Sex segregation ratio and gender expression in the genus Actinidia (original) (raw)
Related papers
Numerically unreduced (2n) gametes and sexual polyploidization in Actinidia
1997
This is the first report on the production of numerically unreduced (2n) gametes in Actinidia species. Their occurrence was apparent from direct observations of microporogenesis in 2x, 3x, 4x and 6x plants and was inferred from ploidy analysis of progenies from 4x-2x and 2x-4x crosses. Both male and female plants were found to produce 2n gametes. 2n gamete producers were detected only in interploidy crosses. The observed frequency of 2n gametes was either similar to or towards the lower end of the ranges reported for other genera. The role of sexual polyploidization in the evolution of the genus is discussed.
Genetic Resources and Crop Evolution, 2019
In the present study, we have performed a comprehensive comparison of different accessions of the genus Actinidia. Simultaneously, we conducted a study of genetic diversity in both female and male plants to assist in the implementation of breeding processes. Different ploidy levels, viz. 2x, 4x, and 6x, were determined for A. kolomikta (Rupr. & Maxim.) Maxim., A. arguta (Siebold & Zucc.) Planch. ex Miq., A. callosa Lindl., and A. melanandra Franch., species. The genetic analysis of Actinidia cultivars and clones at 14 nuclear microsatellite loci showed the that accessions possessed high levels of genetic variability. The genetic analysis conducted by using the STRUCTURE population analysis software revealed high genetic variability between A. arguta cultivars and clones.
Gender variation in Actinidia deliciosa, the kiwifruit
Sexual Plant Reproduction, 1991
Flower and fruit characters were measured in ten female, five male and five fruiting male selections of A. deliciosa var deliciosa (A. Chev) Liang and Ferguson. Flowers from female vines had functional pistils, which contained many ovules. Stamens appeared to be fully developed but produced only empty pollen grains. Flowers from male vines had functional stamens that produced high percentages of pollen grains with stainable cytoplasmic contents. Pistils did not contain ovules and were generally small with vestigial styles. Fruiting male vines had both staminate and bisexual flowers. Staminate flowers were similar to those found on strictly male vines. Bisexual flowers produced ovules and stainable pollen. Pistils were smaller than in pistillate flowers. Although the three flower sexes differed in style length, ovary dimensions and ovules per carpel, staminate and bisexual flowers were similar in number of flowers per inflorescence, stamen filament length, pollen stainability, inflorescence rachis length and carpel number, and differed from pistillate flowers in these characters. The three flower sexes had similar sepal and petal numbers. The fruit of fruiting males were considerably smaller than those of females. Low ovule number appears to be the major factor limiting fruit size in the fruiting males studied. Prospects for developing hermaphroditic kiwifruit cultivars through breeding are discussed.
Chromosome studies in some Actinidia taxa and implications for breeding
New Zealand Journal of Botany, 1989
Microsporogenesis was studiedin eleven Actinidia taxa including A. deliciosa (kiwifruit) and in an interspecific hybrid. From chromosome counts at meiotic metaphase 1 or diakinesis, eight taxa were classified as diploids and two as tetraploids and A. deliciosa was confirmed as hexaploid. A putative 2n = 2x, 2n = 4x, 2n = 6x, x = 29 basis for the genus is therefore supported. Chromosomes in all taxa were very small. Three diploids and two polyploids analysed for meiotic pairing behaviour were all characterised by low chiasma frequencies per bivalent. Chromosome configurations other than bivalents were rare in A. arguta var. arguta (4x) and A. deliciosa (6x), indicating there may be genetic control ofchiasmata distribution in these polyploids.
BMC Genomics, 2009
The genus Actinidia (kiwifruit) consists of woody, scrambling vines, native to China, and only recently propagated as a commercial crop. All species described are dioecious, but the genetic mechanism for sex-determination is unknown, as is the genetic basis for many of the cluster of characteristics making up the unique fruit. It is, however, an important crop in the New Zealand economy, and a classical breeding program would benefit greatly by knowledge of the trait alleles carried by both female and male parents. The application of marker assisted selection (MAS) in seedling populations would also aid the accurate and efficient development of novel fruit types for the market.
Inconstant males' and the maintenance of labile sex expression in subdioecious plants
The New phytologist, 2007
Here, we evaluate the role of pollen limitation and selfing in the maintenance of labile sex expression in subdioecious plant species. • We used a literature survey to explore which factors correlated with a significant occurrence of hermaphrodites in dioecious species. We developed models to explore the selective maintenance of labile sex expression. The models had similar ecological assumptions but differed in the genetic basis of sex lability.
The Diversity and Dynamics of Sex Determination in Dioecious Plants
Frontiers in Plant Science, 2021
The diversity of inflorescences among flowering plants is captivating. Such charm is not only due to the variety of sizes, shapes, colors, and flowers displayed, but also to the range of reproductive systems. For instance, hermaphrodites occur abundantly throughout the plant kingdom with both stamens and carpels within the same flower. Nevertheless, 10% of flowering plants have separate unisexual flowers, either in different locations of the same individual (monoecy) or on different individuals (dioecy). Despite their rarity, dioecious plants provide an excellent opportunity to investigate the mechanisms involved in sex expression and the evolution of sex-determining regions (SDRs) and sex chromosomes. The SDRs and the evolution of dioecy have been studied in many species ranging from Ginkgo to important fruit crops. Some of these studies, for example in asparagus or kiwifruit, identified two sex-determining genes within the non-recombining SDR and may thus be consistent with the cl...
Gender determination mechanisms in plants : foundation for unisexuality
2015
Knowledge of mechanisms determining and maintaining unisexuality in the flowering plants is of ecological, evolutionary and commercial importance. Among the flowering plants sexuality is manifested to various extents. Among these, the dioecious and monoecious plants provide an excellent opportunity to study the gender determination mechanism. Empirical studies carried on dioecious plant species provided a sequence of stages/events that represent the evolution of sex chromosomes in plants. These events include origin of sex determination genes/loci, suppression of recombination at sex determination loci, its extension to adjacent regions, accumulation of random mutations and finally the degeneration of Y chromosome that lead to the origin of heteromorphic pair of sex chromosome. Recent advances in molecular tools have enabled researchers to decipher the role of hormones and micro RNAs. Emerging information from recent studies on various aspects of gender expression in plants suggest ...
Annals of botany, 2012
Some otherwise promising selections of Actinidia chinensis (kiwifruit) have fruit that are too small for successful commercialization. We have therefore made the first detailed study in diploid kiwifruit of the effects of chromosome doubling induced by colchicine on fruit size, shape and crop loading. Flow cytometric analysis of young leaves and chromosome analysis of flower buds and root tips was used to confirm the stability of induced autotetraploids. Fruit weight, size and crop load were measured in the third year after planting in the field and for three consecutive years. DNA fingerprinting was used to confirm the origin of the material. There was a very significant increase in fruit size in induced autotetraploids of different genotypes of A. chinensis. With the commercially important diploid cultivar 'Hort16A', most regenerants, Type A plants, had fruit which were much the same shape as fruit of the diploid but, at the same fruit load, were much larger and heavier. S...