Genetic control of flowering time in Eucalyptus globulus ssp. globulus

Abstract

1Understanding the factors affecting variation in phenology within a species is important as 2 flowering time constitutes one of the major barriers to gene flow. We studied the genetic and 3 environmental control of flower initiation and anthesis time in E. globulus ssp. globulus. For 4 five years, flower initiation and anthesis were monitored in a seed orchard containing clones 5 of 63 genotypes from four different regions of the species' natural distribution. Anthesis 6 occurred over a long period each year, spanning as much as nine months in 2008. This 7 variation was under strong genetic control with little genotype by year interaction (broad-8 sense heritability, Ĥ 2 =0.78±0.04). There were highly significant differences among regions; 9 anthesis occurred earlier for Furneaux and Tasmania than Strzelecki and Otways each year. 10 Surprisingly though, there was little variation in flower initiation time between regions and 11 genotypes, and this was under weak genetic control (Ĥ 2 =0.06±0.05). The average anthesis 12 time in the orchard varied from year to year and there was evidence that heat sum was a 13 major driver of this environmental variation. Anthesis time is controlled by both genetic and 14 environmental factors, with the responses to each being predictable to some extent, and 15 unrelated to the timing of flower initiation. 16 17

Genetic control of flowering in spotted gum, Corymbia citriodora subsp. variegata and C. maculata

“…Although these observations in native stands do not allow us to conclude that these differences are necessarily adaptive (they could be plastic responses to differences in the environment), the correspondence in rankings of populations based on flowering time between translocated and native populations, as evident in our study as well as other studies of eucalypts (E. marginata and E. globulus) (O'Brien et al 2007;Jones et al 2011), suggests genetic control and the potential for adaptive significance in flowering-time differences in some cases. In the case of E. globulus, in contrast to CCV and E. marginata, more northerly populations from Victoria flowered later than eastern coast Tasmanian populations when grown together in a seed orchard at Hobart (Jones et al 2011). This showed that control of flowering time is complex and latitudinal differences are not always a reliable predictor.…”

“…Exposure to warm temperatures can be expressed as heat sum, which is the linear accumulation of temperature above a base temperature measured in degree-days (Trudgill et al 2005). Heat sum has been found to determine the timing of bud break and subsequent reproductive development in temperate eucalypts (Moncur et al 1994;Jones et al 2011), and heat-sum models have been used to predict anthesis time in other trees, e.g. Norway spruce (Nikkanen 2001) and Quercus (García-Mozo et al 2006).…”

“…Several studies have shown that differences in flower opening times between taxa, provenances and families of temperate eucalypts are under genetic control (Gore and Potts 1995;Jones et al 2011). Early and late flowering populations of the temperate Eucalyptus globulus have been identified for example, and the timing of anthesis was shown to be under strong genetic control (Jones et al 2011).…”

Variabilidade genética e alterações morfológicas em progênies de polinização aberta de Eucalyptus grandis sob o efeito de paclobutrazol

“…O período de florescimento, a ocorrência da primeira florada, a intensidade na floração e a irregularidade de florescimento, são alguns dos problemas encontrados na condução de um programa de melhoramento (WILLIANS et al, 2003;JONES et al, 2011).…”

Crossing potential of open pollination in Cajuputi seedling seed orchard at Paliyan, Gunungkidul

“…Sementara penelitian yang dapat memisahkan antara kedua faktor tersebut masih sangat terbatas, terutama untuk jenis-jenis tanaman kehutanan (Johnson, 2007). Pada program pemuliaan, pemahaman variasi genetik yang mengontrol perbedaan karakteritik pembungaan suatu jenis sangat membantu untuk mengidentifikasi dan menyeleksi sifat-sifat penting seperti persentase pembungaan, durasi waktu untuk mencapai tingkat kemasakan benih maupun puncak pembungaan untuk mengetahui persebaran serbuk sari (Jones et al, 2011).…”