Volume 88, Issue 2
March 1979, pages 95-174
pp 95-102 March 1979
This paper reports on the epidemiological studies undertaken on the airborne diseases of sorghum at Mysore including the downy mildew. The circadian and seasonal periodicities are presented and the significant reversal of usual role of conidia and oospores normally found in Peronosporaceae is discussed.
pp 103-107 March 1979
The galls ofMaytenus senegalensis ( =Gymnosporia heyneana Lawson) induced byAlocothrips hadrocerus are histologically unique when compared with the other thrips galls. Principal cecidogenetic phenomena are hypertrophy and hyperplasia. The incidence of tannin containing as well as sclerenchymatous cells, and the epidermal proliferation are discussed in relation to gall development.
pp 109-113 March 1979
Extracts fromColletotrichum-infected chilli fruits contain the enzyme endo-PGTE (Polygalacturonatetrans-eliminase) which appears to increase the permeability of chilli and potato cells. This effect is greater in red ripened fruits which are susceptible to rotting than in the green chilli fruits.
pp 115-141 March 1979
In flowering plants, the pollen grain—the male gametophyte—interacts with the diploid sporophytic tissue of the pistil before liberating the male gametes in the vicinity of the female gamete. During this gametophyte-sporophyte interaction the male gametes are effectively screened by the pistil ensuring the entry of only the appropriate pollen tubes into the embryo sac. This review summarises recent investigations on pollen recognition and rejection, explains the current understanding, and projects future lines of study.
pp 143-154 March 1979
A total of 146 species of angiosperms belonging to 35 taxonomically diverse families were screened for the isolation of living mesophyll cells from the leaves. Seventy-three species belonging to 22 families, on mild maceration in mortar with the isolation medium (pH 5·8) containing 0·7 M mannitoJ, 2 mM EDTA, 5 mM MgCl2, 5 mM K2HPO4 and 1 mM NaNO3, followed by fractional centrifugation, yielded intact mesophyll cells as seen under a research microscope. The high frequency of cell release, associated with the high percentage recovery of chlorophyll in cells was a common feature of most of the plant species examined by us. Nearly 87% of the chlorophyll present in the leaf could be recovered from the isolated cells inDolichos lablab. The isolated cells retained active photosynthetic carbon metabolism as evidenced by high rates of ferricyanide reduction as well as carbon assimilation.
pp 155-160 March 1979
Biseriate nature of the leaf epidermis is established in the genusStylosanthes for the first time. Of the two layers derived from the uniseriate protoderm by one periclinal division, the outer one is differentiated into ordinary epidermal cells (very rare), uni- and multi-seriate (shaggy) hairs, para-mesogenous stomata and crystalliferous idioblasts. On the contrary, the inner layer is composed of large and thick-walled cells. This layer is discontinuous beneath the stomata and thus the stomatal pore always opens into the sub-stomatal chamber. The members of the sub-tribe, Stylosanthinae such asStylosanthes andArachis, show the para-mesogenous stomata predominantly whereasZornia possesses aniso-mesoperigenous stomata more commonly. Thus the stomatal evidence supports the transfer of the latter genus to a new sub-tribe, Poiretiinae from its old sub-tribe, Stylosanthinae.
pp 161-174 March 1979
A comparative study on the veinlet endings in 118 taxa ofHibbertia has been made. The vein-endings have been classified into three categories, namely conventional tracheids, tracheoids and sclereids. Typological features of the tracheoids and sclereids are found to be of exceptional interest in the provisional confirmation of a few taxa and also for understanding the taxonomy of this genus.