Cytological and Ultrastructural Evaluations of Zinc Deficiency in Leaves

Abstract

<jats:p>Zinc deficiency is a widespread nutritional disorder in plants and occurs in both temperate and tropical climates. In spite of its physiological importance, cytological and ultrastructural changes associated with zinc deficiency are lacking, in part because zinc deficiency is difficult to induce. A method was developed to induce zinc deficiency in pecan (<jats:italic>Carya illinoinensis</jats:italic> (Wangenh.) C. Koch) using hydroponic culture. Zinc deficiency was evaluated in leaves using light and electron microscopy. Zinc deficiency symptoms varied with severity ranging from interveinal mottling, overall chlorosis, necrosis, and marginal curving. Zinc deficient leaves were thinner, and palisade cells were shorter, wider, and had more intercellular spaces than zinc sufficient leaves. Cells in zinc deficient leaves had limited cytoplasmic content and accumulated phenolic compounds in vacuoles. Extensive starch accumulation was observed in chloroplasts. This work represents the first detailed microscopic evaluations of zinc deficiency in leaves, and provides insight on how zinc deficiency affects leaf structure and function.</jats:p>

Zinc deficiency in field‐grown pecan trees: changes in leaf nutrient concentrations and structure

“…Leaflet area and TCSA were significantly reduced in both levels of Zn deficiency (Table 2): leaflet area decreased by 24 and 64% in trees with chlorotic and necrotic leaves, respectively, whereas TCSA decreased by 27 and 57% in the same trees when compared to the Zn‐sufficient controls. Similar effects of Zn deficiency on growth parameters have been reported for pecan,16, 24, 34 and other fruit tree species such as peach ( Prunus persica ),35 apple ( Malus domestica )36 and mandarin ( Citrus reticulata ) 37, 38. Reductions in growth parameters with Zn deficiency have also been reported in annual species such as Phaseolus vulgaris 39 and Triticum aestivum 40…”

“…Some Zn deficiency effects on pecan physiology have been described in a few studies, and these include a decrease in the activity of the enzyme carbonic anhydrase in leaf extracts,13 an inhibition of the development of reproductive structures,14 and a reduction in chlorophyll synthesis and photosynthesis rates 15. Leaves of pecan trees grown in hydroponics under Zn deficiency showed symptoms varying in severity, ranging from interveinal mottling to general chlorosis, necrosis and curving of leaf margins 16. Moreover, microscopy studies showed that Zn‐deficient leaves had shorter palisade cells, more intercellular spaces, reduced thickness, and decreased surface when compared to leaves containing sufficient levels of Zn 16.…”

“…Leaves of pecan trees grown in hydroponics under Zn deficiency showed symptoms varying in severity, ranging from interveinal mottling to general chlorosis, necrosis and curving of leaf margins 16. Moreover, microscopy studies showed that Zn‐deficient leaves had shorter palisade cells, more intercellular spaces, reduced thickness, and decreased surface when compared to leaves containing sufficient levels of Zn 16. However, there is little information available on changes in tree vigour, mineral nutrition, and cytological and structural characteristics occurring in pecan trees affected by Zn deficiency in field conditions.…”

Morphology, photosynthesis, and internal structure alterations in field apple leaves under hidden and acute zinc deficiency

“…Zinc deficiency depresses plant growth especially shoot growth and chlorophyll concentrations (Balakrishnan et al, 2001), leading to chlorosis in leaves along with abnormalities in leaf structure and ultimately affecting chloroplast structure (Kim and Wetzstein, 2003). A decline in the net photosynthetic rate (P n ) induced by Zn deficiency is often observed.…”

Western U.S.: Zinc management for western pecans

“…Deficiency in pecans results in rosetting; interveinal chlorosis; small, chlorotic (and necrotic) leaves (Fig. 1); less cytoplasm; and failure of chloroplast formation (limiting photosynthesis) (Kim and Wetzstein, 2003).…”