Ascochyta Blight Caused by Mycosphaerella Pinodes (Berk
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Joanna Marcinkowska, Lech Boros, Anna Wawer Re sponse of pea cultivars and lines to seed in fec tion by Ascochyta blight fungi Ed ward Arseniuk PLANT BREEDING AND SEED SCIENCE Volume 59 2009 DOI:10.2478/v10129-009-0006-6 Joanna Marcinkowska1, Lech Boros2, Anna Wawer2 1 Depart ment of Plant Pa thology of Warsaw Univer sity of Life Sciences , Warsaw, 02-870 Nowoursynowska 159, Poland, 2 Depart ment of Seed Sci ence and Tech nology of Plant Breeding and Acclimatisation In stitute, Radzików, 05-870 B³onie, Poland RESPONSE OF PEA (PISUM SATIVUM L.) CULTIVARS AND LINES TO SEED INFECTION BY ASCOCHYTA BLIGHT FUNGI ABSTRACT Seeds collect ed from 10 cultivars and lines of Pisum sativum of both 'afila' and normal foliage type, in oc u- lated in field by Mycosphaerella pinodes and Phoma pinodella, were eval u ated for inci dence of fungi respon - si ble for Ascochyta blight. Also seed ger mina tion and contam ina tion by other fungi were consid ere d. Sur face ster il ized seeds were plated on Coon agar me dium. A sam ple con tains 50 seeds. Data were taken af ter 8 days of incu ba tion. Fre quency of species occur renc e depended not only on charac ter s of cultivars and lines, weather con ditions dur ing 1998-2001, but on inoc u la tion treatm ent. Clear re sponse betwee n cultivars and lines to tested fac tors was noted. Seeds of norm al leaved line 344/87/3 and cv. Rubin were the most inhab ited by all fungi, and germ inated very poorly. Seeds of eight cultivars and lines, includ ing cvs: Kwestor, Agra, Miko, were less infecte d and better germ inated. Alm ost 40% of non-germ inated seeds were inhab ited by vari - ous fungi, but cultivars and lines differ ences were not clear. Seed infec tion by ascochyta blight fungi was rather low, reaching from 2.26 – 11.34 percent, a mean 4.81, but alway s the high est for M. pinodes. Per cent age of contam inated seeds by other fungi, mainly saprobic, was al ways higher, even 5 times, with an av erage 16.73%. The best for seed ger mina tion was growing sea son of 2000, while for seed infes ta tion, non-ger mi- nated and germ inated, 2001. Key words: Ascochyta blight, oc cur rence, Pisum, seeds re ac tion, in ten sity INTRODUCTION Ascochyta blight caused by Mycosphaerella pinodes (Berk. et Blox.) Vesterg. (syn. Didymella pinodes (Berk. et Blox.) Petrak) anamorph Ascochyta pinodes L. K. Jones, Ascochyta pisi Libert and Phoma pinodella (L.K.Jones) Mor gan-Jones et Burch, is a seri ous disease of Pisum sativum L., es pe cially in wet seasons, of many coun tries over the world, like Can ada (Wallen 1974, Xue et al. 1997), Austra lia (Bretag et al. 1995), France (Roger et al. 1999), Po land (Marcinkowska 2002). The plants may be in- fected dur ing all devel op ment stages (Law yer 1984, Marcinkowska 1996 b, Xue and Warkentin 2001). When seeds were infected reduc tion in pea emergence, and in con sequence grain yield losses oc curred (Bretag et al. Communicated by Ed ward Arseniuk 76 Joanna Marcinkowska, Lech Boros, Anna Wawer 1995, Xue et al. 1997). Differ ent trials were per formed for finding sources of resis tance to the fungi respon sible for Ascochyta blight of pea (Ali et al. 1978, Clulow et al. 1991, Knappe and Hoppe 1995, Boros and Wawer 2007), but no body found sources of high resis tance to the pathogens. In such situ a tion response of newly released pea lines and cultivars to Ascochyta blight fungi have been tested in some coun tries (Kraft et al. 1998, Xue and Warkentin 2001, Zhang et al. 2006). Also in Po land recently bred pea cultivars and lines were tested against fungi respon sible for Ascochyta blight. The stud ies were done on plants in fields (Boros and Marcinkowska, 2008 in print) and on seeds since level of their infec tion can in di cate on ge no type sus cep ti bil ity (Marcinkowska 1996a). The in ves ti ga - tion of oc currence fre quency of fun gal spe cies causing Ascochyta blight, es pe cially A. pinodes and P. pinodella, on seeds of new Pol ish cultivars and lines was the main goal of the pre sented work. Ability of seed germ i na tion and their con tam i na tion when non-germ i nated and ger mi nated was also re- ported. MATERIALS AND METHODS In the vege ta tion seasons of 1998-2001 pea plants of four cultivars: Agra, Kwestor, Miko, Rubin, and 6 lines: 1528/96, 344/87/3, 1166/96, RAH 796, RAH 997, RAH 897, both foliage type, growing on plots in fields of Plant Breed ing and Ac cli ma ti za tion In sti tute (PBAI) at Radzików (Cen tral-East Poland) were in oc u lated prior to flow ering stage with conidial sus pen sion (2 ×106 spores in 1ml of water) of A. pinodes, P. pinodella and mixture of both spe cies (Boros and Marcinkowska 2008). Plots of these three treat- ments and water, as control, were repli cated four times. Af ter harvest a sam - ple of 50 seeds was collected from each plot for evalu a tion. Totally in a year 800 seeds of each geno type were tested from Janu ary to March. Seeds were surface ster il ized as follows: 30 sec. washing in water with de tergent, 60 sec. rinsing un der tap water, 15 sec. keep ing in 96% ethyl al - cohol, and 15 sec. in 15% H2O2, 5sec. rinsing in dis tilled steril ized water. Steril ized seeds were placed into 4 Petri plates (Pp) of 10 cm di am e ter, 2 Pp with 12 and 2 with 13 seeds on Coon’s (CN) agar medium (Ali et al.1978). Num ber of non-germ i nated and ger mi nated seeds, healthy and in fected by M. pinodes, A. pisi and P. pinodella, and those transm it ting all other fungi was counted after (8) eight days from the time the plates were exposed for three 3 days un der dis persed natu ral day light and next four (4) days to bulbs with fluo rescent day light for 14 four teen hours a day. Fun gal species iden- ti fi ca tion pro ce dure was as pre vi ously de scribed (Marcinkowska 1997). Num ber non-germ inated and infected by fungi seeds was ex pressed in percent of 50 seeds in a sam ple. For sta tisti cal eval u a tion percents were transform ed ac cording to Bliss. The GLM pro ce dure was used to ana lyze the differ ences among a fac tor (SAS 2004). Response of pea cultivars and lines to seed infec tion by Ascochyta blight fungi 77 RESULTS Differ ences in the abil ity of seed germ i na tion and fun gal oc currence on them were found be tween tested cultivars and lines, treat ments and years of the perform ed stud ies. When cultivars and lines were com pared over years and treatm ents, the high est (23.4) mean percent of non-germ i nated seeds was noted for line 344/87/3 and the next (17.4) for cv. Rubin of the same ho- mog enous group (Table 1). The other eight cultivars and lines belonged to Ta ble 1 Ability of ger mi na tion and fungi oc currence on seeds of tested cultivars and lines (mean from treatm ents and years) Seeds transmitting fungi Non-germinated seeds Genotype Non-germinated Germinated Percent* HG Percent* HG Percent* HG 1528/96 10.5 b 4.7 b, c, d 12.8 b, c Miko 9.2 b 3.8 d, c 15.1 b, c 344/87/3 23.4 a 6.0 a, b, c, 23.5 a 1166/96 10.3 b 7.3 a, b, 16.4 b Agra 11.7 b 4.3 b, c, d 16.1 b RAH 796 8.0 b 2.2 d 12.5 c RAH 997 11.3 b 3.6 a, b 16.6 b Rubin 17.4 a 9.6 a 21.8 a Kwestor 11.0 b 3.7 b, c, d 14.3 b, c RAH 897 10.2 b 4.0 b, c, d 13.1 b, c Mean 12.3 4.9 16.2 per cent of a sam ple; HG – hom og enous group is marked with the same let ter the second group, with the lowest (8.0) percent age for RAH 796 and next (9.2) for Miko. It was de pending on cultivars and lines but percent age of healthy non-germ i nated seeds was always higher than for seeds trans mit - ting fungi. A mean of non-germ inated seed for all cultivars and lines was 12.3%. Fre quency of fungi occur rence on ger minated seeds reached on an aver age 16.2 per cent and 4.9 for non-germ inated. Percent age of non-germ i- nated seeds trans mitting fungi was covered by 4 hom og enous groups from 2.2 for RAH 796 to 9.6 for Rubin. The differ ences between cultivars and lines for percent age of germ i nated seeds on which oc curred fungi were sta- tis ti cally sig nif i cant (3 ho mog e nous groups).