Genetic diversity and relatedness of mango cultivars assessed by SSR markers.

Assessment of genetic diversity and relatedness is an essential component of germplasm characterization and use. We analyzed 120 mango (Mangifera indica L.) genetic resources in Japan for their parentage, cultivar identification, genetic relatedness, and genetic diversity, using 46 polymorphic simple sequence repeat (SSR) markers. Ten sets of three SSR markers could successfully distinguish 83 genotypes with the exception of synonymous and identical accessions. We successfully assessed parentage, newly identifying or reconfirming both parents of 11 accessions, and revealing over 30 cultivars as offspring of 'Haden'. Genetic relatedness and diversity analyses revealed three distinct clusters. Two clusters correspond to the groups of USA and India, which are closely related. The other includes accessions from Southeast and East Asia. The results agree with the previous identification of genetically distinct Indian and Southeast Asian types, and suggest that the Florida accessions, which originated from hybrids between those two types, are more closely related to the Indian type.

Current status of tropical fruit breeding and genetics for three tropical fruit species cultivated in Japan: pineapple, mango, and papaya.

Tropical fruit crops are predominantly produced in tropical and subtropical developing countries, but some are now grown in southern Japan. Pineapple (Ananas comosus), mango (Mangifera indica) and papaya (Carica papaya) are major tropical fruits cultivated in Japan. Modern, well-organized breeding systems have not yet been developed for most tropical fruit species. Most parts of Japan are in the temperate climate zone, but some southern areas such as the Ryukyu Islands, which stretch from Kyushu to Taiwan, are at the northern limits for tropical fruit production without artificial heating. In this review, we describe the current status of tropical fruit breeding, genetics, genomics, and biotechnology of three main tropical fruits (pineapple, mango, and papaya) that are cultivated and consumed in Japan. More than ten new elite cultivars of pineapple have been released with improved fruit quality and suitability for consumption as fresh fruit. New challenges and perspectives for obtaining high fruit quality are discussed in the context of breeding programs for pineapple.

Minimal marker: an algorithm and computer program for the identification of minimal sets of discriminating DNA markers for efficient variety identification.

DNA markers are frequently used to analyze crop varieties, with the coded marker data summarized in a computer-generated table. Such summary tables often provide extraneous data about individual crop genotypes, needlessly complicating and prolonging DNA-based differentiation between crop varieties. At present, it is difficult to identify minimal marker sets--the smallest sets that can distinguish between all crop varieties listed in a marker-summary table--due to the absence of algorithms capable of such characterization. Here, we describe the development of just such an algorithm and MinimalMarker, its accompanying Perl-based computer program. MinimalMarker has been validated in variety identification of fruit trees using published datasets and is available for use with both dominant and co-dominant markers, regardless of the number of alleles, including SSR markers with numeric notation. We expect that this program will prove useful not only to genomics researchers but also to government agencies that use DNA markers to support a variety of food-inspection and -labeling regulations.