantitative evaluation of yield components was carried out in 150 inter-varietal hybrids of Brassica campestris using five each of the three varieties, brown sarson (BS) , yellow sarson (YS) and toria (TR). The results showed both additive and non-additive gene action for plant height, number of primary and secondary branches and number of siliquae on the main axis in all the six cross combinations BS-YS, YS-BS, BS-TR, TR-BS, YS-TR and TR-YS. The general combining abilities of BS, YS and TR indicated that their nature and magnitude depended largely on the other parents which entered the hybrids. There were differences in combining ability between direct and reciprocal combinations. GBS II, Kanpur Lotni 17, Kanpur Lotni 27 and DS 17D in BS, IB 3, IB 5, IB 6 and BP 12 in YS , and T 165, T 244 and T 1842 in TR were identified as potential parents for inter-varietal hybridisation. Reciprocal effects were found when BS or YS was used as parent and they were least when TR was used as a parent. The amount and degree of heterosis was substantial in inter-varietal crosses. Based on the heterosis-combining ability relationship, the role of inter-varietal hybridisation in population improvement of Brassica campestris is discussed. A number of methods of utilising the inter-varietal hybrids in multiple crosses and synthetic complexes is suggested as potential supplements to population breeding in this crop.Part of a Ph.D. thesis submitted by senior author to P.G. School, Indian Agricultural Research Institute, New Delhi     

Genetic analysis of some seed quality characters in upland cotton (Gossypium hirsutum L.)

Summary A set of diallel crosses involving ten parents was evaluated over two locations to determine the genetic control of protein per cent, oil per cent, seed index, percentage of mature seeds and number of seeds per boll. The analysis of pooled data showed that percentage of mature seeds was controlled by additive (D) and non-additive (H₁ and H₂) genetic effects. Overdominance was noticed. For seed index the D component measuring additive, and the H₂ component measuring dominance, variation were significant. Protein content and oil content were primarily under the control of non-additive (H₁ and H₂) genetic effects, while for number of seeds per boll the variability was accounted for by dominance (H₁) effects only. The development of pure lines through appropriate methods is suggested.Part of the thesis of the senior author, submitted in partial fulfilment for the Ph.D. degree     

Somatic embryogenesis in Zea mays L.

Summary Combining ability studies with respect to such green fodder quality characteristics as oxalic acid, calcium, sodium, potassium and green fodder yield were carried out in a 12 × 12 diallel cross set in pearl millet (Pennisetum typhoides (Burm) S. & H.). With regard to differential expression of gene effects, studies for quality traits were carried out in different seasons and on different plant parts. The relative proportions of general and specific combining variances indicated the preponderance of non-additive genetic variance. Parents possessing desirable fodder quality characteristics were identified on the basis of combining ability and per se performance, and selection criterion for crosses was discussed. It was recommended that leaf portion should be biochemically analysed and manipulated in an environment when the genes are expressed.Part of the Ph. D. dissertation submitted to the Punjab Agricultural University by the senior author in partial fulfilment of the requirements for the degree