Abstract: 【Objective】Actinidia species are native to China, which provides rich germplasm resources for rootstock breeding. Kiwifruit is one of the most successful wild fruit trees domesticated in the 20th century and is increasingly popular among consumers because of its unique taste and high vitamin content. Grafting is an asexual plant propagation technique that combine desired traits from both rootstock and scion. This technique has been used extensively in fruit crops. The current kiwifruit industry relies on a few rootstock cultivars from seedlings of A. chinensis and A. deliciosa. Rootstocks selected from A. valvata are much more tolerant to waterlogging stress than those from A. deliciosa, which are commonly used in kiwifruit production. However, supposed consistent clonal rootstocks of A. valvata accessions are mixed and their genetic backgrounds are various. Genetic diversity analysis of plant germplasm resources could lay a solid foundation for kiwifruit breeding and utilization. To clarify the relationship among different A. valvata accessions, the diversity of 62 A. valvata accessions was analyzed by using seven microsatellite DNA markers and 36 phenotypic traits. Plant sex determination for cultivars and accessions within species is the first step towards the correct classification of kiwifruit germplasm. Present study used sex-related DNA markers to identify plant gender at its juvenile stage and these plants can be maintained as male and female plant populations separately. A. valvata is a new clonal kiwifruit rootstock, which is found that scions grafted on male rootstock performed better than those on female rootstocks during kiwifruit production. The aim of this study is to identify plant genders of these 62 accessions with sex-related DNA markers for better utilize male A. valvata germplasm. 【Methods】 Sixty-two A. valvata accessions were used as materials. Diversity of these studied accessions was evaluated based on their phenotypic characters and genotypes of seven Simple Repeat Sequence (SSR). Sex-related DNA markers was used to identify plant gender, and 34 flower-related attributes were evaluated to verify genotyping results. 【Results】 Among all 36 phenotypic traits, except for lenticel color (grayish white), leaf texture (membranous), leaf tip shape (caudiform), flatness of leaf surface blade (green), flatness of leaf pubescence (none), petal shape (ovate), the main color of the interior of the petal (white), clutch condition base of the petal (reunion), calyx color (green), female style posture (oblique growth), style color (ivory), female ovary shape (bottle), male filament color (white)，anther shape (oblong), anther color (yellow), petal color gradient(none), the remaining 20 traits showed different degrees of phenotypic variation, of which 16 traits were descriptive traits and 10 traits were quantitative traits. There were 25 various types for 10 descriptive traits, according to the characteristics of shoots and leaves, these 62 accessions could be clustered into five groups. The first group had the most diverse twig and leaf traits, and the petioles were mostly purple red. The second group only has one individual--A11 and its internode length and annual branch thickness of this group were lower than the average of all individuals. The internode length of the annual branches of individuals in third group was higher than the average of all samples, and the thickness of the annual branches was lower than the average of all samples and the leaf shape was oval. The length of the fourth group of leaves was higher than the average of all samples. The fifth group only had two individuals, A43 and A27. The internode length of the annual branches in this group was the largest among all samples, and the thickness of the annual branches was higher than the average of all samples. The color of the annual branches was grayish brown, the pores are all elliptical, the leaf shape was oval, the leaf edge was all wavy, the leaf base was all circular, the petiole length was lower than the average of all samples, the petiole color was all greenish yellow, and the leaf length was higher than the sample average. The used seven SSR markers amplified a total of 69 alleles, with an average number of alleles 9.86 on each marker locus, the effective alleles were 2~18, the average polymorphism information content (PIC) was 0.626, and the average observed heterozygosity (Ho) and expected heterozygosity (He) values was 0.994 and 0.696, respectively. According to SSR marker polymorphism, 62 individuals could be clustered into four groups. Gender-related marks had identified 18 female plants and 43 male plants; 34 individuals of flowering had been identified, and 13 female plants and 21 male plants (34 marks identification results were 9 female and 25 male). Plant gender identified from the morphological sex determination and the sex-related DNA markers were 79.14% consistent.【Conclusion】A total of 62 A. valvata showed abundant phenotypic diversity, especially for twig and leaf traits. Combined with plant phenotypic characters and DNA marker genotypes can effectively characterize A. valvata germplasm, which can provide tools and materials for further breeding clonal male A. valvata rootstock.
PDF （）