F1 Plants Of Crosses Research Articles

Inheritance Studies of Amylose Content, Yield and Grain Quality Characters in Different Rice Genotypes (Oryza sativa L.)

Breeding for produced new rice varieties with good grain quality especially for low amylose content has become one of the most important goals in plant breeding programmes. In this experiment, three rice genotypes(Giza178, Giza175 and IR64) were used as a perants to study the inheritance amylose content, heritabilityand genetic parameters for grain yield per plant, 1000-grains weight, grain length, grain shape, hulling%, milling%, head rice% and gelatinization temperature characters. A randomized complete block design (RCBD) was used with three replications for six generations viz., P1, P2, F1, F2, BCP1 and BCP2 of a cross between Giza 178 (low amylose content) x Giza 175 (high amylose content) (cross I) and Giza178 (low amylose content) x IR64 (intermediate amylose content) (cross II) were used for the study. The results showed that the F1 plants of cross I gave intermediate amylose content in the endosperm 22.58%, while, the amylose content of F2 plants varied from 13.10 to 35%. and classified into two categories, i.e. 13.10-19 % and 20.50 -35 %.. These results indicated that high amylose content was incompletely dominant over low amylose. Cross II (Giza 178/IR64) low amylose content parent (Giza178) and intermediate amylose parent (IR64) gave 19.84% amylose content in F1 plants, while in F2 grains amylose values ranged from9.5 to 24.1. The plants could be classified into 3 categories. Category 1 with 9.5% - 11% a, category 2 (14.5-19.05%) and Category 3 (21.1-24.1%). Selection for intermediary segregates would be ineffective because the dosage effects would dissipate in further generations.

Blue aleurone trait diagnoses developmental origin of three pistils in a floret in common wheat

AbstractThe common ‘three‐pistil’ (TP) wheat mutation line expresses TPs in a floret normally containing TPs forming three grains set close back‐to‐back. The developmental origin of the TP trait in common wheat had been diagnosed non‐destructively using the blue aleurone trait. The aleurone colour of F2 seeds grown in F1 plants of cross TP/UC66049 was evaluated. Due to xenia, the hue of blue grain colour depended on dose of the Ba1 gene for blue aleurone in the triploid endosperm. The TP trait produced four types of segregation in three‐seed clusters: (i) white grain only, (ii) two white grains and one blue, (iii) one white grain and two blue, and (iv) three blue grains only. The observed frequency of blue–white seed within clusters followed the binominal distribution 3Cr (0.75)r·(0.25)3–r, where r is the number of colour variants in three‐seed clusters (r = 0–3). Intrafloret segregation of seed colour and F2 segregation derived from aleurone colour of F3 seeds indicated an independent origin of the TP trait.

Cytomorphology of <i>Brassica juncea </i>× <i>B. napus</i> Hybrids and Pattern of Variation in the F<sub>2</sub> Derivatives

Interspecific hybridization is an important tool to elucidate intergenomic relationships, transfer characters across species, create genetic variability, and to develop synthetic amphidiploids. It has been widely used for improving Brassica. The present study was conducted to find out the crossability between Brassica juncea (AABB, 2n=36) and B. napus (AACC, 2n=38), analyze chromosome association in the F1 hybrids, and to estimate variability in F2 progenies of the cross. The crossability between B. juncea and B. napus was higher when B. juncea was used as the female parent. The hybrids, in general, were vigorous and intermediate in morphological attributes. The meiotic studies of F1 plants of cross B. juncea × B. napus (AABC, 2n=37) exhibited 10 bivalents in the majority of the pollen mother cells (PMCs) analyzed. A maximum of 14 bivalents in AABC hybrids and the presence of multivalent associations were attributed to the autoand allosyndetic nature of pairing within and between the B and C genomes. In the F2 generation, a high percentage of plants resembling B. juncea type and transgressive segregation for many characters were found.

Complementary Genes That Cause Black Ripening Hulls in F1 Plants of Crosses between Indica and Japonica Rice Cultivars

The F1 plants of crosses between indica and japonica rice cultivars often have black hulls during ripening, even though both of the parental cultivars have yellow hulls. Complementary genes are suggested to be necessary for the black hull phenotype, and one of them is predicted to be Phr1, which encodes polyphenol oxidase. On the other hand, Bh4, which encodes a tyrosine transporter, is known to cause the black hull phenotype in wild rice species, Oryza rufipogon. However, the relationship between Bh4 and Phr1 in the black hull phenotype has not been elucidated. In this study, a genotype analysis of the segregating populations from the cross between an indica cultivar, Habataki, and a japonica cultivar, Arroz da Terra, indicated that only those plants that had both functional genes, Bh4 and Phr1, showed the black hull phenotype, suggesting that a complementarity of Bh4 and Phr1 was necessary for the black hull phenotype.

Comportamento de somaclones de arroz derivados de híbridos da geração F1 para resistência à brusone

A indução de variabilidade genética em relação à resistência à brusone, utilizando cultura de tecidos como material, constitui uma das alternativas para a obtenção de novas fontes de genes de resistência. O objetivo deste estudo foi aumentar a freqüência de variantes usando como explante panículas imaturas da geração F1 de cruzamentos envolvendo fontes altamente suscetíveis e moderadamente resistentes à brusone como parentais. Somaclones de arroz derivados de plantas F1 dos cruzamentos Bluebelle/Araguaia e Maratelli/Basmati-370 foram avaliados, nas gerações avançadas, quanto à resistência à brusone e a algumas características agronômicas. Nos testes de inoculações em casa de vegetação, todos os somaclones, de ambos os cruzamentos, na geração R4, apresentaram alto grau de resistência aos patótipos IB-1 e IB-9. Alguns dos somaclones mantiveram-se resistentes na geração R5, em avaliações realizadas com alta pressão de brusone. No campo, os somaclones R5 e R6 mostraram alta freqüência de variação quanto à resistência à doença, altura da planta, produtividade, peso e tipo de grãos. Dois somaclones derivados do cruzamento Bluebelle/Araguaia e 31 somaclones derivados do cruzamento Maratelli/Basmati-370 foram identificados como novas fontes de resistência à brusone, e podem ser utilizados no programa de melhoramento de arroz irrigado.

Resistance to Septoria nodorum blotch in several Triticum species

Resistance to septoria nodorum blotch in Triticum monococcum, T. tauschii, T. timopheevii, T. dicoccum and T. durum was evaluated on plants at the three-leaf stage in greenhouse tests. A high frequency of resistant genotypes was found in T. monococcum, T. tauschii and T. timopheevii, but not in T. dicoccum and T. durum. The resistance of F1 plants of crosses of resistant T. monococcum (PI 289599) and T. timopheevii (PI 290518) accessions with susceptible common wheat cv. Park and durum wheat cv. Wakooma, respectively, was evaluated on the basis of percentage leaf necrosis, lesion number, lesion size and incubation period. No dominance was found for long incubation period, but various dominance relationships occurred for low percentage leaf necrosis, low lesion number and small lesion size, depending on the cross. Multiple regression analysis showed that lesion number contributed more to percentage leaf necrosis than lesion size or incubation period. Resistance to septoria nodorum blotch was transferred successfully from T. timopheevii to cultivated durum wheat. Resistant BC1F7 lines, recovered from the T. timopheevii (PI 290518) × Wakooma cross, showed normal chromosome behaviour at meiosis (14 bivalents) and were self-fertile. However, an effective level of resistance was not recovered in lines derived from the other interspecific crosses.

Inheritance of resistance to Meloidogyne spp. in common bean and the genetic basis of its sensitivity to temperature

Bean lines PI 165426, PI 165435, and Alabama no. 1, possessing resistance to Meloidogyne incognita, and bean lines A315 and A445, possessing gene Me1, were tested against several Meloidogyne incognita and M. javanica isolates. Resistance in bean line PI 165426, PI 165435, and Alabama no. 1 was found to be complementary to resistance conferred by gene Me1. Resistance in PI 165426 was found to be dominant and conditioned by one dominant and one recessive gene at 26 °C. We propose Me2me3 as the genotype symbol for this resistance. Resistance in lines PI 165435 and Alabama no. 1 was found to be recessive. Since Alabama no. 1 and PI 165435 were resistant at 26 °C but susceptible at 29 °C, and segregation of F2 progeny derived from crosses involving PI 165426 was 13∶3 at 26 °C and 1∶2∶1 at 28 °C, we concluded that the temperature at which transition from resistance to susceptibility occurs was determined by whether the resistance gene is dominant or recessive. Furthermore, the 1∶2∶1 segregation of F2 plants and an intermediate resistance reaction of F1 plants of crosses involving PI 165426 indicated that allelic dosage of the dominant gene also influenced the transition temperature.

Inheritance of resistance to soybean mosaic virus(SMV) C-strain in soybeans.

Seventy five cultivars were evaluated for their resistance to a virulent strain of soybean mosaic virus (SMV-C) spreading in the central part of Japan. Reactions of trifoliolate leaves of the cultivars to the C strain were classified into the following three types ; no symptoms (resistant : R), necrotic spot symptoms (NS : Fig. 3) and typical mosaic sylriptoms (M). Three resistant cultivars (R), two cultivars with necrotic spots (NS) and seven susceptible ones (M) were used to study the mode of inheritance of the resistance by artificial inoculation tests conducted in the greenhouse. F1 plants of crosses between three resistant and susceptible cultivars (R-S) showed necrotic spots or did not exhibit symptoms, and the F2 plants were classified into three types in the same way as the cultivars (Table 1). If it is considered that the NS plants have the same type of resistance as the resistant plants, all the crosses fit to the ratio 3 resistant : 1 mosaic symptoms, indicating that the resistance is controlled by a single dominant gene. However in the case of the two crosses using “Tousan 140” as resistant cultivar, F2 plants fitted well to the ratio 1 no symptoms : 2 NS : 1 mosaic symptoms. All the F1 plants of these crosses corresponded to the NS group, and the F3 plants which were derived from F2 plants with necrotic spot symptoms segregated into the ratio 3 resistant : 1 mosaic symptoms. The backcross populations between susceptible cultivars and F1 plants segregated into the ratio 1 necrotic symptoms : 1 mosaic symptoms. These results suggest that the plants with the NS symptoms show on heteroallelic phenotypes in the case of “Tousan 140”. Thus the resistant cultivars are considered to have one totally or partially dominant resistance gene. Among the crosses between resistant cultivars (R-R), in two crosses the F2 populations segregated into the ratio 15 resistant : 1 mosaic symptoms while in another cross the populations did not exhibit symptoms (table 2). These data indicate that there are two kinds of independent resistance genes. On the other hand, the R-NS crosses segregsted into the ratio 15 resistant : 1 mosaic symptoms, and the S-NS crosses segregated into the ratio 3 resistant : 1 mosaic symptoms (table 3). These data indicate that the cultivars with necrotic spot symptoms (NS) have a dominant resistance gene which is inherited independently of the two kinds of resistance genes mentioned above. “Raiden” which was bred in Japan is considered to be the source of the resistance gene Rsv2 (BUZZEL and TU 1984), but is susceptible to the C strain. So it is assumed that the three resistant cultivars may have different gene from Rsv2. The relationship between the genes of these cultivars and that of “PI 96983” (gene symbol Rsv : KIIHL and HARTWIG 1979) and “PI 486.355” which was reported by LIM (1985) could not be verified in thls study. Since the reaction of “Ogden” was the same as that of “Tousan 122” and “Dorchsoy 31”, cultivars with NS symptoms such as “Tousan 122” may have the same resistance gene symbolyzed by rsvt (KIIHL and HARTWIG 1979). It is concluded that there are at least three kinds of independent resistance genes to the C strain.

Inheritance of Floating Ability in Rice

Diallel crosses were made among 10 rice varieties which vary in degrees of floating ability. The F1 and F2 generations were tested at the Huntra Deep Water Rice Exp. Station in Ayutthaya in 1975 and 1976, respectively. The F1 plants of crosses between floating and ordinary lowland rice varieties showed intermediate tolerance to 150cm deep water indicating that floating ability was a partially dominant character. Most F2 populations showed continuous distribution for floating ability suggesting that several genes were responsible fcr this character although damages by heavy rain and injuly by crabs disturbed to draw accurate conclusions from the F2 experiment. These results suggest that rice varieties with different degrrees of floati.ng ability could be developed to cope with the various flooding conditions distributed

Accessory Chromosomes and Their Meiotic Behaviour in Hybrids of Grain Sorghum and Johnson Grass

The F1 plants of crosses between S. subglabrescens (2n = 20) and a diploid race of S. halepense (2n = 20 + 4 to 6 B chromosomes) had 4-10 B chromosomes in the PMCs but none in root-tip cells. Of twelve hybrids obtained six had 4, two had 4-6, two had 6-8 and one had 8-10 B chromosomes. The accessory chromosomes were found only in pairs, three kinds of which could be distinguished

A comparison of two rapid screening methods for the selection of high‐lysine barleys

AbstractA ninhydrin colour test based on the higher levels of free amino acids in the grain of a high‐lysine barley mutant, Risø 1508, and a turbidity test based on its lower prolamin content, were used for the selection of single grains from F1plants of crosses, involving it. The prolamin turbidity test was preferred for analysis of single F2 grains because it was more sensitive with grain of lower nitrogen content. In addition, turbidity was not significantly correlated with seed weight or with position in the spike of Risø 1508. Both methods are rapid, simple, inexpensive and sufficiently precise to distinguish genotypes which differ significantly in their lysine contents.

Seedling Vigor of Open‐Pollination Progenies of Intra‐ and Inter‐Source Crosses of Birdsfoot Trefoil, Lotus corniculatus L.1

Seedling vigor traits of open‐pollination seed from F1 plants of crosses within and between two diverse germplasm sources of birdsfoot trefoil (Lotus corniculatus L.) were studied under nonphotosynthetic conditions in a germination chamber. Parents of F1 plants were derived from ‘Empire’ and two Russian introductions. Seedling vigor (as measured by dry weight, hypocotyl length, radicle length, and total seedling length) was positively associated with seed size (r values ranged from 0.47 to 0.87). Progenies of crosses between the Empire and Russian sources exhibited a 5% increase in hypocotyl length at 7 days when compared with the average of progenies of intrasource crosses. Heterosis was not manitested for radicle length or seedling dry weight. Progenies of Empire crosses were superior in those two traits.