From the NCBI database, 81,518 Lactuca sativa EST sequences were downloaded, from which 61,757 non-redundant sequences were obtained. In total, 2040 SSR loci were identified, with the frequency of 3.3%. Trinucleotide ...
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From the NCBI database, 81,518 Lactuca sativa EST sequences were downloaded, from which 61,757 non-redundant sequences were obtained. In total, 2040 SSR loci were identified, with the frequency of 3.3%. Trinucleotide repeat was dominant, followed by dinucieotide and hexanucleotide repeats. Among 181 types of repeat motifs, （AGA）n and （ATG）n were the dominant repeat motif types, taking up 12.01% and 3.53%, respectively. Totally, four material-special EST-SSR markers were characterized. This study enriches molecular markers of L. sativa, and also lays a theoretical foundation for following germplasm identification, molecular marker assisted breeding and genetic map construction.
The growth and development of staminate inflorescence and anatomic structure of male chestnut flower were observed. Results showed that staminate in-florescence on the base of branch formed first, then upward successi...
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The growth and development of staminate inflorescence and anatomic structure of male chestnut flower were observed. Results showed that staminate in-florescence on the base of branch formed first, then upward successively. About 50 days were needed from the formation of staminate inflorescence on the base of branch to ful y develop the staminate inflorescence on the top of the branch. On the same staminate inflorescence, male flower clusters of the base formed first, then upward successively. About 20 days were needed from the formation of stami-nate inflorescence on the base of the male flower cluster to ful y develop the stami-nate inflorescence on the top of the branch. 5-7 male flowers forming a cluster, the flower number in a cluster was odd number usual y, and there was one on the top and each two paral el y arranged downward. The flower on the top came into bloom first, and then downward successively. The flowers paral el y arranged came into bloom at the same time. Sporangium of male flower of chestnut was monolocular. There were a large number of pol en grains in the sporangium. There were large differences between the development process of different sporangium in one male flower. Chestnut had larger quantity of male flowers and pol en and long period of pol ination compared with female flower. It is remained to be further studied whether it was necessary for anemophilous pol ination.
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