| This report is composed of two parts.1. The research of polyphenol oxidase which relating to browning of Agaricus bisporus.(1) The edible fungus Agaricus bisporus is one of the most favorable mushrooms in the world market. Rapid postharvest is recognized as a severe problem in mushroom industry. In contrast to fruits and vegetables, the fruitbodies of mushrooms is easily browning upon storage in few days, even several hours induced by mechanical damage during harvest or transport. The browning can affect the quality of the mushrooms, devalue the merchandise and lead to considerable economic losses. The polyphenoloxidase (PPO) is considered the key enzyme for mushroom browning, which catalyses the oxidation of monophenols into o-quinones with oxygen as substrates, and subsequent non-enzymatic reactions producing brown pigments.(2) 7 exons, 6 introns and typical CuA, CuB domain were found both in PPO3(2080bp)and PPO4(2189bp) genes. Additionally,the connection regions between exons and introns region are highly conserved and meet the GT-AG splicing rule.(3) The two PPO promoters(PPO3 and PPO4) cloned in the research are both longer than 1.5 kb and contain the conservative elements of core promoter, such as TATA-Box and CAAT-Box, as well as some important cis-acting elements, for example I-box, G- Box, AE-box, WUN-motif, ARE-motif, MYB and so on.(4)It is further proved that the relationship existed between the PPO gene and browning from the perspective of molecular biology by using semi-quantitative.2. The building of Lentinula edodes EST-SSR marker.EST-SSR is a type of molecular marker developed from the databank of sequence of expression sequence tags(EST) and/or cDNAs. Development of avalible EST-SSR markers for Lentinula edodes is significant to the genetic and breeding study.In this paper, the Lentinula edodes EST-SSR markers were developed by using the data mining technique were applicated in the genetic relationship between cultivated strains. The main results we obtained are listed below:(1) Totally 4684 Unigenes of Lentinula edodes, about 3681177bp in length were obtained from 12184 ESTs which were downloaded from NCBI.Then 142 SSRs distributed in 120 ESTs were mined out by and accouting for 2.99%(the average distance of distribution: 25.924kb) of all the 4684 Unigenes. In all the SSRs, mononucleoti, dinuclotide, trinucleotide repeates are the main types and A/T, AG/CT, ACG/CTG are the most aboundent repeat motifs, accouting for 23.23%, 21.83%, 10.56% of the total EST-SSRs respectively.(2) 40 EST-SSR primer pairs were designed by PrimerPremier5.0 and detected by 6% denaturing polyacrylamide ge1 in 35 Lentinula edodes genotypes. A set of 22 primer pairs showed polymorphisms, accouting for 55% of all the primers.(3) The range of the 35 varieties'Similarity coefficient was between 0.125-0.781 and PIC value was between 0.056 - 0.826 computed by NTSYS, 35 varieties can be divided into 7 categories at the level of 0.36(genetic distance). |
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