Reação de acessos de Cenchrus a Pyricularia grisea no semiárido brasileiro

O fungo Pyricularia grisea causa manchas foliares em capim buffel (Cenchrus ciliaris), sendo um problema em pastagens dessa forragem no Texas, EUA e México. Apesar desta doença não apresentar problemas graves ao capim buffel no Semiárido brasileiro, a busca de germoplasma com algum nível de tolerância a esta doença tem importância preventiva. O objetivo neste estudo foi avaliar a reação de acessos de Cenchrus spp. a P. grisea, em infecção natural. Foram avaliados 20 acessos pertencentes ao Banco Ativo de Germoplasma (BAG) de Cenchrus da Embrapa Semiárido, em blocos casualizados com três repetições e parcela contento 20 plantas. As avaliações foram realizadas em dois ciclos de avaliação em 2019 e 2020, no período chuvoso, quando as condições ambientais para o desenvolvimento da doença eram favoráveis. Para a avaliação da severidade da doença foi utilizada uma escala de notas variando de 1 a 4 e percentual da área foliar lesionada. Os dados médios das notas por parcelas foram submetidos a análise de variância e as médias comparadas pelo teste de Scott e Knott, à 5% de significância. Houve efeito significativo para a tolerância à doença. Dez acessos receberam nota média acima de 3 (CPATSA 83476; CPATSA 79151; CPATSA 79150; CPATSA 79591; CPATSA 90194; CPATSA 79144; CPATSA 79558; CPATSA 79134; CPATSA 90570; CPATSA 79613), nas duas avaliações, indicando uma moderada resistência em relação a testemunha suscetível, a cultivar Biloela. Existe variabilidade a ser explorada para reação a P. grisea no BAG de Cenchrus da Embrapa Semiárido.

Identifikasi Penyebab Penyakit Blas Padi Pada Kombinasi Pola Tanam System of Rice Intensification (SRI) dan Jajar Legowo

Blas merupakan penyakit penting tanaman padi yang dapat menginfeksi bagian daun dan leher malai. Pengenalan penyebab penyakit penting dilakukan untuk menentukan pengendalian yang tepat. Penelitian ini akan mengidentifikasi penyebab penyakit blas padi pada kombinasi pola tanam SRI dan Jajar legowo. Penelitian dilaksanakan pada bulan Agustus sampai September 2020 di BBPOPT Jatisari, Karawang. Pengamatan lapang dilakukan pada pada 6 petak sawah dengan pola tanam berbeda, meliputi P1: SRI + jarwo 2:1, P2: SRI + jarwo 3:1, P3: SRI + jarwo 4:1, P4: SRI + jarwo 5:1, P5: SRI tanpa kombinasi jarwo, dan P6: Sistem tanam tegal (kontrol). Setiap petak kemudian dibagi menjadi 5 sub petak sebagai ulangan (1 titik di setiap sudut petak dan 1 titik di tengah-tengah petak). Setiap petakan kemudian diamati gejala, kejadian, dan keparahan penyakit. Padi yang menunjukkan gejala blas kemudian di bawa ke Laboratorium Fitopatologi BBPOPT untuk diidentifikasi secara morfologi. Hasil penelitian menunjukkan bahwa gejala blas padi yang ditemukan berupa bercak coklat belah ketupat dengan tepi runcing. Pada bagian tengah bercak berwarna abu-abu dan warna coklat dan sedikit orange di bagian tepi bercak. Adapun persentasi kejadian dan keparahan penyakit berturut-turut sebesar 43.33-46.50% dan 26-28% dengan kategori serangan sedang. Identifikasi secara morfologi menunjukkan bahwa penyebab penyakit blas padi pada kombinasi pola tanam SRI dan jajar legowo adalah Pyricularia grisea yang dicirikan dengan konidia berbentuk oval, agak runcing dibagian ujung, memiliki 2 sampai 3 sekat, dan ujung pangkal konidia tumpul.

Screening of Effective Media for the Growth of Pyricularia grisea under In-vitro Condition

Pearl millet [Pennisetum glaucoma (L.) R. Br.], belongs to family Poaceae (section Paniceae), is the world’s hardiest warm-season cereal crop with the annual rainfall of 150 mm to 1000 mm.Maximum mycelial growth was recorded in potato dextrose carrot agar medium (86.33 mm) followed by Pearl millet Potato dextrose agar (83.67 mm), potato dextrose agar (78.33 mm), Pearl millet carrot dextrose agar (71.67 mm), Pearl millet potato agar (68.33 mm), Carrot dextrose agar (60.67 mm), Pearl millet grain potato dextrose agar (58.33 mm), Oat meal agar (51.67 mm), Pearl millet dextrose agar (51.67 mm), Calcium carbonate agar (42.67 mm), Malt agar (41.00 mm), Water agar (37.33 mm), Pearl millet grain dextrose agar (35.33 mm), Pearl millet agar (30.00) and Yeast extract agar (28.33 mm) while minimum growth was recorded in Pearl millet grain agar (27.33 mm).

Investigation on Cultural Characterization and Parasexual Recombination in Pyricularia Grisea, Causal Agent of Blast of Rice

Blast of rice caused by Pyricularia grisea is one of the most devastating diseases of rice. Because of importance of the disease and the fact that pyricularia grisea is considered to be notorious and model species. The variability in cultural characteristics of fifty isolates of P. grisea were taken from different regions of Jharkhand state. Out of fifty isolates of P. grisea, colony color of six isolates were found to be as greyish white color, three isolates were blackish grey, six isolates as white color, three isolates as whitish grey color, five isolates were whitish black and twenty seven isolates were recorded as blackish white in color. The growth pattern of 47 isolates of P. grisea showed circular growth pattern and three isolates have irregular growth pattern but elevation of the mycelium differs from flat to raised. Out of fifty isolates of P. grisea, sector formation was observed in seventeen isolates and no sector formation was observed in rest isolates. The radial growth of fifty isolates of P. grisea were ranged from 76.0 mm to 90.0 mm. Out of fifty isolates, group I included six isolates, group II and III included eleven and thirty three isolates, respectively. Parasexual recombination rarely causes genetic and phenotypic variation through hyphal anastomosis in India. Parasexual recombination is the principle cause in rice blast fungus and cause infection of resistant rice variety (IR-64) in India .

Efikasi Beberapa Agens Hayati Terhadap Penekanan Pertumbuhan Pyricularia grisea Secara In Vitro

<p>The demand for rice as an important food crop in Indonesia is still constrained by the attack of blast disease caused by <em>Pyricularia grisea</em>. Controlling using synthetic chemical pesticides has a negative impact on the environment so that the use of biological agents is an alternative option. This study aims to determine the effectiveness of several biological agents against the pathogen <em>P. grisea</em> that causes blast disease in rice plants in vitro. The study used a completely randomized design (CRD) with 6 levels of treatment and was repeated 3 times using the dooble culture method. The results of the study showed that the inhibition of <em>P. grisea</em> was the highest in the treatment of <em>P. grisea</em> × <em>Trichoderma</em> sp. and <em>P. grisea</em> × <em>Gliocladium</em> sp. namely 67.04% and 51.85% compared to other treatments. The <em>P. polymyxa</em> and <em>P. fluorescence</em> treatments showed low inhibition, namely 23.70% and 28.89%. Biological agents <em>Trichoderma</em> sp. and <em>Gliocladium</em> sp. able to inhibit the growth of the fungus <em>P. grisea</em>. Each biological agent has a different percentage of inhibition in that caused by the inhibitory mechanism of the biological agent.</p>

KERAGAMAN DAN SUMBER GEN KETAHANAN VARIETAS PADI LOKAL TERHADAP PATOGEN Pyricularia grisea PENYEBAB PENYAKIT BLAS

[DIVERSITY AND THE SOURCE OF RESISTANCE GENE OF LOCAL RICE VARIETIES ON THE PATHOGENIC OF Pyricularia grisea CAUSE OF BLAST DISEASE]. Local rice varieties are known to have resistance or source of genes to pests even though their productivity yield is low. The pathogen of Pyricularia grisea is a cause of blast disease, which is one of the obstacles in rice production. The research aims to characterize the resistance of local rice varieties to the pathogen of P. grisea and to evaluate the virulence level of P. grisea pathogens against local rice varieties. A total of 100 local rice varieties and check varieties are susceptible and resistant namely Kencana Bali and Situ Patenggang tested their resistance to 4 dominant pathogenic of P. grisea i.e. races 033, 073, 133 and 173. Inoculation was carried out on stages 4-5 leaves or 18-21 days after seedling in a green house. The results showed a high genetic diversity of local rice varieties against pathogenic races 033, 073, 133 and 173. Based on the response of local rice varieties resistance i.e. moderately resistant (MR), resistant (R) and susceptible (S) to pathogenic races 033, 073 , 133 and 173 obtained 45 resistance response patterns. Cere Bereum varieties which are local rice varieties from West Java and Situ Patenggang resistant check varieties have a resistant response to 4 P. grisea pathogenic races used. A number of local rice varieties also show a resistant and moderately resistant response to the four pathogenic races used include Siam 11, Pare Siriendah, Menyan, Cere Manggu and Enud-Rawa Bogo. Local rice varieties Djedah and Padi Hitam (2) are local rice varieties that have a specific response of resistant or moderately resistant to race 173. Race 133 and 173 have higher virulence rates than those of races 033 and 073 on local rice varieties. The results of this study indicate that there is a great potential for the utilization of local rice varieties, as a source of resistance genes for blast disease for the assembly of rice varieties that are resistant to blast disease.

Transcriptome-Based Analysis of Phosphite-Induced Resistance against Pathogens in Rice

Phosphite (PHI) has been used in the management of Phytophthora diseases since the 1970s.We assessed the effect of PHI on controlling the incidence of Xanthomonas oryzae pv.oryzae and Pyricularia grisea. As a result, PHI application significantly inhibited the incidence of the diseases. To clarify the molecular mechanism underlying this, a transcriptome study was employed. In total, 2064 differentially expressed genes (DEGs) were identified between control and PHI treatment. The key DEGs could be classified into phenylpropanoid biosynthesis (ko00940), starch and sucrose metabolism (ko00500), and plant hormone signal transduction (ko04075). The expressions of defense-related genes had a higher expression lever upon PHI treatment. This study provides new insights into the mechanism of protection effect of PHI against pathogens.