Assessment and use of sea buckthorn and apple diversity in northern Pakistan

Many local perennial plant genetic resources (P/PGR) are under threat due to over-exploitation, depletion, degradation, farmers’ favoring few cash crops, poor marketing conditions leading to low product prices along with the lack of knowledge about alternative uses and management strategies. Such processes often cause the underutilization and replacement of local P/PGR causing them to become neglected and underutilized species (NUS). The decline of species abundance may cause genetic erosion of these NUS crops and prevents the adaptation or improvement of valuable traits. Many of these traditional NUS crops can be conserved on human-managed farmlands (in-situ conservation). The study area in Gilgit-Baltistan (GB), Pakistan harbors important local P/PGR hotspots with a still largely unknown species diversity reflecting a millennia old trading history along the historic Silk Route. The ongoing depletion and irreversible loss of indigenous plant genetic resources calls for an assessment of status quo of agrobiodiversity and the conservation of plant genetic resources. Sea buckthorn (Hippophae rhamnoides L.) and local apple (Malus × domestica) varieties are typical representatives of such local P/PGR, contribute substantially to farmers’ household incomes, and provide essential ecosystem services. Both species were intensively studied to assess their use, to unravel potential effects of past and present anthropogenic activities on varietal richness and diversity, and to derive location-specific management, conservation, and promotion strategies. As sea buckthorn berries are considered a “superfood” due to their nutritional properties, fruits of the species have a large international market potential, especially in China and Europe. Contrary to the situation in other countries, in Pakistan this species is heavily underutilized and neglected. During 2016-2017, the first study on natural sea buckthorn populations was conducted to assess the effects of putative ongoing domestication. Both, morphological and genetic diversity were characterized and evaluated based on the present variability. For this purpose, 300 individuals from eight different villages were selected where farmers were directly involved in sea buckthorn collection. Within each village the samples were classified as wild and supposedly domesticated stands. Dendrometric, fruit, and leaf morphometric traits were recorded. For genotyping, twelve EST-SSR (expressed sequence tags-simple sequence repeats) markers were used. The results showed significant differences in morphological traits across stands (village and wild) and there was a significant positive correlation among leaf area and altitude. Berries exhibited 22 colour shades and 20 dorsal and 15 ventral leaves colour shades. Mean genetic diversity was high (He = 0.699) and comparable to other studies. Three distinct genetic clusters were found corresponding to the geographical location of the populations with mountains acting as a physical barrier against gene flow. Likely gene flows within and among village of the same valley/region and lacking trends in morphological traits among stands yielded little evidence of domestication. Considering high allelic richness and genetic diversity, the population of GB is likely natural and seems to be a promising source for selection of improved germplasm. The reason for low market performance of sea buckthorn in Gilgit-Baltistan was assessed during a second study (2017–2018) conducted to assess the factors influencing local trade. A total of 111 fruit collectors and 17 commission agents were interviewed using semi-structured questionnaires. This study provided comprehensive data regarding the value chain from collection to post-harvest management practices of sea buckthorn berries including effects of sun and shade drying of fruits on vitamin C. The findings were complemented by an analysis of the underlying supply chain (collectors ~ supplier and commission agents ~ buyer). The results showed that berry marketing is severely hampered by low raw product quality, varying prices, and low local demand. Fruit sale prices were low and not satisfactory for the collectors (1.82 US$ kg−1) although mostly poor households were/are involved in the harvest and sale for their subsistence. Post-harvest conditions such as traditional sun drying, and storage were inappropriate leading to a decline of fruit physical appearance and chemical quality, thereby negatively influencing the sales price of produce. Supply chain analyses indicated lack of coordination among actors and infrastructure which prevent sea buckthorn production at a larger scale. The study provides evidence for an urgent need to define appropriate food quality standards, to increase communication among different stakeholders, and to intensify training of collectors. Malus × domestica is one of the main fruit crops of temperate regions, traded globally, and a comparatively well documented species, whereas diversity of germplasm in remote areas is yet to be explored. In GB, germplasm diversity of apple is threatened by gradual loss due a recent increase in market demand and farmers’ preference for modern, high yielding cultivars. Therefore in 2018–2019, a third study was conducted on local apple cultigens to assess their diversity, varietal richness, arboricultural activities as well as phenotypic and genotypic parameters. To this end, two dead-end valleys (Ishkoman and Baltistan) were selected by assuming that plant genetic materials was introduced from its lower end via roads and trading markets rather than tedious mountain pathways. A total of 106 individual apple trees were sampled, and 35 tree owners were interviewed from seven villages of these two valleys. For the first time in this area dendrometric parameters, fruit traits (qualitative and quantitative), and varietal diversity (based on alpha- and beta-diversity) were measured in each village. Eleven SSR markers were used for genotyping and synonyms and homonyms were distinguished based on cluster analysis. Alpha varietal diversity was highest in Baltistan, where even a wild apple relative (Malus baccata) was found. Beta-diversity revealed three compositionally distinct clusters among villages. Fruit weight, calyx depth, and axis pit width represented highest variability as compared to other assessed characters and seem thus useful traits to distinguish the studied accessions. Arboricultural activities were rarely observed and only a few local varieties were marketed, while most of them were used for home consumption only. Genetic data revealed sixty-one multi-locus genotypes (MLG; mean genotype diversity: 58%) and 18 putative clones (comprising 2 to 9 ramets) while mean genetic diversity was moderate (He = 0.677). Observed negative inbreeding coefficients indicated excess of heterozygotes in three genetic clusters with high gene flow among villages and valleys. Against our expectations there was no apparent effect of accessibility (lower to upper part of the valley) on varietal diversity exhibited by morphological or genetic traits. Moderate correlation (r = 0.627, p = 0.001) between phenotypic and genotypic and dendrogram analysis indicated genetically linked fruit traits, which merit further investigation. The moderate to high varietal, phenotypic, and genetic diversity revealed the need and potential of in situ conservation for the apple germplasm of GB and as a basis for future breeding programs. Our studies show that sea buckthorn and apple can act as model species for P/PGR in GB emphasizing the need for the development of locally suitable conservation and management strategies. The marketing promotion of indigenous P/PGRs may open new income sources for local communities. This will also help to maintain the historical biological heritage of the region. Studies combining results of P/PGR agrobiodiversity with socio-economic data will provide guidance to identify P/PGR that merit conservation and further promotion.