Evaluation and Classification of Leaflet Shape and Size in Wild Soybean

length to width) to indicate leaflet shape. He also defined leaflet shape index at 2.6 to differentiate between Two gene pairs are known to affect leaflet shape in soybean [Glybroad and narrow leaflet shape in Japanese cultivars cine max (L.) Merr.], but only two categories of leaflet shape are routinely used to characterize soybean germplasm. Very little informaand found that broad leaflet is a completely dominant tion has been published about leaflet shape and size for wild soybean trait. Narrow leaflet is associated with an increase in (Glycine soja Sieb. & Zucc.) accessions in the USDA Soybean Germnumber of seeds per pod in G. max (Takahashi, 1934; plasm Collection but these characteristics have been shown to be Domingo, 1945). You et al. (1995) examined 72 lines among the most diverse morphological traits in the Chinese G. soja from China, Japan, and USA for the effects of leaflet collection. The objectives of this research are to evaluate and establish shape on seed yield and its components in cultivated a visual classification system for the variation of leaflet shape and soybean and concluded that there were no significant size in the USDA Soybean Germplasm Collection. In 1998 and 1999, difference between the broad and narrow leaflet lines 661 wild soybean accessions from the USDA Soybean Germplasm in average seed yield or number of pods per plant, but Collection in maturity groups 000 through IX were grown at either significant differences were observed for seed size and Urbana, IL, or Stoneville, MS. Images of fully expanded terminal leaflets were recorded with a digital camera after all accessions were number of seeds per pod. in the reproductive phase. Representative leaflets were selected at There are several ways to analyze leaflet shape and approximately two-thirds of the distance from the ground to the top size data. Frusta et al. (1995) evaluated leaflet shape in of the plant. Images were analyzed by the computer software Image39 cultivated soybeans by principal component analysis Pro Plus (Version 3.0). Six measured or calculated parameters were based on the elliptic Fourier coefficients. Hill (1998) recorded. The FASTCLUS procedure of SAS was used to define used a modified Landmark Eigenshape Analysis (LEA) appropriate categories of leaflet shape and size. Length/width ratio software developed by Dr. J. F. Reid of the Agricultural and length were chosen to define leaflet shape and leaflet size, respecEngineering Department of the University of Illinois to tively. Length/width ratio values ranged from 1.3 to 6.2 and length analyze the images of leaflet shape of Glycine tomentella from 3 to 14 cm. Five categories of leaflet shape are proposed: oval, Hayata accessions. The most recently developed Imageovate, lanceolate, linear, and ultra linear; and three classes for leaflet size: small, intermediate, and large. Leaflet shape and leaflet size are Pro Plus software (Media Cybernetics, Silver Spring, associated with geographical origin. Accessions from South Korea MD) has been widely used in various areas of biology were generally smaller than those from China, Japan, and Russia. (http://www.mediacy.com; verified 28 October 2003). Accessions from China had more leaflet variation than those from Kosina and Wasylikowa (1999) analyzed morphological South Korea or Japan but those from Russia were the most variable. and anatomical features of plants including hazel nut Nearly all of the accessions with lanceolate and linear leaflets origi(Corylus avellana L.) shells, primula (Primula praenitens nated from Russia. Ker Gawl.) and crocus species (Iridaceae) pollen, and Triticum dicoccon Schrank. spikelets with the use of Image-Pro Plus software. The greatest advantage of usL shape is among the most diverse morphologiing a computerized image analysis is that many paramecal traits of wild soybean (Dong et al., 1999). Since ters can be measured or calculated with high accuracy most morphological and pigment traits lack variation in and simultaneously analyzed. wild soybean, this could be an important trait to help Little characterization of leaflet size and shape in characterize G. soja germplasm. Two loci were reported G. soja has been done. Fukui and Sunaga (1978) investito affect leaflet shape in soybean, Ln/ln for ovate leaflet gated morphological variation among 100 accessions of and narrow leaflet (Bernard and Weiss, 1973) and Lo/ G. soja collected from Siberia, northeastern China, lo for ovate and oval leaflet (Domingo, 1945). Oval South Korea, and Japan and found that leaflet shape leaflet is a rare phenotype and G. max germplasm generwas significantly associated with geographical origin. ally is classified either as broad or narrow. Sawada (1988, Zheng and Chen (1980) evaluated 478 accessions of 1992) proposed the leaflet shape index (ratio of leaflet G. soja from Jilin province of China and proposed four categories for leaflet shape (ovate, long ovate, lanceoYiwu Chen, Dep. of Crop Sciences, 1101 W. Peabody Dr., University late and linear) and three classes for leaflet size (small, of Illinois, Urbana, IL 61801; Randall, L. Nelson, USDA-Agricultural intermediate and large) in G. soja. Four types of leaflet Research Service, Soybean/Maize Germplasm, Pathology, and Genetshape also were employed to evaluate G. soja germics Research Unit, Dep. of Crop Sciences, 1101 W. Peabody Dr., plasm in China (Li, 1990, 1994). Only 197 of 1104 G. soja University of Illinois, Urbana, IL 61801. Mention of a trademark, accessions in the USDA Soybean Germplasm Collecproprietary product, or vendor does not constitute a guarantee or warranty of the product by the USDA or the University of Illinois tion have been evaluated for leaflet length and leaflet and does not imply its approval to the exclusion of other products or shape index (Juvik et al., 1989), and no categories of vendors that may also be suitable. Received 17 Mar. 2003. * Correleaflet shape and leaflet size were defined. The objecsponding author ([email protected]). tives of this research are to evaluate and establish a Published in Crop Sci. 44:671–677 (2004).  Crop Science Society of America Abbreviations: MG, Maturity Group; PI, Plant Introduction; LSD, Fisher’s Least Significant Differences. 677 S. Segoe Rd., Madison, WI 53711 USA