Describing Phenotypic Variability in Seed Shapes of Weedy Rice Types in Comparison to Cultivated and Wild Rice Types Using Elliptic Fourier Analysis

Weedy rice is a serious threat to food security in a global scale. They invade lowland ricefields by having intermediate phenotypes between rice cultivars and its wild type. They grow sympatrically with the cultivars and compete effectively with the crop that often result to excessive yield loss, but un-fortunately this pest is difficult to control due to phenotypic resemblance and close genetic relationships with the rice cultivars. The high variability of weedy rice phenotype in the field is suggestive also that it reflect phenotypic relationships to its wild ancestors. In the current study, we explore the phenotypic affinity of weedy rice in the Philippine archipelago using seed shape. The shape is known to have large genetic bases and so its utility in the study is reliable. Using the Geometric Morphometric (GM) tool specifically elliptic Fourier analysis (EFA) and Multivariate Analysis in statistics, we found that 64% of the weedy rice in the archipelago has phenotypic affinity to 13 wild landraces (AA genome) collected from 15 different locations within West Africa, Carribean Islands, Latin America, India, Australia, South Asia and Southeast Asia. Ten populations have affinity to O. meyeriana (GG genome) in the Philippines and Malaysia. Both weedy populations from Misamis Oriental, Philippines (WRMIS1) and Nueva Ecija, Philippines (WRNE2) have affinity to PsBRc 64 and PSBRc 82, respectively while two populations from Iloilo, Philippines (WRILO1 & WRILO2) have affinity to O. latifolia in Costa Rica. Overall results display a complex pattern of phenotypic affinity, thus suggesting multiple origins of weedy rices in the Philippines. (C) 2011 Friends Science Publishers