VARIATION IN FERTILITY AND ITS IMPACT ON GENE DIVERSITY IN A SEEDLING SEED ORCHARD OF <i>EUCALYPTUS TERETICORNIS</i>

Varghese, M.; Ravi, N.; Seog-Gu, Son; Lindgren, D.; Wei, R. P.; Xu, Daping

doi:10.1142/9789812704504_0010

Cited by 5 publications

(11 citation statements)

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“…First-generation plantations or orchards are the critical entry points to a newly introduced location, where rapid loss of alleles can occur (Varghese et al 2003). When assembling seed collections from superior trees for advanced generation breeding, the relatively low levels of flowering observed in this study and in the same orchards at later age of 8-9 years (Kamalakannan et al 2007) would have substantially reduced the genetic diversity passed on to the progeny.…”

Section: Implications For Genetic Improvement Programsmentioning

confidence: 78%

“…At the higher rainfall sites, the E. tereticornis SPA and SSO had lower flowering and lower relative population sizes than did E. camaldulensis. The local selected families derived from the Mysore land race dominated flowering in the pedigreed orchard of E. tereticornis, contributing 59% of the gametes (Varghese et al 2003). The relative effective population size of all orchards was very low at 0.15 or less, except for SPA 2 (E. camaldulensis at the higher rainfall site).…”

Section: Discussionmentioning

confidence: 98%

“…However, in the absence of managed domestication programs, informal seed collection and dissemination from limited introductions of these superior provenances may lead to genetic deterioration through inbreeding and negative selection. Also, high fecundity of Mysore gum, reported for E. tereticornis in India by Varghese et al (2003), means that local selections may contribute disproportionately if included in newly introduced open-pollinated breeding populations (Ellstrand et al 1999). If selections from land races contribute a major share of the gametes in breeding populations or if adequate isolation distance is not provided between them and nearby land race populations, the infusion of genes from new introductions might be diluted and/or effectively lost.…”

Section: Introductionmentioning

confidence: 99%

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Changes in growth performance and fecundity of Eucalyptus camaldulensis and E. tereticornis during domestication in southern India

Varghese

Kamalakannan

Harwood

et al. 2009

Tree Genetics & Genomes

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Bulk seedlots of two unpedigreed multiprovenance seed production areas (SPAs) each of Eucalyptus camaldulensis and Eucalyptus tereticornis and one pedigreed seedling seed orchard (SSO) of E. tereticornis were planted in genetic gain trials at three southern Indian trial sites. At the time of seed collection, fewer than 30% trees flowered in these orchards, except in one E. camaldulensis SPA where 73% of the trees flowered, which had an estimated outcrossing rate of 86%. The E. tereticornis SSO was dominated by pollen from five highly fecund families of the Indian Mysore gum land race, which contributed 59% of the fruits produced. The SPA and SSO seedlots were compared with a bulked natural-provenance seedlot of E. camaldulensis (Morehead, Laura, and Kennedy Rivers, Queensland), another natural-provenance seedlot (Petford, Queensland), commercial eucalypt clones at two sites, and a Mysore gum seedlot at one site. At 3 years, progeny from all the four SPAs displayed good survival (79-93%) and performance similar to that of the natural provenances and the commercial clones. Progeny from the E. tereticornis SSO had significantly lower growth (at two sites) and lower survival at all three test sites. The Mysore gum seedlot displayed high fecundity and lower growth but better survival than the SSO progeny. Seed orchard genetic composition and flowering contributions thus affected progeny performance and the extent to which orchard genetic diversity was captured in the progeny. SPA progeny displayed greater fecundity than the natural provenances, indicating a response to selection for fertility.

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Section: Implications For Genetic Improvement Programsmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Changes in growth performance and fecundity of Eucalyptus camaldulensis and E. tereticornis during domestication in southern India

Varghese

Kamalakannan

Harwood

et al. 2009

Tree Genetics & Genomes

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“…Individual tree seed collection was made from 7-11 trees (or clones) each in three SPAs (SPA 1-3) and two clone trials (CSO 1-2) located in southern India at five years of age (Table 1 and 2). Fecundity of trees was estimated before seed collection as described by Varghese et al (2003). SPA 1&2 were thinned genetic gain trials of bulk seedlots from five first generation (F 1 ) seedling orchards established as per a breeding program for E. camaldulensis (Doran et al, 1996) and SPA 3 was a thinned plantation of one F 1 orchard seed lot maintained for seed production.…”

Section: Methodsmentioning

confidence: 99%

Impact of fertility variation on genetic diversity and phenotypic traits in second generation seed production areas and clonal seed orchards of Eucalyptus camaldulensis

et al. 2019

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Fertility and gene diversity were estimated in three second generation (F2) seed stands (SPA 1-3) and two clone trials (CSO 1&2) of Eucalyptus camaldulensis to assess the impact on seed crop. F2 seedlots were evaluated in comparison to native provenances, ten commercial clones and interspecific hybrids at diverse sites. SPA 1&2 were genetic gain trials of five first generation (F1) orchard seedlots, SPA 3 a plantation of one F1 orchard seedlot, and CSOs were clone trials of 21 commercial clones established at two contrasting sites. Fertility variation, as indicated by sibling coefficient, was high (Ψ, 9-14) in the SPAs as only about 26 % trees were fertile compared to 81 % trees in CSOs. Effective population size was higher in SPA 1 and 2 (Ns, 95 and 74, respectively) than SPA 3 (Ns = 39). Fertility was highly skewed in CSO 2 resulting in low effective population size (Ns = 2) compared to CSO 1 (Ns = 11). Constant seed collection enabled 3-fold increase in relative population size and 22 % higher predicted gene diversity in CSO 2. Genetic diversity (He) estimated using SSR markers was higher in SPA 1&2 and native provenances (NAT), compared to SPA 3 and CSO 1, whereas CSO 2 and clones had lower values. There was a high positive correlation between estimated He and predicted gene diversity values of SPAs and CSOs. He was positively correlated to mean field survival and negatively correlated to kraft pulp yield (KPY), evaluated at three years in progeny trials across three locations. Number of alleles per locus was higher in SPAs and native provenances compared to CSOs and clones. Discriminant principal component analysis clustered CSO, NAT and SPA seedlots in different groups while commercial E. camaldulensis clones clustered close to NAT. Multilocus outcrossing rate was generally high (tm, 91-100 %), though selfing was observed in two families of SPA 3 and CSO 2. Selected interspecific hybrid families of commercial E. camaldulensis clones (with E. urophylla and E. pellita) evaluated at two of the sites had higher He and KPY than clones at three years.

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“…There can be a tremendous variation in the magnitude of fertility variation. For example, Varghese et al (2003) reported a sibling coefficient, Ψ=17.4 in a first generation progeny trial of Eucalyptus tereticornis in south India studied at four years of age with the intention to convert it to a seedling seed orchard. Only 18% trees were fertile out of 200 trees selected for phenotypic superiority.…”

Section: Estimates Of Accumulation Of Relatedness Based On Fertility mentioning

confidence: 99%

Low-Input Tree Breeding Strategies

Lindgren¹,

Wei²,

Xu³

2003

Eucalyptus Plantations

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Low-input strategies for seed production and breeding are discussed. Among such strategies are: phenotypic selection; inefficiency of progeny-testing; absence of testing; unidentified plants; combining objectives; genetic unbalances; seed collection areas; forwarding the breeding population by open pollination instead of controlled crosses; and for some cases vegetative propagation. Sustainable and optimally used low-input strategies require advanced quantitative genetic considerations, in particular concerning the management of relatedness.

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VARIATION IN FERTILITY AND ITS IMPACT ON GENE DIVERSITY IN A SEEDLING SEED ORCHARD OF EUCALYPTUS TERETICORNIS

Cited by 5 publications

References 0 publications

Changes in growth performance and fecundity of Eucalyptus camaldulensis and E. tereticornis during domestication in southern India

Changes in growth performance and fecundity of Eucalyptus camaldulensis and E. tereticornis during domestication in southern India

Impact of fertility variation on genetic diversity and phenotypic traits in second generation seed production areas and clonal seed orchards of Eucalyptus camaldulensis

Low-Input Tree Breeding Strategies

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