Coutinho, M. P.

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Vitis 4, 341-346 (1964) Institute of Agronomy and Center of Research and Development CUF, Sacavem Some Vine Clones Resistant to Plasmopora*) by M. P. COUTINHOThe problem of resistant clones in general is one of the most important in plant breeding (STAKMAN, 1963). In vine-breeding, the res,istance to Plasmopora viticola is specially interesting (HusFELD, 1944). BRANAS (1953) on this subject wrote: "Ce pro­bleme est un des plus importants, sinon le plus important de tous ceux qui se trou­vent poses devant la viticulture europeenne". In the case of the subject of the present paper it is obvious for us since in the majority of Portuguese vineyards mildew is still the most important cryptogamic disease both from the po1int of view of losses and of treatment (to 20% of the total expenses). The present note concernes work carried out since 1945 and which has been described in detail elsewhere (CouTINHO, 1950). A collection was made covering the main varieties cu!Uvated in Portugal and data where obtained on t heir behaviour relative to Plasmopora attack. None were resistant but di.fferences in susceptibility were observed denoting the existence of factors which in convenient combination may originate a type of resistance (HusFELD, 1938). Material and Methods Methods used were: mass sowing, intraspecific crossing (Vitis vinifera) and selection, Mass sowing was indicated since V. vinifera is considered heterozygous (HusFELD, 1943; DALMAsso, 1939). This was confirmed both in the F, of intraspecific crosses and in the population obta,ined through self pollination in single varieties (COUTINHO, 1953): The F, of these two groups were not uniform, the plants showing four and three classes of resistance, respectively (Fig. 1). Over 200 crosses were made using the varieties less susceptible toward Plasmo­pora, and selection was made of F1 and F2 plants. Recently the following backcros­ses have been made and are still being studied: C. 6 (Jaen x Azal branco) x Jaen c. 19 (Jaen x Azal branco) x Jaen c. 27 (Jaen x Azal brnnco) x Jaen The sowing usually were made in Dutch frames in the soil or in the pots. Seedlings surviving natural infection were subject to two inoculations, and in the following years their behaviour toward natural infection was followed. Results Knowledge of the types of leaf tissue reaction to the fungus is necessary in order to define selection criteria. In some plants the cells delimiting, or near, the stomata react to initial mycelium penetration by forming stomatic or peristomatic necroses which appear one or two days after infection, as small, ,disperse, dark brown to *) Thi£ article is mostly based on a paper presented to the XI International Congress of Genetic, (The Hague, The Netherlands, 1963). 342 M. P. COUTINHO 010 50 ' I ' 45 I ' 40 35 30 25 20 15 10 5 0 II ill N V CLASSES Fig. 1: The heterozygous F 1 of V. vinifera. - - - - selfpol!ination, and -- crossing. blackish patches (BOUBALS, 1959). Nor­mally they do not spread simply be­cause the rapid death of the cells affected by the 1haustoria, blocks their development: a case of hypersensivi­ty. In other less common cases, how­ever, the mycelium may spread be­yond the zone of necrosis, and sporu­late. Similar necrotic symptoms m'.l.y result from dessication of infected tissue in restricted zones due to a limited mycelium development; these necroses normally manifest 'before the 5th or 6th day after infection, may or may not show sporulation accord­ing to environmental conditions (e. g. when atmosferic humidity is very high, exterior fungal formation may be found before tissue necrosis takes place. In contrast to susceptible clones when mycelium spread is normally great, in resistant clones penetration of tissues is limited and shows dif­ferent aspects. In the former case (susceptible clones), a particular as­pect representing only a phasic re­sistance related to leaf age and climatic conditions, is that of the limitation due to the stereoma of veins. This aspect is also found under conditions favourable to Plasmopora development and is a cas,e of intrinsic resistance: 'it corresponds to a Limited mycelial development which, even 'before tissue necrosis, is confined to the most reduced areas, hyphae showing less branching and fewer haustoria (Hus­l'ELD, 1933). This type is considered associated with a deficiency of growth factors for hyphae development, and/or for fungus' enzyme synthesis. P10rn (1957) demonstrated in the cell sap the presence of indolic auxins, greater concentrations lbeing found in susceptible plants whereas resistant clones only showed traces. Applications of /J-IAA lowered resistance. Conidiophores were present under favouralble environmental conditions but were sparce and with few spores. When atmospheric humidity decreases, the tissues of the invaded zone dry up giving rise to relati,vely small patches, polygonal in shape and following the vein net-work; in general there is a wvering of spores of low density which may be absent when tissue dessication precedes conidiophora forma­tion. This aspect is the most common in the varieties we are studying (Fig. 2). In some clones under observation we have noted a curious aspect of resistance: a sort of "ringspot". It may be considered a case of "limited patch", lbut is unusual in that necrotic tissues are not central <but marginal (Fig. 3). As complete immun it is unnecessary, our aim being the so-called economic resistance (which dispenses with treatment), selection included also those clones showing limited mycelial development besides those of the necrotic type. In the maintenance of these types of resistance we whish to remark on just two aspects: Vines clones resistant to Plasmopora 343 Fig. 2: Limited patches in leaf tissues. Fig. 3: Limited patches with marginal dessication. 344 M. P. COUTINHOmodification of ecological characteristics and physiological races. Since the host­parasite interaction is influenced 1by such known factors as age, season and micro­climate, diversity of environmental conditions, indicates that work should be car­ried out under the least favourable conditions possible. However, in the types of intrinsic resistance, this character is not destroyed by changes either in temperature or in host nutrition although these factors affect considerably the extent of develop­ment of the disease in susceptible or fairly resistant plants. An example is found in wme of our clones selected as resistant in Sacav-em (near Lisbon), which have .maintained the character in the Madeira Island during the 9 years they have been grown there. As to the aspect physiological races of the fungus, although we accepted the:r existance as logical (COUTINHO, 1956), from the practical point of view we did not find any variation in resistance induced by different behaviour of the fungus and up to the present none of the selected vines have shown significant lowering of resistance by any physiological race. At present 110 F2 clones resistant to mildew are being tested for production and quality. One of them (C. I.-76), with •goLden yellow and very sweet grapes, seems promising as a "table variety" (Fig. 4, 1). Eighteen clones are already under field trial, and some of them seem to be of interest, namely: C. I. - C. 67, a product of the cross: "Souzao X Azal de correr" and C. I. - C. 6; C.19 and C. 27 the products of the cross "Jaen X Azal branco". The clone C. 19 has black grapes. The enological characteristics are listed in ta­ble 1. The clone showing, up to the present, the best sum of qualities is C. 27, named by us "Sacavem" (Fig. 5). The bunch is fairly compact with little branching, an average length between 16-18 cm., with round, firm, very sweet grapes of a beautiful golden yellow at maturity and a slight covering of pruine. It may be considered quite Fig. 4: Clusters of clones C.I-76(1) and C.27(2). Vines clones resistant to Plasmopora 345 productive since 4-5 year old vines have shown productions of 7-8 kg (Fig. 4, 2). The data of must and vine are summarized in table 1. The berries have a clear pleasant tasting, a sui-generis arome, and a good quality. Fig. 5: The "Sacavem" (C.2'7) in Ribeira Brava, Madeira Island. The clone C. 27 is being studied with great interest in the Madeira Island by the Agricultural Station of Funchal (VIEIRA, 1960). The opinion of the Viticulture Depart­ment (VIEIRA, 1962) is the following: "C. 27, besides its high productivity may be r::onsidered a noble european variety showing affinity towar,ds various root stocks. Il is high in sugar and resistant to mildew; any point of fungal attack on a leaf does :1ot spread, indicating that mycelial development is arrested". From the above it may be concluded that, although still in the experimental stage, the results obtained are of interest in relation to the problem of vine resistance toward mildew. Table! The enological characteristics of two Plasmopara resistant grape varieties RPsistant strain c. 19 c. 27 Must: Density 1,0979 1,1025 Sugar 231 229,5 Probable alcohol (vol. %) 13,6 13,5 Total acidity (0/oo) 7,5 9,2 pH 3,42 3,62 Wine: Alcohol (%) 13,9 13,7 Fixed acidity (0/oo) 6,7 7,4 Volatile acidity (0/oo) 0,5 0,8 Total acidity (0/oo) 7,3 8,4 Density 0,9953 0,9920 346 M. P. COUTINHOLiterature Cited BouBALS, D.: Contribution a l'etude des causes de la resistance des vitacees au mildiou de la vigne et de leur mode de transmission hereditaire. Ann. Amel. Plantes, 1, 5-233 (1959). BRAN AS, J.: Le Mildiou - Rapp. et Actes VII Congr. Int. Vigne Vin. 1, 114 (1953 . CounNHO, M. P.: Melhoramento da videira. Seu aspecto particular da resistencia a PLasmopora ,;itico!a. Ann. Junta Nac. Vin. 2, 13-135 (1950). - - : Notes sur le comportement heterozygotique de la Vitis vinifera. Actes VII Congr. 0. I. V. (1953). ·- - : O comportamento de algumas videiras resistentes a P!asmopora vitico!a, perante a modifica9ao das condi9oes ecol6gicas. Actas XXIII Congr. Luso-Espanhol, 427-433 (1956). DALMAsso, G.: Mutabilita delle diverse varieta di viti. Ann. Staz. Sper. Vit. Eno!. Conegliano. 9, 135-152 (1939). HusFELD, B.: 1.Jber die Ziichtung plasmoporawiderstandsfahiger Reben. Gartenbauwiss. 7, 15-92 (1933). - - : Wichtige Kreuzungsergebnisse bei der Rebe. Ziichter, 10, 291-299 (1938). - - : A situa�ao actual do melhoramento da videira e a sua importancia em viticultura. Agron. 26, 243-261 (1943). - - : Que peut attendre la viticulture europeenne de !'amelioration de la vigne. Bull. o. I. V. 161 (1944). MANZANEQUE, M. R. C.: Revision de! estado actual de la genetica de la vid. Bo!. Inst. Nac. In­vest. Agron. 15, 335-373 (1955). P10TH, L. C.: Untersuchungen Uber anatomische und physiologische Eigenschaften resistenter und anfiilliger Reben in Beziehung zur Entwicklung van P!asmopora vitico!a. z. Pflan­zenz. 37, 127-158 (1957). STAKMAN, E. c.: Le role de la science dans la comprehension et la prevention des maladies des plantes (Cyclost.J u. N. c. s. A. T. (1963). VrErnA, R. S.: Uma nova casta de videira. Sup!. Agric. Bo!. Distrital. Funchal, 33, 129-130 (1960). - - : A casta ,,Sacavem". Sua importancia na viticultura madeirense. Actas das Jornadas vitivinicolas. Lisboa (1962). Eingegangen am 19. 10. 1964 Prof. Dr. M. P. COUTINHO Institute of Agronomy and Center of Research and Development CUF, Sacavem 

Some vine clones resistant to Plasmopora

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Some vine clones resistant to Plasmopora

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