FGSC #8412

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Reporting Genes: per-1 al-3; csp-2

Species: crassa

Allele: AR174, RP100; UCLA101

Alternate Strain Number: 9389

Depositor: DDP

Linkage Group: VR, R; VIIL

Mating Type: A

Species Number: 10

Opposite Mating Type: 8413

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
al-3	VR. Between his-1 and inl (1%) (1119, PB). Carotenoids deficient (398). Reported to lack geranylgeranyl pyrophosphate synthetase activity and is blocked in soluble fraction, consistent with lesion between isopentenyl pyrophosphate and geranylgeranyl pyrophosphate (445), but can still produce farnesyl pyrophosphate (445) and steroids (398). (See Fig. 9.) This evidence contradicts in vivo labeling results that indicate a lesion between prephytoene pyrophosphate and phytoene (572). Strains carrying allele Y234M470 (al-3ros), formerly called rosy (49), become partially pigmented but are readily distinguished from the wild type. ylo-1 can be scored in combination with al-3ros (Y234M470) (PB). Strains carrying other alleles (e.g., RP100) (1119) are white with a trace of pink pigment. Biosynthetic pathway for carotenoids. It is thought that the same prenyl transferase catalyzes all the steps from dimethylallyl pyrophosphate to geranylgeranyl pyrophosphate (444; R.W. Harding, personal communication), and it has been proposed that a separate prenyl transferase converts dimethylallyl pyrophosphate to farnesyl pyrophosphate for sterol synthesis (445). The conversion of phytoene to the various carotenoid pigments involves a series of dehydrogenations, cyclizations, and other reactions. There must also be a cis/trans isomerization analogous to that found in tomato (842). The sequence of some of these steps is still uncertain; the pathway must branch, and there may be alternate routes to some of the products. See references 228, 443, 444, 842 and citations therein for proposed sequences. al-1 is probably blocked in phytoene dehydrogenase (398). It is not known whether this enzyme catalyzes the whole series of dehydrogenations. al-2 is reported blocked between geranylgeranyl pyrophosphate and phytoene (445) and between prephytoene pyrophosphate and phytoene (572). al-3 is alternately reported blocked between isopentenyl pyrophosphate and geranylgeranyl pyrophosphate (445) and between prephytoene pyrophosphate and phytoene (572), but it is not blocked in the production of farnesyl pyrophosphate or sterols (398, 445). ylo-1 is evidently blocked in a late step, probably either in the conversion of lycopene to 3,4-dehydrolycopene or in the conversion of either torulene or gamma-carotene to neurosporaxanthin (see citations in reference 398).	VR	B
csp-2	VIIL. Linked to thi-3 (<1%), probably to the right. Left of T(T54M40) (972, PB). Conidia fail to separate and become airborne. Cultures on agar readily scored by the tap test. Resembles csp-1. Conidia are freed in water suspension long after induction of aerial growth and at only 1/100 the concentration of the wild type. A csp-1;csp-2double mutant releases no detectable free conidia under the same conditions (972). Most csp-2alleles complement csp-1 in forced heterokaryons to form the wild-type number of free conidia (972), but csp-2(UCLA102) does not (969). Conidiating colonies of the csp-2;sn cr-1 strain on replica plates can be overlayered without the conidia being spread (744); photograph (747).	VIIL	B
per-1	VR. Right of asp (26%) and at (8 to 14%). Left of ilv(4%) (489, PB) and ts(25%) (527). Perithecial walls are devoid of black pigment when the female parent carries per-1, regardless of genotype of the fertilizing parent (489, 490, 527). Alleles are of two types (490). Type I produces young, completely white perithecia that become pale yellowish after several days, and per-1 ascospores are white (e.g., alleles PBJ1, ABT8, and AR174). Type II produces mature perithecia that are somewhat darker orange with black pigment in the neck, and per-1ascospores are normal black (e.g., alleles 29278, 29-281, and UG1837). Unlike the perithecial wall trait, the ascospore trait shows no maternal effect. Black pigment develops in a ring around the ostiole of type II perithecia, but is pale or lacking in type I perithecia (490). Mosaic perithecia from heterokaryons have been used for a clonal analysis of perithecial development (527, 528). Expression is completely autonomous in ascospores (photographs in reference 529) and at least partially so in the perithecial walls (527-529). Used to test for variegated-type position effect, with negative results (532). White per-1ascospores (type I) germinate without heat shock and are usually killed by hypochlorite or by the 30-min, 60°C treatment used to activate normal ascospores (490, 527). Beaks of perithecia homozygous for allele PBJL (type I) are abnormal, and ascospores are not shot properly (N.B. Raju, personal communication). Type I alleles initially called sw: snow white (527).	VR	B