Morphological and Molecular Characterization of a New Self-Compatible Almond Variety

Abstract

Almonds are one of the most popular nuts, cultivated in countries with Mediterranean climates. In an almond orchard of the self-incompatible cultivar ‘Ferragnes’ in Greece, a tree with different morphological characteristics and signs of self-compatibility was observed. The aim of this study was to study the phenotype, investigate the self-compatibility trait, and elucidate the phylogenetic background of this tree, named ‘Mars’. Morphological traits and kernel and nut characteristics were measured in ‘Mars’, ‘Ferragnes’, ‘Tuono’, and ‘Lauranne’ cultivars. The self-compatibility trait of almonds is attributed to the Sf allele; thus, its existence was investigated in ‘Mars’ by PCR amplification. Moreover, the S-RNase genes of all the cultivars were sequenced. The genetic profile of ‘Mars’ was identified using eight SSR molecular markers and compared with the ‘Ferragnes’, ‘Ferraduel’, ‘Texas’, ‘Tuono’, and ‘Lauranne’ cultivars. The morphological traits suggest that ‘Mars’ is more similar to the ‘Ferragnes’ cultivar, while it bears the Sf allele. S-RNases sequencing revealed that ‘Mars’ has the genotype S1Sf, and the SSR markers showed that it is differentiated genetic material, suggesting it is a cross between ‘Ferragnes’ and ‘Tuono’. Therefore, ‘Mars’ is evaluated as a self-compatible variety with interesting agronomic traits for use in new mono-cultivar almond plantations.

Vegetative and Reproductive Responses Induced by Organo-Mineral Fertilizers on Young Trees of Almond cv. Tuono Grown in a Medium-High Density Plantation

“…Our hull percentage data (on average 44.9%) are consistent with data previously reported in the literature [50], as is the percentage of shelling (on average 30.1%), which fells within the 30-40% range reported in previous research [5,7,24,[51][52][53][54][55]. On the contrary, our data regarding the percentages of double seeds (on average 7.6%) are lower than those obtained for the same Tuono cultivar (between 15% and 31%) by other authors [7,53,56,57]. Indeed, as for the incidence of each single part of the fruit, they are primarily determined by genotype but also by environmental factors [49,[58][59][60].…”

“…Regarding the weight, length, width, and thickness of the kernels, there were no statistical differences both among years and biostimulant treatments, with average values of 1.5 g, 25.6 mm, 16.1 mm, and 7.8 mm, respectively. Overall, our data on the characteristics of the nuts and kernel morphological traits were somewhat superior to those of the same Tuono cultivar reported in other research [7,53,56,63,64], in which for the nuts they varied between 3-4 g, 28-34 mm, 21-23 mm, and 15-20 mm, respectively, and for the kernel they varied between 1.2 and 1.4 g, 23.4 and 23.9 mm, 12.2 and 14.9 mm, and 6.3 and 7.2 mm, respectively. Socias i Compañy et al [65] commented that the general trend in the industry is the preference for large kernels in order to facilitate and cheapen the processes of cracking and blanching.…”

“…Based on the use of almond components, the following information is known: Almond hull is a by-product that can be used as supplemental livestock feed or, due to its beneficial properties (mainly caused by polyphenols and unsaturated fatty acids), in the food, cosmetic, and pharmaceutical industries [61]. The shelling percentage parameter is used to obtain a quantitative measure of shell density and is utilized commercially to calculate kernel yield [56]. Finally, a high presence of double-seeded nuts significantly reduces their commercial value, as having a flat or concave face is undesirable both for the industry (since they present difficulties for confectionery use) and for consumers (because they are less attractive than single-seeded nuts) [62].…”