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- Author or Editor: Mel Chih-Yu Chu x
Pericarps of 4 tomato mutants and 1 cultivar were compared anatomically. Sticky peel (pe) had very little cuticle on its epidermal surface and was devoid of hypodermal cells. Peach (p) possessed a heavily cutinized and rough surface over the epidermis with a hypodermal layer comparable to that of the standard cv. Campbell 146. Easy peeling (ep) was more heavily cutinized than Campbell 146, but the hypodermal layer was comparable in structure. The easy peeling characteristic appeared to be associated with more intercellular space among and disintegration of the fully mature parenchyma cells below the hypodermis. Oblong fruits (obl) have a strong skin resulting from a thick hypodermal layer. They also possess a heavily cutinized epidermis and relatively compact, small inner parenchyma cells.
A crack resistant tomato strain,‘Oregon State University 251’ (OSU 251) with fleshy calyx, was crossed with non-fleshy calyx lines to produce F2 segregations of 1 fleshy : 2 intermediate : 1 non-fleshy and backcross ratios of 1 : 1. Short sepal length, wide lobe width, and thick calyx are pleiotropic effects of the fleshy calyx gene, fl. Comparative anatomy of calyx and pedicel is described. The fleshy pedicel of ‘OSU 251’ had the widest cortex, vascular bundle and pith areas, but the areas occupied by the vascular bundle and pith when expressed on a percentage basis were smaller than those of the other parental lines and F1’s. Fruits of segregates with fleshy calyx were significantly more crack resistant than those with non-fleshy calyx. Crack resistance in ‘OSU 251’ is thought not to be a pleiotropic effect of fl, but the fleshy calyx morphology is considered to be of value in selection of plants resistant to fruit cracking.
Anatomical changes in ‘York Imperial’ apples were studied sequentially throughout the growing season to discover tissue variances occurring within the fruit at different stages of development. Several abnormalities have occurred during fruit enlargement, some of which may develop into corking disorders, including bitter pit and cork spot. Cellular abnormalities appeared contiguous to large lacunae, senescing vascular bundles or in tissues where cell proliferation was apparent.
Abnormalities adjacent to necrotic vascular bundles in the outer cortical region were apparent early in. the life of the fruit, by 14 days after full bloom. Changes in cellular structure continued 65 days after full bloom from the outer cortex to the epidermis, and extended to the bundles underlying this area. Cell division had ceased, and the cell walls were thick with a distinct demarkation line between the affected and unaffected tissues. Tissues of the basin region were susceptible to the development of corking disorders, while senescent vascular bundles and meristematic tissues were evident within the core line.
Necrosis of vascular bundles extended along the core line in the fruit apex 95 days after full bloom, and tissue proliferation occurred by 115 days. Fruit development 126 days after full bloom revealed large lacunae in the outer cortex and extreme cell proliferation resembling callus tissue in the cavity at the point of fruit-pedicel attachment.
Origin of corking disorders, visible on fruit nearing maturation (112 days after full bloom), could be traced from tissue anomalies in the outer cortex. The spots appeared irregular in outline, yellowish-green in color; while a glossy, scalded appearance surrounded this area. Meristematic activity of the parenchyma cells along the core line was apparent 126 days after full bloom.
The effects of freeze injury occurring at anthesis upon young developing fruit were studied anatomically. Slight injury was characterized by separation of the hypodermis from the outer cortex during the initial stages of fruit growth. Necrotic tissues were adjacent to the main part of the injury. The internal cortical tissues and vascular bundles in the core line were uninjured. The basin or fruit apex was sensitive to freeze injury resulting in stylar abscission, abortive ovules, and large breaks in the cortical tissue. Growth distortions in the outer cortex were evident 21 days after injury, indicating sensitivity to frost and to the initiation of corking.
Wound healing occurred 1 week after full bloom with the development of callus or proliferated tissues which united the wound areas.