Morpho-chemical characterization of Huanglongbing in mandarin (Citrus reticulata) and orange (Citrus sinensis) varieties from Pakistan

Abstract

Huanglongbing (HLB) is one of the world's worst diseases of citrus trees. The research was conducted to characterize positive citrus samples of two local varieties, 'Kinnow' mandarin (Citrus reticulata Blanco) and 'Mosambi' orange (C. sinensis (L.) Osbeck), based on morphological, physical and biochemical characters. Physical and biochemical parameters of greening infected and healthy samples of both the cultivars were significantly different. Citrus fruits were lopsided and half to full green in the HLB infected trees compared to healthy. The HLB infected leaves samples were small and narrow. Fruit diameter, leaf area, and juice weight of HLB infected samples were significantly less than healthy samples. The rind thickness of infected fruits (70% and 80%) was significantly higher than healthy ones (20% and 30%). Starch content of leaves from mandarin (5.54 μg mL -1 ) and orange (6.12 μg mL -1 ) were significantly higher in HLB infected plants, while juice percentage of HLB infected fruit samples was lesser in mandarin and orange (22.73%, and 14.70%, respectively) than healthy fruits (38.22% and 31.30%, respectively). Acidity was significantly increased in juice of HLB infected mandarin and orange fruits (0.57%, and 0.53%, respectively). Similarly, there was significant reduction in biochemical parameters; total sugars in mandarin and orange (5.16% and 4.79%), total soluble solids (8.54% and 8.28%), total chlorophyll (13.50 and 14.92 mg mL -1 ) and ascorbic acid (34.28% and 34.12%) in HLB infected samples of both cultivars. This study determined differences of physical and biochemical parameters of two local citrus varieties, commonly cultivated in the Asian region.

A Critical Review on Physiological Changes during Growth Maturation and Ripening of Citrus Fruits

“…Khan et al [26] reported a rapid increase in weight of Orange fruit, from 180 days onwards till 220 days after fruit set; followed by a slow increase up to 250 days. Slightly decreasing trend was observed in Orange at fully mature stage, which might be attributed to higher rate of respiration [27]. In Clementine maximum fruit weight was reported at fully mature stage 95.13g which started to reduce as fruit ripen [28].…”

“…Most citrus fruits showed constant rise in TSS content till semi ripe condition due to synthesis of sucrose which then are hydrolyzed to simple sugar [42]. TSS increased slowly in Oranges and Clementine as 12.1 °Brix and 10.8 °Brix at fully mature stage after 240 days after fruit set [27,28]. Nearly 75% to 85% of TSS in orange juice is sugars.…”

OrangeExpDB: an integrative gene expression database for Citrus spp.

“…Our database includes five species of Citrus: C. sinensis , C. limon , C. maxima , C. reticulata , and P. trifoliata . C. maxima , C. sinensis , C. limon , and C. reticulata are severely affected by HLB [ 32 – 35 ], whereas P. trifoliata is often used as a rootstock and shows tolerance to HLB [ 8 ]. Therefore, we chose the five representative citrus species to construct the database.…”

Decoding Huanglongbing: Understanding the Origins, Impacts, and Remedies for Citrus Greening

“…The total output, the total value added, and labor income all decreased, resulting in a loss of $3.9 billion. Symptom-based diagnosis is not practical and the popularity of the PCR technique has grown because of its ability to quickly and sensitively detect even trace amounts of pathogen DNA in both infected plant samples and insect vectors (Sajid et al, 2022). PCR utilizes a fluorescent reporter that binds to the amplified product and emits fluorescence to indicate its presence.…”