Stem Pigmentation Research Articles

Verification of the parthenogenetic capability of unreduced eggs in an alfalfa mutant by a progeny test based on morphological and molecular markers

AbstractApomixis involves the parthenogenetic development of apomeiotic eggs. It has the potential of cloning plants through seed, and thus furnishes a unique opportunity in breeding of allogamous sexual species, such as alfalfa, for developing superior cultivars with permanently fixed heterosis. Apomixis as a whole has not been detected in the genus Medicago, but components of apomixis have been reported. The formation of unreduced eggs through diplosporic meiosis was documented in a diploid mutant of M. saliva ssp. falcata (L.) Arcang., named PG‐F9. Since in facultative apomictic species non‐reductional meiosis and parthenogenesis could be tightly associated processes, a progeny test based on morphological trait and molecular marker evaluation was carried out to verify the occurrence of parthenogenesis in PG‐F9. Morphological traits such as leaf shape, stipule form, stem pigmentation and flower colour were shown to be effective in the preliminary screening of progenies and most of the plants were classified as non‐maternal (i.e. from sexual reproduction). Molecular investigations by means of random amplified polymorphic DNA (RAPD) fingerprint and heterozygous restriction fragment length polymorphism (RFLP) loci detection conducted on the progenies classified morphologically as maternal allowed two plants, molecularly similar but not identical to PG‐F9, to be discovered. Owing to the high number of molecular markers conserved as in the mother plant, and because of the great discriminating efficiency of the primers and probes used, these progeny plants could most likely be generated through parthenogenesis of diplosporic eggs. In fact, the extraordinary preservation of maternal morphological traits and genomic loci over one generation may be explained only if apomictic reproductive events rarely took place in PG‐F9.

Effectiveness of selection at microtuber crop level in potato

AbstractCorrelation coefficients were computed between microtuber crops and normal seed crop in order to study the selection efficiency for agronomic characters in potato at microtuber crop level. Two types of microtuber, green and white, were produced by inducing microtuberization under light and dark conditions, respectively. Genotypic differences were significant for various characters in both microtuber and normal seed crops. Green and white microtubers were equally useful for selection, judging by the crops raised from them. Selection at microtuber crop level was found to be highly effective for plant height, stem habit, tuber colour and general impression, and moderately effective for internode length, leaf length, leaflet width, stem pigment, plant vigour and tuber shape. Selection efficiency was low for tuber yield, tuber number, average tuber weight, number of nodes, number of stems, leaf colour and number of eyes. The implications of these results for potato breeding and germplasm evaluation programmes are discussed and a procedure for selecting superior genotypes at microtuber crop level is outlined.

Inheritance of Selected Traits in Accessions of Vigna vexillata (L) a Rich of Australian and African Origin

The inheritance of several traits in Vigna vexillata was studied for crosses involving accessions of African and Australian origin. Anthocyanin stem pigmentation, silver leaflet midrib, leaflet hirsuteness, presence of long hairs on the calyx lobes, black pod colour, speckled seed testa and twining stem habit all appeared to be conditioned by single completely dominant gene action, as was apparent resistance to powdery mildew. Width of the floral standard, peduncle length, number of seeds per pod, weight of 100 seeds, tuberous root dry weight, total plant dry weight and harvest indices for seed and tuberous roots all appeared to be quantitatively inherited, with moderate broad sense heritabilities. Leaflet shape, the primary distinguishing attribute between the varieties occurring in Australia, angustifolia and youngiana, appeared to be simply inherited. No difficulties were encountered in obtaining F1 and backcross progenies in any crosses. Further, the inheritance of traits in progeny of Australian × African crosses appeared normal and, in the several instances where direct comparison was possible, similar to that observed in crosses within the Australian material.

High levels of interspecific hybridization betweensolanum sparsipilum ands. stenotomum in experimental plots in the andes

Five experimental plots of 3 x 8 m containing 80 plants each, 60 ofSolarium stenotomum (12 clones) and 20 ofS. sparsipilum (unknown number of clones) interspaced at random, were established at the Granja K’ayra in Cuzco, Peru. The plantings were intended to mimic small fields of traditional farmers on low fertility soil and steep terrain. Plants of each species were distinguished from another by at least four isozyme loci and by stem pigmentation. Ninety five percent of the seedlings grown from either open-pollinated seed ofS. stenotomum orS. sparsipilum were found to be interspecific hybrids. That the majority of the open-pollinated seed were of hybrid origin suggests that gene flow between weedy and diploid cultivated species is important in generating new landraces of potatoes in the Andes.

Reciprocal cross differences in a 6×6 diallel set of groundnut (Arachis hypogaea L.) in the F1 generation

Reciprocal cross differences were studied in a 6×6 diallel full set comprising of thirty hybrid combinations of groundnut in the F1 generation. Reciprocal cross differences were observed for growth habit in four pairs of crosses, for leaf colour, flower colour and stem pigmentation in two pairs of crosses each. It was observed that the inheritance of flower colour, stem pigmentation and testa colour which exhibited different shades of purple colour was likely to be governed by pleiotropic gene(s). Among the quantitative characters significantly positive reciprocal effects were observed in different crosses for number of mature pods per plant, weight of pods per plant and shelling percent. Marked reciprocal cross differences were observed for pod and kernel characters like pod filling, pod beak, pod constriction and testa colour.

Population differentiation of the Stellaria longipes complex within Saskatchewan's Athabasca sand dunes

Stellaria arenicola, a recent derivative within the S. longipes complex, is an endemic of the Athabasca sand dunes. Analysis of 11 morphological characters on 40 genets showed that both the endemic and parental (S. longipes) species are present within the Thomson Bay dune field and that the two forms are distinct. Individuals of S. arenicola were distinguished by only a few characters, typically, large yellow capsules with reflexed teeth and yellowish leaf and stem pigmentation. The endemic also exhibited a higher sexual reproductive output. Many characteristics of vegetative morphology showed plasticity in both species, but the two remained distinct when grown in a common garden. On the sand dunes S. longipes is restricted to beach dunes bordering Lake Athabasca while S. arenicola is predominant on the active dune field inland. The two dune systems represented environmentally distinct microhabitats. The active inner dunes were characterized by an unstable, fine sand substrate and intense insolation. Field reciprocal transplants showed S. longipes was selected against in the inner dune habitat, while S. arenicola performed relatively well on the beach. Stellaria arenicola possibly arose in the active sand dune habitat as a result of selection pressure and genetic isolation.

Phase Change and Intra-Clonal Variability

Abstract There is considerable opportunity for intra-clonal variability due to nongenetic or epigenetic causes because of the well-known and striking age-related changes in developmental patterns in plants propagated from seed. It is well-known that a juvenile phase exists in the development of plants from seed, lasting up to 30-40 years in forest trees, during which flowering does not occur and cannot be induced by normal flower-initiating treatments. The ability to flower is achieved in time, however, and the plant is said to have attained the mature condition. This phenomenon has been referred to as a phase change by Brink (6). Changes in morphological and developmental characteristics, such as leaf cuticular characteristics (13), leaf shape and thickness, phyllotaxis, thominess, shoot orientation (46), and other physiological characteristics such as seasonal leaf retention, stem pigmentation (46), ability to form adventitious roots and buds (7, 46), partitioning of photosynthates into main stem vs. branches (30), disease resistance (W.J. Libby, Jr., personal communication) and cold resistance (27), are associated with the phase change. Phase-change-related characteristics are most obvious in woody, perennial plants but also have been demonstrated in herbaceous annuals and perennials (24, 54). Some of these characteristics are important horticulturally and the ability to control or manipulate them has important practical implications.

Breeding systems in New Zealand plants 6.Gentiana antarcticaandG. antipoda

Abstract Gentiana antarctica of Campbell Island, a monocarpic species, flowers from late December to April and possibly earlier. White-petalled plants ranged from 19.04 to 78.74% in samples from six populations. Other petal colours range from a tinge of pink at the tips to fully rosecoloured. Frequencies are given. The red pigment in leaves and ovaries tends to increase with increasing petal colour. G. antipoda of Antipodes Island, also monocarpic, flowers from early December to April. White-petalled plants ranged from 33.33 to 46.38% in samples from three populations. The range of other petal colours was similar to that in G. antarctica. Mature leaves are always yellow-green and stem pigmentation is not very closely related to petal pigmentation. Inflorescences and flowers of both species are described. Modes of ovule numbers are 12-19 in G. antarctica (samples from five populations) and 4 in G. antipoda (samples from three populations). Flowers are protandrous in both species with no insect visitors known. The occurrence of brighter flower colours than on the mainland is discussed in relation to lack of pollinators, or pleiotropic genes, and this is extended to other relevant island species.

Stem Pigmentation in Lowbush Blueberry

Stem Pigmentation in Lowbush Blueberry