Cone quality and seed efficiency in the clones from mutational witches brooms of Pinus sibirica

Olga Polyakova,Sergei Goroshkevich,Evgeniya Zhuk

doi:10.1051/bioconf/20181100034

Abstract

Mutational witches' broom is a fragment of the tree crown with abnormal morphogenesis including slow shoot growth, abundant branching and decreased apical dominance which caused by somatic mutation that presumably originates in the apical meristem bud. To study the variability in the cone quality and seed efficiency in witches' broom clones of Pinus sibirica, the cone size and structure were assessed in 21 mutant clones. The mutant clones were significantly differentiated both by the cone traits and seed quality. Their cone size varied from less than 3 to 4 cm. The clones had large number of sterile scales in proximal and distal cone parts, and from 16 to 39 fertile scales per cone. Cones from all mutant clones were inferior to average normal cones of the species. Six clones had large portion of filled seeds, more than 70%, and the other clones had less than 50% of filled seeds. The clones had 10-33% of empty seeds and 1-73% of seeds with collapsed megagametophyte per cone. In general, the seed quality in mutants was quite low, but individual clones had almost normal seed quality, and their seed efficiency was within the species norm.

Highlights

Mutational witches' broom (WB) is a fragment of the tree crown with abnormal morphogenesis including slow shoot growth, abundant branching and decreased apical dominance A somatic mutation that presumably originates in the bud in the apical meristem is considered as a cause of the WB [1]
All cone traits were highly variable in WB clones
Mutational WB cones are generally smaller than normal cones in some species

Summary

Introduction

Mutational witches' broom (WB) is a fragment of the tree crown with abnormal morphogenesis including slow shoot growth, abundant branching and decreased apical dominance A somatic mutation that presumably originates in the bud in the apical meristem is considered as a cause of the WB [1]. Unlike pathological WB, mutational WB are sporadically distributed and have a healthy appearance, normal reproduction, and normal longevity [2,3]. Mutational WB is a major source of the majority of ornamental dwarf conifer cultivars [4]. The seed progeny involvement in breeding process has great importance, the information concerning the variability of cone structure and seed efficiency in mutant clones is scarce. The objective of the work was to study the variability of the cone quality and seed efficiency in WB clones of Pinus sibirica

Objectives

Results

Conclusion