Interspecific hybridization between Cicer arietinum and C. pinnatifidum

An interspecific hybrid between Cicer arietinum cv. GL 769 and a wild species C. pinnatifidum was obtained after emasculation, pollination and application of growth regulators. Ovules were cultured and embryos were later dissected to obtain hybrid plants. These plants were albinos and morphologically resembled C. pinnatifidum. Shrivelled seeds were also obtained in 2% of the crosses, which on germination gave rise to albino plants. These plants did not survive beyond 20 days. The hybrid nature of these plants was confirmed by esterase isozyme studies. Hybrid shoots obtained from germinating embryos were cultured on modified ML-6 medium with BAP 2 mg/1, IAA 0.5 mg/1, where they turned green after 3–4 weeks. Transmission electron microscopy (TEM) studies on leaf sections from green hybrid shoots showed an improvement in the chloroplast structure, with better organized grana.     

Investigations into the Barrier(s) to Interspecific Hybridization between Cicer arietinum L. and eight other Annual Cicer species

Barrier(s) to interspecific hybridization between the cultivated chickpea, Cicer arietinum L., and eight other annual wild species, i.e. C. reticulatum Lad., C. echinospermum Dav., C. pinnatifidum J. and S., C. judaicum Boiss., C. bijugum Rech., C. chorassanicum (Bge) M. Pop., C. yamashitae Kit. and C. cuneatum Rich., were investigated. In general, good pollen germination and pollen tube growth were observed in all eight crosses and their reciprocals. En spite of a few pollen cube growth abnormalities in most crosses, pollen tube penetration into the ovule and, thus, fertilization was observed in all cross combinations. However, differences were observed in the time from pollination to fertilization, not only between different interspecific crosses but also between reciprocals of a particular interspecific cross. The crossability barrier is, therefore, believed to be due to factor(s) operating after fertilization.     

Successful interspecific hybridization between Cucumis sativus L. and C. hystrix Chakr.

Interspecific F₁ hybrids were obtained from a cross between Cucumis sativus L. (2n = 2x = 14) and C. hystrix Chakr. (2n = 2x = 24). Controlled crossing resulted in fruit containing embryos which were excised and rescued on a Murashige and Skoog solid medium. A total of 59 vigorous plants were obtained from a fruit containing 159 embryos (37.3% regeneration rate). Hybrid plants were morphologically uniform. The multiple branching habit, densely brown hairs (especially on corolla and pistil), orange-yellow collora, and ovate fruit of F₁ hybrid plants were similar to that of the C. hystrix paternal parent. While appearance of the first pistillate flower was more similar to that of C. sativus maternal parent than to C. hystrix, staminate flower appearance was mid-parent in occurence. The diameter and internode length of stem, shape and size of leaves and flowers were intermediate when compared to the parents. An elongated green, trilobate style/stigma which was not apparent in either parent was observed in staminate flowers of F₁ plants. Similarly, the style/stigma of pistillate flower of F₁ plants were longger when compared to their parents. The brown pubescence observed on pistillate flowers of the F₁ and C. hystrix was not observed on the C. sativus parent. The somatic chromosome number of F₁ plants was 19. Two morphologically distinct groups of chromosomes were observed in the F₁ hybrid; 7 relatively large chromosomes characteristic of C. sativus, and 12 smaller chromosomes characteristic of C. hystrix. Analysis of malate dehydrogenase isozyme banding patterns provided additional comfirmation of hybridity. Reciprocal crossing of F₁ plants to either parent and self-crossing indicated that the hybrids were male and female sterile. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pod volume and pod-filling percentage as additional traits for the characterization of chickpea (Cicer arietinum L.)

Thirty short- to medium-duration chickpea germplasm accessions from diverse geographic origins and with a wide range of physiological and morphological traits were grown in three environments at ICRISAT Asia Center, Patancheru, during 1992/93. Data were recorded on time to flowering, leaf area, 100-seed mass, pod volume, and pod-filling percentage. Quantitative data on the last two traits were recorded for the first time to examine their relevance to the characterization of germplasm accessions and their use as selection criteria in breeding. The accessions exhibited considerable variation for the traits. The broad-sense heritabilities were 0.98 for pod volume and 0.85 for pod-filling percentage. The two traits showed consistent relationships with other morphological characters indicating that the pod volume and pod-filling percentage traits can be utilized in genotype characterization of chickpea.     

Salinity Effects on the Growth and Ion Contents of Some Chickpea (Cicer arietinum L.) and Lentil (Lens culinaris Medic.) Varieties

The effect of salinity on seed germination, plant yield parameters, and plant Na, Cl and K concentrations of chickpea and lentil varieties was studied. Results showed that in both crops percentage emergence was significantly reduced by increasing NaCl levels (0–8dSm^?1). From the plant growth studies it was found that differences existed among chickpea and lentil varieties in their response to NaCl application. In chickpea, the variety Mariye showed the comparatively lowest germination percentage and the lowest seedling shoot dry weight in response to salinity and was also among the two varieties which had the lowest relative plant height, shoot and root dry weight and grain yield at maturity. Similarly, variety DZ-10-16-2, which was the second best in germination percentage and the highest in terms of seedling shoot dry weight, also had the highest relative plant height, shoot and root dry weights, and grain yield at maturity. In lentil, however, such relationships were less pronounced. Chloride concentration (mg g^?1) in the plant parts at salt levels other than the control was about 2–5 times that of Na. K concentration in the plants was significantly reduced by increasing NaCl levels. Chickpea was generally more sensitive to NaCl salinity than lentil. While no seeds were produced at salinity levels beyond 2dSm^?1 in chickpea (no seeds were produced at this salt level in the most sensitive variety, Mariye), most lentil varieties could produce some seeds up to the highest level of NaCl application. Overall, varieties R-186 (lentil) and Mariye (chickpea) were the most sensitive of all varieties. On the other hand, lentil variety NEL-2704 and chickpea variety DZ-10-16-2 gave comparatively higher mean relative shoot and root dry weights, and grain yield, thus showing some degree of superiority over the others. The observed variations among the varieties may be useful indications for screening varieties of both crops for salt tolerance.     

The origin of chickpea Cicer arietinum L.

Summary Species relationship between the cultivated chickpea Cicer arietinum and the two newly discovered wild species C. echinospermum and C. reticulatum were assessed through breeding experiments and cytological examination of the hybrids.The two wild species differed from each other by a major reciprocal translocation and their hybrid was completely sterile. The wild species C. echinospermum also differed from the cultivated species by the same translocation and their hybrid was highly sterile. The other wild species, C' reticulatum, was crossed readily with the cultivated chickpea. Meiosis of the hybrids, involving 4 different C. arietinum lines, was normal, and they were fertile. This wild species therefore can be considered as the wild progenitor of the cultivated chickpea.     

Interactive Effects of Salinity and Biological Nitrogen Fixation on Chickpea (Cicer arietinum L.) Growth

The effect of salinity on the nodulation, N-fixation and plant growth of selected chickpea- Rhizobium symbionts was studied- Eighteen chickpea rhizobial strains were evaluated for their growth in a broth culture at salinity levels of 0 to 20 dS m⁻¹ of NaCl + Na₂SO₄. Variability in response was high. Salinity generally reduced the lag phase and/or slowed the log phase of multiplication of Rhizobium. Nine chickpea genotypes were also evaluated for salt tolerance during germination and early seedling growth in Petri dishes at five salinity levels (0–32 dS m⁻¹). Chickpea genotypes ILC-205 and ILC-1919 were the most salt-tolerant genotypes. The selected rhizobial strains and chickpea cultivars were combined in a pot experiment aimed at investigating the interactive effect of salinity (3, 6 and 9 dS m⁻¹) and N source (symbiosis vs. inorganic N) on plant growth. Symbiotic plants were more sensitive to salinity than plants fed mineral N. Significant reductions in nodule dry weight (59.8 %) and N fixation (63.5 %) were evident even at the lowest salinity level of 3 dS m-¹. Although nodules were observed in inoculated plants grown at 6 dS m-¹, N-fixation was completely inhibited. The findings indicate that symbiosis is more salt-sensitive than both Rhizobium and the host plant, probably due to a breakdown in one of the processes involved in symbiotic-N fixation. Improvement of salinity tolerance in field grown chickpea may be achieved by application of sufficient amounts of mineral nitrogen.     

Cytology and Fertility of Hybrids and Amphiploids between Aegilops caudata L. ×Triticum turgidum (L.) Thell

Interspecific hybrids and amphiploids between Aegilops caudata L. (2n = 2x = 14, CC) and Triticum turgidum (L.) Thell. conv. durum Desf M. K. (2n = 4x = 28, AABB) were produced. Such hybrids can be used to introduce desirable traits such as disease resistance into cultivated durum wheats. One of the durum parents was a ph I mutation of the cv. ‘Cappelli’ used for testing the possibility of direct introduction of alien variation into cultivated species. The amphiploids were obtained both through colchicine chromosome doubling and as natural non-reductional mciosis products. In both hybrids and amphiploids, meiotic pairing and fertility were studied. Hybrids showed varying degrees of pairing and, in addition to the one involving the ph 1 mutant, one high pairing hybrid was found (Ae. caudata× cv. ‘Capinera’). Cytological examination of microsporogenesis in amphiploids revealed a high frequency of bivalent formation. Fertility proved to be a very variable character since some of the amphiploids were almost completely sterile. The use of amphiploids in breeding programmes is discussed in relation to meiotic and fertility data.     

Effect of Weed Removal on Productivity of Chickpea (Cicer arietinum L.) and Lentil (Lens culinaris Med.) in a Mediterranean Environment

Three field experiments were conducted on chickpea ( Cicer arietinum L.) and four on lentil ( Lens culinaris Med.) at different winter-sown rainfed locations in Jordan from 1988/89 to 1990/91 to study the effect of the duration of weed-free and weed-infested conditions on yields and yield components of the crops. Chickpea seed yields were reduced on average by 81 % and straw yields by 63 % when fields remained weed infested until harvest compared with weed-free conditions throughout the growing season. The corresponding lentil seed and straw yield decreases were 63 % and 55 %. As the duration of weed-free period increased and the duration of weed-infested period decreased, yields increased. However, the critical period of weed interference was between 35 and 49 days after emergence in chickpea and between 49 and 56 days after emergence in lentil, when these crops were at an advanced stage of vegetative growth. There were significant negative correlations between the weed dry weight and the seed or straw yields. The reduction in seed yields in both crops because of weed interference occurred mainly through the reduced number of pods /plant, which in turn was partly the result of reduced number of secondary branches. In chickpea, some reduction also occurred through reduced 100-seed weight.     

Genetic gains for yield after two back-crosses of the interspecific hybrid Libusta (Coffea canephora P. × C. liberica Bull. Ex Hiern) to C. canephora P.

The Libusta (Coffea canephora P. × C. liberica B.) programme initiated in the seventies in Côte d'Ivoire aims at improving the quality of coffee grown in low altitudes, with a yield comparable to current commercial C. canephora clones. The second generation of back‐crosses to the C. canephora (CAN) parent, BC2, are now likely to be commercially exploited as far as yield is concerned. The best BC2 progeny yielded 1386 kg of green coffee/ha/y, averaged over five harvest years. On average, the genetic gain for yield from BC1 to BC2 reached 22%. In a factorial mating design, no interaction was observed between BC1 and CAN parents, while both main effects were highly significant. This explained that observed genetic gains and further genetic gains may be achieved with appropriate strategies.     

Pistillate-parental differences and the ability to produce interspecific hybrids between Lycopersicon esculentum and 'peruvianum-complex' species (L. peruvianum and L. chilense)

To overcome the cross-breeding barriers between the cultivated tomato Lycopersicon esculentum and the ‘peruvianum-complex’, hybrid production ability (HPA) and pistillate-parental differences were investigated. As a criterion of HPA, the number of germinated ovules per fruit (GPF) was used. GPF was expressed as GPF = OPF × GPO, where OPF is the number of ovules per fruit, and GPO is the proportion of germinated ovules to total ovules obtained. The interspecific crossing between nine varieties and three ‘peruvianum-complex’ accessions revealed that the cultivars ‘Sekaiichi’,‘Ponde Rooza’ and ‘Early Pink’ showed quite high and stable GPF over the years, but the cv.‘Best of All’ produced no hybrids. Variance analysis for GPF, OPF and GPO, and their correlation with seven sexual organ morphological traits and three fruit morphological traits were performed. These results indicated that choosing both the pistillate parents with wider reproductive organs for high OPF and appropriate environmental conditions for high GPO might be significant for enhancing GPF in interspecific crossing.     

Incongruity in the interspecific crosses of Vitis L. Morphological abnormalities in the F2 progeny

Summary The F₂ generation of interspecific crosses of Vitis were examined for symptoms of incongruity, manifested as morphological abnormalities in the seedlings. Dwarfing, achlorophyllic variegation, deformed leaves, yellow mottling, sparse roots, and enation were documented. Most comparisons between classed of crosses were significantly different. The V. riparia x V. vinifera class exhibited the greatest frequency of abnormalities, the V. riparia x V. riparia class displayed the lowest frequency of abnormalities, and the highly-intercrossed V. riparia x French Hybrid class demonstrated an intermediate frequency of abnormal plants. When incongruity was viewed as a syndrome, or collection of symptoms, differences between classed were consistently evident. The highly-intercrossed nature of the French Hybrid ancestry appears to have been responsible for attenuating incongruity.Minnesota Agricultural Experiment Station, Scientific Journal Series No. 20834     

Meiotic behavior in interspecific hybrids between Brachiaria ruziziensis and Brachiaria brizantha (Poaceae)

The meiotic behavior of two half-sib interspecific tetraploid (2n = 4x = 36) promising hybrids, a sexual and an apomictic one, from crosses B. ruziziensis and B. brizantha, was evaluated. Although chromosome paired predominantly as bivalents, a few tri- and quadrivalents were recorded. Results suggest that B. brizantha and B. ruziziensis are closely related and genetic recombination is expected in hybrids. Introgression of specific target genes from B. ruziziensis into B. brizantha and vice-versa may be foreseen. However, abnormalities such as irregular chromosome segregation, chromosome stickiness and abnormal cytokinesis reported in these hybrids affect pollen fertility. More than 65% of pollen grains are sterile. Since the distinctive cytological feature of these hybrids is abnormal cytokinesis, this fact suggests that both parental genomes are unable to coordinate their activities with regard to this cytological phenomenon. Deployment of such hybrids in the process of developing varieties is discussed.     

Distribution of qualitative traits in the world germplasm of chickpea (Cicer arietinum L.)

Summary The chick pea germplasm collection maintained at ICRISAT Center, Patancheru, India, is the largest collection of this crop available in one place. This collection was grown in instalments and described for qualitative and agronomical traits. The importance and distribution of six qualitative traits, namely flower colour, plant colour, growth habit, seed shape, seed surface and seed colour have been discussed.Approved as J. A. No. 365 by the International Crops Research Institute for the Semi-Arid Tropics (ICRI-SAT).     

Cytogenetic studies on the interspecific hybrid Capsicum baccatum L.× C. frutescens L. and its progeny

Summary Morphological and cytogenetical studies were carried out on the F₁ and F₂ hybrids and backcross derivatives of the interspecific cross Capsicum baccatum L. x C. frutescens L. The F₁ and F₂ hybrids displayed irregular meiosis with a maximum association of eight chromosomes in the former and one quadrivalent in the latter with the appropriate number of bivalents and univalents. It is inferred that C. baccatum differs from C. frutescens (yellow) by at least tow or three interchanges and from the white cultivar by a single interchange. Structural repatterning of chromosomes, erratic meiotic behaviour, genes for pollen sterility, segregational imbalances following intergenomic recombination are believed to be major factors causing sterility in the hybrids. The two species are sympatric and natural hybrids have not been realised.     

Nicotiana tabacum L. as a source of cytoplasmic male sterility in interspecific cross with N. alata Link & Otto

A new source of cytoplasmic male sterility (CMS) in tobacco with interspecific origin is reported. In traditional selection wild tobacco species have been used as donors of cytoplasm. In the present study the cultivated species Nicotiana tabacum L. (n = 24) is a source of CMS. It was used as female parent and N. alata (n = 9) was involved as a pollinator. The F1 hybrid of this cross was completely sterile. Tissue culture method was applied to restore the female fertility. Regenerants obtained from the 5th passage were successfully pollinated with N. tabacum and seed-containing capsules were formed. All BC1P1 plants were male sterile. They possessed normally developed corollas, three-loculed or deformed pistils, and 1–2 stamens modified into secondary pistils. In some plants stamenless flowers were observed. Male sterility of BC1P1 was preserved in BC2P1–BC7P1 progenies confirming its cytoplasmic nature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of Resistance to Downy Mildew (Peronospora destructor [Berk.] Casp.) from Allium roylei Stearn in the Backcross Allium cepa L. × (A. roylei ×A. cepa)

Allium roylei Stearn and both reciprocals of the interspecific hybrid between Allium cepa L. and A. roylei displayed no symptoms of Peronospora destructor (Berk.) Casp. after artificial or natural inoculations, whereas A. cepa was susceptible. In the offspring from the backcross A. cepa× (A. roylei ×A. cepa) resistant and susceptible plants segregated after artificial inoculations, fitting a 1: 1-ratio. This suggests that resistance is controlled by a single, dominantly-inherited locus (designated Pd₁) from the nuclear genome of A. roylei. During a severe epidemic in the field, plants from the same backcross segregated resistant and susceptible individuals in a 3: 1-ratio. Escapes may explain the deviation from the 1: 1-segregation, but the presence of a second resistance locus segregating independently from Pd₁ cannot be excluded, implicating possible differences in virulence between populations of P. destructor. The occurrence in the backcross offspring of plants having a morphology similar to A. cepa without showing symptoms of downy mildew opens perspectives for breeding P. destructor-resistant onion varieties.     

Cytogenetics of a new trispecies hybrid in cotton: [(Gossypium hirsutum L. × G. thurberi Tod.)2 × G. longicalyx Hutch. & Lee]

A three‐species hybrid named HTL including Gossypium hirsutum L. [2n = 4 x = 52, (AD)₁ genome] was created using the pseudophyletic introgression method with G. longicalyx Hutch. & Lee (2n = 2x = 26, F₁ genome) as donor parent and G. thurberi Tod. (2n = 2x = 26, D₁ genome) as bridge species. The new hybrid was totally self‐sterile and its interspecific status was confirmed using simple sequence repeat markers and cytogenetic analysis. Cytogenetic studies showed that its chromosome configuration was 2n = 52 = 14.13 I + 15.10 II + 1.03 III + 0.9 IV + 0.03 V + 0.13 VI (where I, II, III, IV, V and VI are univalents, bivalents, trivalents, tetravalents, pentavalents and hexavalents, respectively). Prospects for successfully exploiting the HTL hybrid in breeding programmes are discussed.     

Incongruity in the interspecific crosses of Vitis L. Reproductive expression in the F1 progeny

Summary F₁ progeny from three classes of crosses were studied for indications of incongruity in the form of reproductive dysfunction. Percent fruit set was found to be approximately equivalent to the additive inverse of percent aborted flowers, as the effect of shot berries was small and not significant. In interspecific crosses, barriers were manifested as reduced fruit set and seed number per berry. These two characters were used to create an index of reproductive efficiency. Nine F₁s from crosses of most divergent class, V. riparia × V. vinifera (R × V), displayed significantly tower reproductive efficiency, percent fruit set, and seed number per berry. Four female F₁s from the least divergent class, V. riparia × V. riparia (R × R), had the highest reproductive efficiency, percent fruit set and seed number per berry, when pollinated by two V. riparia pollen sources. Seventeen F₁s from the highly-intercrossed class, V. riparia × French Hybrid (R × FH), displayed intermediate levels of reproductive efficiency, percent fruit set, and seed number per berry. The R × FH class involved V. vinifera, V. rupestris, V. aestivalis, V. labrusca, V. berlandieri, V. cinerea, and V. riparia. It is proposed that the complex intercrossing in the pedigrees of the R × FH class ameliorated incongruity. In the most divergent class, R × V, progenies of one of the V. riparia parents displayed fewer incongruity effects than progenies of the other V. riparia parents. Progeny testing of many proposed parental combinations may be used to uncover useful congruent combinations.Minnesota Agricultural Experiment Station, Scientific Journal Series No. 20835     

Characterization of morphological variation and cold resistance in interspecific somatic hybrids between potato (Solanum tuberosum L.) and S. brevidens Phil.

Summary Somatic hybrids between Solanum tuberosum L. cv. Gracia (2n=4x=48) and Solanum brevidens Phil. (2n=2x=24) were produced via fusion of mesophyll protoplasts. Selection of the protoplast derived putative hybrid calli was based on their vigorous growth. Additive isozyme patterns and chromosome numbers as well as the expression of parental morphological characters have proved the hybrid origin of the selected regenerants. Extensive chromosome loss during the regeneration process resulted in aneuploid hybrids with high frequency. Genomic instability could not be detected in these plants during the period of vegetative propagation. Regenerants from hybrid tissues exhibited wide morphological variation especially in tuber formation. The detailed morphological analysis based on the use of multivariate method (principal component analysis, PCA) enabled to identify morphological groups among the hybrid clones. The positioning of hybrid clones in the PCA space could not be correlated with chromosome numbers. The genomic ratio represented by the tetraploid and diploid parents influenced the morphology of somatic hybrid population according to the applied analytical system. Two selected hybrid clones have exhibited an intermediate degree of frost tolerance compared to the parents, based on the recovery of plants from lower buds after freezing of potted plants.