000			03154nab a22004217a 4500
001			68149
003			MX-TxCIM
005			20251105091814.0
008			241119s1981 -us|||po p||| 00| 0 eng d
022			_a0011-183X
022			_a1435-0653 (Online)
024	8		_ahttps://doi.org/10.2135/cropsci1981.0011183X002100040031x
040			_aMX-TxCIM
041			_aeng
100	1		_aPhillips, R.L. _937301
245	1	0	_aSeedling screening for lysine-plus-threonine resistant maize
260			_aUnited States of America : _bJohn Wiley & Sons, _c1981.
500			_aPeer review
520			_aOver 200 maize (Zea mays L.) strains were evaluated for seedling growth on lysine-plus-threonine supplemented media in an attempt to find feedback resistant mutants. Five of 92 inbreds, most of which were developed for use in hybrid production, were resistant (i.e., root length on lysine + threonine medium exceeded 50% of control). Resistant inbreds B37 and B76 were from the Iowa Stiff Stalk Synthetic (BSSS) population. Nine of 103 random line isolates from the BSSS population were resistant. From 16 of the 17 original BSSS component lines tested, only Ill. 12-E was resistant. Seven broad base maize populations did not yield resistant types. Resistance was expressed only when seedlings were derived from germinating whole kernels. Seedlings derived from dissected embryos of resistant strains were inhibited. Studies of kernel aspartokinase and homoserine dehydrogenase activities indicated that alterations in the feedback regulation of these enzymes were not the basis of the observed lysine + threonine resistance. The opaque-2 version of B37 was inhibited. This observation and amino acid data led to the tentative hypothesis that resistance is a function of the relative amounts of methionine and lysine (M/L ratio) in the kernel with a high M/L ratio leading to resistance and a low M/L ratio leading to inhibition. All three resistant strains analyzed had a high M/L ratio compared with four inhibited strains. Kernels of one strain, BSSS 53, had approximately 21% more total methionine than the other four inbreds analyzed (two resistant, two inhibited) yet retained the typical dent kernel phenotype. Kernels of the resistant strains also tended to have higher percent protein. Specific approaches are suggested for selecting high methionine or high lysine maize.
546			_aText in English
650		7	_aSeedlings _2AGROVOC _95415
650		7	_aScreening _2AGROVOC _95621
650		7	_aLysine _2AGROVOC _95257
650		7	_aThreonine _2AGROVOC _922526
650		7	_aHybrids _2AGROVOC _91151
650		7	_aMutants _2AGROVOC _94079
650		7	_aEnzymes _2AGROVOC _94657
650		7	_aKernels _2AGROVOC _91168
650		7	_aHomoserine _2AGROVOC _937304
650		7	_aOxidoreductases _2AGROVOC _911420
650		7	_aMethionine _2AGROVOC _925829
650		7	_aZea mays _2AGROVOC _91314
700	1		_aMorris, P.R. _937302
700	1		_aWold, F. _937303
700	1		_aGengenbach, B.G. _9505
773	0		_dUnited States of America : John Wiley & Sons, 1981. _gv. 21, no. 4, p. 601-607 _tCrop Science _wG444244 _x0011-183X
942			_2ddc _cJA _n0
999			_c68149 _d68141