Understanding the micro RNA control of lignification and its impact on organoleptic traits in guava cultivars
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Date
2023
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Punjab Agricultural University
Abstract
Guava, the climacteric "super fruit" when over-ripens develop a rough taste suggesting lignification as observed in loquat, pear, mangosteen, citrus and others. We analysed white (Allahabad Safeda, Hisar Safeda), pink (Punjab Pink, Arka Kiran and Lalit) and purple (Purple Local) fleshed guava genotypes for their biochemical characteristics of lignification and antioxidant potential at development (Immature vs ready to eat), ripening, over ripening and refrigerated conditions. The lignin content was found higher in immature fruits which varied from 2.54 % FW in Punjab Pink to 1.70% FW in Purple local concomitant with high G-POX activity and H2O2 concentration. At harvest maturity lignin content gets reduced along with a reduction in the G-POX activity, making this the most preferable stage from consumer aspect. As the ripening proceeds, lignin content again begins to rise along with high G-POX and PPO activity which altogether might be responsible for development of unpleasant flavor and rough taste. We found refrigeration of fruits tends to retard lignification process than storage under ambient conditions. High anthocyanin content of PL could be a possible reason leading to high CATLASE activity and increased H2O2 content. miRNAs negatively control the expression of target genes. We identified 1183 conserved miRNAs from in-house developed guava genome of cv. Allahabad Safeda. qRT-PCR expression analysis in guava cultivars reveal that laccases LAC4, LAC5, LAC17, CSE and POX 63 play significant role in the lignification process and were inversely related with their corresponding miRNA397b-5p, miRNA397b-3p, miR419 and miR11418. Higher expression of L-APX and few MYBs with downregulation of corresponding miRNAs miR828, miR858, miR159 in PL at various stages of post-harvest might be contributing to anthocyanin development in PL.
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Prabhleen Kaur (2023). Understanding the micro RNA control of lignification and its impact on organoleptic traits in guava cultivars (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.