摘要
Fruits are important as a nutritional source, but biologically more important are their seed protection and dispersal funcions. Dry fruits can be dehiscent and the process of opening of ripe fruits, or pod shattering, causes the seeds to be dispersed （Ferrandiz, 2002）. This process occurs in many crop species, for instance of members of the Brassicaceae family. Arabidopsis thaliana, the model plant species in the laboratory, belongs to this family and also presents pod shattering （Figure 1）. The Arabidopsis fruit is a silique, and before fertilization it is called a gynoecium or pistil. The gynoecium is formed by two carpels that are fused, and the replum is present at their margins and is connected to the septum that divides the silique inside. In between each valve-replum border, the valve margin or dehiscence zone is formed. When the fruit matures, a separation layer and a lignified cell layer are formed in the dehiscence zone. In addition, a lignified layer is formed in the valves, and when the mature fruit starts to desiccate, tension is created, which in association with the effect of middle lamella degrading enzymes in the separation layer, results in shattering of the fruit （Ferrandiz, 2002）. Research has led to the proposal of a model for the gene regulatory network that explains valve margin formation in Arabidopsis （e.g., Ch＆vez Montes et al., 2015）. Mutations in various members of this gene regulatory network result in indehiscent fruits, i.e., the fruit does not open or shatter. One of these genes is the bHLH transcription factor INDEHISCENT （IND）, which is necessary for the formation of the separation layer and the lignified cell layers （Liljegren et al., 2004）. IND has also been related to auxin, more precisely, to auxin distribution, important for gynoecium and fruit patterning （Sorefan et al., 2009; Girin et al., 2011）.
Fruits are important as a nutritional source, but biologically more important are their seed protection and dispersal funcions. Dry fruits can be dehiscent and the process of opening of ripe fruits, or pod shattering, causes the seeds to be dispersed （Ferrandiz, 2002）. This process occurs in many crop species, for instance of members of the Brassicaceae family. Arabidopsis thaliana, the model plant species in the laboratory, belongs to this family and also presents pod shattering （Figure 1）. The Arabidopsis fruit is a silique, and before fertilization it is called a gynoecium or pistil. The gynoecium is formed by two carpels that are fused, and the replum is present at their margins and is connected to the septum that divides the silique inside. In between each valve-replum border, the valve margin or dehiscence zone is formed. When the fruit matures, a separation layer and a lignified cell layer are formed in the dehiscence zone. In addition, a lignified layer is formed in the valves, and when the mature fruit starts to desiccate, tension is created, which in association with the effect of middle lamella degrading enzymes in the separation layer, results in shattering of the fruit （Ferrandiz, 2002）. Research has led to the proposal of a model for the gene regulatory network that explains valve margin formation in Arabidopsis （e.g., Ch＆vez Montes et al., 2015）. Mutations in various members of this gene regulatory network result in indehiscent fruits, i.e., the fruit does not open or shatter. One of these genes is the bHLH transcription factor INDEHISCENT （IND）, which is necessary for the formation of the separation layer and the lignified cell layers （Liljegren et al., 2004）. IND has also been related to auxin, more precisely, to auxin distribution, important for gynoecium and fruit patterning （Sorefan et al., 2009; Girin et al., 2011）.
