1160 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



maize-streak virus. Differing from the 

 type strain in being specialized for at- 

 tacking sugar cane, in which the type 

 (from maize) tends to be localized or 

 finally lost with resultant spontaneous 

 recovery of the temporary host. The 

 cane -streak strain usually spreads readily 

 in the cane plant; leaves become much 

 marked with broken, narrow, pale, longi- 

 tudinal stripes and spots ; stems remain 

 unaffected. One variety of sugar cane, 

 P.O.J. 213, is resistant and, if infected, 

 tends to recover. (McClean, Intern. 

 Soc. Sugar Cane Techn., Bull. 27, 1932; 

 Proc. So. Afr. Sugar Techn. Assoc, 1936, 

 1-11; Storey, Rept. Imp. Bot. Conf., 

 London, 1924, 132-144; Union So. Afr. 

 Dept. Agr., Sci. Bull. 39, 1935; Ann. Appl. 

 Biol., 11, 1930, 691-719. 



lb. Fractilinea maidis var. mitia H. 

 {loc. cit., 58). From Latin mitis, mild. 

 Common name : Mottle strain of maize - 

 streak virus. Differing from the typical 

 strain by the mildness of the disease in- 

 duced in corn (maize), transitory chlo- 

 rotic mottling of newly developed leaves, 

 followed by fading of mottling and pro- 

 duction of apparently normal leaves. 

 Young leaves, while mottled, are less 

 rigid tlian normal and may not remain as 

 nearly erect as healthy leaves. (Storey, 

 Ann. Appl. Biol., 2^, 1937, 87-94.) 



2. Fractilinea oryzae (Holmes) comb, 

 nov. {Marmor oryzae Holmes, loc. cit., 

 64.) From Latin oryza, rice. 



Common name : Rice dwarf -disease 

 virus. 



Hosts: GRAM I NEAE— Oryza saliva 

 L., rice. Experimentally, also Alope- 

 cur^ts fulvxis L.; Avena saliva L., oat; 

 Echinochloa crusgalli Beauv. var. edulis 

 Honda; Panicinn miliaceum L.; Poa 

 pralensis L.; Secale cereale L., rye; 

 Trilicum vulgar e Vill., wheat. 



Insusceptible species : GRAMINEAE 

 — Zea mays L., corn (maize); Hordeum 

 vulgareh., harley; Selaria italica Beauv., 



foxtail millet; Andropogon sorghum Brot. 

 (= Holcus sorghum L.), sorghum. 



Geographical distribution : Japan, Phil- 

 ippine Islands. 



Induced disease: In rice, yellowish 

 green spots along veins of young leaf, fol- 

 lowed by chlorotic spotting and streaking 

 of subsequently formed leaves. Growth 

 stunted, internodes and roots abnormally 

 short, forming a dwarf plant. Vacuolate 

 intracellular bodies, 3 to 10 by 2.5 to 8.5 

 microns in size, close to nuclei of cells in 

 affected tissues. 



Transmission : By leaf hoppers, Nepho- 

 tetlix apicalis var. cincticeps *Uhler, N. 

 bipunctalus Fabr., and Dellocephalus dor- 

 saZts Motsch. (CICADELLIDAE). Vi- 

 rus transmitted through some of the eggs 

 but through none of the sperm of infected 

 individuals of N. apicalis. Transfer 

 from individuals thus infected through 

 the egg to their progeny likewise demon- 

 strated, even to the 7th generation. This 

 is the only confirmed instance of trans- 

 mission of a phytopathogenic virus 

 through the eggs of an insect vector and 

 is considered as evidence that the virus 

 multiplies within the body of its vector as 

 well as in its plant hosts. Incubation 

 period in insect usually 30 to 45 days after 

 first feeding on an infected plant, some- 

 times as short as 10 or as long as 73 days ; 

 nymphs from viruliferous eggs do not be- 

 come infective until 7 to 38 (average 19) 

 days after emergence. Transmission by 

 inoculation of expressed juice has not 

 been demonstrated. No transmission 

 through seeds from diseased rice plants. 

 No soil transmission. 



Literature: Agati et al., Philippine 

 Jour. Agr., 12, 1941, 197-210; Fukushi, 

 Trans. Sapporo Nat. Hist. Soc, 12, 1931, 

 35-41; Proc. Imp. Acad., Tokyo, 9, 1933, 

 457-460; Jour. Fac. Agr. Hokkaido Imp. 

 Univ., 37, 1934, 41-164; Trans. Sapporo 

 Nat. Hist. Soc, 13, 1934, 162-166; Proc. 

 Imp. Acad., Tokyo, 11, 1935, 301-303; 

 13, 1937, 328-331; 15, 1939, 142-145; 

 Jour. Fac Agr. Hokkaido Imp. Univ., 

 45, 1940, 83-154; Katsura, Phytopath., 



