Screening, Morphological and Biochemical Basis of Resistance against Leaf Curl Disease in Sunflower Coordinated Entries
K. Venkataramanamma
*
RARS, Regional Agricultural Research Station, ANGRAU, Nandyal, India.
B. V. Ravi Prakash Reddy
RARS, ANGRAU, Nandyal, India.
K. Prabhakar
Agricultural College, Mahanandi, ANGRAU, India.
S. Ramadevi
RARS, ANGRAU, Nandyal, India.
R. Naseeruddin
RARS, ANGRAU, Nandyal, India.
T. Raghavendra
RARS, ANGRAU, Nandyal, India.
*Author to whom correspondence should be addressed.
Abstract
Background: Sunflower leaf curl disease, caused by begomovirus and transmitted by whitefly (Bemisia tabaci), is a major constraint in sunflower production, leading to significant yield and oil losses. Identifying resistant genotypes and understanding associated resistance mechanisms are essential for effective disease management and breeding programs.
Aims: To screen sunflower coordinated entries to find out the resistant source and also to analyze some morphological and biochemical characters associated with resistance in the entries.
Design: RBD.
Place and Duration of the study: RARS, Nandyal, ANGRAU and duration of study is 2 years i.e., rabi, 2022-23 and 2023-24.
Methodology: A total of 23 coordinated entries were screened for leaf curl disease of sunflower under field conditions along with susceptible check i.e., KBSH-44. Disease observations were recorded at 30, 45 and 60 days after sowing to calculate disease incidence and disease progression. AUDPC values were calculated for all entries. Morphological characters leaf thickness and leaf pubescens were measured by following standard procedures. Biochemical parameters such as phenols, proteins and catalase activity were estimated.
Results: Leaf curl disease was caused by Sunflower leaf curl virus and the results of screening experiment revealed that, during rabi, 2022-23, based on disease reaction, 23 coordinated entries were categorized into 11 entries as highly susceptible, 6 as susceptible, 3 as moderately susceptible, 2 as moderately resistant and 1 entry under resistant category. Three entries (RSFH-1887, DRSH-1 and NDSH-2551) which recorded less than 10% incidence (resistant and moderately resistant) along with 3 highly susceptible entries (showing 100% incidence) were further evaluated and confirmed their resistance during rabi, 2023-24. The three selected entries also showed low AUDPC values andrecorded significantly more leaf thickness in highly susceptible entries. Leaf thickness is one of the symptom exhibited by leaf curl virus in infected leaves. Significant differences were observed for leaf pubescens and more was observed in the selected resistant entries compared to highly susceptible entries. Biochemical parameters such as phenols, proteins and catalase activity were estimated. It was observed that, significantly more phenols, more catalases were recorded in resistant entries compared with highly susceptible entries, while no significant difference was observed in protein content among the entries.
Conclusion: Hence, it was concluded that, these three entries can be considered for areas with high leaf curl incidence. Further, evaluation of additional biochemical traits may further help to distinguish resistant and susceptible entries and screening of the parental lines of these entries would also be useful for resistance breeding programmes.
Keywords: Sunflower, leaf curl, AUDPC, leaf pubescens, phenols, catalases