Apple Cultivation and Breeding in Afghanistan: S-RNase Genotypes and Search System for Suitable Cultivar Combination

We investigated S-RNase genotypes of nine useful Afghan apple cultivars including six original cultivars and one rootstock. We also determined S-RNase genotypes of 11 apple cultivars and lineages and seven rootstocks in Japan. We speculated regarding the unidentified parents of cultivars and lineages from the S-RNase genotypes and their fruit and branch characteristics and also identified mistaken parents. We compiled a database of the apple S-RNase genotypes of 622 apple cultivars investigated, which included a survey system of cultivar combinations showing those that were fully incompatible, semicompatible, and fully compatible, written in the Pashto language.


Introduction
The origin of apple is in Central Asia, and many areas of Afghanistan have native apples.Apple is one of the most cultivated horticultural crops in this country since the climate is appropriate for it.The major areas of apple production, that is, areas producing more than 1,000 metric tons per year, are Ghazni, Kabul, Kandahar, Kapisa, Logar, Paktika, Paktya, Panjshir, Parwan, Uruzgan, and Wardak [1].According to the forecast of the Ministry of Agriculture, Irrigation, and Livestock (MAIL), apple production in Afghanistan increased five to 10% from 2012 to 2013 [1].It was 77,000 metric tons in 2013/14 (April/March) [1].
Self-incompatibility is a genetic mechanism that prevents inbreeding and promotes outcrossing in many flowering plants [2].The gametophytic self-incompatibility (GSI) system in apple is controlled by the multiallelic S-locus [2,3], so that when the pollen S-haplotype matches one of the pistil Shaplotypes, the pollen tube growth is arrested in the style.In apple GSI, F-box gene called SFBB (S-locus F-box brothers) and S-RNase gene act as pollen and pistil factors, respectively [4,5].As fertilization of apple needs at least two cultivars having no or one common S-haplotype, accurate knowledge of the S-genotype that is identified by the S-RNase alleles is important for stable apple production.
In this study, we investigated the S-genotypes of apple cultivars and lineages including Afghan original cultivars for apple breeding and cultivation.In addition, we translated the apple S-RNase allele genotype database to the Pashto language and made a homepage where Afghan apple growers can search for suitable cultivar combination.Indeed, Pashto is Afghanistan's official language and is used by more than 60% of the country's populations.

Database of S-RNase Allele Genotypes and the Search
System for Suitable Apple Cultivar Combination Using the Pashto Language.We previously established a search system for apple cultivar combination, written in English on the homepage (http://www.agr.nagoya-u.ac.jp/∼hort/apple/) [23].In this study, we have developed a Pashto language version of the search system homepage for apple growers in Afghanistan.At first all names of cultivars and their parents in the database were translated from English to the Pashto language.Then, we changed the search system homepage to a Pashto language version.As the writing of the Pashto language reads from right to left, the new homepage looks like an opposite of the English version (Figure 2).

Conclusions
We have investigated 27 S-RNase genotypes of apple cultivars and lineages including the nine most useful Afghanistan apple cultivars.We developed a Pashto language version of the S-genotypes database of apple cultivars, along with a convenient search system for cultivar combination showing three different types of compatibilities, that is, full-compatibility, semicompatibility, and full-incompatibility.The translated Pashto version of the search system will enable apple growers in Afghanistan to select suitable and compatible apple cultivars for successful combination in an orchard to ensure stable fruit production and breeding.

Figure 2 :
Figure 2: Pashto language version of representative screenshots of the search system."Fuji" was selected for searching cultivars on the English version (a) and Pashto version (b).Search results: cultivars incompatible with "Fuji" on the English version (c) and Pashto version (d), cultivars semicompatible with "Fuji" on the Pashto version (e), and cultivars fully compatible with "Fuji" on the Pashto version (f).