Japanese Journal of Phytopathology
Online ISSN : 1882-0484
Print ISSN : 0031-9473
ISSN-L : 0031-9473
Some Observations on the Relation between the Penetration Hypha and Haustorium of the Barley Powdery Mildew (Erysiphe graminis hordei) and the Host Cell.
IV. On the Relation between Haustorium Development and Calcium in the Host Cell.
Koji HIRATA
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JOURNAL FREE ACCESS

1958 Volume 23 Issue 3 Pages 139-144

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Abstract
1. In order to determine the distribution of calcium in the tissue, detached primary leaves of barley, inserted in water or inorganic salt solutions and inoculated with powdery mildew conidia, were immersed in oxalo-alcohol solution and then fixed with formalin-aceto-alcohol. After the green color of the leaves was removed in the fixative, the entire leaves were observed under microscope and the following facts were noticed.
(1) In very young leaves every epidermal cell contains many small crystals of calcium oxalate, while in mature leaves crystals are scanty in most of the epidermal cells, except those in the apical part of the leaves.
(2) Crystals of calcium oxalate are found mainly in the protoplasm along the side walls of epidermal cells.
(3) Crystals are often observed abundantly on the outer surface of the guard cells and auxiliary cells and in the epidermal cells near the stomatal cells. No crystals are found on the surface of mesophyll cells facing the substomatal chamber. These findings suggest that calcium in the leaf tissue may move from mesophyll cells, passing through epidermal cells, to auxiliary cells and guard cells, from which it exudes out.
(4) Mesophyll cells contain generally few crystals, while in strongly chlorotic or weakened leaves some of the mesophyll cells are filled with crystals.
(5) In the epidermal cells inserted with haustoria, abundant crystals are found around the vesicle of the haustoria and on the inner surface of epidermal cells around the penetration pore made by the haustoria. In the weakened leaves crystals are scarce in these parts.
2. In view of the preceding observations, the following accounts may be stated, concerning the relation between calcium in the host cell and barley susceptibility to the powdery mildew.
(1) Increased susceptibility of leaves inserted in calcium salt solutions, as reported in the previous paper, is probably due to the action of calcium protecting the surface of the host protoplasm in contact with the haustorium. Susceptibility reduction by potassium, soda, ammonium and lithium salts seems to be related to thier action to drive calcium away from the protoplasm around the haustorium, making development and function of the haustorium inadequate.
(2) The fact that very young leaves are highly susceptible on their whole surfaces and they become resistant except the apical part and the auxiliary cells as they grow, may be interpreted by the even and uneven calcium distribution in the epidermis, respectively of the young leaves and older ones.
(3) High susceptibility of auxiliary cells seems to be related to abundant quantity of calcium, translocated from the surrounding epidermal cells.
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© The Phytopathological Society of Japan
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