Evaluation of Loofah Lines for Resistance to Tomato Leaf Curl New Delhi Virus and Downy Mildew, as well as Key Horticultural Traits

Narinder P. S. Dhillon,Somchit Pruangwitayakun,Robert L. Jarret,Monpapa Natheung,Mohammed Abu Taher Masud,Suyuporn Lertlam

doi:10.3390/agriculture10070298

Abstract

Two loofah (Luffa) species, the ridge gourd (Luffa acutangula (L.) Roxb.) and the sponge gourd (L. cylindrica (L.) M. Roem.; syn. L. aegyptiaca), are cultivated widely in Asia by smallholder famers. Both species have significant economic and nutritional importance. However, Tomato leaf curl New Delhi virus (ToLCNDV) and downy mildew (DM) caused by Pseudoperonospora cubensis are important biotic constraints to loofah production throughout Asia. Loofah landrace-derived breeding lines, developed at the World Vegetable Center (WorldVeg), were evaluated at the WorldVeg East and Southeast Asia Research and Training Station, Kasetsart University, Kamphaeng Saen, Thailand—where natural epidemics of ToLCNDV and DM regularly occur. The lines were also evaluated for other commercially important horticultural traits such as days to 50% staminate and pistillate flowering, fruit color, fruit bitterness, and market segment classification. Thirteen and 59 lines of ridge gourd and sponge gourd, respectively, were determined to be resistant to both ToLCNDV and DM. These lines covered all market segments of loofah and exhibited variability for all of the evaluated horticultural traits. The results of these evaluations and their implications on loofah breeding are discussed.

Highlights

Ridge gourd (L. acutangula (L.) Roxb.) and sponge gourd (Luffa cylindrica (L.) M
The current study has identified sources of downy mildew (DM) resistance in the short and medium fruit length market segments of ridge gourd, and in the short, medium, and long fruit length market segments of sponge gourd
Ridge gourd and sponge gourd fruit contribute to human nutrition, and their production and sale provides a livelihood for resource-poor farmers in Asia

Summary

Introduction

Ridge gourd (L. acutangula (L.) Roxb.) and sponge gourd (Luffa cylindrica (L.) M. L. aegyptiaca Mill.) are the principal cultivated species in the genus Luffa [1]. Seven additional wild species of Luffa include L. graveolens Roxb. Longistyla), L. echinata Roxb., L. tuberosa Roxb., L. umbellata Roem, L. quinquefda (Hook and Arn), L. astorii Svans, and L. saccata. In Asia, the two cultivated species (hereafter referred to as loofah) are a commercially and nutritionally significant cucurbitaceous market vegetable. Immature loofah fruit have a significant role in Asian cuisines and are eaten boiled, peeled, and fried, and in curries and soups. Loofah fruits contribute calcium (20 mg/100 g Fresh Weight (FW), magnesium (14 mg/100 g FW), potassium (139 mg/100 g FW), and vitamin A (410 IU) to the human diet [2]. A 200 g serving of loofah fruit provides between 5% and 16%

Methods

Discussion

Conclusion