Researches in reproductive biology of sour cherry

Transcription

1 Researches in reproductive biology of sour cherry Radosav Cerović1, Milica FotirićAkšić2, Sanja Radičević3, Djurdjina Ružić3, Milena Đorđević3 & Sladjana Marić3 1 2 Innovation Centre at Faculty of Technology and Metalurgy, University of Belgrade, Karnegijeva 4, Beograd, Republic of Serbia University of Belgrade, Faculty of Agriculture, Nemanjina 6, BelgradeZemun, Republic of Serbia 3 Fruit Research Institute, Kralja Petra I/9, Čačak, Republic of Serbia

2 Research goals The expanding our knowledge on the impact and role of certain factors of the reproductive biology of sour cherry. Predicting the impact of those factors on fruit set of newly developed, existing 'selfsterile' and 'partially selffertile' cultivars of sour cherry.

3 Fields of research Pollen Microsporogenesis Viability Pollen tube growth in the pistil Dynamic Interaction Appearance of incompatibility Ovule Embryo sac development Viability

4 Stages of microsporogenesis A Е B F C G D H Diakinesis (A) (black arrow); Irregular conjugation of chromosomes at metaphase I tetravalent (B) (black arrow); The lagging of chromosomes in anaphase I (black arrow) (C); Early and late telophases (D); Normal tetrad (E); Pentad (black arrow) (F); Octad (G) and Dyad (H).

5 Stage of tetrades Percentage with Cultivar Čačanski Rubin Šumadinka Year Total number of cells normal tetrads abnormal tretrads pentads triads dyads hexads octads First Second First Second , Normal tetrads, irregular tetrads, pentads, triads, dyads, hexads and octads.

6 Characteristic of microsporogenesis Pollen mother cells with uni, tri and tetravalents; The lagging chromosomes ranged from one to five; Among the cultivars there are differences in terms of lagging chromosomes in some years; There is a difference in terms of groups of microspores in some years; The process of microsporogenesis is more or less irregular because of the sour cherry is segmental allotetraploid obtained from natural hybridization between the tetraploid ground cherry (Prunus fruticosa L.) and the diploid sweet cherry (Prunus avium L.).

7 Pollen viability A B Cacanski Rubin First year Cacanski Rubin Second year Sumadinka First year Sumadinka Second year C D 0 10% Pollen grain with stained content (A) (black arow); High pollen germination rate (B) and low pollen germination rate (C); Staining pollen grain with fluorescein diacetate (D) (white arow). 12% 14% Pollen germination (%) of two cultivars sour cherry in two years. The meiotic irregularities during microsporogenesis can be correlated with pollen viability; The functional ability of pollen may affect on the cultivars if they are primarly selfpollinated or serve as pollinators for other sour cherry cultivars.

8 Pollen tube growth in the pistil B A C Growing pollen tubes in the style (A); Sour cherry pollen germination on the stigma (B); Entrance of pollen tube in the nucellus of the ovule (C) ('Čačanski Rubin' 'Šumadinka'). The pollen tube growth through certain pistil parts of sour cherry progamic phase of fertilization.

9 Pollen tube growth rate Average number of pollen tubes in different parts of pistil of sour cherries 'Cacanski Rubin' in tri combinations of pollination. Stu = upper stylar part. O = ovary tissue. Crosspollination with 'Sumadinka'. Dinamics of pollen tube growth through certain pistil parts of sour cherries 'Cacanski Rubin' in three combinations of pollinatiom. Stu, Stc, Stb = upper, central and basal stylar parts. O = ovary tissue; M = micropyle; N = nucellus. Each part of the pistil was represented by the percentage of pistil penetrated by pollen tubes. Crosspolination with 'Sumadinka'. Characteristics of pollen tube growth in the pistil, expressed as certain quantitative parameters can be used for estimating fruit set.

10 The pollen tube growh in the ovary A B C D E F G H I Normal pollen tube growth in the ovary (A); A bundle of pollen tubes in the obturator area (B); Pollen tube growing in wrong direction (C); Pollen tubes bypasses the ovule (D); Pollen tube growth down to the locule of the ovary (E); The pollen tube with swollen tip in the micropyle area (F); Pentration of pollen tube to the nucellus and contuing growth between nucellus and integument (G); Pentration of two pollen tubes to the nucellus (H); The pollen tube filling embryo sac (I); (black arrows). The unusual behaviour of pollen tubes in the ovary indicates the existence of a mechanism of pollen tube growth control.

11 Histochemical analysis of ovule A D B E C F The nucellar cap cells and integumentary epidermal cells with a large and small starch grains (A); A strong PASpositive reaction the cytoplasm of the intergumentary the epidermal cells after pollen tube penetration on the day 4 after pollination (B); Growth of pollen tube toward ovule (C); Starch grains in the nucellar cells of ovule (D); The filiform apparatus of the synergids showing a positive reaction to acid polysaccharides (E); Starch grains in the egg cell (F); (black and white arrows). The localisation of insoluble and pectic polysaccharides in the ovule, can be correlated with the guidance of pollen tubes.

12 Unusual behaviour of pollen tube growth in the ovary Pollination Parts of pistil Ovary Micropyle Nucellus Years open cross open First Second First Second First Second Percentage of pistils of Čačanski Rubin with the occurrence of unusual behaviour of pollen tube growth in different pistil parts. The unusual behaviour of pollen tubes could affect the number of fertilized ovules.

13 Appearance of incompatibility A B Compatible pollen growth in the style (A); Typical incompatible reaction, tubes stopping in the upper third of the style (B) (white arrows). A B C D E F Different incompatible pollen tube ends in sour cherries (A, B, C, D, E i F) (white arrows). The incompatibie pollen tubes occurred in all pollination combinations; The occurance incompatibilty shows yeartoyear variabilty and can be pronouced in some combinations of pollination up to 35% of the total average number of pollen tubes.

14 Embryo sac development A D B E C F The synergids (A); The egg cell (B) and polar nuclei (C); (black arrows). The early stage of the embryo (D); Globular stage ot the embryo with cellular endosperm (E) Heart stages of embryo (F); (black arrows). Embryo sac of sour cherry belongs to the monosporial 8nucleate bipolar Polygonum type.

15 Viability of embryo sac/ovule A C B D Degeneration of whole egg cell (A) (black arrow); Irregular distributions of the individual elements of the egg apparatus (B) (black arrow); Atrophy of ovule (C) and whole ovule fluorescing (D). Loss of viability embryo sac/ovule is factor that can affect the degree of fruit set.

16 Viabilty of embryo sac and fertilization success The ratio of % fuctional embryo sacs to days at full bloom in unipollinated flowers of sour cherry 'Čačanski Rubin' over two year. First year: y= x 0.84x2 (R=0.99); Second year: y= x 1.12x2 (R=0.93). Bs = Balloon stage; On = Onset of full bloom. The ratio of % fuctional embryo sacs in which the embryo is present to days after pollination in sour cherry 'Čačnaski Rubin' over two year. First year:y= x (R=0.98); Second year: y= x 2.08x2 (R=0.99). The functionality of embryo sacs contributes to fertilization success in sour cherries at full bloom.

17 Fruit set Initial fruit set Cultivar Čacanski Rubin Šumadinka Final fruit set Pollination First year Second year First year Second year Self Cross Open Self Cross Open Percentage fruit set in sour cheries 'Čačanski Rubin' and 'Šumadinka' in three combinations of pollinations in two years. The differences between initial and final fruit set indicate the existing of postfertilization factors essential for fruit set.

18 Thank You for your attention! Thank you for your atenttions! This work was conducted under Research Project TR31064 Development and preservation of genetical potentiall of temperate zone fruits, supported by the Ministry of Education, Science and Technological Development of the RS.