Apomixis in Portuguese Walnut Varieties

Valdiviesso, T.

doi:10.17660/actahortic.1990.284.38

Cited by 4 publications

(6 citation statements)

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“…In walnut, apomixis was confirmed (Loiko 1990, Asadian andPieber 2005), and later it was investigated in different cultivars using isoenzyme analysis (San andDumanoğlu 2006, Wu et al 2006). The mechanisms of apomixis in walnut have been reported as adventitious embryony (Valdiviesso 1990), apospory (Terziiski and Stefanova 1990) or diplospory (Sartorius and Stosser 1991). Sartorius and Stösser (1997) and Chen et al (2000) reported development of apomictic embryos from the egg cell in different walnut cultivars.…”

Section: Introductionmentioning

confidence: 99%

A pattern of unique embryogenesis occurring via apomixis in Carya cathayensis

Zhang¹,

Wang²,

Jin³

et al. 2012

Biologia plant.

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Apomixis represents an alteration of classical sexual plant reproduction to produce seeds that have essentially clonal embryos. In this report, hickory (Carya cathayensis Sarg.), which is an important oil tree, is identified as a new apomictic species. The ovary has a chamber containing one ovule that is unitegmic and orthotropous. Embryological investigations indicated that the developmental pattern of embryo sac formation is typical polygonum-type. Zygote embryos were not found during numerous histological investigations, and the embryo originated from nucellar cells. Nucellar embryo initials were found both at the micropylar and chalazal ends of the embryo sac, but the mature embryo developed only at the nucellar beak region. The mass of the nucellar embryo initial at the nucellar beak region developed into a nucellar embryo or split into two nucellar proembryos. The later development of the nucellar embryo was similar to the zygotic embryo and progressed from globular embryo to heart-shape embryo and to cotyledon embryo.Additional key words: adventitious embryony, female gametophyte, hickory, nucellar embryo.

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Section: Introductionmentioning

confidence: 99%

A pattern of unique embryogenesis occurring via apomixis in Carya cathayensis

Zhang¹,

Wang²,

Jin³

et al. 2012

Biologia plant.

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“…Under conditions in Turkey, the percentage of apomictic fruits has varied between 0.5% and 1.6% (Şan and Dumanoğlu, 2006). Asadian and Pieber (2005) reported a maximum apomixis percentage of 58% in 'Milotai 4/R' variety, in the experiments carried out in Austria, and Valdiviesso (1990) showed that the growth of apomictic fruits in 'Rego' cv. was 7% in Portugal.…”

Section: Introductionmentioning

confidence: 96%

“…Research conducted in walnut fruit formation, have shown that some of the genotypes can form fruits without fecundation, through parthenocarpy or apomixis. Opportunities for fruit formation without pollination in walnut, under normal conditions, have raised a keen interest among researchers in biology of flowering and seed formation (Badalov, 1983;Germain et al, 1973;Hanna and Bashaw, 1987;Laiko, 1990;Valdiviesso, 1990). In terms of economic analysis, the phenomenon of parthenocarpy is undesirable because some of the fruits resulted in this way are small, dry, with no commercial value.…”

Section: Introductionmentioning

confidence: 99%

“…Many researchers have reported apomixis in walnut (Germain et al, 1973;Laiko, 1990;Şan and Dumanoğlu, 2006;Valdiviesso, 1990), but it was found that the formation of fruit is weak, almost zero in some cases, so there is no apomictic crop to be expected. Sometimes apomixis percentage is higher, between 23.5% and 81.2%, in some of the genotypes (Laiko, 1990;Solar et al, 1995), but apomictic nuts cannot be always obtained.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Apomictic Fruit Set Ratio in Several Romanian Walnut (Juglans regia L.) Cultivars

Cosmulescu

Botu

Achim

2012

Not Bot Hort Agrobot Cluj

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Apomixis, a natural process that allows clonal propagation by seed, is an important feature of walnut (Juglans regia L.). This study was carried out to determine the ability of apomictic fruit setting in twelve Romanian walnut cultivars. 'Sibisel 44' , 'Geoagiu 65' , 'Germisara' , 'Muscelean' , 'Sarmis' , 'Valcor' , 'Valmit' , 'Valrex' , 'Jupanesti' , 'Velnita' , 'Orastie' and ' Argesean' cultivars were used in the experiment. Female flowers were isolated with pergament paper bags and the apomictic fruit set was determined 8 weeks after anthesis. The apomixis degree was determined as the number of fruit calculated in relation to the number of isolated flowers. The percentage of apomictic fruit set without pollination in cultivars analyzed is low, ranging from 7.86% ('Orastie' cultivar) up to 12.46% ('Jupanesti' cultivar). The results indicated that apomictic fruit set is insufficient for economical seed and crop production in these Romanian walnut cultivars.

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“…Despite the low percentage of seeds produced, the total number of nuts was sufficient to warrant harvesting ( Wood, 1934 ). The primary references made in 1933-1990 suggest that apomixis may have contributed to the high and regular production of some walnut varieties originating from spring frost regions ( Valdiviesso, 1990 ). Scanty studies have reported walnut apomictic mechanisms through cytoembryological analysis.…”

Section: Introductionmentioning

confidence: 99%

Is apomixis occurring in walnut (Juglans regia L.)? New data from progeny molecular tests and cytological investigations shed light on its reproductive system

Solhjoo,

Fatahi,

Zamani

et al. 2023

Front. Plant Sci.

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IntroductionPersian walnut (Juglans regia) is an economically important nut fruit species cultivated worldwide for its nutritious kernel and timber quality wood. Walnut trees are mostly hetero-dichogamous and, depending on the genotype, some cultivars are protogynous, while others are protandrous. Although selfing is possible when male and female blooms overlap, the dichogamy of the species promotes outcrossing. In addition to sexual reproduction, some reports indicate that elements of apomixis may occur in commercial orchards of walnut varieties and in the last two decades, nut production by apomixis has been reported in walnut. However, there are no reliable studies on the occurrence of apomictic reproduction based on cytoembryological observations and/or molecular marker-progeny tests. This study addresses the combined use of molecular and cytological analyses to gain new insights into the population genetics and reproduction systems of J. regia.MethodsWe systematically analyzed the reproductive origin of individual progeny plants from 8 different cultivated walnut genotypes using microsatellite genotyping and carried out cytohistological investigations of 5 cultivated walnut genotypes arising seed sets from isolated flowers, to shed light on the mode of reproduction.Results and discussionThese cytometric and genotyping analyses did not support any asexual mode of reproduction or asexual propagation by seed and all individuals studied were identified as zygotic plants produced by crossing. Likewise, the cytological findings did not confirm completely the first component of apomixis, namely apomeiosis. On the other hand, according to histological evidence, adventitious embryony seems to take place at low frequency. Overall, our findings suggest that the occurrence of gametophytic apomixis is unlikely in J. regia, but sporophytic apomixis cannot be completely ruled out.

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Apomixis in Portuguese Walnut Varieties

Cited by 4 publications

References 0 publications

A pattern of unique embryogenesis occurring via apomixis in Carya cathayensis

A pattern of unique embryogenesis occurring via apomixis in Carya cathayensis

Determination of Apomictic Fruit Set Ratio in Several Romanian Walnut (Juglans regia L.) Cultivars

Is apomixis occurring in walnut (Juglans regia L.)? New data from progeny molecular tests and cytological investigations shed light on its reproductive system

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