Research Article Histological and Molecular Characterization of Grape Early Ripening Bud Mutant Da-Long Guo, Yi-He Yu, Fei-Fei Xi, Yan-Yan Shi, and Guo-Hai Zhang College of Forestry, Henan University of Science and Technology, Luoyang, Henan 471003, China Correspondence should be addressed to Da-Long Guo; guodl2005@126.com Received 21 April 2016; Revised 22 July 2016; Accepted 25 July 2016 Academic Editor: Jinfa Zhang Copyright © 2016 Da-Long Guo et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. An early ripening bud mutant was analyzed based on the histological, SSR, and methylation-sensitive amplifed polymorphism (MSAP) analysis and a layer-specifc approach was used to investigate the diferentiation between the bud mutant and its parent. Te results showed that the thickness of leaf spongy tissue of mutant (MT) is larger than that of wild type (WT) and the diferences are signifcant. Te mean size of cell layer L2 was increased in the mutant and the diference is signifcant. Te genetic background of bud mutant revealed by SSR analysis is highly uniform to its parent; just the variations from VVS2 SSR marker were detected in MT. Te total methylation ratio of MT is lower than that of the corresponding WT. Te outside methylation ratio in MT is much less than that in WT; the average inner methylation ratio in MT is larger than that in WT. Te early ripening bud mutant has certain proportion demethylation in cell layer L2. All the results suggested that cell layer L2 of the early ripening bud mutant has changed from the WT. Tis study provided the basis for a better understanding of the characteristic features of the early ripening bud mutant in grape. 1. Introduction Grape (Vitis vinifera L.) is one of the most widely cultivated fruit trees in the world, which have been cultivated for thousands of years for fresh fruit, dried fruit, and wine production. Tere are thousands of grape varieties in the world. Many of these varieties have been derived from crosses among or between species to produce new cultivars. Te most important group is from crosses between V. vinifera and V. labrusca, such as “Kyoho” which is developed to produce a large berry [1]. “Kyoho” is one of the most important grown varieties in the world today. It was introduced to China in 1959 from Japan. It has many eminent advantages, large berries, high production, and adaptation to high temperature, rainy, and wet environments [2]. An early ripening bud mutant of “Kyoho,” “Fengzao,” was recently presented [2]. It matures in early July in Henan Province, China, and nearly one month earlier than “Kyoho.” All of its traits are similar to those of “Kyoho” except the ripening date. Te pehontypic and physiological diferences between the bud mutant and its parent have been investigated in detail [3, 4]. Bud mutants arising from somatic variants are important genetic materials for cultivar improvement in grape [5]. Any new desirable trait in a given bud mutant could be fxed in grape by vegetative propagation such as grafing. Bud mutants have been widely exploited by vine growers to develop new cultivars of wine grapes and table grapes [5]. Variant traits of bud mutants in grape may include color or favor, date of ripening, and canopy growth, size, and cluster architecture [5]. Spontaneous mutations in Vitis have been studied by some researchers [6–9]. Tese mutations could be present in the entire meristem or only a portion (chimeras) [6]. In grape, the shoot apical meristem (SAM) is considered to be composed of only two (L1 and L2) genetically distinct cell layers [5, 6, 10]. In some cases, bud mutants afect only one-cell layer in grape, resulting in periclinal chimeras [6] which is a specifc structure type of genetic mosaic; that is, the genetic makeup of one-cell layers of the apical meristem is distinct from the others and develops independently from the adjacent layers [5, 11]. In few cases, the small mutations that lead to bud mutant are observable within the noncoding DNA associated with SSR markers in grape [12]. Tree- and four-allele genotypes, Hindawi Publishing Corporation International Journal of Genomics Volume 2016, Article ID 5620106, 7 pages http://dx.doi.org/10.1155/2016/5620106