Outcrossing Rate, Yield, and Selective Fruit Abscission in `Ettinger' and `Ardith' Avocado Plots

Degani, C.; El-Batsri, R.; Gazit, S.

doi:10.21273/jashs.122.6.813

Cited by 32 publications

(45 citation statements)

References 19 publications

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“…Although different factors such as temperature [33,34], outcrossing rate [35,36], water and nutrient availability [37] and alternate bearing [29] have been proposed as limiting factors in avocado fruit production, information is still elusive to explain why most flowers prematurely abscise. In avocado, as in other evergreen woody plant species, vegetative and reproductive growth occur simultaneously and, consequently, vegetative and reproductive organs compete for resources provided by either reserve mobilization or photosynthesis [38,39].…”

Section: Introductionmentioning

confidence: 99%

Pistil Starch Reserves at Anthesis Correlate with Final Flower Fate in Avocado (Persea americana)

2013

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A common observation in different plant species is a massive abscission of flowers and fruitlets even after adequate pollination, but little is known as to the reason for this drop. Previous research has shown the importance of nutritive reserves accumulated in the flower on fertilization success and initial fruit development but direct evidence has been elusive. Avocado (Persea americana) is an extreme case of a species with a very low fruit to flower ratio. In this work, the implications of starch content in the avocado flower on the subsequent fruit set are explored. Firstly, starch content in individual ovaries was analysed from two populations of flowers with a different fruit set capacity showing that the flowers from the population that resulted in a higher percentage of fruit set contained significantly more starch. Secondly, in a different set of flowers, the style of each flower was excised one day after pollination, once the pollen tubes had reached the base of the style, and individually fixed for starch content analysis under the microscope once the fate of its corresponding ovary (that remained in the tree) was known. A high variability in starch content in the style was found among flowers, with some flowers having starch content up to 1,000 times higher than others, and the flowers that successfully developed into fruits presented significantly higher starch content in the style at anthesis than those that abscised. The relationship between starch content in the ovary and the capacity of set of the flower together with the correlation found between the starch content in the style and the fate of the ovary support the hypothesis that the carbohydrate reserves accumulated in the flower at anthesis are related to subsequent abscission or retention of the developing fruit.

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Section: Introductionmentioning

confidence: 99%

Pistil Starch Reserves at Anthesis Correlate with Final Flower Fate in Avocado (Persea americana)

2013

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“…It has been demonstrated that successful penetration of the ovary by pollen is time and temperature-dependent and varies among pollen donors (Sedgley and Grant 1983). Abscission of flowers and immature fruits occurs in avocado and selective abscission of immature fruit is reported to have a genetic basis (Degani et al 1986, Degani et al 1997. Two different types of fruit set are described in avocado, Type 1 and Type 2.…”

Section: Linkage Analysismentioning

confidence: 99%

An EST-SSR-based linkage map for Persea americana Mill. (avocado)

Borrone

Brown

Tondo

et al. 2009

Tree Genetics & Genomes

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Recent enhancement of the pool of known molecular markers for avocado has allowed the construction of the first moderately dense genetic map for this species. Over 300 SSR markers have been characterized and 163 of these were used to construct a map from the reciprocal cross of two Florida cultivars 'Simmonds' and 'Tonnage'. One hundred thirty-five primer pairs amplified 163 usable loci with 20 primer pairs amplifying more than one locus. 'Tonnage' was heterozygous for 152 (93%) loci, whereas 'Simmonds' was heterozygous for 64 (39%). Null alleles were identified at several loci. Linkage maps were produced for both reciprocal crosses and combined to generate a composite linkage map for the F 1 population of 715 individuals. The composite map contains 12 linkage groups. Linkage groups ranged in size from 157.3 cM (LG2) to 2.4 cM (LG12) and the number of loci mapped per group ranged from 29 (LG1) to two (LG12). The total map length was 1,087.4 cM. Only seven markers were observed to have segregation distortion (α≤0.05) across both sub-composite (reciprocal) maps. Phenotypic data from traits of horticultural interest are currently being collected on this population with the ultimate goal of identifying useful quantitative trait loci and the development of a marker-assisted selection program.

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“…Flowering Types A and B complement one another because when one is functionally female (Stage 1), the other is functionally male (Stage 2). DSPD is thought to promote outcrossing between avocado trees of opposite flowering types (Borrone et al, 2008;Degani et al, 1997), but selfing is frequently observed, so factors such as outcrossing rate and the impact of individual pollen donors must also be considered with regard to fruit set and yield. Commercial avocado groves often contain both A and B type cultivars with similar flowering periods.…”

mentioning

confidence: 99%

“…The necessity of interplanting cultivars of opposite flowering type has been much debated among avocado researchers. Using molecular markers, outcrossing has been demonstrated in many studies; however, the rate varies with location, orchard design, developmental stage of the fruit sampled, and the cultivars used as pollen donors Chen et al, 2007;Davenport, 1999;Davenport et al, 1994Davenport et al, , 2007Degani and Gazit, 1984;Degani et al, 1989Degani et al, , 1997Vrecenar-Gadus and Ellstrand, 1985). Borrone et al (2008) used microsatellite markers on Florida avocados and demonstrated that when two complementary cultivars are planted together in almost equal numbers, most of the harvestable fruit result from crosspollination.…”

mentioning

confidence: 99%

“…Almost all of the progeny tested (203 of 204) were the result of outcrossing Chen et al, 2007). Outcrossing and yield have been found to be significantly correlated for a number of avocado cultivars in Israel (Degani et al, 1989(Degani et al, , 1997; however, studies in California estimated no correlation or a very weak correlation between outcrossing and yield (Kobayashi et al, 2000;Vrecenar-Gadus and Ellstrand, 1985). Most recently, Garner et al (2008) estimated outcrossing using 10 6-year-old 'Hass' trees in a commercial grove in California with a single fully informative microsatellite marker.…”

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confidence: 99%

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Outcrossing between ‘Bacon’ Pollinizers and Adjacent ‘Hass’ Avocado Trees and the Description of Two New Lethal Mutants

Schnell¹,

Tondo²,

Brown³

et al. 2009

horts

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Avocado (Persea americana Mill.) has an unusual flowering mechanism, diurnally synchronous protogynous dichogamy, that promotes crosspollination among avocado genotypes. In commercial groves, which usually contain pollinizer rows adjacent to the more desirable commercial cultivars, the rate of outcrossing has been measured with variable results. Using microsatellite markers, we estimated outcrossing in a commercial California ‘Hass’ avocado orchard with adjacent ‘Bacon’ pollinizers. Seedlings grown from mature harvested fruit of both cultivars were genotyped with five fully informative microsatellite markers and their parentage determined. Among the 919 seedlings of ‘Hass’, 688 (75%) were hybrids with ‘Bacon’; the remaining 231 (25%) seedlings were selfs of ‘Hass’. Among the 850 seedlings of ‘Bacon’, 382 (45%) were hybrids with ‘Hass’ and the remaining 468 (55%) seedlings were selfs of ‘Bacon’. The high outcrossing rate observed in the ‘Hass’ seedlings was expected, because adjacent rows of opposite flowering types (A versus B) are expected to outcross. However, the high selfing rate in ‘Bacon’ was unexpected. A previous study in Florida using the cultivars ‘Simmonds’ and ‘Tonnage’ demonstrated differences in outcrossing rates between complementary flowering type cultivars. In both Florida and California, the A type parents (‘Hass’ and ‘Simmonds’) had similar outcrossing rates (≈75%); however, the B type parents (‘Bacon’ and ‘Tonnage”) had highly skewed outcrossing rates of 45% and 96%, respectively. Two new avocado lethal mutants were discovered among the selfed seedlings of ‘Hass’ and ‘Bacon’. These were labeled “spindly” and “gnarly” and are similar in phenotype to mutants described in Arabidopsis and other crop species.

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Outcrossing Rate, Yield, and Selective Fruit Abscission in `Ettinger' and `Ardith' Avocado Plots

Cited by 32 publications

References 19 publications

Pistil Starch Reserves at Anthesis Correlate with Final Flower Fate in Avocado (Persea americana)

Pistil Starch Reserves at Anthesis Correlate with Final Flower Fate in Avocado (Persea americana)

An EST-SSR-based linkage map for Persea americana Mill. (avocado)

Outcrossing between ‘Bacon’ Pollinizers and Adjacent ‘Hass’ Avocado Trees and the Description of Two New Lethal Mutants

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