Journal of Spices and Aromatic Crops 8 (2) : 145-151 (1999) \ )

Natural disease escapes as sources of resistance against cardamom mosaic virus causing katte disease of cardamom (Elettaria cardamomum Maton)

M N VENUGOPAL Indian Institute of Spices Research Cardamom Research Centre Appangala, Madikeri - 571 201, Kamataka, India. Abstract Resistant sources to cardamom mosaic virus causing katte disease of cardamom (Elettaria cardamomum) were identified by collecting 134 disease escapes from hot spots of virus infection in South India and screening them in greenhouse, sick plot and hot spots. Testing of promising collections in four hot spots and also against natural infection confirmed the resistant nature of the collections. Key words : cardamom, cardamom, mosaic virus, Elettaria cardamomum, katte, natural disease escapes, resistance. Abbreviations NKE : Natural katte escape Car MY : Cardamom mosaic virus

Introduction and mosaic type mottling on leaf sheaths and young pseudostems. In the ad­ Cultivation of cardamom (Elettaria vanced stage of infection, the affected Cardamomum Maton) in India and plants produce shorter and slender Guatemala is threatened due to the tillers with few shorter panicles and severe incidence of katte disease caused degenerate gradually. by Car MY which is an aphid transmit­ ted poty virus. In monocropping situa­ So far no reliable source of resistance is tions, the infection on bearing plants known against Car MY. Cardamom reduces the yield up to 69% in the third occurs in its native state only in the year of infection and total decline of tropical evergreen forests of western plants occurs after 3-5 years of infection ghats in India. Iq nature it forms a (Venugopal 1995). The symptoms of the freely interbreeding population with disease include characteristic mosaic rich genetic diversity (Abraham & symptoms with stripes of green tissue Tulasidas 1958; Sudharshanetal. 1989). evenly distributed over the leaf lamina Open pollinated seedling progenies in 146 Venugopal the hot spots offer tremendous scope to clone was assessed for possible mild isolate mosaic tolerant/resistant sources symptoms of virus infection. Three which can be of immense help to sustain clones of each accession were inoculated productivity iIi virus prone plantations. with viruliferous aphids (Pentalonia This paper reports the successful at­ nigronervosa f. caladii Van der Goot) tempts to identifY resistant sources carring local severe isolate of mosaic from the disease escapes collected from virus. In each microplot two leaves of different hot spots of Car MV in western actively growing tillers were rolled to ghats of South India. make leaf funnels and viruliferous Materials and methods aphids were released @ 5 per tiller (Varma & Capoor 1958). The inoculants Collections of disease escapes were were assessed for symptoms up to 45-50 made from hot spots of Car MV in days and the screening was repeated cultivators' ·fields and also from wild twice at an interval of 50 days. The sources during 1986-88. The criteria collections which did not take up infec­ fixed for identifYing the potential dis­ tion after three rounds of greenhouse ease escapes were (i) more than 98% screening were shifted to clonal reposi­ incidence in infected plantation (ii) tory of disease escapes which also minimun 8 years of exposure to virus served as clonal multiplication block. access (iii) vigour of plants (iv) disease All the promising test entries were history (v) planter's opinion on the clonally multiplied and exposed for field identified plants (vi) presence of vectors screening in the sick plot located in the in the infected plantation. Clonal collec­ Experimental Farm of Cardamom Re­ tions were made from the disease search Centre, Appangala. In the sick escapes in quadruplicate from severely plot, infector rows were maintained in infected plantations of Uttara Kannada, every 3rd row so that one side of the Chickmagalur and Hassan districts of tester rows get an access to virus source. Karnataka; Wynad, Malappuram and All the guard rows were also inoculated Idukki districts of Kerahi, and Nilgiris, artificially to create virus inoculum Coimbatore and Madurai districts of pressure from all the sides. The experi­ Tamil N adu. Many forest· areas like ment was maintained under normal Agumbe forests in Karnataka, package of practices under protective Edamalakudi andPlamalakudi in Kerala irrigation. Cultural practices like and Manjolai and Tambraparni valley trashing and plant protection methods in Tamil N adu were surveyed to identify like application of insecticides and disease escapes existing in the wild fungicides were avoided for 6 years to state. provide ideal conditions for vector mul­ tiplication and migration. The clones collected from each disease escape were initially established in Mter 3 years of continuous exposure, microplots in greenhouse for internal the promising entries were simultane­ quarantine. A combination of ously sub cloned, multiplied and tested neamaticides and fungicides were given in four locations namely, Appangala to the clones as pre planting treatment (Madikeri Taluk, Kodagu), Pallakere to avoid nematodes, rhizome borne (Virajpet Taluk, Kodagu), Madenadu insects and. rhizome rot fungal patho­ (Madikeri Taluk, Kodagu)· and Salkeri gens. After satisfactory growth, each (Sirsi Taluk, Uttara Kannada) repre- Resistance to mosaic virus in cardamom 147

senting high, moderate and low rainfall to low incidence of mosaic disease. conditions in hot spots with known Mosaic infection was not recorded in history of higher disease spread. In all Manjolai hills and Tambraparni valley. the locations, the local susceptible The incidence of mosaic disease was cultivar was used as check. The test also less in plantations owned by tribals entries were monitored periodically for in Edamalakudi and Plamalakudi. Two virus infection. collections were made from forests con­ tiguous with Plamalakudi. The collec­ In another trial with disease escapes, tions comprised of 4 Mysore types, 29 the natural infection of mosaic virus in Vazhukka types and 105 Malabar types different years was monitored for 7 and the approximate age of disease years from the initiation of the experi­ escapes ranged from 8-34 years ment. (Table 1). The highly infected continu­ The promising clones were back - in­ ous belt of small holdings in arecanut­ dexed on the susceptible seedlings based spice gardens of Uttara Kannada through aphid vector P. nigroneruosa to was a potential area for disease escapes. assess their virus-free status. Many vigilant and devoted growers in Results and discussion Uttar a Kannada, Kodagu and Chickmagalur districts maintained the Collection and establishment of disease identity of disease escapes for 2-3 escapes decades. All the 134 clonal collections were established successfully and were One hundred and thirty four collections found free from vir.us symptoms. were made from different cardamom growing tracts (Table i). Because of Screening in, greenhouse better awareness and disease manage­ In the three individual screenings in ment practices among planters, only 18 greenhouse conditions, 67 collections collections could be made from Idukki took infection and all. showed clear District. In Wynad and Valparai also; severe mosaic symptoms (Table 2). Test only seven collections could be made due

Table 1. Collection of mosaic disease escapes of cardamom State District No. of disease escapes in different age ,groups (years) in original location 8-10 10-15 15-20 20-30 >30 Total Karnataka Uttara Kannada 11 6 23 12 4 56 Chikmagalur 5 2 14 21 Hassan 13 3 3 8 3 30 Kerala Idukki 7 8 3 18 Wynad 3 2 5 Tamil Nadu Coimbatore 2 2 Madurai 2 2 Total 39 23 45 20 07 134 148 Venugopal " Table 2. Reaction of mosaic disease escapes of cardamom in greenhouse and field screening Stage of screening No. of uninfected collections in different age groups (years) 8-10 10-15 15-20 20-30 >30 Total Initial stage 39 23 45 20 7 134 of screening I round of 14 19 31 18 5 87 greenhouse screening II round of 12 15 29 15 4 75 greenhouse screening III round of 11 12 26 13 5 67 greenhouse screening 2 years of field 5 6 14 5 4 34 screening 4 years of 3 3 9 5 4 24 field screening 6 years of 3 3 8 5 4 23 field screening entries of Mysore and Vazhukka types sure to virus access for 2-6 years (Table showed distinct marble mosaic symp­ 3). Out of 19 entries, 17 appeared toms and Malabar types expressed promising having better agronomical typical mosaic symptoms. characters. Screening in sick plot In a separate trial wherein tester lines were randomized in groups of 4 x 3 rows In the sick plot, the screening was in 1.8 m x 1.8 m spacing with known carried out for 6 years. Most of the susceptible check, all the promising 17 tester lines took infection within 2 years entries continued to show resistance of exposure to natural infection. Only 23 against natural infection (Table 4) which tester lines remained totally free from occurs at random through incoming virus symptoms. Four tester lines migratory aphids from adjacent infected namely, NKE-ll, NKE-16, NKE-22 and plantations. All the known susceptible NKE-71 expressed faint granular symp­ toms in actively growing months (Sep­ test entries took infection during 7 years period. tember-October) which disappeared in emerging leaves. Biological indexing Back-indexing through aphid vector with such sus­ In the biological indexing involving the pected symptomatic leaves did not re­ 17 field grown mosaic resistant clones veal the association of the virus. through aphid vector to known suscep­ Screening in hot spots tible line (Cl 37), none of the inoculants expressed mosaic symptoms in spite of In four simultaneous screening trials repeated inoculations, thus revealing located in diverse conditions, 19 tester the virus free status of the clon!,s. lines were promising in spite of expo- r ! Resistance -to mosaic virus in cardamom 149

Table 3. Field reaction of mosaic disease escapes of cardamom in sick plots Ace. No. Reaction of disease escapes to natural infection Appangala PaIIakere Madenadu Salkani (6 years) (4 years) (3 years) (2 years) NKE-3 R R R R NKE-4 R R R NKE-5 R R R R NKE-8 R R R NKE-9 R R R R NKE-ll R R R R NKE-12 R R R R NKE-16 R R NKE-19 R R R R NKE-22 R R NKE-26 R R R R NKE-27 R R R NKE-28 R R R R NKE-29 R NKE-30 R R NKE-31 R R NKE-32 R R R NKE-34 R R R NKE-38 R S (25%) - NKE-43 R R NKE-48 S (12%) S (25%) S (17%) NKE-56 R R R NKE-71 R R NKE-72 R R NKE-78 R R Control S (93%) S (100%) S (53%) S (58%) R = Resistant; S = Susceptible; - = Not tested

However, this has to be confirmed In a majority of plantations, cardamom through more sensitive biochemical and is mainly cultivated through seedlings immunological techniques. and since the crop is cross pollinated, each seedling is a recombinant and 150 Venugopal

Table 4. F'ield reaction 'of katt~_ resistant present study 'clearly confirms the re­ cardamom selections -.against, natural infec­ sist~nce of l7 Promising accessions are tion of mp~~.,ic disease of typical Malabar type which produce Ace. No. No. of plants prostrat~ panicles with golden yellow capsules at fnll maturity. Since the Planted Infected prefe;'ence in export market is for green NKE-3 36 0 cardamom, futher studies are required to study their characters for direct use NKE-4 36 0 as resistant varieties or hybrids to NKE-5 36 0 combine resistance and desired yield NKE-8 36 0 and :'1uality. NKE-9 36 0 Resistance to virus is controlled by sevefal factors like vector deterrence, 0 NKE-ll 36 interference to vector feeding, delay in NKE-12 36 0 symptom expression and inhibition of NKE-19 36 0 virus mnltiplication (Fraser 1990). At present nothing is known about the NKE-26 36 0 mechanism of resistance in the identi­ NKE-27 36 0 fied :virus resistant lines. Further, oc­ NKE-28 36 0 cUIT'lnce of distinct natural strains of card'amom mosaic virus has been 're­ NKE-31 36 0 ported from different virus jnfected NKE-32 36 0 zones (Rao & Naidu 1973; Naidu et al. 1989; Venugopal & Naidu 1985). Some NKE-34 36 0 zingiberaceous plants like' Alpinia NKE-71 36 0 mutica which was found, resistant NKE-72 ;! 36 0 against Kodagu, Wynad, Hassan and Chickmagalur isolates showed higher NKE-78 36 0 susceptibility to N elliampathy isolate. CCS-1 36 2 Bimilar studies are also required to studs the performance ofvirusresist<>nt MB-3 36 2 , ~ I , , ' . _ " clones against other distinct virulent RR-l .\; \ :' 36 1 1i1!r'aihs of virus from potential carda­ M-1 .;~ 36 1 moI1'. growing are~s. MA 36 4 References Bulk (Malabar) 141 ;:t 28 Abraham P & Tulsidas G 1958Sillith :'-t Indian cardamom and tl>.eiragri­ cultural value. !CAR Tech. Bull. forms:>a :,source to ideaW'y, desirable "i':;' ; 79 : 1-27.: plantspossessirig resistance against the virus.Thegenepoolexistingintheform 'Fnlse~ R S8'1990 The genetics of " "of, million$I\Qfis,~'l.\\lingsci,n"t)l,~ ,planters" ,resistance to plant viruses. Ann. ,fields p<>rticulaIlly,:in:s~lIer~!Y, inf')<;ted: : 'Rev'.' PhYtop~th. 28 : 179-200. pla1ita~io!):s,.Qff~rstl'em~ndolls9PPm-tU- ,. , Naidu ~, ';en~g~p~l '~'·N&.~ajail P ""nity, tq;jdllnJiry "esi.stant' :soJlrce,~·.,',l'he 1985. Investigations on Strainal Resistance to mosaic virus in cardamom 151 Variation, Epidemiology and its transmission by the banana Charaterization of 'Katte' Virus aphid Pentalonia nigronervosa Agent of Small Cardamom. Final Coq. Indian J. Agric. Sci. 28 : 97- Report of Research Project. Cen­ 108. tral Plantation Crops Research Institute, Kasaragod. Venugopal M N 1995 Viral diseases of cardamom (Elettaria cardamom Rao D G & Naidu R 1973 Studies on Maton) and their management. " 'katte' disease of small carda­ J. Spices Aromatic Crops 4 : mom. J. Plantn. Crops 1 (SuppI) 32-39. : 129-136. Venugopal M N & Naidu R. 1985 Sudharshan M R, Madhusoodanan K J Studies on strains of 'katte' & J agadeesan P 1989 Evaluation virus in small cardamom. In : of germplasm in cardamom. J. National Seminar on Advances Plantn. Crops 16 : 331-334. in Rapid Diagnosis of Viral Varma P M & Capoor S P 1958 Mosaic Diseases (Abst.), March 1985, disease of small cardamom and Tirupati.