000			03358nam a22004697a 4500
001			G65852
003			MX-TxCIM
005			20190401213004.0
008			121211s ||||f| 0 p|p||0|| |
020			_a968-6923-93-4
040			_aMX-TxCIM
072		0	_aF30
072		0	_aH50
082	0	4	_a633.153 _bEDM
110	2		_aCentro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico DF (Mexico)
100	1		_9835 _aRibaut, J.M. _gIntegrated Breeding Platform _8INT1991 _uDeveloping Drought- and Low N-Tolerant Maize. Proceedings of a Symposium; El Batan, Tex. (Mexico); 25- 29 Mar 1996
245	0	0	_aIdentification and transfer of ASI quantitative trait loci (QTL): _b A strategy to improve drought tolerance in maize lines and populations
260			_aMexico, DF (Mexico) _bCIMMYT : _c1997
340			_aPrinted
520			_aWhen drought stress occurs just before or during flowering in maize, it delays silking and increases the anthesis-silking interval (ASI). Strong evidence associates an increased ASI with reduced grain yields in maize. In the present study, molecular markers were used to identify genomic segments responsible for the expression of ASI in maize, with the aim of using this information in marker-assisted selection (MAS)for reduced ASI. An F2 population of 260 individuals was genotyped at 150 loci. In 1992 and 1994, F3 families were evaluated under several water regimes in the field for ASI, several morphological traits, yield components and physiological drought variables. For ASI, six QTL (LOD scores greater than 2.5) were identified on chromosomes 1, 2, 5, 6, 8 and 10. These QTL account together for approximately 50% of the phenotypic variability which represented a change of 10.5 d for ASI. Transgressive segregation was observed for this trait. The four QTL segments contributed by the short- ASI line were responsible for a 6.8 d reduction in ASI, represented around 7% of the linkage map, and were stable over years and stress levels. Based mainly 071 these results and on the identification of QTL involved in the expression of grain yield, three different MAS projects are now being conducted at CIMMYT. These schemes, one based on backcrossing, another on line development from F3 families, and a third on changes in allelic frequencies in open-pollinated populations are discussed. Preliminary results suggest that MAS based 071 a strategy combining QTL identified under drought for ASI and grain weight should be a powerful tool to improve drought tolerance of tropical maize inbred lines, and perhaps also of open-pollinated populations.
536			_aGeneration Challenge Program
546			_aEnglish
591			_a9802|AGRIS 9702|anterior|R97-98PROCE|FINAL9798
593			_aJose Juan Caballero
594			_aINT1991
595			_aCPC
650	1	0	_aDrought resistance
650	1	0	_91081 _aDrought stress _gAGROVOC
650	1	0	_aFlowering
650	1	0	_aGenetic inheritance
650	1	0	_91211 _aPlant population _gAGROVOC
650	1	0	_aSelection
650	1	0	_aTropical zones
653	0		_aCIMMYT
650	1	0	_91314 _aZea mays _gAGROVOC
700	1		_aEdmeades, G.O., _ecoaut.
700	1		_aEdmeades, G.O.|Banziger, M.|Mickelson, H.R.|Peña-Valdivia, C.B. _eeds.
700	1		_aGonzález de León, D., _ecoaut.
700	1		_aHoisington, D.A., _ecoaut.
700	1		_aJiang, C., _ecoaut.
942			_cPRO
999			_c3742 _d3742