Enhancing productivity and industrial sustainability of snack seeded pumpkin through interspecific hybridization
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Date
2022
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Punjab Agricultural University, Ludhiana
Abstract
seeded pumpkin through interspecific hybridization’ was planned to combine hull-less seed, bush
growth habit and virus resistance in a single Cucurbita genotype. Interspecific hybridizations
among ten C. pepo (hull-less) and two C. moschata (hulled) rendered HLP-36 (C. pepo) and PVR1343
(C. moschata) as the best cross compatible genotypes. Molecular characterization of the
virus symptoms revealed the predominance of two begomovirus species viz., Squash Leaf Curl
China Virus and Tomato Leaf Curl New Delhi Virus. The intraspecific F2 populations of C.
moschata displayed monogenic dominant and digenic recessive inheritance for bush growth habit
and begomovirus resistance, respectively, whereas for hull-less seed monogenic recessive
expression was observed in C. pepo. However, these best fit ratios were not found with the
interspecific F2 populations due to genomic instability among C. pepo and C. moschata. Multiple
crosses involving HLP-36, HLP-639 and PVR-1343 led to development of three genotypes having
all the targeted traits. To map hull-less character, a 2.06 Mb genomic region on chromosome 12 of
C. pepo was used for developing 21 KASP assays. Genotyping of F2 population derived from
HP111 × HLP36 cross with eight polymorphic KASP assays lead to limit the hull-less seed locus
(Cphl-1) to 40.3cM partial genetic linkage map. The most closely linked marker viz., Cp_3430407
(10 cM) accurately predicted 93.33% hull-less genotypes in the diversity panel. The functional
analysis of candidate genomic region decoded 182 genes, out of which 19 shared homology with
A. thaliana genes related to cell wall, cellulose or lignin biosynthesis. Two of these genes viz.,
‘NAC’ and ‘MYB’ act as master regulators of lignin biosynthesis and were differentially
expressed in hulled and hull-less seeds at different time intervals. The transcriptional differences
between hull-less and hulled seeds at 15 and 20 days after pollinations displayed 3124
differentially expressed genes. Out of these 482 (15.43%) were related to cell wall biosynthesis,
which indicated the seed coat initiation between 15 to 20 DAP. Further, functional
characterization of the gene(s) involved in the lignin/seed coat development will improve the
understanding of hull development in pumpkin. The newly developed hull-less lines with bush
growth habit and begomovirus resistance will revolutionize the hull-less seed industry, while the
KASP markers will be highly useful in marker assisted selections from the segregating
populations.
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Citation
Garcha, Karmvir Singh (2022). Enhancing productivity and industrial sustainability of snack seeded pumpkin through interspecific hybridization (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.