Variation in floral and growth traits in a macadamia breeding population

O’Connor, Katie; Hardner, C. M.; Alam, Mobashwer; Hayes, Ben J.; Topp, Bruce

doi:10.17660/actahortic.2018.1205.77

Cited by 2 publications

(2 citation statements)

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“…Different from herbaceous crops, Macadamia is a large subtropical rainforest tree which originates from Australia [ 58 ]. Cultivated Macadamia nuts grow at an average height of 12–15 m and require an average of 15 years to reach peak yield [ 58 , 59 ]. Both the large plant size and long juvenile period hamper commercial production and breeding efficiency [ 35 , 60 ].…”

Section: Discussionmentioning

confidence: 99%

Genome-Wide Characterization of PEBP Gene Family and Functional Analysis of TERMINAL FLOWER 1 Homologs in Macadamia integrifolia

Yang

Ning

Liu

et al. 2023

Plants

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Edible Macadamia is one of the most important commercial nut trees cultivated in many countries, but its large tree size and long juvenile period pose barriers to commercial cultivation. The short domestication period and well-annotated genome of Macadamia integrifolia create great opportunities to breed commercial varieties with superior traits. Recent studies have shown that members of the phosphatidylethanolamine binding protein (PEBP) family play pivotal roles in regulating plant architecture and flowering time in various plants. In this study, thirteen members of MiPEBP were identified in the genome of M. integrifolia, and they are highly similarity in both motif and gene structure. A phylogenetic analysis divided the MiPEBP genes into three subfamilies: MFT-like, FT-like and TFL1-like. We subsequently identified two TERMINAL FLOWER 1 homologues from the TFL1-like subfamily, MiTFL1 and MiTFL1-like, both of which were highly expressed in stems and vegetative shoots, while MiTFL1-like was highly expressed in young leaves and early flowers. A subcellular location analysis revealed that both MiTFL1 and MiTFL1-like are localized in the cytoplasm and nucleus. The ectopic expression of MiTFL1 can rescue the early-flowering and terminal-flower phenotypes in the tfl1–14 mutant of Arabidopsis thaliana, and it indicates the conserved functions in controlling the inflorescence architecture and flowering time. This study will provide insight into the isolation of PEBP family members and the key targets for breeding M. integrifolia with improved traits in plant architecture and flowering time.

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Section: Discussionmentioning

confidence: 99%

Genome-Wide Characterization of PEBP Gene Family and Functional Analysis of TERMINAL FLOWER 1 Homologs in Macadamia integrifolia

Yang

Ning

Liu

et al. 2023

Plants

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“…The aims of this study were to: (i) compare the phenotypic variances of nut, floral and growth component traits between progenies and families, (ii) estimate the genetic heritability of yield and component traits in the population, (iii) estimate genetic correlations among yield and component traits, and (iv) estimate efficiency of indirectly selecting for high yield through the selection of component traits. This study builds on results of a pilot study byO'Connor et al (2018a).…”

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confidence: 99%

Selection strategies to improve yield in macadamia using component traits and genomics

O’Connor¹

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Macadamias (Macadamia integrifolia, M. tetraphylla, and their hybrids) are native to the east coast of Australia, and are grown commercially around the world for their high quality edible nut kernel. Breeding new cultivars for high nut yield is a lengthy and laborious process that can take over two decades. Evaluations are time-consuming due to the long juvenile period of four or more years, and the low correlation between young and mature tree yield means that at least eight years of evaluations are required. Furthermore, yield has low heritability, and the large tree size necessitates low field planting density, and thus increases land use and evaluation costs. It is hypothesised that genetic gain for yield may be increased, compared to traditional breeding approaches, through the use of strategies including (i) indirect selection using yield component traits, (ii) marker-assisted selection and (iii) genomic selection. This thesis employed an experimental population of 295 seedling progeny and their 29 parents, at four sites across southeast Queensland, that were genotyped for 4,113 SNPs and 16,171 silicoDArT markers detected using Diversity Arrays Technology (DArT) methods. Population structure, genetic diversity and linkage disequilibrium (LD) between SNP markers was quantified to inform subsequent genomics analysis. LD decay was initially rapid at short distances (r 2 = 0.124 for SNPs within 1 kb of each other), but low level LD persisted for long distances. The seedling population was relatively genetically diverse (HE = 0.255), and very similar in diversity to that of the 29 parents (0.250). Furthermore, progeny with M. integrifolia x M. tetraphylla ancestry were more genetically diverse (HE = 0.278) than M. integrifolia seedlings (HE = 0.189). Progeny were moderately differentiated and clustered into three distinct groups, which represented M. integrifolia germplasm and two hybrid groups. Flowering and nut characteristics, tree growth and yield were measured on each tree. Estimations of trait heritability and genetic correlations between each component trait and yield were used to calculate selection efficiency of indirectly selecting for yield using component traits. Kernel recovery, an economically important trait, had high heritability (h 2 = 0.76) but was negatively genetically correlated with yield (rg =-0.27). Trunk circumference correlated strongly with yield (rg = 0.72) and was moderately heritable (h 2 = 0.44); however, a breeding aim is to reduce tree size without compromising yield. No component traits were appropriate or effective for indirectly selecting for high yield.

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Variation in floral and growth traits in a macadamia breeding population

Cited by 2 publications

References 10 publications

Genome-Wide Characterization of PEBP Gene Family and Functional Analysis of TERMINAL FLOWER 1 Homologs in Macadamia integrifolia

Genome-Wide Characterization of PEBP Gene Family and Functional Analysis of TERMINAL FLOWER 1 Homologs in Macadamia integrifolia

Selection strategies to improve yield in macadamia using component traits and genomics

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