Research Article: The establishment of the species-delimits and varietal-identities of the cultivated germplasm of Luffa acutangula and Luffa aegyptiaca in Sri Lanka using morphometric, organoleptic and phylogenetic approaches

Date Published: April 9, 2019

Publisher: Public Library of Science

Author(s): S. A. S. M. Kumari, N. D. U. S. Nakandala, P. W. I. Nawanjana, R. M. S. K. Rathnayake, H. M. T. N. Senavirathna, R. W. K. M. Senevirathna, W. M. D. A. Wijesundara, L. T. Ranaweera, M. A. D. K. Mannanayake, C. K. Weebadde, S. D. S. S. Sooriyapathirana, Branislav T. Šiler.

http://doi.org/10.1371/journal.pone.0215176

Abstract

Luffa acutangula and L. aegyptiaca are two vegetable species commonly found in South and South East Asia. L. acutangula is widely grown; however, L. aegyptiaca is considered as an underutilized crop. The species delimits, phylogenetic positions, and the varietal identities of L. acutangula and L. aegyptiaca in Sri Lanka are not known. Thus, in the present study, we aimed to establish the species delimits and varietal identities of L. acutangula and L. aegyptiaca varieties grown in Sri Lanka using morphometric, phylogenetic and organoleptic assessments. We assessed five varieties of L. acutangula and three varieties of L. aegyptiaca. The vegetative and reproductive data were collected for the morphometric analysis and DNA sequence polymorphism of the makers rbcL, trnH-psbA and ITS for the phylogenetic analysis. We also conducted an organoleptic assessment based on taste parameters; aroma, bitterness, color, texture, and overall preference using the dishes prepared according to the most common Sri Lankan recipe for Luffa. The variation of the vegetative and reproductive traits grouped L. acutangula varieties into two distinct clusters. The trnH-psbA polymorphism provided the basis for the species delimits of L. acutangula and L. aegyptiaca. The rbcL and ITS polymorphisms provided the basis for the identities of the varieties of L. aegyptiaca and L. acutangula respectively. In the phylogeny, the L. acutangula varieties of Sri Lanka formed a unique clade and the L. aegyptiaca varieties formed a reciprocal monophyletic group in comparison to worldwide L. aegyptiaca reported. The taste parameters aroma, texture, color, and overall preference were significantly different among the Luffa varieties. The L. aegyptiaca varieties received lower preference in the organoleptic assessment. The present study sets the species delimits, phylogenetic positions and the varietal identities of the cultivated germplasm of Luffa and revealed the distinct morphological and organoleptic properties of each variety.

Partial Text

Luffa spp., (sponge gourd or dishcloth gourd [1]), are belonging to family Cucurbitaceae [2]. The genus Luffa comprises eight species namely L. aegyptiaca, L. acutangula, L. quinquefida, L. operculata, L. saccata, L. graveolens, L. echinata, and L. astorii [3]. Many studies report the details of morphological characterization [4, 5] and phylogenetics of Luffa spp. [6–9]. L. acutangula (L.) Roxb. and L. aegyptiaca Miller are the domesticated species within the genus Luffa [10]. Luffa spp. have an Asian origin and scattered in tropical regions [11, 12]. L. acutangula and L. aegyptiaca are closely related species [13]. However, their intra-specific variations remain obscured. L. acutangula and L. aegyptiaca are suggested to originate in the South East Asian region, yet, the exact place of origin is not known [3].

The combined data of vegetative and reproductive parameters classifies L. acutangula varieties into two distinct clusters at 29.04% of morphological similarity coefficient. The sequence polymorphism of trnH-psbA establishes the species delimits of L. acutangula and L. aegyptiaca where L. acutangula varieties have the GATTTT haplotype whereas L. aegyptiaca has the TGCA haplotype. The sequence polymorphism in rbcL establishes the varietal identification of L. aegyptiaca whereas ITS polymorphism establishes the varietal identities of L. acutangula. The phylogenetic analysis infers that the cultivated germplasm of L. acutangula forms a separate clade within the worldwide germplasm. The L. aegyptiaca varieties form a reciprocal monophyletic group with respect to other L. aegyptiaca germplasms found elsewhere in the world. L. aegyptiaca varieties studied in the present study could be identified as distinct genetic forms. The organoleptic assessment reveals that the aroma, texture, color, and overall preference are significantly different among the Luffa varieties assessed. Moreover, L. aegyptiaca varieties receive lower preference scores. The organoleptic parameters also differentiate two species where L. aegyptiaca varieties get tightly clustered. Therefore, the present study sets the species delimits, and the varietal identities based on the phylogenetic analysis and also shows the distinct morphological and organoleptic properties.

 

Source:

http://doi.org/10.1371/journal.pone.0215176

 

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