MORPHOLOGICAL, BIOCHEMICAL AND MOLECULAR ANALYSIS OF DIFFERENT APPLE (Malus × domestica Borkh.) CULTIVARS GRAFTED ON CLONAL ROOTSTOCKS UNDER HIGH DENSITY PLANTATIONS
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Date
2024-07-22
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UHF Nauni
Abstract
Apple (Malus × domestica Borkh.) is one of the most popular and widely consumed fruit grown in the temperate
regions of the world which has gained significant importance due to its nutritional and health benefits. Apple cultivation
success depends on fruit quality influenced by traits like size, color, flavor, texture, and nutrition. Apple clonal rootstocks M9,
MM106 and cultivars viz., Gale Gala, Redlum Gala, Jeromine, Auvil Early Fuji, Red Velox, Red Cap Valtod, Scarlet-Spur-II
and Super Chief were introduced in India under World Bank project in the year 2016.These rootstocks were grafted with the
above mentioned commercial cultivars for raising high-density plantations at Nauni, Kandaghat, Mashobra, Bajaura and Sharbo
located at different altitudes. In morphological characterization, Red Velox depicted maximum tree height at HDP Bajaura
(373.1 cm) whereas, it was minimum in Jeromine (213.3 cm) in HDP Sharbo. Red Velox in HDP Bajaura displayed the
maximum annual shoot length (41.51 cm), whereas it was minimum for Redlum Gala (14.84 cm) at HDP Sharbo. Auvil Early
Fuji in HDP Bajaura had the maximum trunk girth (62.56 mm), while it was minimum for Redlum Gala (21.65 mm) at HDP
Sharbo. Red Velox had the maximum fruit length of 73.15 mm at HDP Sharbo, whereas, it was minimum in Gale Gala (43.48
mm) at HDP Bajaura. Jeromine had the maximum fruit diameter (76.75 mm) at HDP Sharbo, whereas it was minimum in Gale
Gala (51.25 mm) at HDP Bajaura. Red Velox had the maximum fruit weight and volume (258.02 g; 272.50 cm3) at HDP
Sharbo, while in Gale Gala it was minimum (69.89 g; 81.50 cm3) at HDP Bajaura. Redlum Gala had the firmest fruit (28.20
lbs2) at Sharbo, while it was minimum in Red Cap Valtod (14.60 lbs2) at HDP Nauni. Fruit shapes varied from globose, obloid,
conic, ovoid, to cylindrical-waisted across locations. The best conic fruit shape was observed for Super Chief at HDPs of Nauni
and Kandaghat. Biochemical analyses revealed diverse profiles among cultivars and locations. Redlum Gala had the maximum
TSS (28.20 ºBrix) at HDP Sharbo, while it was minimum for Red Cap Valtod (14.60 ºBrix) at HDP Nauni. Fruits of Super
Chief at HDP Sharbo displayed the highest total and reducing sugar content (17.0; 10.49 %), whereas it was minimum in Red
Cap Valtod at HDP Nauni (10.50 and 5.07 %). Jeromine fruits at HDP Nauni exhibited the maximum titratable acidity (0.97%),
while Super Chief (0.40%) at HDP Sharbo exhibited minimum. Redlum Gala (58.29 mg/g FW) revealed maximum phenol
content whereas, it was minimum in Jeromine (26.18 mg/g FW) at HDP Nauni. Maximum DPPH (71.30 %) was recorded in
Redlum Gala growing at HDP Sharbo and it was minimum in Jeromine (32.42 %) at HDP Kandaghat. Out of 20 EST-SSR
Primer Hi15a13 associated with TSS and sugar related traits of apple showed polymorphism in Jeromine and Redlum Gala
growing at HDP’s of all locations whereas, 19 other primerswere monomorphic. The highest polymorphism information
content (PIC) value (0.388), Rp value range (76 - 152), EMR (2.00) and MI (0.78) values was observed for Hi15a13.
Transcriptome analysis highlighted differential gene expression (DEGs) between Jeromine and Redlum Gala exhibiting
significant variations, with 2251 DEGs identified, including 673 up-regulated and 1578 down-regulated. Transcription factors
(TFs) such as bHLH, NAC, ERF, MYB related, WRKY, B3, G2-like, and C2H2 were up-regulated, suggesting their
involvement in various metabolic pathways.Among anthocyanin synthesis pathway, 49 DEGs were significantly expressed in
Jeromine and Redlum Gala, out of which 43 DEGs were related to MYB TF’s which is involved in regulating biosynthesis of
anthocyanins. The genes related to energy metabolism, aroma production, and signal transmission in fatty acids biosynthesis
were up-regulated in Redlum Gala compared to Jeromine.Twenty EST-SSRs targeting traits like shape, colour and firmness
were validated. Di-nucleotide repeat motifs were predominant in Jeromine (2160) and Redlum Gala (15698). All the cultivars
were analysed using these EST-SSR primers developed from transcriptome sequencing data out of which only 19 primers were
able to amplify the genomic DNA in all the samples. Primer Md-ACO1 associated with fruit firmness resulted in
polymorphism in Redlum Gala.The PIC value for this primer was 0.229 whereas, Rp value range from 76 – 156, demonstrating
its equal distribution and applicability for evaluating genetic variability of apple in future.