Trichoderma species are able to persist on living sapwood and leaves of cacao (Theobroma cacao) in an endophytic relationship. In this research, we evaluated the ability of Trichodema asperellum introduced at the incision site in the bark for side grafting with the concentration of 4 g/10 mL, 4 g/100 mL, and 4 g/1,000 mL (suspended in water) in suppressing vascular streak dieback (VSD) incidence and promoting growth of side grafts in the field. The incidence of VSD in two local clones of cacao, MCC1 and M04, without application of T. asperellum was 71.2% and 70.1% at 21 wk after grafting, respectively. However, when the two clones were treated with a concentration of 4 g/10 mL T. asperellum, the incidence was 20.6% and 21.7%, respectively, compared to 29.1% and 20.9% at 4 g/100 mL and 18.2% and 15.6% at 4 g/1,000 mL. By comparing to the control, the treatment with the same concentrations of T. asperellum listed above, the total number of stomata in MCC1 decreased by 41.9%, 30.2%, and 14.0% and in M04 by 30.5%, 21.9%, and -2.5% (exception), respectively. Otherwise, the total area of stomata opening increased by 91.4%, 99.7%, and 28.6% in MCC1 and by 203.8%, 253.5%, and 35.9% in M04, respectively. Furthermore, the number of buds and branches treated with a mixture concentration on the the two clones increased by 90.7% and 21.7%, respectively. These data showed that the application of T. asperellum to cacao scions while grafting can decrease VSD incidence in side grafts and increase growth of grafts in addition to decreasing total number of stomata, increasing total area of opened stomata, and increasing number of buds and branches.

Endophytic Association of Trichoderma asperellum within Theobroma cacao Suppresses Vascular Streak Dieback Incidence and Promotes Side Graft Growth

Vascular streak dieback (VSD), caused by Ceratobasidium theobromae (P.H.B. Talbot & Keane), has a considerable impact on cacao (Theobroma cacao L.) production in Southeast Asia. Two biocontrol experiments were set up to explore alternatives to ineffective chemical control of VSD. The effects on VSD development of (i) Trichoderma harzianum, superficially applied to leaves of mature cacao plants, and (ii) an inoculation with fungal (Trichoderma asperellum) and bacterial (Bacillus sp., Pseudomonas sp. and Enterobacter spp.) elicitors of systemic resistance in young cacao plants, were tested. After three months, cacao leaves treated with T. harzianum exhibited a significantly (p < .05) lower disease score compared to the untreated control leaves, with no significant differences or interaction effects between three cacao clones tested. Six months after inoculation of cacao seedlings with elicitors, a significant (p < .05) effect on the number of VSD-affected leaves per plant was evidenced on seedlings ...

Biocontrol of vascular streak dieback (Ceratobasidium theobromae) on cacao (Theobroma cacao) through induced systemic resistance and direct antagonism

Penggunaan bibit sebagai bahan tanam maupun batang bawah untuk perbanyakan klonal sering dilakukan. Bahan tanam berupa bibit merupakan bahan tanam unggul yang berasal dari tetua unggul maupun persilangan antar tetua unggul. Penelitian ini bertujuan untuk mengetahui nilai duga komponen genetik melalui desain persilangan North Carolina II pada karakter morfologi tanaman kakao fase bibit. Persilangan dilakukan dengan menggunakan lima genotipe tetua betina, yaitu; KW 516, Sulawesi 3, TSH 858 dan dua genotipe tetua jantan, yaitu; ICCRI 09, Scavina 6. Pengamatan dilakukan pada tanaman umur 16 MST pada karakter morfologi tanaman yaitu tinggi tanaman, diameter batang, jumlah daun, panjang akar, volume akar, bobot basah tajuk, bobot basah akar, bobot kering tajuk, bobot kering akar, dan rasio akar/tajuk. Genotipe Sulawesi 3 merupakan genotipe tetua betina terbaik, sedangkan Scavina 6 merupakan genotipe tetua jantan terbaik. Genotipe persilangan terbaik berdasarkan nilai DGK nya adalah genotipe TSH 858 x Scavina 6, KW 516 x ICCRI 09, dan Sulawesi 3 x ICCRI 09. Genotipe persilangan Sulawesi 3 x ICCRI 09 merupakan genotipe dengan vigor yang baik yang memenuhi kriteria bibit unggul dan siap untuk ditanam di kebun. Karakter morfologi pada tanaman kakao fase bibit dikendalikan oleh gen dominan pada semua karakter kecuali pada karakter volume akar.
Kata kunci: bibit, daya gabung khusus, daya gabung umum, North Carolina II

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Estimation of Genetic Components of Cocoa Populations (Theobroma cacao L.) in Seedling Phase

Characteristics of leaf-stomata indicate having relationship with  the resistance of  cocoa  to  vascular-streak  dieback  (VSD)  caused  by  Ceratobasidum  theobromae. This  research  has  objective  to  identify  the  relationship  between leaf-stomata haracteristicsto VSD resistance in order to develop criteria for selection. Trial was establised in  randomized-complete  block design  with three  blocks as replications  in  Kaliwining Experimental Station of Indonesian Coffee and Cocoa Research Institute (ICCRI) using 15  clones  which  had  different  background  on  VSD  resistance.  Leaf-stomata  of  the tested  clones  were characterized  using variables of number of stomata,  stomata size, width  of  opened-stomata  and  size  of  stomata  mouth  in  three  different  level  of  leaf growth,  namely  flush,  young  and  mature.  VSD  resistance  was  assessed  by  scoring the damage in the scale of 0-6 that  the tested clones were classified into five group sof resistance.  Analysis  of  variance  indicated  a  significant  effect  of  cocoa  clone  to  the number of  stomata  in  all categories  of leaf  sample  but the  other leaf-stomata  haracteristics  were  significantly  affected  by  cocoa  clone  just  at  the  young  and  mature leaf.  Correlation  analysis  performed  a  significant inter-correlation  between  variables of leaf-stomata characteristics in young leaf and the score of VSD resistance. However, number of stomata and width of opened-stomata in the mature leaf were significantly correlated  to  the  score  of  VSD  resistance.  Genetic  variance  analysis  showed  a  high category of broad sense heritability for the number of stomata and width of the  penedstomata  in  young  leaf  that  both  of  the  variables  can  be  developed  as  criteria  for selection on  VSD  resistance.

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Relationship Analysis Between Leaf-Stomata Characteristics with Cocoa Resistance to Vascular-Streak Dieback

Breeding for cocoa resistance to VSD is the main goal in breeding program in Indonesia. Research for selection criteria on cocoa (Theobroma cacaoL.) resistance to vascular-streak dieback (VSD) has being carried out by exploring leaf stomatal characteristics corresponding to VSD damages. This research had objectives to select best crosses by observing the estimated value of heterosis and heterobeltiosis on F1 hybrid populations based on leaf stomata characteristics related to VSD resistance. Trial was established at Kaliwining Experimental Station of Indonesian Coffee and Cocoa Research Institute (ICCRI) in a VSD endemic area. Treatments consisted of 5 F1 hybrid populations generated by biparental crosses of TSH 858(S) x Sulawesi 1 (R), TSH 858 (S) x KEE 2 (R), TSH 858 (S) x Sulawesi 3 (R), Sca 6 (R) x KW 264 (S) and KW 617 (R) x KW 264 (S). Each cross consisted of 100-300 genotypes planted in high planting density of 0.5 m x 0.5 m. The resistance was evaluated by scoring the plant damage in the scale of 0-3 at three years after planting. Stomata characteristics were assessed microscopically based on the variables of density, length, width and diameter of stomata and width of opening stomata. Analysis of correlation indicated that most of stomatal charac-teristicssignificantly correlated to VSD damage but the width of opening stomata performedthe highest coefficient of correlation (r = 0.49) and contributed to VSD damage (0.45). Meanwhile, path analysis indicated higher value of the char-acteristics performed less resistance of the tested hybrids, KW 617 x KW 264 showed lower value of heterosis and heterobeltiosis for the characteristics which of the best crosses for generating VSD-resistant genotype.

/pdf/heterosis-analysis-of-leaf-stomatal-characteristics-on-f-1-48r1k9p7co.pdf

Heterosis Analysis of Leaf Stomatal Characteristics on F 1 Population of Cocoa (Theobroma cacao L.) Related to Vascular-Streak Dieback Resistance

Vascular-streak dieback (VSD, Oncobasidium theobromae) is the most prevalent disease of Theobroma cacao L. in Indonesia. This study aims to analyze resistance mechanism to VSD based on terpene profile, leaf anatomy, chitinase, and peroxidase study. Resistant clones of Sulawesi 1 and Sca 6 and susceptible clones of ICS 60 and TSH 858 were used for terpene profile, leaf anatomy analysis, chitinase, peroxides, polyphenol, lignin, and cellulose analysis. Those clones and KEE 2, KKM 22 and ICS 13 were used for peroxides analysis. For trichome study, the resistant clones of Sulawesi 1, Sca 6, KEE 2, and KKM 22, and susceptible clones of ICS 60 and TSH 858 were used. GCMS analysis showed that chromatogram pattern of resistant and susceptible groups were quite similar, but resistant clones contained 22% more components than the susceptible ones. Resistant clones contained groups of pinene, decane, myrcene, and octadecanoic acid, while those substances on usceptible clones were absent. Trichome was thicker on younger leaf, and its density on the basal was higher than that on the middle and tip leaf parts. Trichome density of resistant clone was not always thicker than that of susceptible ones. On resistant clones, stomatal density was lower and width of stomate pits was narrower, while thickness of epidermis layer and pallisade parenchym were higher. Polyphenol content of resistant clones were higher but lignin and cellulose of both groups were similar. Chitinase activity which has a role in hydrolysis of mycelia cell wall was higher on the resistant clones, but peroxides which has a role in polymeration of lignin biosynthesis was similar between both groups. It is concluded that groups of terpene pinene, decane, myrcene, and octadecanoic acid, thickness of leaf epidermis, density and width of stomata pit, and chitinase activity plays important role in cocoa resistance to VSD. Key words: Theobroma cacaoL., clone, vascular-streak dieback, resistance, leaf anatomy, chitinase, polyphenol

Sutikno Slamet Sastroutomo

Papers

Terpene Profile, Leaf Anatomy, and Enzyme Activity of Resistant and Susceptible Cocoa Clonesto Vascular Streak Dieback Disease