000			04266nam a22004817a 4500
001			G79727
003			MX-TxCIM
005			20240919021019.0
008			121211s ||||f| 0 p|p||0|| |
040			_aMX-TxCIM
072		0	_aF01
072		0	_aH20
090			_aCIS-4085
100	1		_aMercado, D. _uFourth annual progress report: Year 2003. Evaluation of cropping systems on the development of wheat pathogens and research for better resistance to foliar blights. The non-specific foliar wheat pathogens. Phase II
110	0		_aCentro Internacional de Mejoramiento de Maíz y Trigo CIMMYT, Nepal (India)
245	0	0	_aInfluence of wheat developmental stage on the sensitivity to the helminthosporol toxin and its relationships with the disease reaction to B. Sorokiniana
260			_aKathmandu (Nepal) _bCIMMYT : _c2004
300			_ap. 105-115
340			_aPrinted
520			_aBipolaris sorokiniana causes spot blotch on leaves, root and crown rots, node cankers and seedling blight on wheat (21 ). Early symptoms on leaves are characterized by small dark brown lesions 1 to 2 mm long without chlorotic margin. In susceptible genotypes, these lesions extend very fast into oval to elongated blotches, light brown to dark brown in colour, reaching several cm long before coalescing and inducing the dead of the leaf. However, disease expression has been reported to be modulated by abiotic factors such as soil fertility and moisture stresses (15, 16), high temperature(7), as well as by biotic factors such as pathogen virulence (9, 11, 13), leaf age (11, 18) and plant growth stage (4, 5).Progressive breakdown of resistance between GS 69 (anthesis completed) and GS 77 (late milk grain) leads to the increased production of conidia on the increasing amount of senescing tissues of wheat plants and thus of the conidial population of B. sorokiniana under field conditions (4). Nevertheless, no evidence has been published regarding the modulation of resistance to one or more of the B. sorokiniana phytotoxins during plant developmental stages. In culture media B. sorokiniana is producing several sesquiterpenoids toxins, the most important being helminthosporol (HL). It has been shown that this metabolite, together with its dialdehyde analogue, helminthosporal were the substances responsible for inducing the plant disease symptoms (6). More recently, it has been suggested that the precursor prehelminthosporol (PHL) is the main substance responsible for the biological phytotoxicity (3), affecting the activity of enzymes located on the plasma membrane and disrupting cell membranes (1,2). Similarly, HL is supposed to play an important role in pathogenesis by killing or weakening plant cells in advance of the growing hyphae (2). Evidence of strong effects in decreasing cell permeability of 1-mM HL toxin solution were reported by different authors (2, 19). HL has a non-specific membrane disrupting effect (2), but the correlation between HL sensitivity and known B. sorokiniana resistance levels in wheat cultivars has not yet been studied (12). This study was undertaken to test the hypothesis that the plant developmental stages influence the disease expression of wheat genotypes differing in their genetic background regarding maturity and spot blotch resistance when inoculated at similar growth stages with B. sorokiniana, and to evaluate, under controlled environmental conditions the correlation between the disease reaction and the HL sensitivity at various developmental stages.
536			_aResearch and Partnership Program
546			_aEnglish
591			_a0407|AGRIS 0401|AL-Wheat Program
593			_aJuan Carlos Mendieta
594			_aINT1237
595			_aCSC
650	1	0	_aBipolaris sorokiniana
650	1	0	_aDisease control
650	1	0	_aFungal diseases _gAGROVOC _91539
650	1	0	_aHelminthosporium
650	1	0	_aInoculation
650	1	0	_aSeedlings
650	1	0	_aWheat
653	0		_aCIMMYT
653	0		_aUCL
650	1	0	_91952 _aSoil fertility _gAGROVOC
650	1	0	_91134 _aGenotypes _gAGROVOC
700	1		_aDuveiller, E.|Mercado, D.|Maraite, H.
700	1		_aMaraite, H., _ecoaut.
700	1		_aRenard, M.E., _ecoaut.
700	1		_9826 _aDuveiller, E. _gDG's Office _8INT1237
942			_cREP
999			_c7090 _d7090