Genome-wide identification and expression analysis of the mitogen-activated protein kinase gene family from banana suggest involvement of specific members in different stages of fruit ripening

Mitogen-activated protein kinases (MAPKs) are important components of the tripartite mitogen-activated protein kinase signaling cascade and play an important role in plant growth and development. Although members of the MAPK gene family have been identified in model plants, little information is available regarding this gene family in fruit crops. In this study, we carried out a computational analysis using the Musa Genome database to identify members of the MAPK gene family in banana, an economically important crop and the most popular fruit worldwide. Our analysis identified 25 members of the MAP kinase (MAPK or MPK) gene family. Phylogenetic analyses of MPKs in Arabidopsis, Oryza, and Populus have classified these MPKs into four subgroups. The presence of conserved domains in the deduced amino acid sequences, phylogeny, and genomic organization strongly support their identity as members of the MPK gene family. Expression analysis during ethylene-induced banana fruit ripening suggests the involvement of several MPKs in the ethylene signal transduction pathway that are necessary for banana fruit ripening. Analysis of the cis-regulatory elements in the promoter regions and the involvement of the identified MPKs in various cellular processes, as analyzed using Pathway Studio, suggest a role for the banana MPK gene family in diverse functions related to growth, development, and the stress response. This report is the first concerning the identification of members of a gene family and the elucidation of their role in various processes using the Musa Genome database.     

Apple 1-Aminocyclopropane-1-Carboxylic Acid Synthase Genes, MdACS1 and MdACS3a, are Expressed in Different Systems of Ethylene Biosynthesis

1-Aminocyclopropane-1-carboxylic acid synthase (ACS) is one of the key regulatory enzymes involved in the synthesis of ethylene. Climacteric fruit ripening is accompanied by increased ethylene production, in which ethylene biosynthesis is changed from system 1 to system 2. In apple, at least four members of the ACS gene family have been identified, two of which, MdACS1 and MdACS3a, have been studied extensively due to their specific expression in fruit tissue. However, the regulatory role of MdACS1 and MdACS3a in the ethylene biosynthesis system is unknown. Here we addressed this issue by investigating ACS expression in ripening apple fruits. Expression analysis in ‘Golden Delicious’ and ‘Red Fuji’ fruits, in combination with treatments of 1-MCP (1-methylcyclopropene, an ethylene inhibitor) and Ethephon (an ethylene releaser) has demonstrated that MdACS3a and MdACS1operate in system 1 and system 2 ethylene biosynthesis, respectively.     

PRO－LONG涂膜处理对后熟香蕉果实乙烯形成以及其它有关生理变化的影响

香蕉（ＭｕｓａａｃｕｍｉｎａｔａＣｏｌｌａｃｖ．ＤｗａｒｆＣａｖｅｎｄｉｓｈ）果实采后以商业上推荐使用的１．５％Ｐｒｏ－ｌｏｎｇ溶液处理,贮藏于２０℃和７５％相对湿度下,分别测定果实的ＡＣＣ含量、ＭＡＣＣ含量、ＥＦＥ酶活性、乙烯释放、叶绿素含量的变化和果实的硬度变化．结果表明,ＰＲＯ－ＬＯＮＧ处理延缓了香蕉果实果皮的叶绿素降解、硬度的下降以及乙烯释放的增加．在后熟过程中,处理果实的ＡＣＣ含量发生积累．ＡＣＣ含量的高峰在乙烯释放高峰和ＥＦＥ酶活性高峰之前出现．与对照比较,处理果实的ＡＣＣ含量和ＥＦＥ酶活性的高峰延迟了５ｄ出现．在后熟过程中,以Ｐｒｏ－ｌｏｎｇ处理果肉四片,其ＥＦＥ酶活性受部分抑制（抑制率为１９．４５％至４０．５１％）．果实ＭＡＣＣ含量在贮藏起初处于一个较显著水平,随着后熟的发展而逐步增加,但与ＡＣＣ含量的明显增加相比变化是微小的．我们的研究进一步阐明了ＰＲＯ－ＬＯＮＧ涂膜对香蕉果实后熟的影响主要是通过减少氧的供给,部分地抑制了ＥＦＥ酶活性,延缓了乙烯的形成和释放,从而延长了后熟过程．