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J Lloyd - One of the best experts on this subject based on the ideXlab platform.
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Modelling Stomatal Responses to Environment in Macadamia integrifolia
Functional Plant Biology, 1991Co-Authors: J LloydAbstract:Gas exchange measurements were made of photosynthetic and stomatal responses of Macadamia integrifolia under controlled conditions. Test leaves were subjected to a range of temperatures, humidities and photon irradiances. When stomatal responses to humidity were plotted as a function of vapour mol fraction difference (D) a similar curvilinear response was observed at all temperatures and at photon irradiances of 200 and 1500 μmol quanta m-2 s-1. By contrast, when expressed as a function of relative humidity, different slopes in the humidity response were observed, and at high photon irradiances, stomatal conductances (gs) appeared to have an optimum temperature below 15oC. Simple equations to quantify responses to leaf temperature (TI) and D were developed, the best of which was gs = [1-k1(1-[Tl/Topt)]/k2√D, where Topt is the leaf temperature at which maximal stomatal opening is observed and k1 and k2 are constants fitted by non-linear least squares regression analysis. Calculation of the gain ratio of CO2 assimilation (A) to transpiration (E) (δA/δE) was complicated by effects of D on the relationship between A and leaf intercellular mol fraction of CO2 (CI). Calculation of δA/δE using A/CI relationships derived by varying external CO2 mol fraction at constant D showed the gain ratio to be virtually constant (1.5 mmol mol-1) across a range of leaf temperatures and vapour mol fraction differences but, when calculated directly from the relationship between A and gs, a decrease in δA/δE with D was observed. Macadamia leaves have heavily sclerified bundle sheath extensions and it is considered that this dependence was an artefact due to non-uniform stomatal closure in response to increasing D. It is shown that, at any given temperature, a stomatal response of the form gsD-1/2 gives rise to an approximately constant δA/δE.
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Modelling Stornatal Responses to Environment in Macadamia integrifolia
1991Co-Authors: J LloydAbstract:Gas exchange measurements were made of photosynthetic and stomatal responses of Macadamia integrifolia under controlled conditions. Test leaves were subjected to a range of temperatures, humidities and photon irradiances. When stomatal responses to humidity were plotted as a function of vapour rnol fraction difference (D) a similar curvilinear response was observed at all temperatures and at photon irradiances of 200 and 1500 amol quanta m-2 s-'. By contrast, when expressed as a function of relative humidity, different slopes in the humidity response were observed, and at high photon irradiances, stomatal conductances (g,) appeared to have an optimum temperature below 15°C. Simple equations to quantify responses to leaf temperature (TI) and D were developed, the best of which was where To,, is the leaf temperature at which maximal stomatal opening is observed and kl and k2 are constants fitted by non-linear least squares regression analysis. Calculation of the gain ratio of C02 assimilation (A) to transpiration (E) (BADE) was complicated by effects of D on the relationship between A and leaf intercellular mol fraction of C02 (Ci). Calculation of aA/BE using A/Ci relationships derived by varying external COz mol fraction at constant D showed the gain ratio to be virtually constant (1 $5 mmol mol-') across a range of leaf temperatures and vapour mol fraction differences but, when calculated directly from the relationship between A and g,, a decrease in BA/BE with D was observed. Macadamia leaves have heavily sclerified bundle sheath extensions and it is considered that this dependence was an artefact due to non-uniform stomatal closure in response to increasing D. It is shown that, at any given temperature, a stomatal response of the form g,=~-'" gives rise to an approximately constant BA/BE.
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Stomatal responses and whole-tree hydraulic conductivity of orchard Macadamia integrifolia under irrigated and non-irrigated conditions.
Functional Plant Biology, 1991Co-Authors: J Lloyd, T. Trochoulias, R EnsbeyAbstract:Diurnal patterns of stomatal conductance (gs) and leaf water potential (Ψ1) were determined for leaves on irrigated and non-irrigated 5-year-old Macadamia integrifolia trees over a 4-month period from September to December 1989. An empirical model for stomatal conductance was developed for irrigated trees using relationships to photon irradiance (I), leaf temperature (T1) and vapour mole fraction difference (D). This model accounted for 69% of the variance in gs, and was not improved by the inclusion of Ψ1 as an independent variable. Fitted parameters led to the effective prediction of gs for untried combinations of environmental variables. By using a simple expression to link leaf water potential to transpiration rate (E), the model was extended to prediction of Ψ1 from measurements of I, T1 and D. Stornatal conductances were significantly lower on non-irrigated trees after a 2-month dry period. Lower stornatal conductances were not accompanied by more negative Ψ1 indicating that soil rather than leaf water status may control gs in Macadamia trees under non-irrigated conditions.
Catherine J Nock - One of the best experts on this subject based on the ideXlab platform.
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Chromosome-scale assembly and annotation of the Macadamia genome (Macadamia integrifolia HAES 741)
2020Co-Authors: Catherine J Nock, Craig Hardner, Abdul Baten, Ramil Mauleon, Kirsty S. Langdon, Bruce Topp, Agnelo Furtado, Robert J Henry, Graham J.w. KingAbstract:Macadamia integrifolia is a representative of the large basal eudicot family Proteaceae and the main progenitor species of the Australian native nut crop Macadamia. Since its commercialisation in Hawaii fewer than 100 years ago, global production has expanded rapidly. However, genomic resources are limited in comparison to other horticultural crops. The first draft assembly of M. integrifolia had good coverage of the functional gene space but its high fragmentation has restricted its use in comparative genomics and association studies. Here we have generated an improved assembly of cultivar HAES 741 (4,094 scaffolds, 745 Mb, N50 413 kb) using a combination of Illumina paired and PacBio long read sequences. Scaffolds were anchored to 14 pseudo-chromosomes using seven genetic linkage maps. This assembly has improved contiguity and coverage, with >120 Gb of additional sequence. Following annotation, 34,274 protein-coding genes were predicted, representing 92% of the expected gene content. Our results indicate that the Macadamia genome is repetitive and heterozygous. The total repeat content was 55% and genome-wide heterozygosity, estimated by read mapping, was 0.98% or one SNP per 102 bp. This is the first chromosome-scale genome assembly for Macadamia and the Proteaceae. It is expected to be valuable resource for breeding, gene discovery, conservation and evolutionary genomics.
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Genome and transcriptome sequencing characterises the gene space of Macadamia integrifolia (Proteaceae).
BMC genomics, 2016Co-Authors: Catherine J Nock, Abdul Baten, Agnelo Furtado, Robert J Henry, Bronwyn J. Barkla, Graham J.w. KingAbstract:The large Gondwanan plant family Proteaceae is an early-diverging eudicot lineage renowned for its morphological, taxonomic and ecological diversity. Macadamia is the most economically important Proteaceae crop and represents an ancient rainforest-restricted lineage. The family is a focus for studies of adaptive radiation due to remarkable species diversification in Mediterranean-climate biodiversity hotspots, and numerous evolutionary transitions between biomes. Despite a long history of research, comparative analyses in the Proteaceae and Macadamia breeding programs are restricted by a paucity of genetic information. To address this, we sequenced the genome and transcriptome of the widely grown Macadamia integrifolia cultivar 741. Over 95 gigabases of DNA and RNA-seq sequence data were de novo assembled and annotated. The draft assembly has a total length of 518 Mb and spans approximately 79% of the estimated genome size. Following annotation, 35,337 protein-coding genes were predicted of which over 90% were expressed in at least one of the leaf, shoot or flower tissues examined. Gene family comparisons with five other eudicot species revealed 13,689 clusters containing Macadamia genes and 1005 Macadamia-specific clusters, and provides evidence for linage-specific expansion of gene families involved in pathogen recognition, plant defense and monoterpene synthesis. Cyanogenesis is an important defense strategy in the Proteaceae, and a detailed analysis of Macadamia gene homologues potentially involved in cyanogenic glycoside biosynthesis revealed several highly expressed candidate genes. The gene space of Macadamia provides a foundation for comparative genomics, gene discovery and the acceleration of molecular-assisted breeding. This study presents the first available genomic resources for the large basal eudicot family Proteaceae, access to most Macadamia genes and opportunities to uncover the genetic basis of traits of importance for adaptation and crop improvement.
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SNP analysis of Macadamia integrifolia chloroplast genomes to determine the genetic structure of wild populations
Acta Horticulturae, 2016Co-Authors: A. A. Ahmad Termizi, Craig Hardner, Jacqueline Batley, Catherine J Nock, Satomi Hayashi, Juan D. Montenegro, David EdwardsAbstract:Macadamia is an iconic Australian plant, being the only international commercial food crop developed from the indigenous flora. The preferred species for commercial production of the highly valued kernel is Macadamia integrifolia, which is endemic to the subtropical rainforests of south-east Queensland. The first domesticated Macadamia is probably a tree planted in the Brisbane Botanical gardens by Walter Hill in 1858. Crop development was led in Hawaii following introductions in the late 19th century. Complete chloroplast (cp) genome sequencing, using next generation sequencing technology, of 13 trees was used to examine the structure of the wild populations. The 516 Single Nucleotide Polymorphisms (SNPs) identified with reference to the cp genome sequence of Hawaiian 'H.741 Mauka' cultivar produced 12 unique chlorotypes in addition to the reference. The results of this study suggest there is a strong geographic structure to the genetic variation in M. integrifolia. Northern populations were a source of germplasm for the development of the 'Mauka' cultivar, and the origin of the Walter Hill tree was likely a southern population of M. integrifolia.
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Complete chloroplast genome of Macadamia integrifolia confirms the position of the Gondwanan early-diverging eudicot family Proteaceae.
BMC genomics, 2014Co-Authors: Catherine J Nock, Abdul Baten, Graham J KingAbstract:Sequence data from the chloroplast genome have played a central role in elucidating the evolutionary history of flowering plants, Angiospermae. In the past decade, the number of complete chloroplast genomes has burgeoned, leading to well-supported angiosperm phylogenies. However, some relationships, particulary among early-diverging lineages, remain unresolved. The diverse Southern Hemisphere plant family Proteaceae arose on the ancient supercontinent Gondwana early in angiosperm history and is a model group for adaptive radiation in response to changing climatic conditions. Genomic resources for the family are limited, and until now it is one of the few early-diverging 'basal eudicot' lineages not represented in chloroplast phylogenomic analyses. The chloroplast genome of the Australian nut crop tree Macadamia integrifolia was assembled de novo from Illumina paired-end sequence reads. Three contigs, corresponding to a collapsed inverted repeat, a large and a small single copy region were identified, and used for genome reconstruction. The complete genome is 159,714 bp in length and was assembled at deep coverage (3.29 million reads; ~2000 x). Phylogenetic analyses based on 83-gene and inverted repeat region alignments, the largest sequence-rich datasets to include the basal eudicot family Proteaceae, provide strong support for a Proteales clade that includes Macadamia, Platanus and Nelumbo. Genome structure and content followed the ancestral angiosperm pattern and were highly conserved in the Proteales, whilst size differences were largely explained by the relative contraction of the single copy regions and expansion of the inverted repeats in Macadamia. The Macadamia chloroplast genome presented here is the first in the Proteaceae, and confirms the placement of this family with the morphologically divergent Plantanaceae (plane tree family) and Nelumbonaceae (sacred lotus family) in the basal eudicot order Proteales. It provides a high-quality reference genome for future evolutionary studies and will be of benefit for taxon-rich phylogenomic analyses aimed at resolving relationships among early-diverging angiosperms, and more broadly across the plant tree of life.
Johanna C. Mader - One of the best experts on this subject based on the ideXlab platform.
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Hormone Profiling by LC-QToF-MS/MS in Dormant Macadamia integrifolia: Correlations with Abnormal Vertical Growth
Journal of Plant Growth Regulation, 2007Co-Authors: Andrew T. Fletcher, Johanna C. MaderAbstract:A method for analyzing multiple plant hormone groups in small samples with a complex matrix was developed to initiate a study of the physiology of abnormal vertical growth (AVG) in Macadamia integrifolia (cv. HAES344). Cytokinins (CKs), gibberellins (GAs), abscisic acid (ABA), and auxins were detected in xylem sap and apical and lateral buds using high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QToF-MS/MS). The extraction method separated compounds with high sensitivity in positive (CKs) and negative (ABA, auxins, GAs) modes of QToF-MS/MS. CK profiles differed in xylem sap and apical and lateral buds irrespective of AVG symptoms. Trans -zeatin riboside ( t -ZR) was dominant in sap of normal and AVG trees (∼4 and 6 pmol g^−1 FW, respectively). In apical buds isopentenyl adenine (iP) (∼30 pmol g^−1 FW) was the most abundant CK, and in lateral buds trans -zeatin ( t -Z) (22–24 pmol g^−1 FW) and iP (24–30 pmol g^−1 FW) were the most abundant. t- Z levels of AVG trees were higher in apical buds (13.88 vs. 6.6 pmol g^−1 FW, p
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Hormone Profiling by LC-QToF-MS/MS in Dormant Macadamia integrifolia: Correlations with Abnormal Vertical Growth
Journal of Plant Growth Regulation, 2007Co-Authors: Andrew T. Fletcher, Johanna C. MaderAbstract:A method for analyzing multiple plant hormone groups in small samples with a complex matrix was developed to initiate a study of the physiology of abnormal vertical growth (AVG) in Macadamia integrifolia (cv. HAES344). Cytokinins (CKs), gibberellins (GAs), abscisic acid (ABA), and auxins were detected in xylem sap and apical and lateral buds using high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QToF-MS/MS). The extraction method separated compounds with high sensitivity in positive (CKs) and negative (ABA, auxins, GAs) modes of QToF-MS/MS. CK profiles differed in xylem sap and apical and lateral buds irrespective of AVG symptoms. Trans -zeatin riboside ( t -ZR) was dominant in sap of normal and AVG trees (∼4 and 6 pmol g^−1 FW, respectively). In apical buds isopentenyl adenine (iP) (∼30 pmol g^−1 FW) was the most abundant CK, and in lateral buds trans -zeatin ( t -Z) (22–24 pmol g^−1 FW) and iP (24–30 pmol g^−1 FW) were the most abundant. t- Z levels of AVG trees were higher in apical buds (13.88 vs. 6.6 pmol g^−1 FW, p
S.z. De Pinho - One of the best experts on this subject based on the ideXlab platform.
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estudo da embebicao e da viabilidade de sementes de macadâmia Macadamia integrifolia maiden betche
Scientia Agricola, 1993Co-Authors: E.o. Ono, J.d. Rodrigues, J.c. Sabino, S.z. De PinhoAbstract:O presente trabalho teve como objetivo, verificar o tempo de armazenamento necessario para que seja atingida a viabilidade maxima e o tempo de embebicao maxima de sementes de macadâmia (Macadamia integrifolia Maiden & Betche var. IAC-4-20). As sementes foram pesadas e colocadas em recipientes com agua para que ocorresse o processo da embebicao, sendo realizada a pesagem a cada 6 horas. Pode-se concluir que a embebicao foi maxima ao redor de 90 horas apos o inicio da embebicao. Para a analise da viabilidade das sementes, estas foram semeadas mensalmente, durante 12 meses a partir da colheita. Verificou-se que a viabilidade maxima das sementes e atingida, 4 meses apos o inicio do armazenamento.
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Estudo da embebição e da viabilidade de sementes de macadâmia (Macadamia integrifolia Maiden & Betche)
Scientia Agricola, 1993Co-Authors: E.o. Ono, J.d. Rodrigues, J.c. Sabino, S.z. De PinhoAbstract:O presente trabalho teve como objetivo, verificar o tempo de armazenamento necessario para que seja atingida a viabilidade maxima e o tempo de embebicao maxima de sementes de macadâmia (Macadamia integrifolia Maiden & Betche var. IAC-4-20). As sementes foram pesadas e colocadas em recipientes com agua para que ocorresse o processo da embebicao, sendo realizada a pesagem a cada 6 horas. Pode-se concluir que a embebicao foi maxima ao redor de 90 horas apos o inicio da embebicao. Para a analise da viabilidade das sementes, estas foram semeadas mensalmente, durante 12 meses a partir da colheita. Verificou-se que a viabilidade maxima das sementes e atingida, 4 meses apos o inicio do armazenamento.
R Ensbey - One of the best experts on this subject based on the ideXlab platform.
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Stomatal responses and whole-tree hydraulic conductivity of orchard Macadamia integrifolia under irrigated and non-irrigated conditions.
Functional Plant Biology, 1991Co-Authors: J Lloyd, T. Trochoulias, R EnsbeyAbstract:Diurnal patterns of stomatal conductance (gs) and leaf water potential (Ψ1) were determined for leaves on irrigated and non-irrigated 5-year-old Macadamia integrifolia trees over a 4-month period from September to December 1989. An empirical model for stomatal conductance was developed for irrigated trees using relationships to photon irradiance (I), leaf temperature (T1) and vapour mole fraction difference (D). This model accounted for 69% of the variance in gs, and was not improved by the inclusion of Ψ1 as an independent variable. Fitted parameters led to the effective prediction of gs for untried combinations of environmental variables. By using a simple expression to link leaf water potential to transpiration rate (E), the model was extended to prediction of Ψ1 from measurements of I, T1 and D. Stornatal conductances were significantly lower on non-irrigated trees after a 2-month dry period. Lower stornatal conductances were not accompanied by more negative Ψ1 indicating that soil rather than leaf water status may control gs in Macadamia trees under non-irrigated conditions.