Histopathology of Seed-Borne Infections - Applied Research Center ...

60 Histopathology of Seed-Borne Infections3.4.4 FABACEAE (LEGUMINOSAE) SUBFAMILY FABOIDEAE(PAPILIONATAE) (FIGURE 3.7A TO G)(Vaughan, 1970; Lersten, 1981; Wolf, Baker, and Bernard, 1981; Yaklich, Vigil, andWergin, 1984, 1986; Jha and Pandey, 1989; Baker and Mebrahtu, 1990; Kulik andYaklich, 1991)External: Seeds turgid, usually bean shaped (reniform, ovoid [Cicer] or nearlyspherical [Pisum]), oblong, (rhomboid [Trigonella] or straight cylindrical [Arachis]),smooth or wrinkled; glossy or dull; monochrome (brown, black, green, red, cream,white, or their shades) or dichrome due to mottling or areas of two distinct colors;hilum conspicuous, nearly central or terminal, white or dull cream colored, withoutor with a colored margin, oval or elongate with a longitudinal split; micropyleinconspicuous to conspicuous, closed or open; arillate (rim-aril a collar-like outgrowtharound the hilum, well to poorly developed) or nonarillate; lens (a raisedarea between the hilum and chalaza, area where water penetrates in the otherwiseimpermeable testa) distinct or inconspicuous, color as of testa or variable; raphedistinct or indistinct, discolored or with a different color (Lablab).Spermoderm patterns in SEM, smooth, reticulate, striate, tuberculate, rugose,and faveolate; seed coat with or without pores; covered with bloom or other depositsderived from endocarp of pod (Newell and Hymowitz, 1978; Wolf, Baker, andBernard, 1981; Yaklich, Vigil, and Wergin, 1986).Internal: Seed coat exotestal, seed epidermis — thick-walled palisade — likeprismatic cells (Malpighian cells) with linea lucida, in transections outer and innerfacets hexagonal, lumen linear and often substellate; weakly lignified or unlignified;hypodermis one-layered; rarely two-layered in hilar region (Cajanus), thick-walled,unlignified; hourglass cells with prominent air-spaces; remaining mesophyll includinginner epidermis unspecialized, cells thin-walled, greatly compressed, a few outerlayers distinct. In Cicer, the palisade layer is without thickening in kabuli seeds, butit is thick-walled and possesses pigmented contents in seeds of desi cultivars (Singhet al., 1984).The chalaza is simple. The hilum is well differentiated, differentiation takingplace in the young developing seed (Baker and Mebrahtu, 1990). The hilar layer isin continuation with the macrosclereid of the seed coat, radially elongated forminghilar palisade layer, funicle cells, opposite the hilar macrosclereids develop into anadditional macrosclereid layer referred to as counter palisade layer (confined to hilarregion only), palisade and counter palisade layers interrupted along the mid lineforming suture or groove leading to the tracheid bar (hilar median groove), tracheidbar below hilar groove, cells elongate or isodiametric, lignified, thickenings reticulate;funicular remnants cover hilum-epihilum; rim aril present or absent; subhilartissue of stellate parenchyma.Seed vascular supply variable, usually extends into the antiraphe, postchalazalsupply unbranched or branched; two recurrent bundles provided to the hilar region.Embryo: Cotyledons two, thick, radicle exposed and embryonic axis inflexed;epicotyl with one or more buds, one or more seminal leaves, reserve food proteinand starch in most pulses; protein and oil in oil seeds (Arachis, Glycine).