Fine Structure of Fruit Development in Tomato

Abstract

Fine structurar chanses o."o.rrrtufJLl"l."".n"matous outer pericarp of romaro fruit (a repreientative higli-nroisture, edible plrnt tissue) were followcd throughout the fruit's normal gro:wth cycle on thc plant. Illustrated in electron micrographs, these changes involve the structura-l components-.ot the protooiasnr]both membranousind non-membranous. Normal intercellular space eni"rn"-"r.t and cell wall separadon are also shorvn. The observations are discuised in relation ro some of the biochemical and physiological changes knor'vn ro occur in the devcloping fruir. The results indicate thi porential value of electron microscopy in'ext-ending presenr knowledge of cerrain. problem areas in fruit and vegetible research, s'oih "t the process=es involved in the onset of senescence, the* mechanism of' physiologicai disorders, and the fundamental nature of quality changes affecting the tissue's edible propcrties.

Plastid gene expression during fruit ripening in tomato

“…Ultrastructural and physiological alterations, the drastic degradation of thylakoid membranes, and the decrease of the chlorophyll content occur during chloroplast/chromoplast differentiation in tomato (21,22,28,33,39). These events are consistent with the molecular data presented here.…”

“…This chloroplast/chromoplast transition is one example of tissue-specific differentiation of plastids found throughout plant development (56). The ultrastructural changes observed during chloroplast/chromoplast conversion in tomato fruit include the disappearance of the thylakoid membrane system and the degradation of chlorophyll (21,22,39,51). Since the lightharvesting chlorophyll a/b binding proteins are unstable without chlorophyll, it is assumed that the photosynthetic apparatus breaks down during conversion (2,3,20).…”

Changes in Transcriptional Profiles Are Associated with Early Fruit Tissue Specialization in Tomato

“…Since most of the studies to date have focused on the entire fruit or on the carpel wall, how the different fruit tissues contribute to fruit growth and affect fruit quality remains poorly understood. There are nevertheless some indications of early tissue specialization in the fruit, since structural and biochemical changes such as cell size (Mohr and Stein, 1969;Gillaspy et al, 1993), endoreduplication level (Joubès et al, 1999), photosynthesis (Laval-Martin et al, 1977;Meier et al, 1995), starch accumulation (Schaffer and Petreikov, 1997), cell wall polysaccharides (Cheng and Huber, 1996), and flavonoid composition (Muir et al, 2001) show great variation among the different fruit tissues. These data suggest coordinated expressions of genes with specific roles in the control of growth and regional differentiation in the various tissues of the developing fruit.…”

“…In addition, our data show that the expansion of locular cells is concomitant with the expression of genes controlling water flow, organic acid synthesis, sugar storage, and photosynthesis and suggest that hormones (auxin and gibberellin) regulate this process. The data presented provide a basis for tissue-specific analyses of gene function in growing tomato fruit.After ovule fertilization, early tomato (Solanum lycopersicum) fruit development is characterized by a period of cell division followed by cell expansion, resulting in the formation of large vacuolated cells (Mohr and Stein, 1969). Cell expansion is the longest phase in fruit development and may contribute to 90% of the increase in fruit weight, depending on the cultivar.…”

“…After ovule fertilization, early tomato (Solanum lycopersicum) fruit development is characterized by a period of cell division followed by cell expansion, resulting in the formation of large vacuolated cells (Mohr and Stein, 1969). Cell expansion is the longest phase in fruit development and may contribute to 90% of the increase in fruit weight, depending on the cultivar.…”